Everlast POWER DIGITAL SERIES User manual

1
EVERLAST
POWER ® DIGITAL SERIES
DIGITAL TIG AC/DC
Operator ’ s Manual
Includes DIGITAL AC/DC 210 EXT/ 320 EXT
Safety, Setup and General Use Guide
Rev. 1 0612-12

2
IMPORTANT NOTICE:
This document has been prepared by Everlast Power Equipment INC. as general information
and does not contain and is not to be taken as containing any specific recommendation. The
document has been prepared in good faith and is professional opinion only. Information in this
document has been derived from third parties, and though Everlast believes it to be reliable as at
the time of printing. Everlast makes no representation or warranty as to the accuracy, reliability or
completeness of information in this document and does not assume any responsibility for updat-
ing any information or correcting any error or omission which may become apparent after the
document has been issued, Neither Everlast nor any of its agents has independently verified the
accuracy of the information contained in this document. The information is commercial in confi-
dence and not to be reproduced.
The recipient acknowledges and agrees that it must make its own independent investigation and
should consider seeking appropriate professional recommendation in reviewing and evaluating
the information. This document does not take into account the particular circumstances of the re-
cipient and the recipient should not rely on this document in making any decisions, including but
not limited to business, safety or other operations decisions. Except insofar as liability under any
statute cannot be excluded. Everlast and its affiliates, directors, employees, contractors and con-
sultants do no accept any liability ( whether arising in contract, tort or otherwise ) for any error or
omission in this document or for any resulting loss or damage ( whether direct, indirect, conse-
quential or otherwise) suffered by the recipient of this document or any other person relying on
the information contained herein. The recipient agrees that it shall not seek to sue or hold Ever-
last or their respective agents liable in any such respect for the provision or this document or any
other information.

3
Serial number: __________________________
Model number: ____________________________
Date of Purchase: ___________________________
EVERLAST
Contact Information
Everlast US:
Everlast consumer satisfaction email: sa[email protected]
Everlast Website: everlastwelders.com
Everlast Technical Support: [e-mail]
Everlast Support Forum: http://www.everlastgenerators.com/forums/index.php
Main toll free number: 1-877-755 WELD (9353) 9am—5pm PST M-F
11am-4pm PST Sat.
FAX: [phone]
Everlast Canada:
Everlast consumer satisfaction email: sa[email protected]
Everlast Website: everlastwelders.ca
Everlast Technical Support: s[email protected]
Telephone: [phone]am-4:00pm EST M-F
10am-2pm EST Sat.
FAX: [phone]
Everlast Austrailia:
Sydney: 5A Karloo Parade Newport NSW 2106 (02) 9999 2949
Port Macquarie: 4/18 Acacia Avenue Port Macquarie [phone]
After hours support: 0413 447 492 Everlast Technical Support: [email protected]

4

DearCustomer,
THANKS!Youhadachoice,andyouboughtanEverlast.Weappreciateyouasacustomer
andhopethatyouwillenjoyyearsofusefromyourwelder.

PleasegodirectlytotheEverlastwebsitetoregisteryourunitandreceiveyourwarrantyinformaon.Yourunitreg-
istraonisimportantshouldanyinformaonsuchasproductupdatesorrecallsbeissued.Itisalsoimportantso
thatwemaytrackyoursasfaconwithEverlastproductsandservices.Ifyouareunabletoregisterbywebsite,
contactEverlastdirectlythroughthesalesdepartmentthroughthemaincustomerservicenumberinyourcountry.
Yourunitwillberegisteredandwarrantywillbeissuedandinfulleffect.Keepallinformaonregardingyourpur-
chase.Intheeventofaproblemyoumustcontacttechnicalsupportbeforeyourweldercanbeacandidatefor
warrantyserviceandreturned.

Please review the current online warranty statement and informaƟon found on the website of the Everlast
division located in or nearest to your country. Print it for your records and become familiar of its terms and
condiƟons.

Everlastoffersfulltechnicalsupport,inseveraldifferentforms.Wehaveonlinesupportavailablethroughemail,
andaweldingsupportforumdesignedforcustomersandnoncustomerinteracon.Technicaladvisorsareacveon
theforumdaily.Wealsodivideoursupportintotwodivisions:technicalandweldingperformance.Shouldyouhave
anissueorquesonconcerningyourunit,pleasecontactperformance/technicalsupportavailablethroughthe
maincompanyheadquartersavailableinyourcountry.Forbestservicecalltheappropriatesupportlineandfollow
upwithanemail,parcularlyifoffhours,oryoucannotreachaliveperson.Intheeventyoudonotreachalive
person,parcularlyduringheavycallvolumemes,holidays,andoffhours,leaveamessageandyourcallwillnor-
mallybereturnedwithin24hours.Alsoforquickanswerstoyourbasicquesons,jointhecompanyownedforum
availablethroughthewebsite.You’llfindknowledgeable,helpfulpeopleandstaffavailabletoansweryourques-
ons,andperhapsfindatopicthatalreadyaddressesyourquesonathp://www.everlastgenerators.com/
forums/.

