PROSPECTS OF WATER JET MACHININING

IN MARBLE INDUSTRY OF PAKISTAN

Submitted To: Assistant Professor Dr Imran Akhtar

Submitted By: NS Umair Khalid

NS Sufyan Tariq

NS Talal Jameel

NS Zulkeefal Dar

NS Usama Waheed

NS Muhammad Taha

NS Muhammad Saqib Anwar

NS Muhammad Nouman

NS Abdul Samad Nasir

NS Hamza Ahmed

NS Mudassar Hussain

GC Farooq Azam

DE-32 (MECAHANICAL ENGINEERING)

SYNDICATE: B

DATE: DECEMBER 26TH, 2011

Dedicated

to

All those people in our country

who work with unbounded

devotion but remain unsung.

CONTENTS

Introduction and the Classification of Stones

History of the Stones

Introduction to Marbles

History Of Marbles

Geo-economical perspective of the Marble Industry

Pakistan‘s geological potential and untapped marble

reservoirs

Outlook of Water jet machining process

Minutiae of Pressurized Water Jet Cutter

Future trends in Water jet Technology

INTRODUCTION AND CLASSIFICATION OF STONES

Introduction

From the early dawn of human kind stones have played a significant role in the development of

human civilization and surely will continue to play an equally important role in the future. Rock

material which is used in the construction of buildings or structures shaped to men‘s needs is

called stone. Gemstones for bracelets and necklaces are not included. Mankind has been using

the stone since time immemorial.

For many centuries stone has been generating the construction materials and non-compromised

form of art for the human being by its strength, durability, elegance, color and sophisticated

structure. Many civilizations such as Hittites, Ancient Egyptians, Phrygians, Mesopotamians,

Persians, Lydian, Ancient Greeks, Greco Romans, Romans, Seljukians, and Ottomans had used

stone for their statures and in architecture which enlighten their own time and survived until

today.

Stones are classified into three groups based on their origin of formation; metamorphic,

sedimentary, and igneous rocks. However, in industry and commerce, stones are classified into

six groups: marble, limestone, travertine, onyx, granite and sandstone. Currently, these

geological and industrial classifications of stone are becoming more and more insufficient.

Therefore, there is a significant need for a more comprehensive classification of stones as a

building material especially for the use of architects and civil engineers. In this study, natural

stones are being classified in a different manner. For classification purposes, we assess their

geological, chemical and mechanical properties which affect their ease of cutting and

processing, hygiene, aesthetics, structural safety and decay.

Global Stone Production

Raw material Growth rate: 260% (1986-2009) Value: 20 billion for 2009 Finished products Growth rate: 61% (1996-2009) Value: 35 billion for 2009

The world stone production and the volume of global stone market is expected to experience a

five times increase till 2025.

Stone Production chain CLASSIFICATION OF ROCKS

Classification according to their geological origin is one of the most common methods of

classification of rocks. According to their origin, rocks are classified as igneous, sedimentary

and metamorphic. Igneous or magmatic rocks are primarily crystallized from a fiery fluid

silicate melt, taking place either deep below the earth‘s surface or at the surface. Granite and

basalt are the most common members of this group igneous rocks have been classified with

respect to their textures, structures, content of silica and color by a number of scientists. The

most commonly accepted classification and nomenclature are made by Streckeisen. Sedimentary

rocks are formed by the concentration of inorganic or organic debris of variable size and shape,

deposited by mechanical means or by chemical precipitation. These sedimentary rocks have been

classified according to their type of sedimentation, grain shape, cement type, CaCO3, clay and

silica content and layer thickness. In classification of sedimentary rocks, mostly the studies of Folk, Dunham and Pettijohn et al. are being accepted.

In addition to those mentioned, Fookes and Higginbttom have classified sedimentary rocks with

respect to their calcite and dolomite contents .Metamorphic rocks are igneous or sedimentary

rocks recrystallized by the effect of temperature and pressure .Yardley classified that group as

contact, regional, dynamic, hydrothermal and impact metamorphism rocks . Grain size is also

often used for classification of metamorphic rocks.

Another methodology which is often utilized for rock classification is separation rocks with

respect to their physical and mechanical properties. Rocks are classified by their uniaxial,

bending, point load strengths and porosity . They are also being classified as hard or soft

depending on their ability to crack geologist hammer. All known rock classifications can only be

used in engineering geology, geotechnical and mining industries but not in building industry.

BUILDING STONES

The common rock classifications summarized above are not sufficient for classification of stones

used in building industry. Classification is totally different in natural stone industry and trade. In

these sectors, more practical and common nomenclatures are being used. In natural stone

industry and commerce, carbonate rocks that can yield commercially viable blocks, can be

dimensioned and polished, and be used in buildings are all called marble. The term granite is

used for any strong or hard igneous rocks and even for some metamorphic rocks. Commercially,

granite includes basic igneous rocks, which do not contain quartz, such as basalt, dolerite.

Gabbros often called black granite and the metamorphic rock, gneiss.

However, true granite is an igneous rock largely composed of an interlocking mass of crystalline

grains of three minerals; quartz, feldspar, and mica. Travertine is a general term given to

lacustrine and shallow lacustrine younger limestones that is a sedimentary rock.

Travertine is highly porous rock, often banded structure. True travertine is a freshwater

limestone formed on land from hot springs. Onyx is a massif or banded sedimentary rock

contains calcite or aragonite formed by hot and cold water that are rich in mineral. True onyx is

a chalcedony. Slate is used for any rock that exfoliates into thin slabs or roof tiles. True slate are

metamorphic rocks composed originally of fine-grained particles (silt, clay) tightly compressed

together and hardened. In this context, Winkler summarized the major common rock types used

in stone industry. Smith classified the rocks according to their mass structure and hardness

which in fact effect extraction and processing performance. Rocks are very hard and have high

strength. Mohs‘ Scale of Hardness was introduced by Friedrich Mohs German Mineralogi 1773-

1839. Mohs‘ Scale of Relative Hardness Published in 1822.

Stone Classifications

For architects, civil engineers and final users, stones‘ color, aesthetics, hygiene, its ability to be

customized and decay are important. Most of the time, designers, owners and applicators in a

project are under the influence of their past experiences, habits and other reference projects.

This causes errors in production, false applications and other problems as well. In stone

industry, all procurement, timing and quality aspects are equally important. These might yield

problems between producers, traders, architects and final users. One should not ignore

geological parameters and physico-mechanic properties of the stone and only concentrate on

aesthetics. Therefore, there is a need for a new classification where both material characteristics

and industrial and architectural properties of the stone are taken into account.

In Table 1, natural building stones have been classified as marble, limestone, travertine, onyx,

hard stone and decorative stone.

Table 1: Classification of natural building stones

Porosity and SiO2 is important for all building stones. Stones are classified as very compact, compact, porous, high porous and very high porous .When porosity increases, durability of stone

decrease and the effect of thawing freezing, biological and environmental attacks increase as

decay accelerate. Increase of porosity also affects the hygiene and aesthetics of the stone

negatively. On the other hand, polishing quality of porous stones is lower. Filling materials can

be used in stones that are porous like travertine, and sealers can be used in sealer can change

the aspect of the stone and may cause some fabrication and application problems. Therefore,

costs increase with increasing porosity. Stones are classified as treatable, moderate treatable,

hard treatable, very hard treatable and super hard treatable according to their SiO2 content

(Table 1). SiO2 is an important parameter that increases extraction and processing costs of the

stone. There is need for sophisticated machinery for extraction and processing of stones with

SiO2 content other than treatable, moderate treatable stones.

Existence of SiO2 in marble and limestones is a rare event and it jeopardizes quality in some

processes like polishing and chamfering. On the other hand, SiO2 increases the stones durability and improves their strength. According to their MgO content (Table 2) marbles are classified as calcitic, low magnesian and

dolomitic. MgO content is also important in projects. The allurement of MgO ions is greater

than other components. In places that will be exposed to liquids like water, rain, coffee or dust,

stones with lower MgO content should be used. Fluids and dust affects the stone and changes the

color to a darker tone and yields a patchy look. In colder places, dolomitic stones are affected

from frost more easily. However, MgO increases the hardness and strength of the stone.

Table 2: Summary of the marbles used in the building

Size of crystals is important for marbles. In industry and commerce, marble are also called

crystal or crystallized marble. By increasing of crystal size, toughness, attraction and polish

taking decreases and porosity, water absorption, processing costs increases, aging of the stone

accelerates.

Bitumen is important for marble, limestone and travertine. Stone that contain bitumen are of

black, grey-black color. One can smell bitumen during extraction and processing of stone but it doesn‘t smell after installation. Bituminous stones are affected from sun, their black color fade

Marble Limestone Travertine Onyx Hard Stone Decorative Stone

very compact porosity< 0.5%

compact 0.5% <porosity<

1%

porous 1% <porosity< 5%

high porous 5% <porosity< 10%

very high porous 10% <porosity

treatable SiO2< 2%

moderate treatable 2% <SiO2< 5%

hard treatable 5% <SiO2< 25%

very hard treatable 25% <SiO2< 60%

super hard treatable 60% <SiO2

Calcitic Low Magnesian 4% <MgO< 10%

Dolomitic 10% <MgO

very fine crystalline < 150 mm

fine crystalline 150 mm <grain<

800 mm

medium crystalline 800 mm <grain< 2

mm

coarse crystalline 2 mm <grain< 5 mm

very coarse crystalline

5 mm <

gradually. Breccia and conglomerate adds marble, limestone and sandstones extra movement

and attraction. On the other hand, breccia and conglomerate content causes important problems

during processing. They reduce chamfering quality and increases costs. Breccia and

conglomerate stones should be used in custom size rather than cut-to-size in projects. This stones

are also affected more from atmosphere.

Banded texture is related with stone initial deposition. Banded structure is observed most in

travertines and onyxes and least in igneous stones. Colour differences in, between, and out of

bands adds attraction and aesthetics to the stone. Symmetric structures like vein-cut and

openbook are more valuable than cross-cut. Bands in stone add depth and movement to the

project. On the other hand, differences in and between bands reduces stone productivity and

processing quality. Strength of bonds between the bands and pores along the edges along the

bands affect the resistance of onyx and travertine.

Layer formations are observed at the stones other than the igneous ones. Structural and textural

differences between layers affect projects negatively. Marble and similar metamorphic

decorative stones are used by separating them in their natural borders of laminates. Slate is the

most commonly know example of this type of a usage. Lamination decreases productivity

significantly; however brushing yields better results and improves attraction in laminated stones.

If not enough attention is paid, lineation also increases the costs of production. Very few

producer, trader, architect and civil engineer recognize the lineation and pay enough attention

to it. Lined stones, especially lined sandstone add depth to the project work. Stones being cut

parallel and perpendicular to the lineation, if laid together create a wave movement effect.

