GTAW Lesson Plan

8/10/2019 GTAW Lesson Plan

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Presentation Outline Additional Presentation Points

Slide # 1: Gas Tungsten Arc WeldingGTAW(TIG)

Gas Tungsten Arc Welding is often known as GTAW

and/or TIG welding.

TIG stands for tungsten inert gas. Tungsten is the non-

consumable electrode that is shielded by an eternalinert shielding gas. !eat for this "rocess is deri#edfrom an electric arc between the tungsten and the work"iece being welded. The inert gas "rotects the tungsten

and molten metal from oidation and to "ro#ide aconducting "ath for the arc current.

The "rocess was de#elo"ed in $%&$ initially to "ro#ide a

means of arc welding aluminum and magnesiumsu"erior to 'AW or stick welding.

The "rocess later was ada"ted to weld almost all

metals and alloys.

Slide # 2: What is GTAW? GTAW is the AW' name used by the American Welding

'ociety for Gas Tungsten Arc Welding.

TIG is the most commonly used name for GTAW. It

stands for Tungsten Inert Gas.

TIG is a "rocess in which a non-consumable

tungsten electrode establishes the arc with an inertshielding gas which also "rotects the weld. The mostcommon inert gas used is Argon although !elium oradditions of !elium to Argon are also sometimes used.

Slide # 3: What is GTAW?*ontinued

A* "olarity is used for TIG welding aluminum and

magnesium.

+*- "olarity is used to TIG weld all other base materials

+*, "olarity is rarely if e#er used in TIG welding.

GTAW can be done with or without the use of filler rods.

TIG welding uses a tungsten (non-consumable)electrode to create a molten "ool.

iller metal may or may not be continuously fed into a

molten "ool to add to the weld.

or the #ast maority of GTAW a""lications +*0

(+irect *urrent lectrode 0egati#e or 'traight 1olarity)and A* (Alternating *urrent) are used.

Slide # 4: GTAW - Gas Tungsten Arc Welding This is the American Welding 'ociety (AW') definition

for the Gas Tungsten Arc Welding "rocess.

GTAW has also been referred to as TIG welding or

!elium Arc Welding. GTAW is always done with an eternal inert shielding

gas or gas miture. It can be done with or without aconsumable filler material.

Slide # 5: GTAW - Adantages There are se#eral ad#antages to GTAW the main one

being that high 2uality welds can be made in a #ariety ofmetals and alloys. This is because the inert shieldinggas "rotects the metal from contamination.

TIG welding can be done in all welding "ositions which

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eliminates the need for e"ensi#e fituring ormani"ulation of the "art being welded.

A #ariety of metals can be welded with this "rocess. In

fact GTAW is the only method a#ailable for many of themore eotic ty"es of materials.

3ery thin materials can be TIG welded because the

"ower su""lies used in TIG welding can initiate andsustain the arc e#en at #ery low am"erages.

Slide # !: GTAW - Adantages The addition of filler material is used in thicker sectionsof base materials in fillet welds and to "re#ent conca#ityof other welds. iller material is also used when theaddition of alloys is needed and when deoidi4ers areneeded to get rid of contaminants. iller materials canalso add mechanical "ro"erties to the weld.

TIG welding is uni2ue in the fact that a sound weld can

be made with or without the use of a filler rod. usionwelding or autogenous welding is the term used todescribe TIG welding done without the use of a filler rod.usion welding is great on thin materials butt edge

corner or la" welds and on clean material. The use of afiller material in TIG welding makes this "rocess moredi#erse. The filler materials are s"ecific alloys that matchthe alloy in the base material. The filler material adds tothe weld. Therefore thicker material can be welded.

'ince the filler materials ha#e deoidi4ers in them they

allow TIG welding to be a little tolerant of surfacecontaminants. *onca#e welds are crack sensiti#e andthe filler rod hel"s to 5build6 u" the weld.

TIG welding is also #ery clean with no s"atter or slag

making it is #ery efficient with #ery little smoke

de#elo"ing. fficiency in TIG welding can be defined by the

amount of the filler metal that becomes "art of the weld.TIG welding uses a non-consumable tungsten electrodeThere is no slag and no s"atter which are losses ofefficiency. All of the filler material if used 1roduces theweldment.

Slide # ": GTAW - i$itations There are some limitations to TIG welding. 'ince a

shielding gas is needed TIG welding is less "ortablethan self-contained "rocesses such as 'AW and self-shielded *AW. The gas bottles hoses and regulatorsmay be cumbersome.

'ince shielding gas is susce"tible to winds and drafts

TIG welding may not be the best "rocess to dooutdoors es"ecially if the weld 4one is not tented orblocked off.

The base material used in TIG welding must be clean

es"ecially when fusion welding. This is because thetungsten only carries the current to establish the weldingarc. It does not add otherwise to the weld. There are no



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deoidi4ers in the tungsten so there is nothing in thetungsten to "rotect the weld from contaminants such ashydrocarbons or oides. This is one reason to add fillermaterial to the weld. iller material has the same AW'classification as IG wire. Therefore it containsdeoidi4ers to remo#e contaminants from the weld 4oneand "re#ents them from causing weld defects.

Slide # %: GTAW - i$itations TIG welding re2uires greater o"erator skill than the other

"rocesses. Generally there is low filler metal de"osition rates. TIG

welding is also generally slower than other arc welding"rocesses.

Slide # &: Gas Tungsten Arc Welding'afety

'afety title slide.

Slide # 1': GTAW - Sa(et)

(Ask, Why is safety important in welding?

Get feedback from audience.

May want to list some of their ideas on an oerhead, whiteboard, or chalkboard!

There are a number of safety issues to consider when

Gas Tungsten Arc Welding.

1ersonal safety as well as safety in the welding area

need to be considered.

When considering "ersonal safety all 7 senses need to

be "rotected when welding (sight touch hearing smelland taste).

In terms of taste it goes without saying that nothing

concerning welding is "ut into the mouth.

As with any career you must dress the "art. While

welding the heat of the central annulus can reach in

ecess of $8888 ultra#iolet radiation also is emitted

from the welding arc.

1rotecti#e clothing must be worn that "ro#ides co#erage

not only from burns s"arks and s"atter9 but also from

:3 arc radiation. Welding glo#es ackets or bib ando"tional "ants "rotection is also a#ailable. The clothesshould also be free from oil or grease that are #eryflammable and can be ignited from the arc.

Welders may in fact want to use sun tanning lotion ('1

;8) on some "arts of their body that get e"osed toreflecti#e :3 rays.

*a"s and welding helmets should also be worn to

"rotect you head and face from the arc.


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0e#er look directly at the arc without a shaded lens.

!ow to a""ro"riately choose a lens shade will bediscussed during this "resentation. Welding shields(also called welding helmets) "ro#ide eye and face"rotection for welders from ultra#iolet and infraredradiation.

ar "rotection is necessary to "re#ent hearing loss from

noise and welding debris. ar "lugs (or ear muffs)

should be worn to kee" flying s"arks or "articles fromentering your ears and to "re#ent hearing loss due tothe noisy atmos"here in most welding sho"s or areas.0ot unlike your eyes damage to the ears can occurfrom o#ere"osure and is cumulati#e damage.


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Welding !elmet

(#ae e$amples of arious welding helmets to pass around!

eye and face "rotection for welders.

'ome shields are e2ui""ed with handles but most are

worn on the head.

'hields either connect to helmet-like headgear or attach

to a hardhat.

'hields can be raised when not needed.

The welder obser#es the arc through a window that is

either = by & $/& inches or & 7 $/& inches.

The window contains a glass filter "late and an outerclear glass or "lastic safety lens to "rotect the morecostly filter "late from damage by s"atter and debris.

'ometimes an additional clear safety lens is also "laced

on the inside of the filter "late.

The window can be fied or hinged to the shield.

>n hinged ty"es when the hinged filter "late is raised a

clear safety "late remains to "rotect the eyes from flyingdebris during surface cleaning.

Slide # 13: AWS*A+S, ens Shade +u$ers ilter "lates come in #arying shades.

The shade re2uired de"ends on the maimum amountof am"erage to be used.

The higher the am"erage the darker the filter "late must

be to "rotect the eyes9 and the higher number of filter"late that should be used9 start with a darker filter "lateand go to a lighter filter "late as re2uired.

Slide # 14: GTAW - Sa(et)Welding Glo#es and >"tional *o#ering

(#ae e$amples of gloes and other body protection to passaround!

When welding the heat of the central annulus can reach

in ecess of $8888 and ultra#iolet radiation is

emitted.

1rotecti#e co#ering "ro#ides "rotection from s"arks

s"atter and ultra#iolet radiation.

ther "rotecti#e clothing includes leather a"rons s"lit

leg a"rons slee#es and ackets.


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burns.

Wool or cotton is more resistant to s"arks and so should

be worn.

+ark clothing is "referred because it minimi4es the

reflection of arc rays which could be deflected under thewelding helmet.

Wear shirts with "ocket fla"s that can be buttoned to

kee" out the s"arks and to kee" collars buttoned.

1ants should be cuffless and hang straight down the legwith no frayed edges.

+o not wear low-to" shoes while welding because

s"arks can fall into the shoes causing se#ere burns.


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"re#alent in dam" en#ironments. Therefore wear dryclean "rotecti#e glo#es kee" your welding cables ingood condition and do not touch any "art of theelectrode circuit with your bare hands or with wetclothing.

ost GTAW welding machines are connected to

dangerous alternating current (A*) #oltages of =8C-&B8#olts. *ontact with these #oltages can cause etreme

shock and "ossibly death. Gases dust and fumes caused by Gas Tungsten Arc

Welding can be ha4ardous if the a""ro"riate safety"recautions are not obser#ed. 1ro"er #entilation isessential for welder safety.

