L4-Other Welding Process

8/18/2019 L4-Other Welding Process

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ManufacturingProcess I

OTHER WELDING PROCESSES


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Friction Welding

Friction welding is a solid-state welding process in which coalescence is achieved by frictional heat combined with pressure. The heat is generated by the friction between the two components surfaces, usually by rotation of one part relative tothe other. Then the parts are driven toward each other with sufficient force toform a metallurgical bond. The sequence is portrayed in the figure for the typicalapplication of this operation, welding of two cylindrical parts.


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Welding Variables for Friction and Inertia Welding

(i) Relative speed(ii) Friction pressure

(iii) uration of heating (burn off)(iv) Forge pressure.

For most materials, there is wide range of combinationsof speed and pressure that may be used to give e!cellentmechanical and metallurgical integrity in the weld.


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Materials Welded by Friction Welding (i)Aluminium and its alloys(ii) Nickel alloys(iii) Brass and bronze(iv) Alloy steels(v) Magnesium alloys(vi) Carbon steels(vii) Stainless steel(viii) Tool steel(ix) Tantalum

(x) Titanium alloys(xi) Tungsten(xii) Zirconium alloys(xiii) Alloy steel to carbon steel

(xiv) Coer to carbon steels

(xv) Sueralloys to carbonsteels(xvi) Stainless steel to carbonsteels(xvii) Sintered steels to carbonsteels

(xviii) Aluminium to stainlesssteels


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Advantages of Friction Welding(i) Simlicity o# oeration"(ii) $o% o%er re&uirements"

(iii) 'nce te %elding arameters #or a ob ave been determined!te %elding takes only a #e% seconds"(iv) Sur#ace imurities and oxide *lms are broken u and tro%n o+during te #riction eating rocess"(v) As comared to conventional ,as or resistance butt %elding!#riction-inertia %elding roduces imroved %elds at iger seed and

lo%er cost! less electric current is re&uired! and costly coer*xtures to old comonents are eliminated"(vi) .eat is localized at te %eld and is &uickly dissiated so tattere is only a sligt e+ect on te arts oined" Te eat a+ectedzone adacent to te %eld is con*ned to a narro% band and tere#oredoes not a+ect te temer o# te surrounding area"

Te %eld may not ave to be eat treated"(vii) /it inertia-#riction %elding tere is less sortening o# tecomonent! as comared to tat in ,as or butt %elding"(viii) 0eeatability is reorted as excellent! and several obs avebeen #ully automated"(ix) Tere is no ,ux! gas! *ller metal or slag resent to cause

imer#ections in %elds" Also no smoke! #umes or satter areroduced"


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(i) Te use o# tis rocess is restricted to ,at and angular butt%elds! %ere one art is normal to te oter art"(ii) So #ar te rocess as been alied only to te oining o#small ieces in te #orm o# bar stock"(iii) Sometimes! &uite a eavy ,as is #orced out in all inertia and

#riction %elds"(iv) 1# tubing is %elded! ,as may ave to be removed #rom insidete oint"(v) 2las #rom medium and ig carbon steels being ard! musteiter be removed %ile it is ot or annealed be#ore it ismacined"

(vi) Trust ressures in inertia %elding %ill range #rom 344 to5644 kg-cm5! %ic re&uires a eavy rigid macine"

Disadvantages of Friction Welding


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Applications of Friction Welding

(i) 2riction-inertia %elding is *nding varied alications #or oiningsteels! suer alloys! non #errous metals and combinations o# metals"(ii) 1t #re&uently relaces brazing and (metallic) are! electron beam!ressure! ,as or resistance butt %elding"(iii) Among its varied alications are7

8roduction o# steering sa#ts and %orm gears! control sa#ts! axlesa#ts! engine valves! transmission sa#ts etc"! #or automobileindustry"

8roduction o# bimetallic sa#ts! oining o# sueralloy turbine %eelsto steels sa#ts! oining o# tin %alled containers to bases etc"8roduction o# cutting tools like drills! tas! reamers and some o# tesanked milling cutters %ere .SS cutting body is %elded to carbonsteel sanks"


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• Forge welding is a solid state welding process which produces

coalescence of metals by heating them in a forge and by applyingpressure or blows sufficient to cause permanent deformation at theinterface.

• "t is a crude method of welding and quality depends upon the s#ill of the welder.

Forge Welding FW!


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"##lications $la#e-smith shop, rail road shop

"d$antages "f made correctly, %oint has every quality of the original metal

Disad$antages illed wor#er is necessary Restricted to wrought iron and mild steel &olid steel stoc# &low process


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Thermit welding differs from other welding processes principally in that the heating is obtained fromthe thermit chemical reaction rather than from fire or electric current. ' mi!ture of a %etallico&ide and finely divided al'%in'% were ignited. The two materials react e!othermically thereby

converting the mi!ture into a superheated mass of the metal itself and a slag. The superheated metalflows into a mood around the parts to be united and weld them into one homogeneous mass while theslag overflows on top of the mold. Thermit welding now finds only limited application, chiefly in therepair of large iron and steel castings, though it was the traditional method for %oining rails on site.