Shouldyouneedtocallorwrite,alwaysknowyourmodelname,purchasedateandweldermanufacturinginspec-
ondate.Thiswillassurethequickandaccuratecustomerservice.REMEMBER:Beasspecificandinformedas
possible.Technicalandperformanceadvisorsrelyuponyoutocarefullydescribethecondionsandcircumstanc-
esofyourproblemorqueson.Takenotesofanyissuesasbestyoucan.Youmaybeaskedmanyquesonsby
theadvisorstoclarifyproblemsorissuesthatmayseemverybasic.However,diagnosisproceduresMUSTbefol-
lowedtobeginthewarrantyprocess.Advisorscan’tassumeanything,evenwithexperiencedusers,andmust
coverallaspectstoproperlydiagnosetheproblem.
.
Letusknowhowwemaybeofservicetoyoushouldyouhaveanyquesons.

Sincerely,
EverlastCustomerService

5
TABLE OF CONTENTS
SECTION PAGE
General 6
SECTION 1
Safety Precautions 7-9
SECTION 2
Know your Machine 10-17
SECTION 3
Gas Tungsten Arc Welding (GTAW/TIG) 18-26
SECTION 4
Welding Materials 27-29
SECTION 5
Trouble Shooting 31-33

6
Everlast is dedicated to providing you with the best possible equipment and
service to meet the demanding jobs that you have. We want to go beyond deliv-
ering a satisfactory product to you. That is the reason we offer technical sup-
port to assist you with your needs should an occasion occur. With proper use
and care your product should deliver years of trouble free service.
Safe operation and proper maintenance is your responsibility.
We have compiled this operator’s manual, to instruct you in basic safety, oper-
ation and maintenance of your Everlast product to give you the best possible
experience. Much of welding and cutting is based upon experience and com-
mon sense. As thorough as this welding manual may be, it is no substitute for
either. Exercise extreme caution and care in all activities related to welding or
cutting. Your safety, health and even life depends upon it. While accidents are
never planned, preventing an accident requires careful planning.
Please carefully read this manual before you operate your Everlast unit. This
manual is not only for the use of the machine, but to assist in obtaining the
best performance out of your unit. Do not operate the unit until you have read
this manual and you are thoroughly familiar with the safe operation of the unit.
If you feel you need more information please contact Everlast Support.
The warranty does not cover improper use, maintenance or consumables. Do
not attempt to alter or defeat any piece or part of your unit, particularly any
safety device. Keep all shields and covers in place during unit operation should
an unlikely failure of internal components result in the possible presence of
sparks and explosions. If a failure occurs, discontinue further use until mal-
functioning parts or accessories have been repaired or replaced by qualified
personnel.
Note on High Frequency electromagnetic disturbances:
Certain welding and cutting processes generate High Frequency (HF) waves.
These waves may disturb sensitive electronic equipment such as televisions,
radios, computers, cell phones, and related equipment. High Frequency may
also interfere with fluorescent lights. Consult with an electrician if disturb-
ance is noted. Sometimes, improper wire routing or poor shielding may be the
cause.
HF can interfere with pacemakers. See EMF warnings in following safety sec-
tion for further information. Always consult your physician before entering an
area known to have welding or cutting equipment if you have a pacemaker.
GENERAL