The fume "lume contains solid "articles from the

consumable and base material. ost side effects fromthese elements are tem"orary and can include burningof the eyes irritation of the skin and di44iness. #erhead hoods ca"ture mostof the fumes only after they ha#e "assed through thebreathing 4one of the o"erator.


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welding arc. It will ehaust a large area near it.

The net solution is the high #acuum/low #olume

systems. This is a source ca"ture solution where thefume is remo#ed directly at the source within inches ofthe arc. oth means are customer and ob s"ecific andare ecellent means to reduce the e"osure of smokeand fumes to the welder.

*om"ressed gas cylinders should be handled carefully

and should be ade2uately secured when in use.Enocks falls or rough handling may damage cylinders#al#es or fuse "lugs and cause leakage or cause thecylinder to e"lode.

*lose attention must be "aid to their storage and use.

*ylinders must be secured in an u"right "osition with the

#al#e ca"s in "lace and away from combustibles andfuels. Eee" them out of high traffic areas and away froms"arks. 0e#er allow an electrically hot "art of the weldertouch the cylinder. *rack the #al#e o"en to "re#ent dirtfrom entering the regulator before securing the regulator

to the cylinder. >nly o"en the cylinder #al#e whenstanding on the side o""osite of the regulator #al#e and"ressure gauges.

Slide # 1": GTAW - Sa(et)lectrical !a4ards

lectrical shock is a serious risk for welders.

lectrical shock can be from "rimary or secondary

#oltage.

1rimary #oltage shock results from in"ut #oltage and

can be caused by touching a lead inside the welding"ower source while the "ower is on and the o"erator isgrounded.

To "re#ent this most serious ty"e of electrical shock do

not work on anything inside the "ower source unless thewelder is un"lugged or the "ower has been.disconnected9 sim"ly turning the switch to 6off6 does notshut "ower off inside the "ower source.

'econdary #oltage shock is caused when the o"erator

touches "art of the electrode circuit and the work"iecesimultaneously9 to hel" "re#ent this ty"e of shock do nottouch the electrode circuit with bare hands or wet glo#esand make sure electrical connections the workconnection and welding cables are in good re"air with

no cracks s"lits or frayed wires. ost GTAW machines are connected to dangerous

alternating current (A*) #oltages of =8C-&B8 #olts.

*ontact with these #oltages can cause etreme shock

and "ossibly death not to mention the associatedam"erage of these connections.

The welding machine must always be grounded.

This is necessary to "re#ent electrical shock which can

result from contact with a defecti#e welding machine or

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other electrical de#ice by "ro#iding a "ath from thee2ui"ment to ground for stray electrical current createdby a short or other defect.

Without a ground the stray electricity would be "resent

in the frame of the e2ui"ment and would go to groundthrough any "erson that touched the e2ui"ment.

Water increases the "otential for electrical shock both

the work area and the welder must be dry. 0e#er weld

with wet glo#es in GTAW. They can cause shocks fromthe high fre2uency used and needed in GTAW welding.

Slide # 1%: GTAW - Sa(et)umes and Gases

Gases dust and fumes caused by GTAW can be

ha4ardous if the a""ro"riate safety "recautions are notobser#ed.

The GTAW "rocess "roduces the least amount of

welding fumes of any arc welding "rocess.

The maor toic gas associated with GTAW is o4one.

or eam"le? the ultra#iolet light emitted by GTAW arcsact on oygen in the atmos"here to "roduce o4one. Ascurrent (am"erage) increases so does the amount of

o4one. >4one dis"laces oygen that can 5suffocate6 the"erson welding. Therefore res"iratory de#ices shouldbe used es"ecially when welding in restricted orconfined areas.

etals heated during GTAW may gi#e off toic fumes

and smoke which are not considered dangerous as longas there is ade2uate #entilation.

The fume "lume contains solid "articles from the

consumable and the base metal.

"osure to toic fumes usually causes tem"orary

sym"toms such as burning of the eyes irritation of theskin and di44iness.

"osure to elements such as manganese chromium

and nickel can be ha4ardous. 0ickel is found in Inconelty"e "roducts and low-alloy/high-strength materials.*hromium is found in stainless steels. It is the elementthat gi#es stainless steels their corrosion resistance.*hromium in small amounts can be toic. inallymanganese is found in manganese steels.

nclosed areas with "oor #entilation can be a ha4ard

because the shielding gas may dis"lace en#ironmental

air causing suffocation. +o not weld near substances such as cleaning materials

that contain chlorinated hydrocarbons.

:se the following rules to ensure ade2uate #entilation?

The welding area should contain at least $8888 cubicfeet of air for each welder9 there should be "ositi#e aircirculation and air circulation should not be blocked by"artitions structural barriers or e2ui"ment. Weldinghoods or high #olume smoke etraction e2ui"ment hel"

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in remo#ing smoke and fumes from the weld area.

The welding hood system uses a low #acuum/high

#olume smoke etraction system9 it is the mostcommonly seen #ersion of smoke etraction-smoke andfumes are sucked into the hood and remo#ed from thewelding area.

A disad#antage of the hood system is that fumes ha#e

already "assed through the breathing 4one of the

o"erator before being remo#ed.


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glo#es hea#y shirt cuff less trousers high shoes and aca" o#er your hair. Wear ear"lugs when welding out of"osition or in confined "laces.

*onnect the work cable to the work as close to the

welding area as "ractical. Work cables connected to thebuilding framework or other locations away from thewelding area increase the "ossibility of the weldingcurrent "assing through lifting chains crane cables or

other alternati#e circuits. This can create fire ha4ards oro#erheat lifting chains or cables until they fail.

Slide # 21: GTAW - Sa(et)General !a4ards in the Work Area

Eee" "ower source cables welding materials and tools

neatly organi4ed.

*onnect work cable as close as "ossible to the weld

area.

:se only "ro"erly grounded e2ui"ment

Always disconnect "ower to arc welding e2ui"ment

before ser#icing.

Slide # 22: GTAW - Sa(et)*om"ressed Gas !a4ards

Gas cylinders are "otentially e"losi#e.

*ylinders contain gases under high "ressure9 if the

cylinder should ti" and the #al#e breaks off the cylinderwould become a 5rocket6 due to the force of "ro"ulsionof the esca"ing gas.

*om"ressed gas cylinders should be handled carefully

and should be ade2uately secured when in use.

Enocks falls or rough handling may damage cylinders

#al#es or fuse "lugs and cause leakage or accident.

3al#e "rotecting ca"s when su""lied should be ke"t in

"lace (hand-tight) until the connecting of gas out"uta""aratus.

*ylinders must be ke"t away from combustibles s"arksand high traffic areas9 ne#er allow any electrically hot"art of the welder to come in contact with the cylinder.

The following should be obser#ed when setting u" and

using cylinders of shielding gas?

1ro"erly secure the cylinder in an u"right "osition.

efore connecting a regulator to the cylinder #al#e the

#al#e should momentarily be slightly o"ened and closedimmediately to clear the #al#e of dust or dirt thatotherwise might enter the regulator. The #al#e o"eratorshould stand to one side of the regulator gauges ne#er

in front of them.

After the regulator is attached the adusting screw

should be released by turning counter-clockwise. Thecylinder #al#e should then be o"ened the entire wayslowly to "re#ent a too-ra"id surge of high "ressure gasinto the regulator.

The source of the gas su""ly (i.e. the cylinder #al#e)

should be shut off if it is to be left unattended.

Slide # 23: GTAW - Sa(et) 'afety 3ideo



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3ideo

Slide # 24: Gas Tungsten Arc Weldingasic lectricity? Transformer +esign

GTAW title slide for asic lectricity? Transformer

+esign.

Slide # 25: .asic Trans(or$er /esign

(%he first & bullet points are in introduction to how electricityis produced by power companies.!

('ullet points )** are an intro into power source design,and the remaining bullet pertain to the illustration.!

1ower *om"anies "roduce electricity by se#eral means?

coal-burning oil nuclear and hydroelectric. 0o matterwhat the source of "roduction in general "owercom"anies "roduce Alternating *urrent (A*).

A* is "roduced because it can be transformed #ery

easily from a #ery high current le#el all the way down toyour household current and it can be transmitted o#erlong distances without a""reciable loss as would be thecase with +irect *urrent (+*).

lectricity by "ower com"anies is made at

a""roimately $;788 #olts and B8 !4. It is thenste""ed u" to as high as ;78888 #olts and lowam"erages for long distance tra#el. It is then sent tosubstations to reduce the #oltage to tra#el to localdistribution centers.

rom the distribution centers it is sent to a series of

transformers again to reduce the #oltage to useful#oltages i.e. 77# &B8# =;8# and $$7# and to raisethe am"erage for usage in sho"s and homes.

This electricity is deli#ered to you at almost the instant it

is "roduced and tra#els at nearly the s"eed of light($CB888 miles "er second).

All arc welding "rocesses re2uire a continuous su""ly of

electrical current with sufficient am"erage and #oltage tomaintain an arc. This current can be A* or +* but itmust be su""lied to the welding electrode through a"ower su""ly that has "recise control.

1ro"er settings and controls of the "ower su""ly allow

desirable arc characteristics and o"timi4e efficiency.

*urrent can be su""lied to the "ower su""ly from "ower

lines as discussed abo#e or de#elo"ed within itself asin the case of engine-dri#en alternators and generators.ither way "ower sources "ro#ide a #oltage range forwelding from about $;-&7 #olts and current from = am"sto $788 am"s or more.

The welding "rocess and consumables determine not

only the si4e of the "ower su""ly needed but also the

ty"e of "ower su""ly needed i.e. *onstant *urrent(**) and/or *onstant 3oltage (*3).

'AW and GTAW as well as some 'ubmerged Arc

Welding ('AW) and GAW a""lications utili4e **"ower su""lies. GAW *AW and 'AW use *3"ower su""lies. oth ty"es of "ower su""lies *3and/or ** con#ert the in"ut "ower to welding "ower insimilar manners.