Limestones are the second most widely used stones after hard stones around the globe (Table

3). Limestones are classified as recrystallized, micritic, fossils and marl. Toughness of

recrystallized limestone is higher and their porosities are lower generally. Characteristic of

micritic limestone are variable and fissures are often observed. Containing fossils are one of the

general characteristics of limestones. On the other hand, some particular limestones contain

more fossils than the others. Size of the fossils and their homogeneity are also important. Larger

size (1 cm) fossils might yield decorative looks but their reserves of fossil accumulations are

generally pretty little. Fossils cause problems in chamfering and polishing.

Table 3: Summary of the limestones used in the building

Travertines are classified as massive and layered in Table 4. Massive travertine is tougher and

their porosities are usually lower than layered travertine. Massive travertines are also more

homogenic. The most important issue with layered travertines is the strength bond between

layers. Sand and clay accumulated between layer boundaries decreases efficiency a lot and

cause surface and polish problems. Sandy travertine which has sand content in the mass should

not be polished and should never be laid on the floor with polished finish. Sand particles

separate from the surface during polishing operation and scratch the surface in place.

Recrytallized Micritic Fossils Marl Pure low magnesian

4% <MgO< 10% dolomitic

10% <MgO Dark Light

Breccias layered banded

bituminous

Plant fossils and shells are observed abundantly in travertines. Plant fossiled travertines are

usually dark coloured, they are not homogeneous and they have higher porosities. Some shells

may contain SiO2. Generally, shells also do cause problems during polishing and chamfering. Shells with homogeneous distribution and uniform size yield a decorative look on the stone.

Travertines with plant fossils and shells have lower deposit reserves.

Table 4: Summary of the travertines used in the building

The most important characteristics of onyxes that differs them from other stones is their

semitransparency.

Some marbles also are semi-transparent. However, transparency of onyx is significantly higher.

Onyxes are classified as calcite, aragonite and alabaster (Table 5). Their hardness is alabaster,

calcite and aragonite, respectively. Alabaster is gypsum and should not be used outdoors.

Banded onyxes add depth to the project where watered onyxes add motion.

Table 5: Summary of the onyxes used in the building

Hard stones are classified as sandstone, igneous stones, gneiss and migmatite in Table 6. Hard

stones are the first stone that is known that have been used by humanity and they are the most

abundant type of stone with the biggest reserves. Any form of surface and edge finish like

flaming can be used on hard stones. More sophisticated machinery and equipment are being

used during extraction and processing of hard stones which contain hard minerals like quartz

and feldspar. Because of their durability, hard stones are both used as masonry block and kerb

as well as panel. Hard stones have high permeability. Imbibition of water and rain into the

material increases the affect of biological and environmental factors on these stones. As with

other type of stones, the grain size decrease so does porosity and durability increases. By the

increase of grain size, processing of stones becomes more difficult and processing costs

increase.

Massive Layered Sandy

banded plant fossils

dark shells light

Bituminous

Calcite Aragonite Alabaster

massive watered banded

Layered

Sandstone Igneous Stone Gneiss Migmatite

Clay carbonate granite syenite labradorite diabase gabbro andesite basalt layered massive layered

breccia fossils

very fine grain

< 0.1 mm

fine grain

0.1 mm <grain< 1 mm

medium grain

1 mm <grain< 4 mm

coarse grain

4 mm <

Table 6: Summary of the hard stones used in the building

Decorative stones except serpentine and pebble are used as sawn masonry blocks or by splitting

from their lamination borders (Table 7). Technological advancement and search for new and

different stones and finishes enabled those stones to be used in strip and slab forms.

Serpentine are used polished. Talk and fissure content in serpentine obstructs outdoor use. In

addition to that, serpentine are affected from sunlight and loses their color shortly. Pebble and

other stones in chip form are usually used at garden decoration. Recently, pebbles are being

used outdoors being fixed on concrete.

Table 7: Summary of the decorative stones used in the building

Deductions

Classification of building stones in Table 1 and Table 2-6 are being prepared to enable usage of

building stones accurately, correctly and precisely by trader, architect, civil engineer and end

user. This classification of stones that have been done will reduce problems in the chain of

trader-supplier-investor-architect-civil engineer-end user. The classification is important by

means of increasing usage of natural stones and decreasing of related costs and building an

internationally accepted nomenclature. Classification of building stones will prevent confusion

of terminology at industry and commerce. The classification will also help projects to be

functional, aesthetic, hygienic and economical.

Schist Calc-schist Slate Phyllite Hornfels Tuff Serpentine Pebble Laminated

Lined banded Layered

HISTORY OF STONES

Stone is a natural solid formation of one or many minerals. There are thousands of types of stone

that have been quarried through the centuries. Quarries are located all around the world. A

majority of natural stone comes from Italy, Spain, Turkey, United States, Mexico, China, Taiwan,

India, Greece, Canada, France, and Brazil.

The minerals in stone came from the same liquid and gas minerals that formed the earth. The

Earth developed as a massive body of gas and liquid minerals that slowly cooled and condensed

to a solid core. Through pressure, the Earth's crust began to form and heavy minerals were

forced down to the core of the Earth where they were trapped. As the crust got thicker, it

squeezed around the inner core which created intense pressure and heat from within the Earth.

Crystals and other solid forms began to grow from the mineral vapors that were being released.

As the Earth's crust began to expand and erode, heat and pressure pushed the solid minerals up

to the Earth's surface which formed colossal rock beds. It took up to one-hundred million years

to form some of these beds. Many of the beds are now used as quarries where the stone is mined.

Most of these minerals can be identified by their color, hardness, and crystal formation. Crystals

come in a variety of shapes and sizes. The wide array of these minerals are often difficult to

identify. Many stones look very similar to each other; however, they are all very different.

It is imperative to know the exact type of stone that is to be maintained. Stone is natural and may

have adverse reactions to certain cleaning chemicals and procedures. Most stones are also

natural alkalis and so are dirt and soil; therefore, stone and dirt are attracted to each other

which often makes cleaning very difficult. This makes the proper selection of cleaning

procedures and chemicals for stone very complex.

Stones used in the construction of Taj Mahal and Pyramids of Egypt

Construction of Taj Mahal began around 1632 and was completed around 1653. In 1983, the Taj

Mahal became a UNESCO World Heritage Site.

In the construction of the Taj Mahal three types of stones have been used :

Semi-precious stones like Aqiq (agate), Yemeni, Firoza (turquoise), Lajwad (Lapis-

lazuli); moonga (coral), Sulaimani (onyx), Lahsunia (cat's eye), Yasheb (jade) and

Pitunia (blood stone). These were mainly used for inlaying work.

Rare and scarce stones such as Tilai (goldstone), Zahar-mohra, Ajuba, Abri, Khathu,

Nakhod and Maknatis (magnet stone) were used for bold inlay and mosaic work chiefly

on floors, exterior dados and turrets.

Common stones: sang-i-Gwaliari (grey and yellow sandstone) sang-i-Surkh (red

sandstone), sang-i-moosa (black slate) and sang-i-Rukhan (sang-i-marmar; white

marble) were used in foundations, masonry and for giving finishing touch to the external

surfaces. Red stone was brought from the neighboring towns like Fatehpur Sikri,

Karauli-Hindaun, Tantpur and Paharpur whereas white marble was brought from

Makrana mines (Rajasthan). Semi precious and rare stones were occasionally brought

from as distant places such as Upper Tibet, Kumaon, Jaisalmer, Cambay and Ceylon.

Gold stone Magnet Stone Agate

Turquoise Lapis- lazuli Coral

Onyx cat's eye Jade

Yellow Sand Stone Grey Sand Stone Red Sand Stone

Black Slate White Marble

The Great Pyramid consists of an estimated

2.3 million limestone blocks with most

believed to have been transported from

nearby quarries. The Tura limestone used

for the casing was quarried across the

river. The largest granite stones in the

pyramid, found in the "King's" chamber,

weigh 25 to 80 tonnes and were

transported from Aswan, more than 500

miles away. Traditionally, ancient

Egyptians cut stone blocks by hammering wooden wedges into the stone which were then soaked

with water. As the water was absorbed, the wedges expanded, causing the rock to crack. Once

they were cut, they were carried by boat either up or down the Nile River to the pyramid. It is

estimated that 5.5 million tons of limestone, 8,000 tons of granite (imported from Aswan), and

500,000 tons of mortar were used in the construction of the Great Pyramid.

Granite Lime stone

FROM STONES TO MARBLES

Natural stones are rock formations formed by nature. These stones are formed naturally by

enormous pressure under the earth. Natural stones were used in decorating and sculpturing

right from the moment civilization was born. These natural stones are time tested for their

natural beauty. Ancient buildings and monuments made of natural stones during early

civilizations still stand erect narrating the beauty and durability of natural stones.

Modern people want to make their home stand out of the rest and they used natural stones for

their floors and walls to bring about eternal beauty. Granite and marble are two main natural

stones widely used in the stone industry. These stones are used in constructions as well as in

monumental sculpture. Commercially, these stones are mined for use as architectural stones for

flooring, cladding, curbing, counter tops and much more to be used at home.

Pure white marble is a metamorphic rock of very pure limestone. Marble is found extensively in

various countries like Belgium, France, Great Britain, Greece, India, Spain and Italy. From

classical times, pure white marble was considered as the best of its kind. In the beginning, only

white marble was considered worthy and colored marble was considered impure. However, this

belief was just short-lived because very soon, ancient civilizations appreciated colored marbles

too and used colored marbles in various monuments and sculptures even though pure white

marble is always regarded high. Freshly quarried marble is easy to sculpture and the stone

hardens as it ages.

Ancient Greeks were very much advanced in civilization and they were really fascinated about

marble. Finest architecture and sculpting are specialties of Greek architecture and marble has

been used in various Greek buildings. Exquisite statues with detailed carvings were made out of

marble. Buildings built using Marble lasted for several ages. The Parthenon which was built in

441-437 BC is considered as a symbol of ancient Greek civilization and this scintillating

building was built using Pentelicon marble.

The Greek empire extensively used marbles in their constructions. Temple of Artemis is one of

the ancient wonders of the world and it consists of 127 marble columns each of which is 5 stories

tall. It was the first grand structure made using marble. The magnificent construction was

destroyed by various civilizations that took over Greece, but you can still find foundation and a

few columns of the wondrous marbles.

When natural stones were widely used in constructing monuments and temples, it was the Greek

empire that brought marble to personal use. References to baths and pools lined with marble can

be seen in ancient literature. Thassos marble was widely used in bathrooms and this type of

marble is still quarried today for commercial uses. Building constructions using marble was

popular in India too and the Taj Mahal, one of the Seven Wonders of the World was constructed

using pure white marble stones.