7
SAFETY PRECAUTIONS
These safety precautions are for protection of safety and health. Failure to
follow these guidelines may result in serious injury or death. Be careful to
read and follow all cautions and warnings. Protect yourself and others.
Welding and cutting processes produce high levels of ultraviolet (UV) radiation that
can cause severe skin burn and damage. There are other potential hazards involved
with welding such as severe burns and respiratory related illnesses. Therefore ob-
serve the following to minimize potential accidents and injury:
Use appropriate safety glasses with wrap around shields while in the work area, even
under welding helmets to protect your eyes from flying sparks and debris. When chip-
ping slag or grinding, goggles and face shields may be required.
When welding or cutting, always use an approved shielding device, with the correct
shade of filter installed. Always use a welding helmet in good condition. Discard any
broken or cracked filters or helmets. Using broken or cracked filters or helmets can
cause severe eye injury and burn. Filter shades of no less than shade 5 for cutting
and no less than shade 9 for welding are highly recommended. Shades greater than 9
may be required for high amperage welds. Keep filter lenses clean and clear for maxi-
mum visibility. It is also advisable to consult with your eye doctor should you wear
contacts for corrective vision before you wear them while welding.
Do not allow personnel to watch or observe the welding or cutting operation unless
fully protected by a filter screen, protective curtains or equivalent protective equip-
ment. If no protection is available, exclude them from the work area. Even brief expo-
sure to the rays from the welding arc can damage unprotected eyes.
Always wear hearing protection because welding and cutting can be extremely noisy.
Ear protection is necessary to prevent hearing loss. Even prolonged low levels of
noise has been known to create long term hearing damage. Hearing protection also
further protects against hot sparks and debris from entering the ear canal and doing
harm.
Always wear personal protective clothing. Flame proof clothing is required at all
times. Sparks and hot metal can lodge in pockets, hems and cuffs. Make sure loose
clothing is tucked in neatly. Leather aprons and jackets are recommended. Suitable
welding jackets and coats may be purchased made from fire proof material from
welding supply stores. Discard any burned or frayed clothing. Keep clothing away
from oil, grease and flammable liquids.
Leather boots or steel toed leather boots with rubber bottoms are required for ade-
quate foot protection. Canvas, polyester and other man made materials often found
in shoes will either burn or melt. Rubber or other non conductive soles are necessary
to help protect from electrical shock.
Flame proof and insulated gauntlet gloves are required whether welding or cutting or
handling metal. Simple work gloves for the garden or chore work are not sufficient.
Gauntlet type welding gloves are available from your local welding supply companies.
Never attempt to weld with out gloves. Welding with out gloves can result in serious
burns and electrical shock. If your hand or body parts comes into contact with the
arc of a plasma cutter or welder, instant and serious burns will occur. Proper hand
protection is required at all times when working with welding or cutting machines!

8
SAFETY PRECAUTIONS
continued
WARNING! Persons with pacemakers should not weld, cut or be in the welding area
until they consult with their physician. Some pacemakers are sensitive to EMF radiation
and could severely malfunction while welding or while being in the vicinity of someone
welding. Serious injury or death may occur!
Welding and plasma cutting processes generate electro-magnetic fields and radiation.
While the effects of EMF radiation are not known, it is suspected that there may be
some harm from long term exposure to electromagnetic fields. Therefore, certain pre-
cautions should be taken to minimize exposure:
 Lay welding leads and lines neatly away from the body.
 Never coil cables around the body.
 Secure cables with tape if necessary to keep from the body.
 Keep all cables and leads on the same side the body.
 Never stand between cables or leads.
 Keep as far away from the power source (welder) as possible while welding.
 Never stand between the ground clamp and the torch.
 Keep the ground clamp grounded as close to the weld or cut as possible.
Welding and cutting processes pose certain inhalation risks. Be sure to follow any
guidelines from your chosen consumable and electrode suppliers regarding possible
need for respiratory equipment while welding or cutting. Always weld with adequate
ventilation. Never weld in closed rooms or confined spaces. Fumes and gases re-
leased while welding or cutting may be poisonous. Take precautions at all times.
Any burning of the eyes, nose or throat are signs that you need to increase ventilation.
 Stop immediately and relocate work if necessary until adequate ventilation is ob-
tained.
 Stop work completely and seek medical help if irritation and discomfort persists.
WARNING! Do not weld on galvanized steel, stainless steel, beryllium, titanium, cop-
per, cadmium, lead or zinc without proper respiratory equipment and or ventilation.
WARNING! This product when used for welding or cutting produces fumes and gas-
es which contains chemicals known to the State of California to cause birth defects
and in some cases cancer. (California Safety and Health Code §25249.5
et seq .)
WARNING! Do not weld or cut around Chlorinated solvents or degreasing areas.
Release of Phosgene gas can be deadly. Consider all chemicals to have potential
deadly results if welded on or near metal containing residual amounts of chemicals.
Keep all cylinders upright and chained to a wall or appropriate holding pen. Certain
regulations regarding high pressure cylinders can be obtained from OSHA or local
regulatory agency. Consult also with your welding supply company in your area for
further recommendations. The regulatory changes are frequent so keep informed.
All cylinders have a potential explosion hazard. When not in use, keep capped and
closed. Store chained so that overturn is not likely. Transporting cylinders incorrectly
can lead to an explosion. Do not attempt to adapt regulators to fit cylinders. Do not
use faulty regulators. Do not allow cylinders to come into contact with work piece or
work. Do not weld or strike arcs on cylinders. Keep cylinders away from direct heat,
flame and sparks.