We are now going to discuss the internal com"onents of



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a transformer and transformer/rectifier ty"e "owersu""ly that con#erts in"ut "ower into welding "ower.

This illustration de"icts a ty"ical basic transformer "ower

su""ly showing the internal com"onents.

To the far left of the slide you see the "rimary windings

of the transformer. In general there is one winding "erin"ut #olt. or eam"le if your in"ut "ower su""ly is=;8 #olts there will be =;8 turns of fine wire.

The right side of the "hoto shows the secondary of thetransformer and takes it through to the arc. Thesecondary windings of the transformer are hea#ier wireand fewer turns ha#ing only one turn "er each #olt ofo"en circuit #oltage (>*3).

Slide # 2!: Trans(or$er The transformer in a "ower su""ly is a ste"-down

transformer that takes high-#oltage low-am"erage A*in"ut su""lied from "ower com"anies and changes it tolow-#oltage high-am"erage A* welding current.

or eam"le your in"ut "ower may be =;8 #olts on a

78-am" branch circuit. This #oltage is much too high

and the am"erage is much too low for weldinga""lications. The transformer takes this condition andre#erses it to a much lower #oltage in the range of $;-&7 #olts (most a""lications $7-;7 #olts) and increasesthe am"erage to a much higher le#el a""ro"riate forwelding.

Slide # 2": 0eactor rom the transformer the electricity goes to a control

that stabili4es and adusts the welding current. This iscalled the reactor.

The reactor can be a ta" reactor that selects am"erage

ranges to weld with. A ta" reactor 5ta"s6 into segmentsof the secondary of the transformer and "ro#ides ste"control. This is the least e"ensi#e means of controllingwelding out"ut.

Another reactor is a mo#eable iron reactor. This is

generally done by kee"ing the windings in thetransformer stationary and mo#ing a "iece of ironbetween the windings to control am"erage. A mo#eableiron reactor "ro#ides continuous ste"-less control ofam"erage.

A saturable reactor or 'ilicon *ontrolled Fectifier ('*F)

can also be used and also "ro#ides a continuous ste"-less control for more "recise control of welding out"ut.An '*F is an electrical control that uses a low #oltagelow am"erage +* circuit to change the effecti#emagnetic characteristics of the reactor core.

In a "ower su""ly that deli#ers only A* to the arc these

are the internal electrical com"onents of the "owersu""ly. We now need to discuss how we con#ert A* to+* which is the current "rimarily used in arc welding.



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Slide # 2%: .ridge 0ecti(ier In "ower su""lies that deli#er +* and/or A* current to

the arc there needs to be a de#ice that changes thisnow low-#oltage high-am"erage A* into +*.

This de#ice is called a rectifier. A rectifier con#erts A* to

+*. They are #ery efficient and #ery reliable.

A rectifier is a de#ice that allows current to flow in only

one direction.

If we remember the "ath that A* takes it takes one of a

sine wa#e "ath. This re"resents one cycle in whichcurrent flows in one direction for H of the cycle andsto"s at the 4ero line then re#erses its direction of flowfor the other H cycle. This cycle re"eats itself o#er ando#er again at a fre2uency of B8 !4 or B8 times a secondin the :nited 'tates.

A rectifier does not allow current to re#erse itself. It only

allows current to flow in one direction. In essence itdirects current in the same direction rather that allowingit to change direction. This is called direct current of +*The direction of current flow determines whether the

"olarity is +*, or +*-.Slide # 2&: ,nductance oil We often call the current coming out of a rectifier

5cho""y6 or ri""led +*. In other words the "ath ofcurrent is not as smooth as it could be and therefore thearc characteristics are not as smooth as they could be.

A de#ice is "laced inside "ower su""lies to correct this

"roblem. This de#ice is called an inductance coil whichis sometimes called a choke or stabili4er. The mainfunction of the choke is to smooth out the rectifiedri""led +* and therefore smoothes out the +* arccharacteristics.

F


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literally changing A* to +*.

inally an inductance coil or choke filters out this ri""led

+* and a smooth +* is deli#ered to the welding arc.

Slide # 31: .asic lectricit)3ideo

asic lectricity 3ideo

Slide # 32: Gas Tungsten Arc WeldingIn#erter Technology

GTAW title slide for In#erter Technology.

Slide # 33: ,nerter Technolog)

The state-of-the-art A* and/or +* transformer "ower

source is an in#erter. There are se#eral ad#antages ofin#erters o#er traditional transformer designed "owersu""lies which will be discussed later. There are also afew concerns or limitations of in#erters that will also bediscussed.

The design of an in#erter is more com"le than that of a

traditional "ower su""ly with more com"onents andelectrical circuitry. The illustration is a block diagramde"icting the B main com"onents of an in#erter.

Slide # 34: 0ecti(ier

The in"ut "ower coming in to the in#erter "ower su""ly

is again alternating current or A* as "roduced by "ower

com"anies. It is of high-#oltage and low-am"erage andis not suited for welding. The fre2uency is B8 !4 in the:nited 'tates and 78 !4 in many foreign countries.

In an in#erter based "ower su""ly this in"ut "ower is

immediately "assed through a rectifier. Femember thata rectifier is a de#ice that only allows current to flow inone direction and in essence changes A* to +*.

This +* is ri""led or not smooth and is still high-#oltage

and low-am"erage which is not suitable for welding.

Slide # 35: ilter This ri""led +* is net "assed through a filter to smooth

it out. This has the same effect as the choke orinductance coil in the basic transformer designedmachine.

This "ower is still of high-#oltage and low-am"erage and

is not suitable for welding as of yet.

Slide # 3!: ,G.T The net com"onent of an in#erter is a de#ice that

identifies and distinguishes an in#erter from a basictransformer designed machine.

This com"onent is a high-s"eed switching de#ice and

can come in many forms that include ield ffectTransistors (Ts) Insulated Gate i"olar Transistors

(IGTs) and +arlington switches. An IGT re2uires an incoming +* signal. The IGTs

ele#ate the fre2uency to le#els such as =8888 !4 asfound in all


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timing of the IGT switch boards induce an A* s2uarewa#e out"ut signal at the secondary of the maintransformer.

Slide # 3": ,G.T - ,nsulated Gate .iolar Transistor The IGT or high-s"eed switch is what makes an

in#erter what it is and what it does.

The +* coming out of a IGT is at =8888 !4 but is still

high-#oltage and low-am"erage and not suitable forwelding yet.

Kou might be asking yourself 5What is the ad#antage ofan ele#ated fre2uencyL6 This will be discussed later.

Slide # 3%: ,ron at 2''''' )cles As seen on this illustration transformers o"erating at

higher fre2uencies are lighter and more efficient.

In#erters are a fraction of the si4e of a transformer-

based machine which makes them ecellent choices for"ortable or maintenance welding machine.

+ue to the fact that the transformers are more efficient in

an in#erter and heat losses are at a minimum the si4eof the transformer is much smaller cooling fans aremuch smaller and "ower consum"tion is less.

This conce"t is not a new one. As seen on the slide

this theory was disco#ered back in $%$$.

Slide # 3&: ,ron at 2''''' )cles This chart again from $%$$ shows how efficiency

greatly increases in a transformer as the fre2uency ofo"eration increases. It also shows how the si4e of thetransformer decreases accordingly.

Slide # 4': Trans(or$er Going back to the remaining com"onents of an of an

in#erter from the IGTs the rest of the in#erter greatlyresembles that of a basic transformer machine.

rom the IGT we ha#e A* at =8888 !4 at high-

#oltage low-am"erage. This is "assed through a ste"-down transformer to

change this A* to low-#oltage and high-am"erage at=8888 !4.

+ue to the efficiency of the "rocess attained through

high fre2uency transformers are #ery small andcom"act when com"ared to basic machines.

Slide # 41: 0ecti(ier The net com"onent is a rectifier. A rectifier only allows

current to flow in one direction (changes A* to +*).

The +* that comes out of the rectifier is ri""led or not as

smooth as it can be. It is also of low-#oltage and high-am"erage.

Slide # 42: ho6e rom the rectifier the ri""led +* goes to the choke (or

inductance coil) that smoothes out the +* at low-#oltageand high-am"erage so that it is suitable for welding.

The +* is etremely smooth and smoother than that of

a standard transformer due to the ele#ated fre2uencyused in an in#erter.

Slide # 43: ,nerter Technolog) - Su$$ar) This com"letes the internal com"onents of an in#erter

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from in"ut "ower to etremely smooth +* weldingcurrent.

Slide # 44: ,nerter Technolog) - .ene(its The following slide highlights the maor ad#antages of

an in#erter based "ower su""ly.

Slide # 45: ,nerter Technolog)3ideo

In#erter Technology 3ideo

Slide # 4!: Gas Tungsten Arc Welding*ho""er Technology

GTAW title slide for *ho""er Technology.

Slide # 4": hoer Technolog)

>ne ty"e of state-of-the-art +* "ower source is acho""er. There are se#eral ad#antages of cho""erso#er traditional transformer designed "ower su""lieswhich will be discussed later. There are also a fewconcerns or limitations of cho""ers that will also bediscussed.

*ho""er Technology is a trademark of the


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contaminants (oygen nitrogen and hydrogen) and to"ro#ide a conducti#e "ath for the arc current.

GTAW can be done with or without a filler material.

Without a filler material is often called fusion welding orautogenous welding. If a filler rod is used it is generallyadded in the leading edge of the weld "uddle and should03F touch the tungsten to "re#ent tungstencontamination.

Generally a 5"ush6 techni2ue is used to ensure goodgas co#erage and ecellent "enetration.

The weld bead should be flat shiny and ri""led.

The result is a #isually "leasant ri""led weld bead with

no slag and no s"atter. The weld should resemble a rollof dimes that has been slightly s"read out.