T(er%it Welding TW!

T(er%it )elding


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"##lications

For repairing fractured rails (railway trac#s). For butt-welding pipes end to end. For welding large fractured cran#shafts. For welding bro#en frames of machines For replacing bro#en teeth on large gears. For welding new nec#s to rolling mill rolls and pinions. For welding cables for electrical conductors. For end welding of reinforcing bars to be used in concrete (building)

construction.)

"d$antages The heat necessary for welding is obtained from a chemical reaction and thus no

costly power-supply is required. Therefore bro#en parts (rails etc.) can be weldedon the site itself.

Disad$antages Thermit welding is applicable only to ferrous metal parts of heavy sections, i.e.,

mill housings and heavy rail sections. The process is uneconomical if used to weld cheap metals or light parts.


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Electron beam welding(EBM) is defined as a fusionwelding process whereincoalescence is produced bythe heat obtained from aconcentrated beamcomposed primarily of highvelocity electrons. As the

high velocity electrons strikethe surfaces to be oined!their kinetic energy changesto thermal energy therebycausing the workpiece metalto melt and fuse.

Electron *ea% Welding E*W!


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Electron beam welding

"he electron beam is produced in a high vacuum environment by an

electron gun! usually consisting of a tungsten or tantalum cathode! a

grid or forming electrode and an anode. A stream of electrons is

giving off from a tungsten filament heated to about ##$$o%. "heelectrons are gathered! accelerated to a high velocity and shaped

into a beam by the potential difference between cathode and anode.

"he beam is collimated and focusing by passing through the field of

an electro&magnetic focusing coil or magnetic lens. Beams typically

are focused to about $.#' to mm diameter and have a power

density of about $ k*mm#! which is sufficient to melt and vapori+e

any metal.

,ecture- oining /rocesses 13'


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"d$antages 'bility to ma#e welds that are deeper, narrower and less tapered than arc welds

with a total heat input much lower than in arc welding &uperior control over penetration and other weld dimensions and properties

igh welding speeds are common no filler metal is required* the process can beperformed in all positions and preheating or post heating is generally unnecessary

+lean and sound welds nergy conversion efficiency is high, about /

Disad$antages The equipment is e!pensive and high operating cost

igh cost of precision %oint preparation and precision tooling 0imitations of the vacuum chamber. 1or# si2e is limited by the si2e of the

chamber 3roduction rate and unit welding cost are adversely affected by the need to pump

down the wor# chamber for each load. "##lications 4aterials that are difficult to weld by other processes, such as 2irconium,

beryllium and tungsten can be welded successfully by this method but the weldconfiguration should be simple and preferably flat. 5arrow weld can be obtained with remar#able penetrations The high power and heat concentrations can produce fusion 2ones with depth-to-

width ratios of 67 with low total heat input, low distortion and a very narrowheat-affected 2one

eat sensitive materials can be welded without damage to the base metal.


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The word 0'&R stands for0ight 'mplification by&timulated mission ofRadiation.

0aser beam welding is definedas a welding process whereincoalescence is produced by theheat obtained from the

application of a concentratedcoherent light beam impingingupon the surface to be %oined.

Laser *ea% Welding L*W!


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The laser crystal (Ruby) is in the form of a cylinder, the ends beingflat and parallel to a high degree of accuracy and silvered to give

mirror-reflecting surfaces. There is a small aperture on the a!is ofthe crystal, through the mirror at the output end. 1hen the crystal ispumped with high-intensity white light from a !enon or #ryptonlamp, the +r ions in the crystal get e!cited. The e!cited ions possesmore energy and some of it are given as a red fluorescent light. Thislight is reflected bac#ward and forward in the crystal between the

two ends (mirrors), stri#ing more +r ions on the path. These ionsaffected by the collisions are each caused to emit their quota of redlight. There is a cumulative effect of the increasing red light e!istingmore and more +r ions, until the number of collisions is highenough to cause a burst of red light through the small aperture in

the mirror at the output end of the crystal. The beam produced ise!tremely narrow and can be focused to a pinpoint area by anoptical lens.

,ecture- oining /rocesses 16'


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"d$antages 1elds can be made inside transparent glass or plastic housings ' wide variety of materials can be welded, including some formerly considered as unweldable

combinations 's no electrode is used, electrode contamination or high electric current effects are eliminated

8nli#e electron beam welding it operates in air, no vacuum is required 0aser beam being highly concentrated and narrowly defined produces narrow si2e of the heat

affected 2one "t is possible to weld heat-treated alloys without affecting their heat-treated condition $ecause it is light, it is clean 9 no vapori2ed metal or electrodes dirty up the delicate

assemblies.

Disad$antages

The ma%or drawbac# to laser beam welds is the slow welding speeds (6-6: mm;min)resulting from the pulse rates and puddle si2es at the fusion point

0aser welding is limited to depths of appro!imately 7. mm and additional energy only tendsto create gas voids and undercuts in the wor#

4ost industrial laser are of the +

L4-Other Welding Process

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