After the Egyptian and Greek civilizations made some wonders with natural stones of granite

and marble, the Roman Empire decided to try its hands on both granite and marble. Many of the

roads of the Roman Empire were built using granite. Public baths became popular in Rome and

these baths were made of granite. Pantheon in Rome used granite stones for columns and you

can see these columns standing tall even today.

Romans loved granite and marble for different reasons. They used granite extensively for

constructions because the stone is highly durable and strong. Marble was mainly used for

aesthetic reasons because Romans believed marble to be the most beautiful stone. Construction

pattern of Egyptians and Greek was different from Romans. While the former civilizations used

massive granite and marble stones to build constructions, Romans used bricks and mortar for

buildings and then, lined them with marble and granite slabs. It is because of this reason that

Romans were able to build marble cities in a short duration.

The renaissance period is a golden period for all types of artwork. Artists and sculptors were

interested in using natural stones for their artwork. Quarrying methods were improved by the

time and technical use was invented. Innovative and novel users of natural stones increased

during the renaissance period. Famous Michelangelo made several beautiful sculptures out of

marble. Ornate decorations made using marble and granite were used in decorating churches,

temples and other buildings of magnificent nature. Meanwhile, natural stones were carved into

decorative pieces for use at home.

It was only during modern times that natural stones were brought close to mankind. Quarrying

techniques were improved greatly and there was no need for men to die in quarries dealing with

dynamites. Innovative technologies were used in mining natural stones. Also, the world started

thinking about eco friendly materials to be used to construct homes. Architects and designers

were overly enthusiastic about natural stones that were used in building monuments. In the last

decade, people preferred to use more durable, yet stylish materials for constructing homes.

Marble and granite are available in various patterns and colors and it was not easy to find the

same pattern of stones. This uniqueness of natural stones made people want for more use of

natural stones. In the ancient periods, marble and granite were used for lining and decoration.

People trusted durable stones and lay flooring using granite and marble. Apart from their baths,

living room, bed room and other rooms in the home had natural stone flooring.

Even though natural stones add exquisite beauty to the home, they are highly porous in nature.

Harsh substances can easily damage these natural stones. However, thanks to latest

technologies, that it is possible to add more strength to the stones and seal the porous nature so

that these stones can be used extensively at homes. It was only during the last few years that

countertops made of marble and granite became popular.

In this report we shall be focusing on marble, its production and trends and discuss the fluid

mechanics involved in water jet cutting technology for cutting marbles.

MARBLE

The word dimensional stones refer to the durable stones which can be cut to sizes, polished and

used for construction purposes, i.e. marble, granite, slates etc. These stones belong to a same

family resulted from the combinations of different minerals such as calcium compounds

(calcareous) for marbles, Silica compounds (siliceous) for granite and Shale clay for slate and it is the mineral base in these stones which distinguishes them from each other. Marble is a

crystalline, compact variety of metamorphosed limestone, consisting primarily of calcite

(CaCO3), dolomite (CaMg (CO3)2 or a combination of both minerals. The formation of marble

takes place from the contact metamorphism of sedimentary carbonate rocks such as limestone,

dolomite or metamorphism of older marble, thus it is a metamorphic rock. This chemical

formation results in to an interlocking mosaic of calcite, aragonite and/or dolomite crystals from

the recrystallization of the original rock. The fossils and sedimentary textures present in the

original rock get destroyed due to the temperatures and pressures. The metamorphism of very

pure limestone results in to a pure white marble, whereas clay, silt, sand, iron oxides, or chert

present as a layers or grains in the limestone result in varieties of colored marble. Mineral

impurities add color in multicolored patterns, though pure calcite is white. Wide deposits of

marble lie in various countries like Italy, India, Pakistan, Spain, Greece, Brazil, China,

Afghanistan, Turkey, and Great Britain and in the United States. If taken in a commercial term,

marble refers to the composition of any rock with calcium carbonate including limestone that

takes polish. If we extend the term further, it includes other stones too, such as alabaster,

serpentine and other soft rocks. The thickness of marble in terms of gravity varies between 2.68

to 2.72. Marble is quite sensitive towards moist or acidic environment and disintegrated easily

under such environment. Thus, it must be protected from such environment and rain as it is a

durable product under a dry atmosphere. Statuary marble is the purest white form of marble

with visible crystalline structure. The unique shine of these marble results from the reflection of

light lying in the surface of inner crystals.

HISTORY OF MARBLE

Small, round objects made from stone have been unearthed in the excavations of ancient cultures

all around the globe. The antecedent of the marble was probably the nut, polished by youngsters

in ancient times into a smooth surface for playing games. Both Greek and Roman youths played

games with small balls made from clay, and marbles were discovered in the tomb of the young

Egyptian pharaoh Tutankhamen. In North America, objects of stone and clay that appear to be

marbles have been unearthed from several sites. One of the most famous is the Hopewell burial

sites in Ohio. Marbles and marble games for children continued to be a popular form of

entertainment well through the Middle Ages. Unfortunately, youngsters playing marble games

came to be seen as delinquents, and efforts were made to restrict their marble-playing activities.

Most of the marbles used in medieval and Elizabethan times were made from clay. Around 1600,

water-powered stone mills in Germany began producing more polished versions from the marble

and alabaster quarries nearby, especially in the regions near Coburg and Oberstein. The word

marble is derived from the German term "for the rock," and has come to mean any small, round

sphere used as such. Soon the mills began grinding out versions from agate, limestone, brass,

and gemstone, and these large operations could grind a marble into shape at the rate of about

800 an hour. This made Germany the center of marble manufacturing for several centuries.

Glass marbles, the most common version of the object today, only came into existence relatively

recently in the history of the object. It is debated whether they originated in Venice, where

glassblowing had become a well-developed industry since the ninth century, or back in

Germany. Historians point to 1846 as the invention of marbelschere (marble scissors) by a glass

factory employee in Germany. This tool resembled a pair of tongs with a small cup on one end

and a slicing device on the other. A molten glass rod would be forcefully inserted into the cup,

and the worker would then twist the cup, which would help form the sphere of the marble.

Squeezing the tongs shut sliced off the rest of the glass. Such marbles can be identified by their

pontil marks, the two tiny tags at each end of the sphere where the cooling glass was severed

from the rest of the rod. The objects were further cooled inside a wooden barrel and then taken

up with an iron spoon and inserted into an annealing oven, a process which yielded a tougher

piece of process which yielded a tougher piece of glass not likely to break or become brittle.

Marble manufacturing migrated to American shores in the later decades of the 19th century. In

1900 Martin Frederick Christensen received a patent for a machine that made near-perfect

spheres of steel ball bearings. The first machine-made marbles were manufactured in a barn

behind Christensen's house in Ohio, which eventually led to a prosperous manufacturing facility.

By 1910 the 33 workers at the M.F. Christensen and Son plant were producing 10,000 marbles a

day. The furnaces were fired by natural gas, however, and the onset of World War I brought

rationing of the resource and spelled the fiscal end of Christensen's operation.

Today, marbles are still produced in record numbers, but most are made in Third World

factories. One such operation, Vacor de Mexico, located in Guadalajara, produces about 12

million marbles a day, which are then shipped to 35 different countries.

RAW MATERIALS

Modern marbles are made from a combination of sand, soda lime, silica, and several other

ingredients added for pigment or decoration. These other additives range from aluminum

hydrate to zinc oxide. The primary component, sand, is essentially loose, granular particles of

disintegrated rock. Soda lime is the chemical term for the mixture of calcium hydroxide and

sodium or potassium hydroxide. It is a drying agent and absorbs carbon dioxide. Another

compound used in marble manufacturing is silica, a white or colorless crystalline found in agate,

flint, quartz, and other rocks. Some marbles are also made from cullet, or scrap glass.

THE MANUFACTURING PROCESS

Meltdown

Sand, soda lime, and crushed cullet are fed into a large, furnace-driven tank. In the tank, the

mixture is heated to 2300°F (1260°C) to melt the raw materials. This can take as long as 28

hours.

Injection

Next, the molten mixture moves out of the tank through an opening into another vat known as the

flow tank. There an opening in the tank injects molten colored glass. This hot, pigmented glass

gives the marbles their distinct appearance. A green marble has been injected with glass

containing iron oxide; cobalt results in a blue marble; and manganese will yield a purple one.

The use of uranium oxide gives marbles an eerie, greenish-yellow cast. The speed and force of

the injection determines the final design of the marble.

Cutting and cooling

Next, the still-molten glass is released from the flow tank as globs of glass. Automatic cutting

devices slice the mixture into equal parts. The globs travel down metal ramps that

simultaneously cool them and perfect their spherical shape. Next, they travel down a second

metal slide and are sorted by hand. Marbles with flaws are sent back to another area of the

factory for re-melting. The marbles cool off in 5-gallon (191) containers that house 5,000

marbles at a time.

TYPES OF MARBLE FOUND WORLDWIDE

The major categories of marble comprises of ‗Beijing White‘, ‗Boticena and Onyx‘ (Green),

‗Carrara‘, ‗Danby‘, ‗Fauske‘ ‗Katni‘, ‗Llano Pink‘, ‗Macael Nabresina‘, ‗Parian‘, ‗Red‘,

‗Thassos‘, ‗Vencac‘, ‗White‘ and ‗Yule‘ that are available worldwide. Since the ancient times,

white marble have been a primary choice for the monuments for its softness, relative isotropy,

homogeneity and a comparative confrontation to devastating. Besides, the waxy looks of a

human body sculptures form due to the low index of calcite which allows light to penetrate some

millimeters in to the stone before being scattered out. The table below shows historically notable

marble varieties throughout the world.

MARBLE PRODUCT PARAMETRES AND MARKET

PARAMETERS FOR THE SELECTION OF MARBLE

Marble is selected on the basis of various parameter meant for its specific and end use. They are

rated on three basic characteristics namely, color, pattern and grain size.

Colour

Color has its importance in the market for marble which varies as per time, markets, and marble

type from country to country, i.e. European markets prefer white marble while Middle East & far

eastern markets demand for white, black & beige marble.

Pattern

Pattern has its effect on the looks of marble, thus it plays a major role.

Grain Size

Fine, medium and large grain materials are the general form of grain size. Grain size is meant

for the use of marble

rather than its looks. Fine grain materials have a micro hardness and are meant for load

bearing areas and sharp corners, whereas Medium and especially the large grain materials are

unsuitable for those areas as there are chances of their breakage and cracks. Thus, the vary

combinations of colors, sizes and patterns are meant for different segments of customers, i.e.

customers with high price range look for rare color, fine grain and homogeneous pattern of

marble or for medium grain, common colors and homogeneous pattern. and for the medium

price range, the market has the marble with rare colors, large grain size and heterogeneous

pattern.