Slide # 5&: GTAW - lectrode Polarit)+*0 ('traight) 1olarity

In TIG welding the welding "olarity is chosen based

u"on the a""lication and the base material. +*- and A*are the commonly used "olarities for TIG welding. +*,is rarely if e#er used.

+*- "olarity in TIG welding can be easily defined in

terms of the direction that ions flow as well as where theheat of the arc is directed. Ions flow from the work"ieceu" the tungsten and electrons are easily emitted fromthe tungsten down to the work"iece.

In this condition 8M of the heat is at the work "iece

and ;8M is at the tungsten electrode.

'ince the maority of the heat is directed at the work

"iece +*- "olarity "roduces a weld with a dee" narrow"enetration "rofile.

'ince only ;8M of the heat is directed at the electrode

the electrode has ecellent current carrying ca"acity.or eam"le a $/C6 electrode can carry &88 Am"swithout deteriorating.

+*- "olarity is used for all base materials in TIG welding

ece"t for aluminum and magnesium.

Slide # !': GTAW - lectrode Polarit)+*1 (Fe#erse) 1olarity

+*, "olarity in TIG welding also can be easily defined in

terms of the direction the electrons and ions flow wherethe heat of the arc is directed.

+*, is ust the o""osite of +*-. Ions are emitted from

the electrode and electrons are emitted from the work"iece. In this condition 8M of the heat is at the

electrode and ;8M is at the work "iece. 'ince the maority of the heat is at the electrode +*,

"olarity is not desirable due to the "oor current carryingca"acity of the electrode in TIG welding and the result isshallow "enetration.

+*, "olarity is rarely if e#er used in TIG welding. Also

since little heat is directed at the work "iece "enetrationis shallow because the maority of the heat is directed atthe tungsten. This deteriorates the tungsten.

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or eam"le an $/C6 tungsten electrode can only carry

$=8 am"s and then it will begin to deteriorate.

Slide # !1: GTAW - lectrode Polarit)Alternating *urrent

Alternating current or A* "olarity is a 78/78 miture of

+*, and +*- "olarities. The desirable features of bothother "olarities are obtained. 78M of the time ions areemitted from the tungsten electrode and 78M of thetime ions are emitted from the work "iece.

Think of A* as being electrode "ositi#e for 78M of the

time or for one half of the cycle and electrode negati#efor the other half of a cycle. The results are as follows?when on the "ositi#e half cycle the maority of the heatis at the electrode but the ions that are emitted from thetungsten 5blast6 the work"iece to clean off the oidesfound on the base materials commonly welded using A*"olarity? aluminum and magnesium. This is calledcleaning action. Aluminum and magnesium form anoide coating at room tem"erature. This oide melts ata tem"erature that is higher than the melting "oint of thebase materials. Therefore there needs to be a cleaning

action to remo#e the oide. This ha""ens during the"ositi#e half cycle. +uring the "ositi#e half cyclerectification occurs and less current flows. Thiscondition eists because the aluminum surface does notemit electrons as readily as the hot tungsten electrode.When on the negati#e half cycle an o""osite effectoccurs? the maority of the heat is at the work"iece andelectrons are emitted easily from the tungsten to"enetrate the work"iece. This is called the "enetrationhalf cycle and more heat is focused at the base materiaand therefore "enetration occurs. Also since

significantly less current is focused at the electrode onthe negati#e half cycle tungsten cooling occurs.

+uring A* welding the tungsten electrode has good

current carrying ca"acity. or eam"le an $/C6electrode can carry ==7 am"s.

Slide # !2: A Sine Wae Technolog) The drawing shown is that of an A* sine wa#e. This is

the "ath that current takes in alternating current and thedrawing shows $ cycle.

In the :nited 'tates we o"erate on a B8 !4 cycle which

means that current takes this "ath B8 times a second.any other countries o"erate on a 78 !4 cycle. This is

also called the fre2uency. The sine wa#e is com"osed of a "ositi#e half cycle

which is the cleaning half cycle and the negati#e halfcycle which is the "enetration half cycle.

*urrent starts at the 4ero line and slowly rises to the

o"timal "ositi#e "oint then slowly falls and crosses the4ero line where current sto"s flowing and then re#ersesdirection of flow in the negati#e half cycle. When currentsto"s it re-ignites as it crosses through the 4ero "oint

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and then re#erses direction.

>n the negati#e half cycle there is a slow rise to the

o"timal "enetration "oint and then a slow fall back to4ero. This cycle re"eats itself o#er and o#er again whilewelding.

When welding using A* there are three areas of

concern. They include crossing through the 4ero "ointwhere the arc etinguishes and there is slow re-ignition

of the arc9 there is #ery little time s"ent at the o"timalcleaning "oint9 and there is #ery little time s"ent at theo"timal "enetration "oint.

'o"histicated "ower su""lies for TIG welding resol#e

these "roblems found in A* welding. This feature willbe discussed as the training "rogresses.

Slide # !3: A S7uare Wae Technolog) The concerns of arc starting and arc re-ignition during

A* TIG welding ha#e been addressed on the "re#iousscreen. A third concern of con#entional sine wa#etechnology is that minimal time is s"ent at the o"timalcleaning and o"timal "enetration "oints.

In s2uare wa#e technology the sine wa#e is 5s2uaredoff6 due to electronics that are "laced inside themachine. Instead of the sine wa#e a""earing roundedit is blocked off or s2uared off. The "ositi#e half cyclere"resents a s2uare as does the negati#e half cycle.

'2uare wa#e technology allows the transition between

the "ositi#e and negati#e half cycles of A* welding to beinstantaneous. This is much faster than con#entionalA* sine wa#e technology because the "ath from"ositi#e to negati#e is now a #ertical one instead of aslo"ing "ath. This allows arc re-ignition to be enhanced

"re#enting "otential weld defects. '2uare wa#etechnology also allows more time to be s"ent at theo"timal "ositi#e and o"timal negati#e #alues enhancingthe A* arc characteristics of cleaning "enetration andim"ro#ed welds.

Slide # !4: A S7uare Wae Technolog) An o"timum amount of time is s"ent cleaning and

"enetrating. This "re#ents the tungsten fromo#erheating and aids in the longe#ity of the tungsten. Italso aids in "roducing a better more e#en "enetration"rofile.

+ue to the 5s2uaring6 off of the wa#eform the 5"eaks6 on

the "ositi#e and negati#e half cycles are remo#ed. Atthese "oints o#erheating of the tungsten can occur onthe "ositi#e half cycle and o#er-"enetration can occur onthe negati#e half cycle.

Slide # !5: A S7uare Wae Technolog) Another ad#antage of s2uare wa#e technology is the

ability for the welder from the "ower su""ly to alter thelength of time the machine s"ends in the "ositi#e ornegati#e "ortions of the A* cycle. This is called A*wa#e balance.



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This illustration highlights '2uare Wa#e Technology.

The result is an asymmetrical A* wa#e sha"e with more

time either s"ent on the "ositi#e half cycle (the cleaninghalf cycle) or more time s"ent on the negati#e half cycle(the "enetration half cycle).

>n the slide the three drawings re"resent a balance

s2uare wa#e with e2ual amounts of time s"ent on the"ositi#e and negati#e half cycle as well as two

unbalanced s2uare wa#es. >ne shows more time s"enton the "ositi#e or cleaning half cycle and one showsmore time s"ent at the negati#e or "enetration halfcycle.

The benefits of this feature are twofold? If the

unbalanced s2uare wa#e fa#ors the negati#e half cyclemaimum "enetration can be achie#ed. In this casecurrent flows from the electrode to the work and moreheat de#elo"s in the work. *onse2uently dee"er"enetration is achie#ed. If the unbalanced s2uare wa#es"ends more time at the "ositi#e half cycle maimum

cleaning is achie#ed. 1ower su""lies "ut a lower limiton the maimum cleaning half cycle than on maimum"enetration. This is because increasing the "ositi#e halfcycle increases the time s"ent with the current flowingfrom the work to the tungsten and "roduces more heatat the tungsten. If the limit is too high melting anddegradation of the tungsten can occur.

There are also benefits to a balanced A* wa#eform. In

this condition 78M of the time is s"ent at the "ositi#ehalf cycle and 78M of the time is s"ent at the negati#ehalf cycle resulting in 78M of the time cleaning and

78M of the time "enetrating. cellent cleaning isa#ailable as well as ade2uate "enetration time. Abalanced s2uare wa#e is used for normal weldingconditions.

Slide # !!: A ,nerter Technolog) In#erter Technology has unlocked many of the doors to

A* welding.

>ne of these controls is fre2uency.

re2uency allows the o"erator to select ranges other

than the standard B8!4 s2uare wa#e out"ut found onmost transformer-rectifier TIG machines on the markettoday.

Adusting the fre2uency allows the o"erator to tailor the

arc for the s"ecific a""lication. Increasing fre2uencynarrows the arc and focuses it to where you want it togo.

ost in#erters run well between $88-$;8 !4.

The increased fre2uencies also allow for the use of =M

Thoriated tungsten which is shar"ened to "oint likewhen welding +*-.



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This allows one to decrease the si4e of the weld which

can hel" to limit distortion and increase tra#el s"eeds.

eing able to use one tungsten reduces change o#er

time from +* to A* welding.

Slide # !": A ,nerter Technolog) Another feature im"ortant to welders is the ability to

"recisely set the balance control.

With digital read outs and com"uter controlled out"ut an

o"erator can select the "recise amount of +*-/+*,

desired for each indi#idual welding a""lication. This allows for the welding of thicker materials faster

and thinner materials more easily.

Additionally one can control the si4e of the cleaning

4one to get the desired looked for an a""lication.

Slide # !%: A ,nerter Technolog) ne last ad#antage to welding sho"s is the fact that

in#erters do not use high fre2uency continuously whenwelding in A*. These machines only ha#e highfre2uency starts because they ha#e truer out"ut than

con#entional machines which allows them not to ha#eto run continuous high fre2unecy.

