1. Introduction to 3D Printing

3D printing is a form of additive manufacturing technology where a

three dimensional object is created by laying down successive layers of

material. It is also known as rapid prototyping, is a mechanized method

whereby 3D objects are quickly made on a reasonably sized machine

connected to a computer containing blueprints for the object. The 3D

printing concept of custom manufacturing is exciting to nearly everyone.

This revolutionary method for creating 3D models with the use of inkjet

technology saves time and cost by eliminating the need to design; print

and glue together separate model parts. Now, you can create a complete

model in a single process using 3D printing. The basic principles include

materials cartridges, flexibility of output, and translation of code into a

visible pattern.

1.1 Typical 3D Printer

3D Printers are machines that produce physical 3D models from digital

data by printing layer by layer. It can make physical models of objects

either designed with a CAD program or scanned with a 3D Scanner. It

is used in a variety of industries including jewelry, footwear, industrial

design, architecture, engineering and construction, automotive,

aerospace, dental and medical industries, education and consumer

products.

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2. History of 3d Printing

The technology for printing physical 3D objects from digital data was

first developed by Charles Hull in 1984. He named the technique as

Stereo lithography and obtained a patent for the technique in 1986.

While Stereo lithography systems had become popular by the end of

1980s, other similar technologies such as Fused Deposition Modeling

(FDM) and Selective Laser Sintering (SLS) were introduced.

In 1993, Massachusetts Institute of Technology (MIT) patented another

technology, named "3 Dimensional Printing techniques", which is

similar to the inkjet technology used in 2D Printers.

In 1996, three major products, "Genisys" from Stratasys, "Actua 2100"

from 3D Systems and "Z402" from Z Corporation were introduced. In

2005, Z Corp. launched a breakthrough product, named Spectrum Z510,

which was the first high definition color 3D Printer in the market.

Another breakthrough in 3D Printing occurred in 2006 with the initiation

of an open source project, named Reprap, which was aimed at

developing a self-replicating 3D printer.

As of 2013, domestic 3D printing has mainly captivated hobbyists and

enthusiasts and has not quite gained recognition for practical household

applications but is slowly getting there.

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3.Current 3d Printing Technologies

3.1 Fused Deposition Modeling: Fused deposition modeling uses a

plastic filament or metal wire that is wound on a coil and unreeled to

supply material to an extrusion nozzle, which turns the flow on and off.

The nozzle heats to melt the material and can be moved in both

horizontal and vertical directions by a numerically controlled mechanism

that is directly controlled by a computer-aided manufacturing (CAM)

software package. The model or part is produced by extruding small

beads of thermoplastic material to form layers as the material hardens

immediately after extrusion from the nozzle.

3.2 Stereolithography: Stereo lithographic 3D printers (known as SLAs

or stereo lithography apparatus) position a perforated platform just

below the surface of a vat of liquid photo curable polymer. A UV laser

beam then traces the first slice of an object on the surface of this liquid,

causing a very thin layer of photopolymer to harden. The perforated

platform is then lowered very slightly and another slice is traced out and

hardened by the laser. Another slice is then created, and then another,

until a complete object has been printed and can be removed from the

vat of photopolymer, drained of excess liquid, and cured.

3.3 Electron beam Melting: EBM) is a type of additive manufacturing

technology for metal parts (e.g. titanium alloys). EBM manufactures

parts by melting metal powder layer by layer with an electron beam in a

high vacuum. Unlike metal sintering techniques that operate below

melting point, EBM parts are fully dense, void-free, and very strong.

3.4 Selective Laser Sinistering: Another 3D printing approach is the

selective fusing of materials in a granular bed. The technique fuses parts

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of the layer, and then moves the working area downwards, adding

another layer of granules and repeating the process until the piece has

built up. This process uses the unfused media to support overhangs and

thin walls in the part being produced, which reduces the need for

temporary auxiliary supports for the piece. A laser is typically used to

sinter the media into a solid.