Marble Specifications

Production of International Standard Size blocks divides of cracks and fractures in international

market the standard size of block is according to the following specification:

Length: 1.9m, 2.6m

Width: 1.4m, 1.8m

Height: 1.1m, 1.4m

The standard weights of these blocks are 13.7tons, 22.7 tons even large up-to 30tons.

Slabs

American sizes of Slabs are 120 inches.

Tiles

The International standard sizes of tiles are 22 up-to 24.

APPLICATIONS OF MARBLE

Blocks of cut Marble

Colorless or light-colored marbles are a very pure source of calcium carbonate, which is used in

a wide variety of industries. Finely ground marble or calcium carbonate powder is a component

in paper, and in consumer products such as toothpaste, plastics, and carbonate can be made

from limestone, chalk, and marble; about three-quarters of the ground calcium carbonate

worldwide is made from marble. Ground calcium carbonate is used as a coating pigment for

paper because of its high brightness and as a paper filler because it strengthens the sheet and

imparts high brightness.

Consumer Products

Ground calcium carbonate is used in consumer products such as a food additive, in toothpaste,

and as inert filler in pills. It is used in plastics because it imparts stiffness, impact strength,

dimensional stability, and thermal conductivity. It is used in paints because it is good filler and

extender, has high brightness, and is weather resistant. However, the growth in demand for

ground calcium carbonate in the last decade has mostly been for a coating pigment in paper

Calcium carbonate can also be reduced under high heat to calcium oxide (also known as

"lime"), which has many applications including being a primary component of many forms of

cement.

Production Sculpture

White marble has been prized for its use in sculptures since classical times. This preference has

to do with its softness, relative isotropy and homogeneity, and a relative resistance to shattering.

Also, the low index of refraction of calcite allows light to penetrate several millimeters into the

stone before being scattered out, resulting in the characteristic waxy look which gives "life" to

marble sculptures of the human body.

Construction Marble

Construction marble is a stone which is composed of calcite, dolomite or serpentine which is

capable of taking a polish. More generally in construction, specifically the Dimension stone

trade, the term "marble" is used for any crystalline calcitic rock (and some non-calcitic rocks)

useful as building stone. For example, Tennessee marble is really a dense granular fossil ferrous

gray to pink to maroon Ordovician limestone that Geologists call the Holston Formation.

According to the United States Geological Survey, U.S. dimension marble production in 2006

was 46,400 tons valued at $18.1 million, compared to 72,300 tons valued at $18.9 million in

2005. Crushed marble production (for aggregate and industrial uses) in 2006 was 11.8 million

tons valued at $116 million, of which 6.5 million tons was finely ground calcium carbonate and

the rest was construction aggregate. For comparison, 2005 crushed marble production was 7.76

million tons valued at $58.7 million, of which 4.8 million tons was finely ground calcium

carbonate and the rest was construction aggregate. U.S. dimension marble demand is about 1.3

million tons.

Artificial Marble

Marble dust is combined with cement or synthetic resins to make reconstituted or cultured

marble. The appearance of marble can be simulated with faux marbling, a painting technique

that imitates the stone's color patterns. Ancient Marble columns in the prayers Hall of the

mosque of Uqba in Kairouan,Tunisia.

As the favorite medium for Greek and Roman sculptors and architects (see classical sculpture),

marble has become a cultural symbol of tradition and refined taste. Its extremely varied and

colorful patterns make it a favorite decorative material, and it is often imitated in background

patterns for computer displays, etc.

Places named after the stone include Marblehead,Ohio; Marble Arch, London; the Sea of

Marmara; India's Marble Rocks; and the towns of Minnesota; Marble; and Marble Hill,

Manhattan, New York. The Elgin Marbles are marble sculptures from the Parthenon that are on

display in the British Museum. They were brought to Britain by the Earl of Elgin

GEO-ECONOMICAL PERSPECTIVE OF THE MARBLE

INDUSTRY

WORLD MARBLE INDUSTRY

According to the site ―tunisianindustry.net‖, approximately 57% of the world's marble exports

are contributed primarily by five countries; namely, Italy (20%), China (16%), India (10%),

Spain (6%), and Portugal (5%). While it comes to major importer countries of marble, the top

marble importer countries series wise are: Germany, Japan & Taiwan for the import of nearly 4

million tons together. Whereas other countries such as USA, the Benelux countries, Hong Kong,

France, Switzerland & Saudi Arabia import over one million tons.

2003 2004 2005 2006 2007

Figure above shows the demand of marble worldwide (in a span of five years) from the year

2003 till 2007. It represents a constant growth in the demand of marble which is supposed to be

the total finished marble exported by some major exporting countries, i.e. Turkey, Italy, Spain &

China. The world‟ s demand for marble on the measure of average annual increase, it is 13.7%

while keeping the year 2000 as the base year (2000=100).

GEOGRAPHICAL ANALYSIS

ITALY

Along with the availability of stone materials, Italian stones possess a greater diversity, with

respect to color and sizes that adds to their attractive global demand. A traditional world leader

in its sector Italy has advantages like highly skilled workers, modern technologies that are

constantly established communication between stone suppliers & machine manufacturers

keeping them ahead in the competitive arena.

Italian marble blocks are majorly exported to the European markets such as Spain, Portugal,

Greece, Slovenia & Turkey. Furthermore markets such as Russia, Poland, Croatia, Morocco,

Algeria, Switzerland & the Arab Emirates, in 2007, fueled the demand for the Italian marble

other than prominent countries like the US and Germany.

EXPORTS

As per IMM Carara, Italy reports Egypt, Libya, India, Tunisia and China as the top five

countries with respect to the export of rough blocks and slabs of marble. Figure below depicts

the quantity in thousand tons for export to the respective countries.

ITALY-TOP FIVE COUNTRIES WHERE ROUGH BLOCKS AND SLABS OF MARBLE EXPORTED

Similarly, the worked and finished marble products are primarily exported to Spain, Germany,

UAE, Saudi Arabia and USA. Figure below shows the top five countries with quantity in

thousand tons.

ITALY-TOP FIVE COUNTRIES FOR THE EXPORTS OF WORKED AND FINISHED PRODUCTS OF MARBLE TURKEY

The Turkish stone industry, as of today, comprises of 2000 quarries & 1500 factories. 60% of the

deposits and factories are spread over a radius of 400 Km near Izmir.

Turkey‟ s vast marble reserves are easily & well compatible with the marble found worldwide

with their more than 100 varieties such as very light gray to black & brilliant white shades.

Besides, Turkey has other world famous range of marble such as Afyon White, Afyon Tigerskin,

Bilecik Pink, Marmara White, Burdur Brown, Denizli Travertine, Elazig Cherry, Karacabey

Black, Golpazarı Beige, Milas Kavaklidere, Aeagan Bordeaux, and Aksehir Black.

In the recent years, Turkey has enjoyed 25% of exports due to its availability of diverse color

patterns as highlighted above. Additionally, the Turkish marble industry is quite promising for

its national & international investors in terms of future profit.

EXPORTS

Turkish stone industry showed a rapid growth within a time span of ten years. The amount of the

total value of natural stone exports accounted to US$ 1.3 billion in 2008, of which nearly 63%

was cut & polished processed marble.

Amongst the processed & block marble, processed marble accounts for approximately US$ 887

million export value that were primarily exported to the countries like U.S.A., the United

Kingdom, Canada, Saudi Arabia & the United Arab Emirates in 2008. Whereas, block marble

with US$ 438 million, in export value, were majorly exported to China, India, Italy, Syria &

Greece.

As per the reports from the Undersecretarial for Foreign Trade & IGEME, the total amount of

marble exported by Turkey since the year 2004 till the year 2008 in tons is depicted below in

figure TURKEY'S MARBLE EXPORT (QUANTITY: TON)

CHINA

There are approximately 123 mines 26 provinces for the marble production in China. Hebei

Quyang, Jiangsu Yixin and Ganyu, Hubei Huangshi, Sichuan Baoxin, Shanxi Liuba and

Guangdong Yingde marble mine are some of the main marble mining provinces amongst which

Guangdong and Hebei hold leadership positioning. Until the year 2006, the total marble

production in China was 900 million sq. meters.

EXPORTS

A total of approximately 31000 tons of worked and finished marble stones were exported from

China in 2008. The period from the year 2004 through 2008 has experienced a growth of

approximately 2% to South Korea, being the largest importer in the finished marble stones

segment. Figure below shows the top five countries in terms of worked & finished marble

exported to by China as per the data provided by IMM:- CHINA-TOP FIVE COUNTRIES WHERE WORKED AND FINISHED PRODUCTS OF MARBLE EXPORTED

The scenario for the rough blocks and marble slabs is quite different from the finished products.

As figure shown below indicates, Taiwan remained a dominant importer of unprocessed marbles

with 41000 tons in 2008. Other regions that contributed to this segment were Holland, Japan,

South Korea and Hong Kong.

CHINA-TOP FIVE COUNTRIES WHERE ROUGH BLOCKS AND SLABS OF MARBLE EXPORTED SPAIN

There are more than 1000 small & medium companies & 700 quarries in Spain trading with the

dimensional stones such as marble, granite & slate. Various reports including the above one

were presented at Piedra 2008 giving various details of Spanish marble industry such as the size

& activities of that sector on an international level.

EXPORTS

UAE, Italy, USA, Hong Kong & China were the top five countries where the most amount of

rough blocks & slabs of marble were exported between the time period of 2004 to 2008.

SPAIN-TOP FIVE COUNTRIES WHERE ROUGH BLOCK AND SLABS OF MARBLE EXPORTED

When it comes to worked & finished products of marble exported by Spain, UAE & Italy again

have their place in the top five countries where worked & finished products of marble were

exported during last four year, that is, from the year 2004 till the year 2008. Figure below shows

the amount of marble in tons being exported by Spain (representing only top five countries it was

exported to):-

SPAIN-TOP FIVE COUNTRIES WHERE WORKED AND FINISHED PRODUCTS OF MARBLE EXPORTED GREECE

Greece too holds a good status in the world for its marble. During the year 2004 it was ranked

4th in the world marble exports & 6th in the world marble production. Throughout the world it is considered as top level architectural material & thus used that way.