Slide # !&: GTAW - 8igh re7uenc) *onstant current TIG "ower su""lies are e2ui""ed with

an additional feature to aid in TIG welding that is calledhigh fre2uency.

!igh fre2uency is an ele#ated fre2uency that is

su"erim"osed o#er the welding current that aids in arcstarting for A* and +* TIG welding and in arc re-ignition as current crosses through 4ero during A* TIGwelding.

!igh fre2uency along with the inert shielding gas"ro#ides an ioni4ed "ath that allows welding current to5um"6 an air ga" of about $/C6 from the end of theelectrode to the work "iece to start the welding arc.

!igh fre2uency allows arc starting in TIG welding withou

touching the electrode to the work "iece. If the tungstentouches the work "iece contaminations on the tungstenwill be generated. These contaminants will e#entuallyend u" in the weld "uddle as a defect and deterioratethe tungsten electrode.



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!igh fre2uency should always be used for arc starting in

TIG welding when "ossible.

Another ad#antage of high fre2uency is used during A*

welding. In A* welding current ele#ates and reachesthe o"timal cleaning "oint during the "ositi#e half cycle.It then declines crosses the 4ero line where the arcetinguishes and then re-ignites and re#erses directionon the negati#e half cycle. >nce in the negati#e half

cycle it ele#ates and reaches it o"timal "enetration"oint. It crosses the 4ero "oint again where the arcetinguishes and then re-ignites. This cycle re"eatsitself at a fre2uency of B8 !4 or B8 times/second in the:nited 'tates. When the arc etinguishes it is not adesirable condition and weld defects can occur. !igh-fre2uency hel"s this condition.

!igh fre2uency kee"s the arc established as current

crosses through 4ero during A*.

'ome "ower sources ha#e a switch to determine when

high fre2uency should be used. The three "ositions are

as follows? 'tart only for +*- welding *ontinuous forA* and >ff for 'AW or scratch start TIG welding.

'cratch start TIG welding should only be used when

absolutely necessary because contamination of thetungsten and the weld bead can occur. 'cratch startingis a techni2ue in which the tungsten strikes the work"iece in a manner similar to striking a match. Thiscom"letes the electrical circuit that allows current to flowthrough the tungsten to the work "iece and creates anarc. Any time the tungsten comes into contact withsomething else (i.e. the work "iece filler material) it

can and will "ick u" contaminations that get transferredto the weld "uddle.

>n other "ower su""lies high fre2uency is automatically

detected according to how the "olarity switch is set.When in the TIG welding mode if the "olarity switch isset on +*- high fre2uency is acti#ated for starting only.When using A* continuously and when in the stickmode high fre2uency is >.

Slide # "': GTAW - 8igh re7uenc) Protection There are some areas of concern when welding using

high fre2uency. >ne of these concerns is highfre2uency interference. !igh fre2uency is a radiofre2uency and will interfere with other radio fre2uenciesunless etra consideration is taken to diffuse this"roblem. The s"ark ga" oscillator in the high fre2uencygenerator is similar to a radio transmitter. It can beblamed for many radio T3 and electronic e2ui"mentinterference "roblems.

!igh fre2uency will take the "ath of least resistance to

ground. Therefore "ro"er grounding techni2ues needto be done in order for this "ath to be directed to ground



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and not through other e2ui"ment or com"onents of thewelding sho".

This radiated interference can de#elo" in the following

ways?

+irect interference radiated from the welder.

+irect interference radiated from the welding leads.

+irect interference radiated from feedback into the

"ower lines and interference 5"icked u"6 from metallic

obects.Slide # "1: GTAW - 8igh re7uenc) ,nter(erence There are s"ecific "recautions that must be taken in

installing and o"erating TIG e2ui"ment that can reducehigh fre2uency interference.

The best way to minimi4e high fre2uency interference is

to earth ground each TIG machine to its own se"arateearth ground.

A recommended "rocedure for earth grounding the TIG

machine is as follows? The work terminal must beconnected to a ground within $8 of the welder usingone of the following methods?

A metal underground water "i"e in direct contact with

the earth for ten feet or more or more commonly

:se a N6 gal#ani4ed "i"e or a 7/C6 solid gal#ani4ed iron

steel or co""er rod dri#en at least eight feet into theground.

The ground should be secure and the cable as short as

"ossible using cable the same si4e as the work cable orlarger. +> 0>T GF>:0+ T> T! FA > T!:I


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key com"onents and allow students to touch and feel) am"erage remains constant e#en for changes inwelding #oltage. These changes occur as changes inarc length occur. Arc length is the distance from the endof the electrode to the work"iece.

Arc length is directly "ro"ortional to #oltage. As arc

length changes so does welding #oltage. !owe#er theconstant current "ower su""ly kee"s current(am"erage) close to its "reset #alue e#en for these

changes. Welding current is set on a ** "ower source #oltage

03F is. 3oltage is determined by arc length. Inconunction with a ** "ower su""ly a TIG torch isneeded to TIG weld.

The TIG torch "erforms se#eral functions?

It holds the tungsten electrode

It "ro#ides an electrical connection to the electrode

It "ro#ides an inert gas co#erage of the electrode ti" the

arc and weld 4one and

It insulates the electrode and electrical connections from

the o"erator or mounting bracket.

The GTAW "rocess re2uires a gas or water cooled torch

to hold the electrode and is connected to the "owersu""lys electrode connection.

When lower currents are used (less than =88 am"s)

generally an air-cooled torch is used. There are twoty"es of air-cooled torches. 'ome are one "iecetorches. In these torches the "ower cable is inside thegas hose which also "ro#ides insulation for theconductor. There are also two-"iece air-cooled torches

that ha#e the "ower cable and gas hose se"arated. Water-cooled torches generally ha#e three cables. >ne

cable is for the water su""ly one for the water returnand "ower and one for the gas su""ly. If a water-cooledtorch is used there needs to be a water su""ly to flowthrough the torch to aid in cooling. In most instances awater cooler is used to "ro#ide this function. A watercooler is shown mounted hori4ontally in the "hoto on theillustration.

The TIG torch consists of se#eral consumable "arts and

"ieces each ha#ing s"ecific functions. The torch

consists of a collet a collet holder/collet body and atightening ca" or back ca" and the shield cu". Thecollets main function is to hold the tungsten in "laceandis si4ed according to the diameter of the electrode.The collet holder holds the collet in "lace and "ro#ides a"assage way for shielding gas to diffuse gas o#er theweld bead. The back ca" holds the tungsten in the torchand comes in se#eral lengths each one a""ro"riate fordifferent oint designs and/or o"erator comfort.

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GTAW welding can be done with or without a filler rod.

Without a filler rod is called fusion welding or sometimescalled autogenous welding. usion welding is generallydone on #ery thin materials materials that are #eryclean that do not need the deoidi4ers found in the fillermaterial and for butt welds or la" welds. As "latethickness increases on base material with some mildcontaminants and for other welding oint designs it is

necessary to use a filler material. iller materials carrythe same AW' classification as GAW wires and comein a #ariety of alloys and diameters de"ending u"on thebase material being welded.

iller material is added in the leading edge of the weld

"uddle at about a $7-=8 degree angle from the "late.The filler material is then "ulled back out of the "oolslightly but not out of the inert shielding gas. The"rocess is re"eated at the weld "rogresses.

iller material can be added either manually which is

most common or through a wire feeder used in

automated GTAW welding. 'hielding gas is directedaround the electrode end and the weld 4one #ia theshield cu".

In GTAW welding an inert gas is used. The two most

commonly used gases are argon and to a much lesserdegree helium. The shielding gas "rotects the weld"uddle from contaminants in the atmos"here and"ro#ides a conducti#e "ath for current to flow. 'hieldinggases are su""lied in bulk as li2uids or as gases in"ressuri4ed cylinders of #arious si4es.

A flow meter is re2uired when setting u" with shielding

gas to meter the shielding gas to the TIG torch at the"ro"er flow rate. A ty"ical flow meter consists of a"reset "ressure regulator with cylinder "ressure gaugeand cylinder #al#e a flow metering needle #al#e and aflow rate gauge. The metering #al#e is used to adustthe gas flow to the TIG torch. The flow gauge shows thegas flow rate in cubic feet "er hour or in liters "ersecond. ulti-gas gauges ha#e different scales forgases of different densities.

A gas hose is re2uired from the regulator/flow meter to

the gas solenoid in the TIG "ower su""ly.

An arc starting mechanism or remote control such as afoot or hand am"trol is also needed to energi4e theout"ut of the machine to create the arc without needingto touch the tungsten to the work"iece. In the "hoto afoot am"trol (foot "edal) is shown.

Slide # "3: Gas Tungsten Arc Welding1ower 'ources

Title slide for Gas Tungsten Arc Welding "ower sources.

Slide # "4: incoln 7ui$ent - The illustration shows ; machines that ha#e s"ecific

similarities. They are all transformer based "ower

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su""lies they all come as com"lete "ackages thatinclude the work cable and clam" the electrode holderand cable a sam"le "ackage of electrodes and a asicWelding Guide for eginner Welders and finally they allcome with an in"ut "ower cord and "lug ready to "luginto a =;8 #olt single "hase rece"tacle. Generally usedfor 'AW they can be ada"ted for GTAW.

The A* ==7 is a similar machine to the A* ==7 * with

slightly higher out"ut ratings. It is rated at ==7 am"s=8M duty cycle at =7 #olts. This machine has a slightlyhigher o"en circuit #oltage than the A* ==7* with %>.*.3. The welding out"ut of the machine is onlyalternating current with a current range of &8-==7 am"s.This machine howe#er has a 5ta"6 selector out"utcontrol rather than continuous. A ta" selector ta"s ormo#es to segmented o#erla""ing am"erage ranges.The am"erage listed at each ta" is the maimumam"erage that can be achie#ed at that setting. '"ecificam"erages are not set on this machine9 only ranges.