3.5 Inkjet 3d Printing: In this method the printer creates the model one

layer at a time by spreading a layer of powder (plaster, or resins) and

printing a binder in the cross-section of the part using an inkjet-like

process. This is repeated until every layer has been printed. This

technology allows the printing of full color prototypes, overhangs, and

elastomer parts. The strength of bonded powder prints can be enhanced

with wax or thermoset polymer impregnation.

This is the most widely used 3d Printing technology today for reasons

listed below:

⦁ It allows for the printing of full color prototypes.

⦁ Unlike stereo lithography, inkjet 3D printing is optimized for speed, low cost, and ease-of-use.

⦁ No toxic chemicals like those used in stereo lithography are required.

⦁ Minimal post printing finish work is needed; one needs only to use the printer itself to blow off surrounding powder after the printing process.

⦁ Allows overhangs and excess powder can be easily removed with an air blower.

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Fig 1.1 Fused Deposition Modeling - 1) Nozzle, (2) Depositted Material (model), (3) Controlled movable table

Fig 1.2 Stereolithography apparatus.

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4. Manufacturing a Model with 3d Printer

The model to be manufactured is built up a layer at a time. A layer of

powder is automatically deposited in the model tray. The print head then

applies resin in the shape of the model. The layer dries solid almost

immediately. The model tray then moves down the distance of a layer

and another layer of power is deposited in position, in the model tray.

The print head again applies resin in the shape of the model, binding it to

the first layer. This sequence occurs one layer at a time until the model is

complete.

4.1 Algorithm: The algorithm used in the Inkjet 3-D Printing is depicted

in the figure mentioned below.

Fig 4.1

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5. Workflow

The workflow can be easily understood with the help of the flowchart given below. A 3-D prototype of a desired object is created in three basic steps and these steps are:

⦁ Pre-Process (preparations)

⦁ 3-D Printing

⦁ Post-Process

Fig 5.1 Processes in 3d Printing

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6. Process

6.1 Pre-Process (Designing and Preparation): Computer-aided design (CAD), also known as computer-aided design and drafting (CADD), is used to prepare a 3-D or 2-D model of the desired object. Modern CAD packages can also frequently allow rotations in three dimensions, allowing viewing of a designed object from any desired angle. Most 3D printers require a special file (typically .stl format) to print. Additionally, we need to modify the design to make up for limitations of the printer and build material.

Fig 6.1 Design of a simple 3d Object modelled in a CAD software

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6.2 Printing: The 3D printer runs automatically, depositing materials at

layers ~.003″ thick. This is roughly the thickness of a human hair or

sheet of paper. The time it takes to print a given object depends

primarily on the height of the design, but most designs take a minimum

of several hours. The average cost for printing a full color prototype is

somewhere between 20 - 100 $.

Fig 6.2 A 3d Printing in action

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6.3 Cleaning 3d Printouts (Post-Process): Every 3D printer uses some

sort of material to support parts of the design that have an overhang.

Some printers use a loose powder which can be blown off and reused in

future models.

Fig 6.3.1 the Han Solo in Carbonite stage.

6.3.1 Powder Removal: In this phase dust is removed from the model

and it is then dipped in special glue that makes the structure stronger and

more colorful.

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Fig 6.3.2 A 3d Model being dusted.

6.3.2 Heating: In this phase the models are heated to set the glue. Commercial Microwave ovens is sometimes used in this process.

Fig 6.3.3 A 3d Printout in a standard oven.

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6.3.3 Final Touches: The output of all existing 3D printers is rough.

The textures vary from pronounced "wood grain" to merely "sandy".

With a little elbow grease you can get stunning results.

Fig 6.3.4

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7. Benefits of 3d Printing

The most successful companies have adopted 3D printing as a critical

part of the iterative design process to:

Boost Innovation:

⦁ Print prototypes in hours, obtain feedback, refine designs and repeat the cycle until designs are perfect.

Improve Communication:

⦁ Hold a full color, realistic 3D model in your hands to impart infinitely more information than a computer image.

⦁ Create physical 3D models quickly, easily and affordably for a wide variety of applications.

Rapid prototyping:

⦁ Compress design cycles by 3D printing multiple prototypes on demand, right in your office.

Reduce Development Costs:

⦁ Cut traditional prototyping and tooling costs.