EXPORTS

As per the data provided by IMM, following is the amount in ton for the exports of worked &

finished products of marble by Greece. Singapore, Spain, Brazil, Cyprus & USA were marked as

the top countries for that:-

GREECE-TOP FIVE COUNTRIES WHERE WORKED AND FINISHED PRODUCTS OF MARBLE EXPORTED

Greece exported most of its rough blocks & slabs of marble to J Rep, Hong Kong, Bulgaria,

Albania & China during last five years, that is, 2004 to 2008:-

GREECE-TOP FIVE COUNTRIES WHERE ROUGHBLOCKS AND SLABS OF MARBLE EXPORTED

PAKISTAN’S GEOLOGICAL POTENTIAL AND

UNTAPPED MARBLE RESERVOIRS

MARBLE INDUSTRY OF PAKISTAN

Marble industry is one of the most important industries in Pakistan. Since 1990 mining &

quarrying has consistently contributed 0.5% to the GDP. According to the industry estimates

1.37 million tons of marble and granite were produced while 97% of it was consumed locally.

Little efforts were made in the past to identify and estimate marble and granite reserves in the

country. Some of the reserves of marble and granite were however calculated with the efforts

made by development projects and concerned departments. Known reserves of Marble in

Pakistan are 160 million tones while actual reserves could be manifold. These reserves are

mostly concentrated in NWFP and Balochistan. Estimated reserves of Granite in Pakistan are 2

billion M.T. out of which 1.15 Billion M.T. are in Thar - Sindh. Major mining areas can be

identified as Chitral, Buner, Swat, Lasbela, Swabi, Khuzdar, Mohmand Agency, Mardan,

Kashmir and Mansehra. Mine in Mianwali has also started meager operations.

DEPOSITS IN PAKISTAN

Pakistan has enormous wealth of marble, re-crystallized lime stone, fossil-ferrous limestone,

dolomite and granite. These materials occur on the surface suitable for open cast bulk.

RESERVES

Not specifically measured, however Marble& Onyx more than 300 billion tons of reserves are

estimated.

MAJOR COLOURS

White, Black, Green, Pink, Grey, Brown and Yellow colours.

LOCATION

Mohmand Agency, Chitral, Buner, Swat, Parachinar, Gilgit, Hunza, Swabi, Bajour, Mardan,

Wazirstan, Azad Kashmir, Lasbela, Chagai & Khuzdar.

MARBLE DEPOSITS IN PAKISTAN

MARBLE INDUSTRY IN NORTH WESTERN PARTS OF PAKISTAN

Marble mining and cutting is one of the most important industries in Pakistan. It provides the

local population employment opportunities as well as contributing a substantial share to the

economy of the country. In spite of the immense economical importance of the marble sector, the

relevant industry has not been developed enough to sustain its growth and optimize its

utilization. The economical potential of the marble industry and its slow growth can be estimated

from the fact that in the fiscal year 1980-81, its production was about 1,14,000 tones which

increased to 1,22,000 tons in 1985-86. This is about 7% increase in 5 years period. The deposits

of marble, onyx and granite are not only huge in quantity but excellent in quality as well. Marble

deposits are found in the northern parts of the NWFP and Balochistan. Deposits of calcite

marble containing gem-quality ruby has been discovered in the Hunza valley, Northwestern

mountains, and Kashmir valley as well. Vast reserves of marble are also found in different areas

of NWFP including Mardan, Nowshera, Swabi, Buner, Swat, Chitral and, Malakand, Khyber

and Mohmand belts. The NWFP marble reserves constitute about 97 per cent of the country‟ s

total marble deposits. The marble processing industry in Pakistan is around 33 years old, when

the first major marble deposits were discovered at Mullagori and Swabi in NWFP in the country.

Marbles with a variety of colours occur in NWFP but white marble has universal demand in the

international market. Various types and colours of marble available in NWFP are given in the

table below.

DEPOSITS IN BALUCHISTAN

Baluchistan-Chaghi District

Deposits of high quality onyx (travertine) marble locally known as Malmal are found in Chaghi

District at seven localities, 50 to 80 Km away from the railheads of Dalbandin and Nokkundi.

JUHLI DEPOSITS

Pale to deep green beds.

Deep green variety is the most desired decorative stones.

Reddish and rusty brown known as multicolor onyx.

Reserves of 1.5 million cubic feet.

ZARD KHAN DEPOSITS

Yellow, pale green, grayish white and white dense, thinly bedded and fine grained.

Reserves of 30 million cubic feet

MASHKI CHAH DEPOSITS

Transparent to translucent white, pale yellowish marble.

Reserves of 6 million cubic feet.

Patkok Deposits – 3 feet thick bed pale green marble of 24,000 cubic feet reserves.

Butak Deposits – Good quality thin bedded, dense yellow marble of 60,000 cubic feet

reserves.

Tozghi Deposits – Opaque having off white color with ferruginous layers of 24,000

cubic feet reserves

Zeh Deposits – Green good quality reserves – studies to be carried out to determine its

quality and quantity.

DEPOSITS IN SINDH

THANO BULA KHAN

Travertine Deposits occurring in Cavern and Cavities in the limestone. Reserves have been

estimated at 360,000 tons.

THATTA

Braudabad, Sonda – Jherak, Jangshahi dense grey, greyish white limestone and dolomite in

considerable quantities.

DEPOSITS IN PUNJAB

Crystalline grey, grayish white limestone and dolomite in district Mianwali (Punjab).Crystalline

grey, grayish white limestone and dolomite in district Mianwali (Punjab).

Table provided below shows the types of marbles found in different parts of Pakistan.

TYPE LOCATION COLOUR

WHITE

Mohmand Agency, Chitral Buner, Swat, Parachinar, Gilgit, Hunza, Swabi, Malakan

Pure white: white with pink, brown and Green shades

white to grey with yellowish

patches, white to light grey with yellowish brown

Patches; Creamy white

MARBLE PRODUCTION IN PAKISTAN STATISTICS

Tables provided below show the amount of marble produced in tones per annum in Pakistan.

PROVINCE

KHYBER-P

Product 2006-2007 2007-2008

Marble 428,649 196,545

PROVINCE

BALOCHISTAN

Product 2006-2007 2007-2008

Marble 461465 337756

PROVINCE SINDH Product 2006-2007 2007-2008

Marble 3,305 1,415

PROVINCE

PUNJAB

Product 2006-2007 2007-2008

Marble 10059 42016

BLACK Buner,Bajour.Mardan,Bela Deep Black :with patches of

white: Black with white and

golden steaks

GREEN Swat,Swabi,Buner,Azad Kashmir and Lasbela

Dark Green,green with streak & patches of white grey and black,greenish

white,

PINK Nowshehra,chitral,Lasbela Pink with streaks and

patches white, grey,redand

brown :pink with fossils

GREY Buner,Bajour,Mardan,Swat,M- uhammad Agency,Lasbela

Grey with white bands grey

with pink ,beown and green

patches

BROWN

Bunner Swat,Kohat,Waziristan,Khuz- dar

Dark Brown with white lines

,brown with yellow

Patches,light brown with fossils

YELLOW Bunner Swat,Kohat,Waziristan,Khuz- dar

Yellow with golden patches: Yellowish golden with fossils

GREEN Jhuli,Zard Khan,Zeh Dark Green with layers of

light green, green with streaks of white and yellow

Outlook of Water jet machining process

Primordial Marble and Granite Cutting Tools

Marble is a very hard surface. Granite is significantly harder. These materials are so hard that

normal household tools would not be strong enough to properly cut and shape them. A hammer

or drill that easily goes through wood or drywall would do likely do little other than scratch or

damage these very hard stones. Specialty tools are required to shape these sturdy, beautiful and

classic materials. These tools are often stronger than other tools. In the case of granite, most

tools are made of diamond.

1. Hammer Drills

o Most power drills works by quickly rotating a drill bit into wood, drywall, or

other materials, basically acting as a high powered screwdriver. A hammer drill

adds a pounding action. While the drill spins, it is also being pounded in. This is

necessary to get the drill further into the marble or granite as a normal drill

would not be powerful enough.

Chisels

o A chisel is a tool with a cutting blade on one end. It is forced into a substance by

a hammer or mallet. This cuts away a small piece of the substance. There are

many different types of chisels. Each is used for a specific purpose such as cutting

a specific shape or area. Granite and marble work require special chisels, often

with diamond blades.

Grinder

o A grinder is used for cutting, polishing, removing excess material, and shaping. A

grinder rotates a blade at great speed to do this. There are many different types of

grinder blades, each with different strengths and uses. When working with

marble, and especially granite, blades with diamond edges are recommended.

Tile Saw

o A tile saw is used for shaping marble into specific sizes. These saws work

similarly to electric saws used for wood or other materials. Tile saws used for

marble work typically have diamond blades.

WATER JET

Preliminaries

Figure Courtesy of Xinology Corp.

Engineering and manufacturing departments are constantly on the lookout for an edge. The

water jet process provides many unique capabilities and advantages that can prove very effective

in the cost battle. Learning more about the water jet technology will give us an opportunity to

put these cost-cutting capabilities to work. Beyond cost cutting, the water jet process is

recognized as the most versatile and fastest growing process in the world. Water jets are used in

high production applications across the globe. They compliment other technologies such as

milling, laser, EDM, plasma and routers. No poisonous gases or liquids are used in water jet

cutting, and water jets do not create hazardous materials or vapors. No heat effected zones or

mechanical stresses are left on a water jet cut surface. It is truly a versatile, productive, cold

cutting process. The water jet has shown that it can do things that other technologies simply

cannot. From cutting whisper, thin details in stone, glass and metals; to rapid whole drilling of

titanium; for cutting of food, to the killing of pathogens in beverages and dips, the water jet has

proven itself unique.

A water jet is a tool used in machine shops to cut metal parts with a (very) high-pressure stream

of water. As amazing as it sounds; if you get water flowing fast enough it can actually cut metal.

Beyond cost cutting, the water jet process is recognized as the most versatile and fastest

growingprocess in the world (per Frost & Sullivan and the Market Intelligence Research Corporation).

Water jets are used in high production applications across the globe. They compliment other

technologies such as milling, laser, EDM, plasma and routers. No noxious gases or liquids are

used in water jet cutting, and water jets do not create hazardous materials

or vapors.No heat effected zones or mechanical stresses are

left ona water jet cut surface. It is truly a versatile,

productive,cold cutting process. The water jet has shown that it can do things that other technologies simply cannot. From

cutting whisper thin details in stone, glass and metals; to rapid hole drilling of titanium; to

cutting of food, to the killing of pathogens in beverages and dips, the water jet has proven itself

unique. Water jets remove material without heat. In this cold cutting process, the supersonic

water jet stream performs a supersonic erosion process to "grind" away small grains of

material. After this water jet stream has been created, abrasive can be added to the stream to

increase the power of the process many times.

The key to cutting metal with water is to keep the spray coherent. Water jets are able to cut

because the spray is channeled through a very narrow jeweled nozzle at a very high pressure to

keep the spray coherent. Unlike metal cutters, a water jet never gets dull and it cannot overheat.