Therefore less "recise control is achie#ed on thismachine. A 5ta"6 selector has a manufacturingad#antage in that it is the least e"ensi#e welding out"utselector that can be "laced on a welding "ower su""ly.As a rule the ta" selector should 03F be changedduring welding otherwise a high am"erage will be"resent on the soldered ta"s and the ta"s will burn out.

The A* ==7* is rated at $8 am"s =8M duty cycle at

=7 #olts. The welding out"ut of the machine is onlyalternating current with a current range of &8-==7 am"s.The machine has a lower than normal o"en circuit

#oltage (oc#) of 7C o"en circuit #olts s"ecificallydesigned that way for safety "ur"oses. >"en circuit#oltage is a no-load #oltage. This means that if the"ower to the machine is turned on e#en though notwelding there is a "otential across the out"ut studs.>"en circuit #oltage aids in arc starting and the higherthe oc#. the easier it is to strike the arc. !owe#er0A (0ational lectrical anufacturers Association)sets limits on how high the oc# can be for safety"ur"oses. Their limits are $88 oc# for a +* machineand C8 oc# for an A* machine. Also from a

manufacturers stand"oint the higher the oc# the moree"ensi#e the "ower su""ly. Therefore many smallnon-industrial "ower su""lies ha#e lower oc# out"uts forsafety and cost reasons. The am"erage out"ut controlis a continuous one which is what the 5*6 stands for inthe name of the machine. The continuous control is aknob on the right hand side of the machine that adustswelding am"erage from the low end through eacham"ere to the high end of the range. This allows for"recise control of the welding out"ut. >n the front of the

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machine is an easy reference chart that lists? #arious A*shielded metal arc welding electrodes the diametersthat the machine can weld and the welding am"erageneeded to do so. 3oltage is not set or controlled at theconstant current "ower su""ly but is determined by thearc length of the electrode.

The A*/+* ==7/$=7 is also #ery similar to the A* ==7'.

It is howe#er a multi-"olarity machine ha#ing A* +*,

and +*- welding ca"abilities. >n the A* side it is ratedthe same as the A* ==7 at ==7 am"s =8M duty cycleat =7 #olts. It is rated at $=7 am"s =7 #olts with a =8Mduty cycle on +* due to the am"erage limitations of therectifier. A rectifier is the de#ice in the "ower su""ly thatallows current to flow in only one direction or inessence changes A* to +*. The A* am"erage rangeis &8-==7 am"s and the +* am"erage range is ;8-$=7am"s. A* has an o"en circuit #oltage of 8 and +*has an oc# of ;. Welding "olarity is determined by the"osition of the "olarity ta" selector. The welding

am"erage is also determined by a ta" selector that ta"sor mo#es to segmented o#erla""ing am"erage ranges.The am"erage listed at each ta" is the maimumam"erage that can be achie#ed at that setting. Thereare two am"erage #alues listed at each ta" one for A*(the to" one) and one for +* (the bottom one).

This machine has the most #ersatility in the grou"

because the maority of 'AW electrodes o"erate on+* "olarity.

All of the machines on this slide are non-industrial

machines that are designed for the hobbyist home user

farmer etc.Slide # "5: incoln 7ui$ent - All of these machines are also transformer based "ower

su""lies. !owe#er they are designed for industriala""lications rather than hobby home user machines asis the case with the A*-==7* A*-==7 and A*/+*==7/$=7.

Again these are generally used as 'AW machines but

they are used for some GTAW a""lications.

The I+A


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mo#able dial that is turned on at the front of themachine. This dial is called a mo#able iron control.Turning the dial mo#es the big 5chunk6 of iron in thetransformer to either increase or decrease weldingam"erage. As the dial is turned an am"erage indicatormo#es down an am"erage range to dis"lay the weldingam"erage. There are two ranges one for A* and onefor +*. This is a continuous ty"e control for #ery "recise

welding am"erage control. The two F;F machines are similar machines in nature.

They are similar in that the machines are ; "haseindustrial machines with only +* welding out"ut rated ata B8M duty cycle at their name"late am"erage rating.or eam"le the F;F-&88 is rated at &88 am"s B8Mduty cycle at ;B #olts. The F;F-788 is rated at 788am"s B8M duty cycle at &8 #olts.

The F;F-&88 is a multi"le in"ut #oltage machine with

=;8/&B8 #olts in"ut "ower re2uirements. There are twomodels of the F;F-&88 one that comes only with a

continuous am"erage out"ut control and arc forcecontrol with no meters and no "olarity switch and onewith all the mentioned features. The +* am"eragerange of this machine is B8-788 am"s.

The F;F-788 is a multi"le in"ut #oltage machine with

=;8/&B8 #olts in"ut "ower re2uirements. There arethree models of the F;F-788 one that comes only witha continuous am"erage out"ut control and arc forcecontrol with no meters and no "olarity switch one withall the mentioned features and a third one with all of thementioned features and "ocket am"trol hardware. A

"ocket am"trol is a cordless remote control. Themachine is "laced on Femote >ut"ut *ontrol and the"ocket am"trol is first "laced in the electrode holder(stinger) and touched to the work"iece to establish thestarting am"erage. Then it is taken remotely away fromthe "ower su""ly and am"erage can be adusted fromthe dial on the "ocket am"trol. The dial on the "ocketam"trol co#ers the entire am"erage range of the "owersu""ly. The +* am"erage range of this machine is 7-B=7 am"s.

Slide # "!: incoln 7ui$ent - Gas Tungsten Arc Welding machines are also constant

current. Therefore they can also be used for 'AWwelding. :sually there is an out"ut dial on the face ofthe "ower source to choose between GTAW and 'AW.


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Technology which greatly im"ro#es the 2uality of the A*arc. They ha#e A* and +* welding out"uts and carrythe three year


32/75

Feady-to-Weld "ackage.

icro 'tart Technology allows for ecellent starting of

the tungsten es"ecially on the low end.

A* arc control allows for o"timal control of the arc

whether or not using auto balance and when crateringout "re#ents the re-establishing of the high fre2uency toha#e better crater features on aluminum and to limittungsten PfrostingP.

All "ulsing controls come as standard on this machine. The accessories such as the torch am"trol etc. are

ordered s"ecific to a""lications and customer comfort.'e#eral o"tions are also a#ailable for the 1recision TIG;7 for air/water-cooled torches. This machine isdesigned for industrial use.

Slide # "": incoln 7ui$ent - *9 The +*-&88 +*-B88 and +*-B77 are transformer

based multi-"rocess "ower sources9 they ha#e theca"ability of welding with many different "rocesses suchas 'hielded etal Arc Welding (stick) Gas Tungsten ArcWelding (TIG) and wire feed welding (GAW and

*AW). They are *onstant *urrent/*onstant 3oltage (**/*3)

machines that deli#er +irect *urrent (+*) out"ut only.

These "ower sources are ;-"hase and are named

according to their am"erage out"ut at $88M +uty *ycle(or eam"le the +*-&88 is a ;-"hase **/*3 "owersource deli#ering only direct current out"ut and is ratedat &88 Am"s with $88M +uty *ycle).

Slide # "%: incoln 7ui$ent - ,nerter


33/75

The machine is full featured with "ulsing controls for

both A* and +* welding.

The o"erator when welding on A* has the ability to

adust the amount of +*0 (+*-) from ;7-C7M and thefre2uency on the s2uare wa#e setting from =8-$78 !4.

The o"erator can choose different out"uts (sinusoidal

triangular or s2uare) de"ending u"on the welding need.

=M Thoriated tungsten is used at all times and it is

"re"ared the same for A* as one would for +*. Thisgi#es a #ery focussed arc which does not wander andgi#es the o"erator a great deal of control.

Slide # "&: incoln 7ui$ent - ,nerter


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technology of the in#erter family. This is a 7 to 78 am""ower source. It will shielded metal arc weld. If a few ofthe o"tional "anels are added the shielded metal arcwelding arc can be controlled with a 5soft6 or 5cris"6control. The machine is dri#en by Wa#eform *ontrolTechnology

The 1ower Wa#e &77/'TT has some of the highest

technology of the in#erter family. This is a 7 to 78 am"

"ower source. It will shielded metal arc weld. If a few ofthe o"tional "anels are added the shielded metal arcwelding arc can be controlled with a 5soft6 or 5cris"6control. The machine is dri#en by Wa#eform *ontrolTechnology.

Slide # %1: incoln 7ui$ent - hoer *9;


35/75

(+*1) or +*- straight "olarity (+*F1). This allow fordee" "enetration welds on mild steel. 'tainless steeland cast iron can be also be welded and hardfacing canbe done with this "ower source. The com"act si4e andtubular roll gage make this machine #ery "ortablewhether it is used for welding needs or as an A*generator.

Slide # %3: incoln 7ui$ent - ngine /ries


36/75

family that are more suitable. Also these engine dri#esdo 0>T ha#e an internal contactor as a standardfeature. The wire feeder must ha#e a contactor in orderto ha#e an electrically cold wire until the gun trigger is"ulled. >therwise the wire will be electrically hot andcould "otentially cause arc flash or "otential ha4ards.

The FA0GF GQT is a slightly larger machine found

within this family. It is rated at =78 Am"s at $88M duty

cycle for both A* and +* for constant current weldingas well as for +* constant #oltage welding. It has$$888 watts of auiliary "ower. The engine is a =8 !1Eohler engine. It has o#erla""ing current ranges ando#erla""ing #oltage ta"s with a #oltage range of $=-;7#olts. The fine tuner adusts to s"ecific am"erages or#oltages within a ta". It also "ro#ides the ability to run alower "rocedures for smaller wire diameters and thinnermaterials and larger wire diameters and thickermaterials. This engine dri#e is more suited for a broaderrange of constant #oltage a""lications.