⦁ Identify design errors earlier.

⦁ Reduce travel to production facilities.

Win Business:

⦁ Bring realistic 3D models to prospective accounts, sponsors and focus groups.

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8. Applications

8.1 Design Prototypes: 3-Dimensional Printing produces concept

model, functional prototypes and presentation models for evaluating and

refining design, including Finite Element Analysis (FEA) results and

packaging.

Fig 8.1 A dummy of a Nokia mobile phone for further study and demonstration

Size: 3.5 x 2 x 0.7 inches

Printing time: 30 min

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8.2 Mass Customization: Companies have created services where

consumers can customize objects using simplified web based

customization software, and order the resulting items as 3D printed

unique objects.

8.3 Education: Engage students by bringing digital concepts into the

real world, turning their ideas into real-life 3D color models that they

can actually hold in their hands.

Fig 8.2 An electronic device circuit has come to life with the help of a 3-D Printer

Size: 8 x 5 x 2.5 inches

Printing Time: 3 hr

8.4 Healthcare: Rapidly produce 3D models to reduce operating time,

enhance patient and physician communications, and improve patient

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outcomes.

Fig 8.3 A 3d model of a rib cage and set of lungs

Fig 8.4 A 3-D Prototype of the horizontal crossection of a human skull

Size: 9.8 x 7.9 x 3.9 inches

Printing Time: 5.5 hr

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9. 3d Printing Success Story

⦁ 3D printing is becoming inexpensive enough for everyday enthusiasts to test the technology.

⦁ Some bioprinting labs are using cells to print sheets of skin for skin grafting procedures (see Fig 9.1).

⦁ Camera mounts for the M1 tank and Bradley fighting vehicle were built and tested directly from digital files using the Dimension 3D Printer.

⦁ Modern Meadow is a 3D bioprinting startup that aims to develop cell-based products to replace beef and leather. PayPal co-founder Peter Thiel is investing $350,000 in the company.

⦁ A 3D printer proved to be a valuable asset and played a key role in developing concepts for the AMP Research Alloy Fuel Door for General Motors' Hummer H2 sport utility vehicle.

⦁ Scientists at Cornell Creative Machines Lab are testing bioprinting products that are edible such as cakes that can include printed letters and logos inside (see Fig 9.2).

⦁ Scientists at the Wake Forest Institute for Regenerative Medicine have developed tissue aimed at replicating the outer ear using bioprinting (see Fig 9.3).

⦁ The scientists at Wake Forest IRM are also using bioprinting to develop a replacement bladder (see Fig 9.4).

⦁ Scientists at Vienna University of Technology took this photo with an electron microscope to show their nano-scale model of an F1 racing car model, an example created by their 3D printing

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technique for nano structures (see Fig 9.5).

⦁ Dancer Dita Von Teese recently modeled a 3D printed dress by designer Michael Schmidt and architect Francis Bitonti. They used laser infused nylon powder in a technique called selective laser sintering (SLS) to build up layers into a spiral design and netted structure to give it flexibility.

⦁ Connecticut-based Oxford Performance Materials used 3D printing to replace bone and insert the material into an American patient's skull in March 2013 (see Fig 9.6).

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10. Conclusion

Nothing communicates ideas faster than a three-dimensional part or

model. With a 3D printer you can bring CAD files and design ideas to

life – right from your desktop. Test form, fit and function – and as many

design variations as you like – with functional parts. In an age in which

the news, books, music, video and even our communities are all the

subjects of digital dematerialization, the development and application of

3D printing reminds us that human beings have both a physical and a

psychological need to keep at least one foot in the real world. 3D

printing has a bright future, not least in rapid prototyping (where its

impact is already highly significant), but also in medicine the arts, and

outer space. Desktop 3D printers for the home are already a reality if you

are prepared to pay for one and/or build one yourself. 3D printers

capable of outputting in color and multiple materials also exist and will

continue to improve to a point where functional products will be able to

be output. As devices that will provide a solid bridge between

cyberspace and the physical world, and as an important manifestation of

the Second Digital Revolution, 3D printing is therefore likely to play

some part in all of our futures.

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