Think of a water jet as something with about 30

times the pressure of the power washer wand at

your local car wash. Power washing at car

washes is an everyday example of a dirt film

being "cut" off the body, wheels and tires of an

automobile.

Computer-controlled water jet and abrasivejet cutting are used today in industry to cut many soft

and hard materials. The plain water-abrasive mixture leaves the nozzle at more than 900 mph.

The latest machines can cut to within two thousandths of an inch, and have jet speeds around

Mach 3.

Water jets can cut:

Marble

Granite

Stone

Metal

Plastic

Wood

Stainless steel

A water jet can remove the bark

from a tree at a distance of 40 feet

if one alters the chemistry of plain

water by adding a soluble

polymeric chemical that acts like a

series of molecular spinal columns

or concrete reinforcement bars

that tie the individual water

molecules together in more

structured way to form a coherent

jet. Imagine the potential for

cutting down roadside weeds.

A water jet can cut a "sandwich" of different materials up to four inches thick. This odorless,

dust-free and relatively heat-free process can also cut something as thin as five thousandths of

an inch. The tiny jet stream permits the first cut to also be the final finished surface. This single

cutting process saves material costs and machining costs. For example, the engineer merely

gives a gear drawing to the cutting shop via a diskette or e-mail and gets the finished gear back.

Water jets cut softer materials, while abrasive jets are used for harder materials. The actual

cutting is often done under water to reduce splash and noise. Faster feed rates are used to

prevent the jet from cutting all the way through.

The water pressure is typically between 20,000 and 55,000 pounds per square inch (PSI). The

water is forced through a 0.010" to 0.015" in diameter orifice (hole) in a jewel.

HISTORY

Water jet cutting can be traced back to hydraulic mining of coal in the Soviet Union and New

Zealand. Water was collected from streams and aimed to wash over a blasted rock face carrying

away the loose coal and rock. This method of mining was redeveloped in South African gold

mines to remove blasted rock from the work area into a collection drift or tunnel. In the

California Gold Country between 1853-1886, pressurized water was first used to excavate soft

gold rock from the mining surfaces. The pressurized water allowed the miner to stand further

back from the face being washed. This was safer because there was less danger of being covered

by a collapsing wall of blasted rock. By early 1900s this method of mining had re ached Prussia

and Russia. In these two countries the pressurized water was used to wash blasted coal away.

In the 1930s it was Russia that made the first attempt at actually cutting the rock with the

pressurized water. A water cannon was used to generate a pressure of 7000 Bars. In the 1970s

technology was developed in the USA that was capable of creating a 40,000 bar pressure.

Most of the water jet mining growth after this involved combining a drill with the water jet. In

1972 Professor Norman Franz of Michigan worked with McCartney Manufacturing Company to

install the first industrial water jet cutter. The equipment was installed in Alton Boxboard. Flow

industries also began to market industrial water jet cutting equipment. It was Flow Industries

who added sand to a pressurized cleaning system to give metal a white finish. After this it was

demonstrated that abrasive water jet systems could cut through metal and ceramics. From here

the water jet cutting industry took off.

How Stuff Works

Most water jet cutting theories explain water jet cutting as a form of micro erosion as described

here. Water jet cutting works by forcing a large volume of water through a small orifice in the

nozzle. The constant volume of water traveling through a reduced cross sectional area causes

the particles to rapidly accelerate. This accelerated stream leaving the nozzle impacts the

material to be cut. The extreme pressure of the accelerated water particles contacts a small area

of the work piece. In this small area the work piece develops small cracks due to stream impact.

The water jet washes away the material that "erodes" from the surface of the work piece. The

crack caused by the water jet impact is now exposed to the water jet. The extreme pressure and

impact of particles in the following stream cause the small crack to propagate until the material

is cut through.

TYPES OF WATER JET CUTTING

Essentially there are two main types of water jet cutting which include Pure water jet and

Abrasive water jet.

PURE WATER JET CUTTING

Pure water jet is the original water cutting method. The first commercial applications were in

the early to mid 1970s, and involved the cutting of corrugated cardboard.The largest uses for

pure water jet cutting are disposable diapers, tissue paper, and automotive interiors. In the cases

of tissue paper and disposable diapers the water jet process creates less moisture on the material

than touching or breathing on it.

Attributes

Very thin stream (0.004 to 0.010 inch in diameter is the common range)

Extremely detailed geometry

Very little material loss due to cutting

Non-heat cutting

Cut very thick

Cut very thin

Usually cuts very quickly

Able to cut soft, light materials

(e.g., fiberglass insulation up to 24" thick)

Extremely low cutting forces

Simple fixturing

24 hour per day operation

ABRASIVE WATER JET CUTTING

Abrasive water jet cutting differs from pure water jetcutting in just a few ways. In pure water jet

cutting, the supersonic stream erodes the material.In the abrasivewater jet, the water jet stream

accelerates abrasive particles and those particles, not the water, erode the material.The abrasive

water jet is hundreds, if not thousands of times more powerful than a pure water jet. Both the

water jetand the abrasive water jet have their place. Where the purewater jet cuts soft materials,

the abrasive water jet cuts hard materials, such as metals, stone, composites and

ceramics.

Abrasive water jets using standard parameters can cut materials with hardness up to and slightly

beyond aluminum oxide ceramic.

Attributes

Used to cut much harder materials

Water is not used directly to cut material as in Pure, instead water is used to accelerate

abrasive particles which do the cutting

80-mesh garnet (sandpaper) is typically used though 50 and 120-mesh is also used

Standoff distance between mixing tube and work part is typically 0.010-0.200 – important

to keep to a minimum to keep a good surface finish

Evolution of mixing tube technology

Standard Tungsten Carbide lasts 4-6 hours (not used much anymore)

Premium Composite Carbide lasts 100-150 hours

Consumables include water, abrasive, orifice and mixing tube

Tolerance

Typically +/- 0.005 inch

Machines usually have repeatability of 0.001 inch

Comparatively traditional machining centers can hold tolerances 0f 0.0001 inch with

similar repeatability

Water Jet tolerance range is good for many applications where critical tolerances are

not crucial to workpart design

Schematics of Abrasive and Simple water jet

Abrasive

Simple

MULTI AXIS WATER JET

With recent advances in control and motion technology, 5-axis water jet cutting (abrasive and

pure) has become a reality. Where the normal axes on a water jet are named X (back/forth),

Y(left/right) and Z (up/down), a 5-axis system will typically add an A axis (angle from

perpendicular) and C axes (rotation around the Z-axis). Depending on the cutting head, the

maximum cutting angle for the A axis can be anywhere from 55, 60, or in some cases even 90

degrees from vertical. As such, 5-axis cutting opens up a wide range of applications that can be

machined on a water jet cutting machine.

A 5-axis cutting head can be used to cut 4-axis parts, where the bottom surface geometries are

shifted a certain amount to produce the appropriate angle and the Z-axis remains at one height.

This can be useful for applications like weld preparation where a bevel angle needs to be cut on

all sides of a part that will later be welded, or for taper compensation purposes where the kerf

angle is transferred to the waste material - thus eliminating the taper commonly found on water

jet-cut parts. A 5-axis head can cut parts where the Z-axis is also moving along with all the other

axis. This full 5-axis cutting could be used for cutting contours on various surfaces of formed

parts.Because of the angles that can be cut, part programs may need to have additional cuts to

free the part from the sheet. Attempting to slide a complex part at a severe angle from a plate

can be difficult without appropriate relief cuts.

Advantages

Cheaper than other processes.

Cut virtually any material. (pre hardened steel, mild steel, copper, brass, aluminum;

brittle materials like glass,

ceramic, quartz, stone)

Cut thin stuff, or thick stuff.

Make all sorts of shapes with only

one tool.

No heat generated.

Leaves a satin smooth finish, thus reducing secondary operations.

Clean cutting process without gasses or oils.

Modern systems are now very easy to learn.

Is very safe.

Machine stacks of thin parts all

at once.

Unlike machining or grinding, water jet cutting does not produce any dust or particles

that are harmful if inhaled.

The kerf width in water jet cutting is very small, and very little material is wasted.

Water jet cutting can be easily used to produce prototype parts very efficiently. An

operator can program the dimensions of the part into the control station, and the water

jet will cut the part out exactly as programmed. This is much faster and cheaper than

drawing detailed prints of a part and then having a machinist cut the

part out.

Water jets are much lighter than equivalent laser cutters, and when mounted on an

automated robot. This reduces the problems of accelerating and decelerating the robot

head, as well as taking less energy.

CNC WATER JET CUTTING

CNC water jet cutting is a process that produces

shapes by cutting sheet material using a high

pressure stream of water containing abrasive

particles.

CNC water jet cutting is an economical way

to cut 2Dshapes in a very wide range of materials

with no tooling costs. The unique process of

CNC water jetcuttingprovides reasonably good

edge quality, no burrs and usually eliminates the

need for secondary finishing processes. The process

also generates no heat so the material edge is unaffected and there is no distortion.

CNC water jet cutting can cut single or multi-layer materials from as thin as .001" to as thick as

several inches. The process yields no poisonous gas when cutting plastics or rubber.

Shapes possible with CNC water jet cutting include 2D shapes with cutouts of almost any

complexity. Examples of parts that are often cut using CNC water jet cutting include: Robot

Parts, Washers, Front Panels, Automotive Parts, Metal boxes and Chassis etc.

PROS AND CONS OF WATER JET CUTTING

Advantages

Water jet cutting has many applications, and there are many reasons why water jet cutting is

preferable over other cutting methods. Listed below are several advantages, along with a brief

explanation.

In water jet cutting, there is no heat generated. This is especially useful for cutting tool

steel and other metals where excessive heat may change the properties of the material.

Unlike machining or grinding, water jet cutting does not produce any dust or particles

that are harmful if inhaled.

The kerf width in water jet cutting is very small, and very little material is wasted.

Water jet cutting can be easily used to produce prototype parts very efficiently. An

operator can program the dimensions of the part into the control station, and the water

jet will cut the part out exactly as programmed. This is much faster and cheaper than

drawing detailed prints of a part and then having a machinist cut the part out.

Water jet cutting can be easily automated for production use.

Water jet cutting does not leave a burr or a rough edge, and eliminates other machining

operations such as finish sanding and grinding.

Water jets are much lighter than equivalent laser cutters, and when mounted on an

automated robot. This reduces the problems of accelerating and decelerating the robot

head, as well as taking less energy.

Disadvantages

Water jet cutting is a very useful machining process that can be readily substituted for many

other cutting methods; however, it has some limitations to what it can cut. Listed below are these

limitations, and a brief description of each.