The fine tuner must be at the maimum setting in orderto achie#e full auiliary "ower.

Across the arc welding "rocesses there is an o"tion for

wire feed welding with a #oltage-sensing wire feeder forall of the engine dri#es. The Fanger GQT also comesstandard with a $&-"in am"henol for connection of amultitude of wire feeders and B-"in am"henol forremote control ca"abilities.

The FA0GF ;-1hase is similar to the Fanger $8888.

!owe#er it generates $$788 watts of ;-"hase "owerand $8788 watts of single "hase "ower.

The other ece"tion is that it is only a#ailable with theEohler engine

Slide # %4: incoln 7ui$ent - ngine /ries hoer; The FA0GF =78 / FA0GF =78


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cycle for +* constant current and constant #oltagewelding. The auiliary "ower is C888 watts. ullauiliary "ower is achie#ed inde"endent of where theout"ut control knob is set. The FA0GF =78 useseither a =8 !1 >nan engine or a =8 !1 Eohler o#erhead#al#e designed engine that has a fuel tank ca"acity of$= gallons. This machine has one out"ut control dial toset am"erage or #oltage de"ending u"on the ty"e of

welding being done (** or *3). The current range is&8-=78 am"s for 'AW welding and =8-=78 for touchstart TIG welding. The #oltage range is $&-=C #olts for*3 welding. There is also a "i"e welding mode on theFanger =78 that is ideal for downhill 'AW welding on"i"e that acts as a slo"e control as well as a currentcontrol. This machine comes standard with a $& "in andB-"in am"henol for wire feeder connection and remotecontrol ca"abilities res"ecti#ely. This machine has acom"letely enclosed case to maimi4e "erformance andto "rotect the engine. This also minimi4es the noisele#els of the machine while it is running.

The FA0GF ;87 is a ;88 am" $88M duty cycle "ower

source. The 5G6 in the FA0GF ;87 G stands forgasoline dri#en engine. It deli#ers %888 watts of A*"ower with a == horse"ower air-cooled gasoline engine.The "ower source is totally enclosed which makes it a2uiet running machine. It has all of the features of theFanger =78. >ne of the features that makes thismachine #ery attracti#e to contractors and maintenance"eo"le is the single full-range out"ut control dial. Thiseliminates the confusion caused by ta" ty"e controls.

Slide # %5: incoln 7ui$ent - ngine /ries

This family of welding machines are 5True6 generators. Generators are engine dri#en e2ui"ment that "roduce

"ure +* (direct current) welding "ower. This is unlikealternators that "roduce A* (alternating current) which isrectified to +*. 1ure +* is much smoother thanrectified +*. Therefore the arc characteristics of agenerator are significantly smoother than that of analternator. They are #ery attracti#e to "i"e welders andcontractors.

The 'A &88 / 'A &88 'e#ere +uty is "owered by a

hea#y duty 1erkins &-cylinder water-cooled industrial

diesel engine. It has a current range of C8 to 77 am"sand is "owered by a $ horse "ower engine. This"ower source is large enough to thaw fro4en water linesIt is im"ortant to read bulletin -B%7.$ dated @une $%C%or later before attem"ting to thaw fro4en lines. 'tandardgauges on this machine are the engine hour meter oil"ressure tem"erature meter and battery charging am"smeter. All day welding with a ==.7-gallon fuel tank is nota "roblem.

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The 'A &88 Weld and Air is #ery similar to the 'A

&88 but it has a built-in air com"ressor. It was designedes"ecially for "i"e welders field welders and for use ingeneral maintenance on demanding obs. Thecom"ressor will deli#er ;7 cfm at $88 "si. The air su""lyoutlet is con#eniently located for easy access. It has an$$-gallon recei#er tank with a water drain #al#e. Allcom"ressor controls are located on the front control

"anel for easy access. inally base "lates beneath thecom"ressor "rotect the air tanks from "uncture. Aircom"ressors are used for carbon arc gouging and/or forthe o"eration of air-"owered tools.

Slide # %!: incoln 7ui$ent - ngine /ries The 1i"eliner =88G / 1i"eliner =88+ is a "ure +*

generator with su"erior out"ut. It has been known foro#er B8 years for its long-life reliability in o"eration andgreat resale #alue. eatures included are oil "ressurelight and engine hour meter. The 1i"eliner generatorwith co""er windings creates the 5classic arc6 for "i"ewelding and other critical a""lications. The 1i"eliner

generator has +* auiliary which is different than thenormal A* auiliary "ower from most engine dri#es. The+* auiliary is $78 watts. In addition there is anengine r"m controller on the inside of the machine thatallows for easy control of the >*3 for "i"e weldinga""lications.

The *lassic ;88G / *lassic ;88+ is a "ure +* generato

with su"erior out"ut. It has been known for o#er B8years for its long-life reliability in o"eration and greatresale #alue. eatures included are oil "ressure lightand engine hour meter. The 1i"eliner generator with

co""er windings creates the 5classic arc6 for "i"ewelding and other critical a""lications. The machine has;888 Watts of A* auillary "ower. The 1i"elinergenerator has A* auiliary "ower and ;888 watts. Inaddition there is an engine r"m controller on the insideof the machine that allows for easy control of >*3 for"i"e welding a""lications.

Slide # %": incoln 7ui$ent - ngine /ries hoer; The net family of alternator engine dri#es to be

discussed is the 3antage engine dri#es. They include3antage 788 and Air 3antage 788.

These engine dri#es also em"loy 5*ho""er Technology6as mentioned concerning the Fanger =78 and Fanger;87G. The 3antages are ; "hase asynchronousalternators. This is unlike the other alternators that aresingle "hase.

The 3antage 788 / Air 3antage 788 is rated at 788 Am"s

with a $88M duty cycle and has a current range of &8-77 am"s and a #oltage range of $=-&C #olts. It hasfi#e o#erla""ing current ranges and a fine tuner to adust

Copyright 2002 Lincoln Global, Inc. 3% E-Date: 10/29/10


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to a s"ecific am"erage within the range. It has $=888watts of auiliary "ower.

*hoices of engines are the air-cooled +eut4 or water-

cooled *ummins. (Air 3antage 788 only a#ailable in*ummins "ackage.

Slide # %%: GTAW - T,G "tions such

as a contactor for cold tungsten on "ower sources thatdo not ha#e an out"ut contactor TIG torches etc. are

also a#ailable. This de#ice is ecellent for both field use on an engine

dri#en "iece of e2ui"ment as well as sho" use on staticmachines.

Slide # %&: GTAW - onstant urrent This is the #olt-am" cur#e from a ** "ower su""ly

It is commonly referred to as a droo"er cur#e.

3oltage is "ro"ortional to arc length the distance from

the end of the electrode to the work"iece.

As this distance changes #oltage changes. !owe#er

there is little to no change in the "reset welding current.

Slide # &': GTAW - Start ontrol 'o"histicated TIG "ower su""lies ha#e additionalfeatures to o"timi4e arc characteristics and the welditself.

'tarting controls are one such feature. 'tarting controls

allow the o"erator to do one of three things? !a#e thearc start be a 5hot start6 when the starting current ishigher than welding current 5cold start6 when thestarting current is lower than the welding current or >to ha#e the arc starting am"erage the same as the"reset welding am"erage. There are two dials. >ne dialallows you to "reset starting am"erage and the other

dial allows you to "reset a starting am"erage time.When the time e"ires the machine will ha#e adustedfrom the starting am"erage to the "reset weldingam"erage.

The ad#antage of 5hot starts6 is to ensure good

"enetration at the beginning of the weld and/or to"reheat the base material on base materials thatdissi"ate heat readily.

*old starts are ecellent on #ery thin materials and on

Copyright 2002 Lincoln Global, Inc. 3& E-Date: 10/29/10


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o"en roots or "oor fit-u".

The o#erall ad#antage of ha#ing a starting control is

im"ro#ed starting and weld 2uality.

Slide # &1: GTAW - Pulse ontrols Another so"histicated feature on ad#anced "ower

su""lies allowing "ulsing of the current with essentiallys2uare "ulses.

The "ulse wa#eform is the amount and duration of two

different current le#els of the "ower su""ly the "eak or

"ulse current and the background current. 1ulsedGTAW switches back and forth between this high "eakcurrent and a much lower background current.

GTAW "ulse rates are much lower than those used in

GAW welding and are in the =-$8 "ulses "er secondrange. The "eak or "ulse current is much higher thannormal TIG welding current le#els and the backgroundis much lower than normal TIG welding current.

The "eak welding current determines "enetration le#els.

ut before the base material becomes o#erheated theam"erage is reduced to the background le#el where the

weld "uddle and base material cool down. Thisbackground current also maintains the welding arc.

1ulses "er second is the fre2uency or the number of

times "er second that the "eak current is on. The"ercentage on time re"resents the duration of the "ulsecurrent as a "ercentage of the total arc on time. Itdetermines how long the "eak current is on before itgoes back to the background current le#el. All of thesefeatures are adustable on so"histicated "ulsing TIGmachines.

An ad#antage of "ulsed TIG welding includes ecellent

"enetration at lower heat le#els than what would occurat a constant am"erage le#el. This feature allows TIGwelding to be ecellent on #ery thin materials without theconcern of distortion and for o"en roots or "oor fit-u"a""lications.

1ulse GTAW welding is also a great way to maintain

good "uddle control for out of "osition welding. The"ulsed arc greatly reduces the need for adusting theheat in"ut as the weld "rogresses. All of thesead#antages occur with the same weld 2uality as thestandard arc.

1ulsing controls can be set directly at the "ower su""ly

or from a remote "endant for control directly at the work"iece.

1ulsing ca"abilities are standard on some machines. >n

others it can be added as an o"tion.

Slide # &2: GTAW - nd ontrols Another feature found on some GTAW "ower su""lies is

a crater control otherwise known as crater fill. Thisfeature o"timi4es the end of the weld bead. When

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GTAW welding a crater or unfilled "ortion of the weldbead forms at the termination of the weld bead. *ratersare not only #isually un"leasant they offer a "otential forcracking. To "re#ent this condition some ty"e of craterfill needs to take "lace.

>ne method is to slowly ease u" on the foot or hand

am"trol to slowly reduce the welding current down to4ero while adding filler material. This re2uires skill when

trying to maneu#er both hands and your foot at thesame time.

'o"histicated TIG machines ha#e a feature downslo"e

and finish current. The downslo"e feature gi#es theo"erator the ability to "reset a downslo"e time and afinish current le#el.

When the downslo"e o"tion is acti#ated the downslo"e

fade out begins when the arc start mechanism (arc startswitch or am"trol) is released while in the =-ste" modeor if "ressed and released a second time while in the &-ste" mode. This control regulates the rate of current

decline. Ty"ical times of current decline from weldingcurrent to finish current range from about H second to=8 seconds. +uring the decline time filler material isadded to the crater to fill i t and "re#ent it from cracking.

Slide # &3: GTAW - /ut) )cle The duty cycle of a "ower source is the "ercentage of a

ten-minute "eriod that it o"erates at its rated out"utcurrent setting.

If a "ower source is rated at ;88 am"s at a B8M duty

cycle it means that the machine can be o"erated safelyat ;88 am"s welding current for B out of e#ery $8minutes. If this duty cycle is reduced in actual o"eration

the maimum "ermissible current is increased. Thus ata ;7M duty cycle this same ;88 am" "ower sourcecould be o"erated at ;7 am"s.

Slide # &4: GTAW - /ut) )cle The following is an eam"le of a machineDs duty cycle?

The ty"ical duty cycle for this machine at =78 am"s

would be ;8M. This means that the "ower source cano"erated safely at =78 am"s for ; out of e#ery $8minutes.

At =88 am"s it has a 78M duty cycle9 or can be

o"erated safely at =88 am"s for 7 out of e#ery $8minutes.

At $&8 am"s it has a $88M duty cycle and can be safely

o"erated at $&8 am"s for $8 minutes out of e#ery $8minutes.

Slide # &5: GTAW - T,G Torches

(!a#e eam"les of different ty"es of torches to "ass around)


42/75

with a B8M duty cycle. The air-cooled line consists of an1TA-% 1TA-$ 1TA-$3 and 1TA-=B and 1TA-=B3torch. The 536 designator indicates that it is a #al#e inhand torch design to regulate shielding gas flow. Thisty"e of torch would be used if TIG welding with a **"ower su""ly without a gas solenoid in it that wouldnormally regulate gas flow. The #al#e on the torchwould control gas flow so that gas is not flowing

continuously which is wasteful and costly. The water-cooled torches are called 1ro Torches Water-

*ooled (1TW) and are rated at a s"ecific am"erage witha $88M duty cycle. The water-cooled line consists of a1TW-$C and 1TW-=8 torch. The lengths of all TIGtorches are $=.7 and =7.

Slide # &!: GTAW - Wor6 la$s

Slide # &": GTAW - Prearing the Tungsten lectrodes used in TIG welding differ tremendously from

those used in other "rocesses in which the electrode isconsumed and becomes "art of the weld itself.Tungsten is not intended to be consumed or melted but

can be when the wrong ty"e wrong si4e wrong"rocedures wrong "re"aration or wrong techni2ues areused. 1ro"er time and care must be taken whenselecting the tungsten.

After choosing the correct tungsten to use for the

a""lication the tungsten needs to be "re"ared "rior towelding. >n +* "olarity the tungsten needs to beground to a "oint as shown in the illustration. Thetungsten should be ground to a conical angle that is =-;times the diameter of the electrode. Grinding shouldalways be done "arallel to the tungsten to "ro#ide a

clean "ath for electrons to flow down the tungsten to thework"iece. If grind marks are not "arallel to thetungsten electrons will be emitted off the sides of thetungsten. This will "roduce an erratic arc and tungstendegradation.

There are se#eral ways to grind tungsten. The best way

is to use a Tungsten Grinder. These grinders ha#e beenmanufactured s"ecifically to grind tungsten. Thetungsten fits inside a fiture with a fied "ortion e"osedto the grinder and the ta"er angle of the grind is set.The machine then accurately grinds the tungsten.

A con#entional grinder or grinding wheel can also beused but remember grinding should be "arallel to thetungsten. Also if using a coarse stone some grindmarks can be concentric with the electrode. Thesesmall ridges can melt off and float into the weld "uddle.The grinders should be dedicated >0


43/75

of the tungsten instead of at the ti". This can "roducean erratic arc and ecessi#e tungsten degradation.

A final method to "re"are tungsten is to use a chemical

grinding com"ound. After heating the tungsten bycreating an arc the tungsten is then di""ed into thiscom"ound forming a chemical reaction. The chemicalreaction causes a conical erosion of the tungstenforming a "recise ti". This means of "re"aring tungsten

is great for "ortable TIG welding. The most common ty"e of tungsten used for +*- GTAW

welding is =M thoriated. !owe#er there are se#eralothers as well.

When "re"aring the tungsten the end without the color

band should be ground. The color band is the onlyidentification marking on the tungsten and onceremo#ed it will become difficult to identify.

Slide # &%: GTAW - Prearing the Tungsten Grinding the tungsten #ideo.

Slide # &&: GTAW - Prearing the Tungsten or A* TIG welding the "ro"er "olarity for aluminum

and magnesium the tungsten needs to be "re"ared

differently. or A* welding the desired electrode ti" sha"e is a

5balled6 or hemis"here sha"ed end. This ball should be$-$ H times the diameter of the electrode. This isbeneficial because on A* current switches from +*, to+*- "olarity or from recei#ing electrons to emittingelectrons. Tungsten emits electrons #ery readily butneeds hel" recei#ing them. The 5balled6 tungsten aidsin this function.

Tungsten electrodes that are designed "rimarily for A*

welding will form a ball readily on A* or if the "olarity is>0TAFI


44/75

"ieces of tungsten usually =M thoriated.

There are se#eral com"onents of TIG torches that make

them com"lete. ach com"onent comes in #arioussha"es and si4es that are chosen de"endant u"on thediameter of the tungsten and the a""lication at hand.

Gas no44les or 5cu"s6 are one com"onent. These

no44les are either screwed on to the end of the torch orsna" in "lace. Gas 0o44les are usually made of a hard

heat-resistant ceramic. >ther no44les made of metalhigh tem"erature glass like #icor or acketed ceramicare also a#ailable. *eramic no44les break fairly easilyes"ecially when you are not careful of storage or"lacement of the TIG torch after use. roken no44lesmust be re"laced to ensure "ro"er gas co#erage of theweld.

Gas no44les "ro#ide shielding gas co#erage o#er the

weld "ool to "rotect it from contaminants in theatmos"here. +ifferent si4es are a#ailable to "ro#idemore or less gas co#erage.

'ome gas no44les also ha#e ta"ered edges to betterdirect gas flow or for small or constricted welds.

There are also no44les that are fitted with an insert

washer made u" of se#eral layers of fine wire screen.These no44les are often called gas lenses. Gas lenses"roduce a diffused gas flow rather than a turbulent flowof inert gas to increase the efficiency of shielding.*ritical a""lications and sensiti#e base materials suchas titanium etc. re2uire the use of gas lens no44les.

Gas lenses utili4e the same conce"t of the screen mesh

found under the s"igot of a water faucet where the water

flow is directed in a straight "ath rather than in a diffusedmanner.

The collet and collet body are other TIG torch "arts.

The collets main function is to hold the tungsten in

"lace and the collet body holds the collet.

The collet body also dis"erses gas flow around the

tungsten to "rotect the tungsten from contamination andto ensure "ro"er gas co#erage of the weld "ool.

The collet and collet body are si4ed according to the

tungsten diameter.

The back ca" holds all of the "arts and "ieces togetherand acts as a handle or rest for the torch to rest on theo"erators hand.

:sually a few "ieces of tungsten are included in different

diameters in this kit and are generally =M thoriated.

Slide # 1'2: GTAW - Water oolers Water coolers are o"tional "ieces of e2ui"ment for TIG

machines. They are used in conunction with water-cooled torches and "ro#ide a means of circulating waterto and from the TIG torch to kee" it cool.



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A "um" inside the cooler circulates water and/or water-

antifree4e mitures to and from the torches to kee" themcool during welding. Ty"ically water-cooled systems areused when welding at am"erage le#els abo#e =88am"s.


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Slide # 1'4: GTAW - 0e$ote urrent ontrols There are also two de#ices that not only allow arc

initiation to take "lace but also allow remote #ariablecontrol of the current while welding. These de#ices arecalled the hand am"trol and the foot am"trol (alsoknown as the foot "edal). These items address theneed for adusting the current while welding on longwelds or on materials that absorb heat readily such asaluminum so that o#erheating and/or burnthrough do not

occur. >nce the foot "edal and/or hand am"trol isde"ressed or acti#ated the arc starts. If the foot "edalis de"ressed com"letely and/or if the hand am"trol is atits highest "osition the current will be at the "resetwelding current. As you ease u" on either de#icecurrent ram"s down until you release the am"trols. Atthis "oint the arc is etinguished. These de#ices actsimilar to an accelerator in a car. The further you "ushthe accelerator down (or the am"trols down) the higherthe s"eed of the car (or the higher the am"erage.) Thehighest current le#el is where you ha#e "reset the

machine or full range of the machine if the machine isset at maimum out"ut. The other end of the foot orhand am"trol is "lugged into the "ower su""lys remotecontrol am"henol.

The arc start switch hand am"trol and foot am"trol also

acti#ate the internal contactor of the "ower su""ly ifthere is one as well as gas and water solenoids ifa""lic

Documents

GTAW Lesson Plan