One of the main disadvantages of water jet cutting is that a limited number of materials

can be cut economically. While it is possible to cut tool steels, and other hard materials,

the cutting rate has to be greatly reduced, and the time to cut a part can be very long.

Because of this, water jet cutting can be very costly and outweigh the advantages.

Another disadvantage is that very thick parts cannot be cut with water jet cutting and still

hold dimensional accuracy. If the part is too thick, the jet may dissipate some, and cause

it to cut on a diagonal, or to have a wider cut at the bottom of the part than the top. It can

also cause a ruff wave pattern on the cut surface.

Taper is also a problem with water jet cutting in very thick materials. Taper is when the

jet exits the part at a different angle than it enters the part, and can cause dimensional

inaccuracy. Decreasing the speed of the head may reduce this, although it can still be a

problem.

APPLICATIONS OF WATER JET CUTTING

Due to the uniqueness of water jet cutting, there are many applications where it is more useful

and economical than standard machining processes. In this section, some of the major

applications and uses for water jet cutting will be discussed, and the reasons why this method

works better.

First of all, water jet cutting is used mostly to cut lower strength materials such as wood,

plastics, and aluminum. When abrasives are added, stronger materials such as steel, and even

some tool steels can be cut, although the applications are somewhat limited. Listed below are

different applications, and reasons why water jet cutting is used for each one.

Printed Circuit Boards: For circuit boards, water jet cutting is mostly used to cut out smaller

boards from a large piece of stock. This is a desired method, since it has a very small kerf, or

cutting width, and does not waste a lot of material. Because the stream is so concentrated, it can

also cut very close to the given tolerances for parts mounted on the circuit board without

damaging them. Another benefit is that water jet cutting does not produce the vibrations and

forces on the board that a saw would, and thus components would be less likely to be damaged.

Wire Stripping: Wire stripping is another application that can be used effectively in water jet

cutting. If no abrasives are used, the stream is powerful enough to remove any insulation from

wires, without damaging the wires themselves. It is also much faster and efficient than using

human power to strip wires.

Food Preparation: The cutting of certain foods such as bread can also be easily done with water

jet cutting. Since the water jet exerts such a small force on the food, it does not crush it, and with

a small kerf width, very little is wasted.

Tool Steel: For abrasive water jet cutting, tool steels are one application, although a limited

one. It can be very useful though because tool steel is generally very difficult to cut with

conventional machining methods, and may cause an unwanted byproduct: heat. Abrasive water

jets, however, do not produce heat that could alter the structure of the material being cut, and

thus the strength of the tool is retained.

Wood Cutting: Woodworking is another application that abrasive water jet machining can be

used for. Since wood is a softer material compared to steel, almost all wood can be cut, and the

abrasive particles sand the surface, leaving a smooth finish that doesn‟ t require sanding.

Defense: Manufacturers working with the military are constantly exploring advanced

applications for the latest in lightweight, high strength materials. Cutting these exotic materials

can pose a serious challenge to traditional methods.Water jets effortlessly cut through the

toughest materials including Super alloys, Ceramic matrix composites, Armor, Carbides,

Titanium, Kevlar and Ballistic materials etc.

Automotive:Water jets are used to cut a wide-range of interior and exterior components such as

headliners, carpets, acoustical materials, instrument and door panels as well as side moldings,

weather-stripping and castings.Removing paint overspray and build-up is a critical step in

automotive quality, and water jet systems do the job quickly and thoroughly.

Tank and Tote Cleaning: Tanks, reactors and totes are quickly cleaned with high-pressure

water jets, generally in a fraction of the time needed for manual or caustic cleaning. Water jets

are friendly to the environment and personnel. Since water jet cleaning eliminates the need for

anyone to enter a tank, meeting the latest confined space standards is no problem at all.

Artistic andArchitectural Applications: Imagination is the only limitation for creating unique

designs with the water jet.From metal architecture for parking structures to decorative glass

Christmas tree ornaments for the White House Christmas tree, artists and architects alike have

discovered the ease of use and versatility of water jets to help create works of art.

Aerospace: Water jet cutting technology has an effective use in aerospace industry. It is used in

making titanium bodies for military aircrafts, engine components of aircrafts and interior cabin

panels etc.

WATER JET VERSUS OTHER MACHINING PROCESSES

WATER JETS VS. LASERS

Abrasive water jets can machine many materials that lasers cannot. (Reflective materials

in particular, such as Aluminum and Copper.

Uniformity of material is not very important to a water jet.

Water jets do not heat your part. Thus there is no thermal distortion or hardening of the

material.

Precision abrasive jet machines can obtain about the same or higher tolerances than

lasers (especially as thickness increases).

Water jets are safer.

Maintenance on the abrasive jet nozzle is simpler than that of a laser, though probably

just as frequent.

After laser After water jet

WATER JETS VS. EDM

Water jets are much faster than EDM.

Water jets machine a wider variety of materials (virtually any material).

Uniformity of material is not very important to a water jet.

Water jets make their own pierce holes.

Water jets are capable of ignoring material aberrations that would cause wire EDM to

lose flushing.

Water jets do not heat the surface of what they machine.

Water jets require less setup.

Many EDM shops are also buying water jets. Water jets can be considered to be like

super-fast EDM machines with less precision.

WATER JET VS PLASMA

Water jets provide a nicer edge finish.

Water jets don't heat the part.

Water jets can cut virtually any material.

Water jets are more precise.

Plasma is typically faster.

Water jets would make a great compliment to a plasma shop where more precision or

higher quality is required, or for parts where heating is not good, or where there is a

need to cut a wider range of materials.

After plasma cutting After water jet

MECHANICAL PROCESSES VS. WATER JET CUTTER

Unlike mechanical methods, such as jackhammering, Cutter hydrodemolition does not damage the rebar

or cause micro-cracks in the concrete. Furthermore, it is far more effective than the use of a hand lance,

which is the simplest form of water jetting and is often incorrectly referred to hydrodemolition or concrete

cutting.

Selective removal

Hydrodemolition removes the concrete only down to a preset „quality depth‟ , leaving a jagged or craggy

surface that provides an extensive bonding area.

Jackhammers tend to leave a flatter surface, with fewer peaks and valleys and therefore less bonding area.

Another advantage of hydrodemolition is that the Cutter typically removes damaged concrete several

times faster than jackhammers – and users have found that it can be up to 25 times faster. Directing high-

velocity water jets against a surface to produce a destructive effect has long been successfully used for the

high-speed cutting or drilling of rocky materials and particularly concrete. Hydrodemolition developed

from the uses of high-pressure water for drilling, cutting or hole-making in concrete.

Water-jet cutting has also proved to be a versatile technique in many other areas of industry, from early

uses in cleaning inaccessible machine parts to modern specialist applications such as the precision cutting

of intricate components.

Efficient flexibility

Jet Cutter robots are the most advanced on the market thanks to their extensive range of features,

ensuring that top quality results are achieved safely at a high production rate with low operating and

on-going costs.

The robots are small and compact but at the same time big enough to handle the toughest applications.

Their versatility enables hydrodemolition to take place in even the most difficult situations and the use of

tracks instead of wheels makes the machines easy to manoeuvre across any terrain.

A multi-axis system has been developed, that enables fast 3D positioning of the front power head so that

the unit can be rapidly put to work on any vertical, curved or horizontal surface.

Hydraulically controlled side shifting of the power head offers better reach and easier operation in

confined spaces and the power head can be quickly tilted and turned for vertical and ceiling demolition,

with no need for additional equipment. Tower sections can be erected easily if required.

Optimum capacity

The Water jet Cutters operates using an easily programmed automated control system, which optimizes

the settings and applies only the minimal required force.

The robot works selectively, with its high-pressure jet of water penetrating into the weak concrete as it passes across the surface. The jet breaks up the damaged concrete and flushes it away. All that is then

needed is a final clean-up to remove any debris, leaving the clean, rough surface ready for concreting.

The high-pressure water is delivered to the robot through a flexible high-pressure hose. The water travels

down a lance where it meets a nozzle, whose opening is sized according to the pressure and flow

requirements. The lance manipulates the jet as it leaves the nozzle and can either oscillate or rotate,

depending on the type of removal required.

Water jets accomplish their destructive action on concrete by means of three separate processes: direct

impact, cavitations and pressurization of micro- and macro-cracks. The nozzle is played rapidly and

continuously over the area to be removed. Jet efficiency is maximized when the jet itself is stable, and

stability is influenced by the machine design, distance from the nozzle to point of impact, the shape and

configuration of the nozzle, the water exit speed, the jet‟ s movement and the angle of attack.

Fig: MECHANICAL DEMOLITION TECHNIQUES. [Orthodox]

Fig: HYDRODEMOLITION [Precise and Cost Effective]

FLAME CUTTING

Water jets would make a great compliment to a flame cutting where more precision or higher

quality is required, or for parts where heating is not good, or where there is a need to cut a

wider range of materials.

MILLING

Water jets are used a lot for complimenting or replacing milling operations. They are used for

roughing out parts prior to milling, for replacing milling entirely, or for providing secondary

machining on parts that just came off the mill. For this reason, many traditional machine shops

are adding water jet capability to provide a competitive edge.

PUNCH PRESS

Some stamping houses are using water jets for fast turn-around, or for low quantity or

prototyping work. Water jets make a great complimentary tool for punch presses and the like

because they offer a wider range of capability for similar parts.

PROSPECTS OF USING WATER JET FOR CUTTING MARBLE

For impeccable quality and true elegance and beauty, water jet cutting provides the

perfect stone and tile cut and finish.

Ability to cut the most intricate stone, tile and marble designs.

With speeds up to Mach 4 or 90,000psi water pressure capability for the fastest cutting

process in the water jet industry using the Next Generation in stone and tile fabrication.

Ideal for cutting up to 12‖ of materials depending on density of product.

The LARGEST International network of motion control water jet table system OEM

integrators, including X-Y, X-Y-Z, or up to 6 Axis, offering you flexibility of choices

including Saw and water jet combination systems. You decide what you need.

Eliminates most secondary finishing… no rough edges

No Heat Affected Zone (HAZ) which is ideal for glass, stone, tile, marble and more.

Eliminates the risk of discoloring or deformation.

Safe for the Environment; no toxic fumes or dust and garnet is disposable.

Omni-directional cutting. Minimal tolerances. No wasteful raw materials.

Cutting heads do not have to be changed out during manufacturing avoiding aggravating

delays.

Thick or thin, water jet cutting is the most flexible process in manufacturing.

Minimal set up for automated cutting process.

Cuts without melting.

Can pierce material directly without the need for a pre-drilled starter hole.

Complex Shapes

Precision Cutting

Small cutting kerf

No tool sharpening

Capable of cutting 90 degree angles and corners.

High or low surface pressure flexibility for sensitive or thick materials

Tolerances around about(±0.003")

Performance Quality

The Water Jet Cutting has been put to many seemingly impossible tasks of cutting mammoth

concrete structures, yet the machines implementing state of the art Fluid Mechanics Techniques

have lived up to the expectations of researchers and industrialists.

Test slabs designed to provide a tough challenge to this new technology have been completely

undone (The margin figure preserves the aftermath of one such test).

Minutiae of Pressurized Water Jet Cutter

Cutting Performance Measures

The cutting performance and precision are the key factor behind the adoption of a material

machining process on an industrial scale. The criteria keep on varying from one application

(each demanding a new level of specificity) to another, and each application provides new

challenges to researchers.

Some of the performance yardsticks are stated as follows:

traverse speed

flow rate

standoff distance

water pressure.

feed rate.

Pressure Jet Morphology

Pulsating Jet Scheme

Generating of sufficiently high pressure pulsations in pressure water upstream the nozzle exit

enables to create a pulsating liquid jet that emerges from the nozzle as a continuous liquid jet

and it forms into pulses at certain distance from the nozzle exit. The advantage of such a

pulsating jet over the continuous one is based on the fact that

the initial impact of pulses of pulsating jet on the target

surface generates the impact pressure that is several times

higher than the stagnation pressure generated by the action

of continuous jet under the same working conditions. In Fig: Fatigue Fracture

addition, the action of pulsating jet induces also fatigue

stress in the target material due to the cyclic loading of the

target surface.

Fig: Fatigue Fracture

FIG: Damage morphology produced due to cyclic loading.

According to tests conducted at The Institute of Geonics ASCR, in Ostrava (IGN), the

performance of pulsating water jets in cutting of various materials is at least two times higher

compared to that obtained using continuous ones under the same working conditions.

Analyses

The efficient transfer of the high-frequency pulsation energy in the high-pressure system to

longer distances (in order of meters) represents one of prerequisites for creation of a highly

effective pulsating liquid jet with required properties. To achieve that goal, the amplification of

pressure pulsations propagated through the high-pressure system is necessary. Therefore, both

analytical and numerical models of the high-pressure system including the acoustic generator of

pressure pulsations are used to study process of excitation and propagation of pressure waves in

the system.

Fig: Tubular acoustic pressure wave generator.

Modeling and Simulation of Pulsating Jet

Analytical Model

A majority of Analytical models are based on linearized Navier-Stokes equations and wave

equation for propagation of pressure wave. Both standard kinematical viscosity and kinematical

second viscosity that is related to the liquid compressibility are taken into account. Based on

analytical solution in 3D domain with circular cross section, the transfer matrices are set up.

Both pressure and flow pulsations of hydraulic systems can be solved on the basis of the transfer

matrices. Simulations reveal that oscillations of a acoustic actuator can generate a standing

wave in the hydraulic system. The standing wave converts to the travelling one at the

area close to the nozzle exit. Based on the quality of the design of the diffuser-type nozzle

, the amplitude of pressure pulsations at the exit of the pulsating nozzle can be increased many

folds.

Fig: Standing Wave Pattern.

Numerical Model

The Numerical models are generally used for numerical simulation of 3D, Unsteady , turbulent

flow of compressible water in the high pressure system. The model behaviour is verified by the

comparison with the experimental measurement of the pressure using corresponding

configuration of the system under the same working conditions. It is a common finding that

numerical model provide information on time behavior of pressure in high-pressure system that

is in relatively very good agreement with experimental measurement. It can be also stated that

the numerical model is able to simulate influence of geometry changes on the amplitude of

pressure accurately and thus also to simulate acoustic (and/or pressure) wave propagation and

transmission in the high-pressure system.

Flow Visualization

Digital Flow visualization techniques are used to probe morphology of the pulsating

water jets.

The motives behind this effort are the following:

1. Examination of characteristics of the jet such as mean velocity and break-up

length of the pulsating.

2. Study the process of formation of the jet and development of pulses in the jet.

3. Validate results obtained from CFD models.

Among the common flow visualization techniques, the illumination of the pulsating jet by

stroboscope is the most frequently put to use. However for high speed pulsating water jet, pulsed

laser light produces best results. To study an instantaneous structure of the pulsating jet,

the visualization tests such as Particle Image

Velocimetry (PIV) are performed.

Fig: The instantaneous structure of the flat pulsating

water jet generated at 20 MPa. (illumination by pulsed laser)

Fig: The mean structure of the pulsating water jet generated at 30 MPa (illumination by the stroboscope)

Abrasive Water Jet technology (AWJ)

The abrasive waterjet cutting technique is a controlled erosive process in which the

impact of high velocity water and abrasives cause cutting of the target material.

Basic Geometry

The primary components of an abrasive waterjet cutting system are the dual intensifying pump,

the nozzle assembly and the abrasive catcher assembly. These components are connected by a

network of hoses and swivels and are controlled by a system of control valves and sensors. Fig: Typical nozzle configuration for mixing abrasive with waterjet in an abrasive waterjet cutting head.

Fig: Block diagram of abrasive waterjet system components

Salient Features

No thermal distortion,

high machining versatility

Little (if any)postmachining required.

Coherent water stream laden with abrasives acts a s a focused high-velocity stream of

particles. These particle travel at about twice the speed of sound and produce a very

narrow kerf.

Cuts can be initiated at any point on the workpiece and can be made in any direction of

contour, linear, or tangential.

No delamination.

No thermal or nonthermal stresses along the cutting path.

Mathematical Models

For the past 4 decades, since the inception of Water jet Cutting Technology many Mathematical

Models have been proposed. The important feature of all of the Models has been their

individuality and versatility. Each Model of Fluid Dynamics has focused on nailing down the

most crucial parameters involved in maximizing the efficiency of the cutting process. So far the

few parameters which have been recognized as ―important‖ are:

feed rate

water pressure

Abrasive flow(If abrasives are added )

Following figures in indicate the importance of two of the parameters: Fig: Variation of depth of mill as a function of feed rate and water pressure usingabrasive rate 0.55 kg/min

Fig: Variation of depth of mill as a function of feed rate and abrasive flow using a water pressure 3094 Bar

Type of analyses developed to construct Flow Models

regression analysis.

fracture mechanics.[1]

dimensional analysis.[2]

Analyses based on solid particle erosive theories.[3][4]

FUTURE TRENDS IN WATER JET TECHNOLOGY

Since its development, water jet machining has seen many improvements in its design. Many

different types of abrasives, nozzles, flow rates, and jet positions have been experimented with to

name a few. Certain expected improvements and innovations in the water jet technology in the

future are as under.

General trend towards smaller water jet machines

In general, there is a push towards smaller, more precise, and cheaper machines. These make

great compliments to existing machine shop operations, or additions to existing water jet shops.

Expect to see a lot of new machines of this type.

This trend is analogous to what has happened with the printing industry beginning in the last

part of the 20th century. Back then, if you wanted something printed, you went to a specialty

shop that had a printing press, and paid a lot to get your printing work done. To keep costs

manageable, you printed huge quantities at once. The setup was tedious, the equipment was big

and messy, and it required a lot of special skills.

Today, most offices have several printers, and a photocopier. You might still send some work to

the printers for large volumes, but for the most part you do everything on your easy to use, small,

and affordable desktop printer.

This trend is already underway and will probably continue. There are even people who suggest

that "desktop water jets" are possible—although they would be lower power (that is, slower) they

would still be able to cut most materials. Like the printing press, there will still be a market for

huge machines and high production.

Between now and the year 2015

In the next half-dozen years or so, you can expect to see the following changes:

More manufacturers

Machines will be made by more manufacturers, most of whom will be system integrators who

buy existing components and assemble them in unique ways. Others will spawn from job shops

that have abrasive jet equipment, but think they can make it better. This is close to the current

situation.

More machines in different shops

You can expect to see more and more machines out there in many different shops. Most of these

shops at this moment do not think they have a need for such machines because they don't yet

understand what they are really capable of.

Easier maintenance

There will be many improvements in terms of maintenance on the machines, and overall quality

of the parts used in construction of the machines. In general, there will be a lot of refinements

and polish in the machines, making them more user friendly, nicer looking, and easier to work

on.

Faster and more accurate machines

Manufacturers will make incremental, but steady, improvements in precision and speed. By

2015, the machines of the early 1990's will seem quaint and crude.

More direct drive pumps

The shift from older intensifier pump designs to more efficient and faster cutting direct drive

pumps will continue. Nearly all manufacturers will have direct drive pumps by 2015. Intensifier

pumps will probably still be used on some older machines, or for specialty applications.

Cheaper better mixing tubes

Somebody will make an absolute fortune by introducing a cheap, long-lasting mixing tube.

Mixing tubes are expensive and tend to be worn down in only a few hundred hours of use.

Before the year 2030

The water jet industry is at about the same place the automotive industry was in the 1920's.

There are a lot of companies that are making a lot of strange contraptions with different designs,

but as time goes on we will see a more standard look to the machines as all the manufacturers

borrow the good ideas from their competitors.

There will be small size water jet machine tools in nearly every shop that has a vertical

machining center, or a lathe.

There will be even more huge machines used for high production.

There will always be a lot of custom machines as well for custom applications.

The total number of water jet manufacturers will decrease as companies merge. A few of

the others will appear and disappear. A few will be very successful.

Beyond 2030

Looking this far into the future, especially with technology changing at an ever accelerating

pace, it gets harder to accurately predict. Still, there are certain trends that are bound to

continue.

Throughout the machine tool world and other industries, controller technology will be

astonishingly flexible. This will be driven by a combination of:

Neural Network software

Genetic Algorithms

Nano technology

Software and hardware architectures that use fractal like neural net structures

A continuation of the current trend of exponential increases in computer speed and

memory

New processor architectures that exploit the various aspects of serial and parallel

computing, as well as 3-D design and advanced cooling and organic electro-optical

materials and devices

Chemical computing (for example DNA), optical computing, and quantum computing

may also play a part in this, though maybe not too soon.

Other technologies yet to be discovered, such as holographic multidimensional

computation and display devices..

Eventually, this will lead to the ultimate machine tool controller. This will be one that you walk

up to and say, "Make something that pleases me."

In the future, people will look back at the early 21st century as the beginning of the most exciting

period in the water jet industry. Just as the Ford Model-T is seen as quaint and old-fashioned,

the state-of-the-art water jet machines of today will seem out-of-date and underpowered.

REFERENCES

[1] A.A. Abdel-Rahman, and A. A. El-Domiaty, ―Maximum depth of cut for ceramics using

abrasive water jet technique‖, Wear, 218, pp. 216-222, 1998.

[2] J. Wang, ―A new model for predicting the depth of cut in abrasive waterjet contouring of

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