9
SAFETY PRECAUTIONS
continued
WARNING! Electrical shock can kill. Make sure all electrical equipment is properly
grounded. Do not use frayed, cut or otherwise damaged cables and leads. Do not
stand, lean or rest on ground clamp. Do not stand in water or damp areas while weld-
ing or cutting. Keep work surface dry. Do not use welder or plasma cutter in the rain
or in extremely humid conditions. Use dry rubber soled shoes and dry gloves when
welding or cutting to insulate against electrical shock. Turn machine on or off only
with gloved hand. Keep all parts of the body insulated from work, and work tables.
Keep away from direct contact with skin against work. If tight or close quarters ne-
cessitates standing or resting on work piece, insulate with dry boards and rubber
mats designed to insulate the body from direct contact.
All work cables, leads, and hoses pose trip hazards. Be aware of their location and
make sure all personnel in area are advised of their location. Taping or securing ca-
bles with appropriate restraints can help reduce trips and falls.
WARNING! Fire and explosions are real risks while welding or cutting. Always keep
fire extinguishers close by and additionally a water hose or bucket of sand. Periodi-
cally check work area for smoldering embers or smoke. It is a good idea to have
someone help watch for possible fires while you are welding. Sparks and hot metal
may travel a long distance. They may go into cracks in walls and floors and start a fire
that would not be immediately visible. Here are some things you can do to reduce the
possibility of fire or explosion:
 Keep all combustible materials including rags and spare clothing away from area.
 Keep all flammable fuels and liquids stored separately from work area.
 Visually inspect work area when job is completed for the slightest traces of smoke
or embers.
 If welding or cutting outside, make sure you are in a cleared off area, free from
dry tender and debris that might start a forest or grass fire.
 Do not weld on tanks, drums or barrels that are closed, pressurized or anything
that held flammable liquid or material.
Metal is hot after welding or cutting! Always use gloves and or tongs when handling
hot pieces of metal. Remember to place hot metal on fire-proof surfaces after han-
dling. Serious burns and injury can result if material is improperly handled.
WARNING! Faulty or poorly maintained equipment can cause injury or death. Prop-
er maintenance is your responsibility. Make sure all equipment is properly maintained
and serviced by qualified personnel. Do not abuse or misuse equipment.
Keep all covers in place. A faulty machine may shoot sparks or may have exploding
parts. Touching uncovered parts inside machine can cause discharge of high
amounts of electricity. Do not allow employees to operate poorly serviced equipment.
Always check condition of equipment thoroughly before start up. Disconnect unit
from power source before any service attempt is made and for long term storage or
electrical storms.
Further information can be obtained from The American Welding Society (AWS) that
relates directly to safe welding and plasma cutting. Additionally, your local welding
supply company may have additional pamphlets available concerning their products.
Do not operate machinery until your are comfortable with proper operation and are
able to assume inherent risks of cutting or welding.

10
SECTION 2 KNOW YOUR MACHINE
2.0 Connecting your Everlast TIG AC/DC ma-
chine
2.1.1 TIG 210EXT This machine is designed to
operate on 240v +/- 15% input single phase AC
outlet. Ensure there is adequate ventilation
around the machine when it is connected to the
main power supply.
2.1.2 TIG 320EXT This machine depending on
your country is designed to work on a 220v,
380v or 460v (verify the voltage on your ma-
chine) +/- 15% input 3 phase supply. Ensure
that there is adequate ventilation around the
when it is connected to the main power supply.
2.2 Shielding Gas When working the machine
in the TIG mode of welding the process re-
quires a shielding gas. The shielding gas
can be supplied via a pressure regulator to
the machine from either a fixed installation or
single cylinder of gas. If a cylinder of gas is
used, please ensure that the cylinder is secure-
ly fastened before starting any welding opera-
tion. Refer to the application section for the
selection of the correct shielding gas.
2.3 TIG Torch Connection The TIG torch is fit-
ted to the welding machine by means of the
dinse connector. The TIG torch dinse connect-
or is connected to the negative output port lo-
cated on the front bottom panel of the machine.
The gas hose is fitted to the gas fitting (GAS).
The TIG torch switch or the foot pedal is con-
nected using the 5 pin connection on the front
bottom panel of the machine.
2.4 MMA Operation The Everlast AC/DC range
can be used as a MMA welding machine by fit-
ting an electrode holder and a work clamp to
the respective dinse connectors (dependent on
the type of electrodes being used. Please con-
sult the electrode packaging for the correct
polarities.)
2.5.1 For Direct Current (DC) Welding Select
the correct size and type of non-consumable
tungsten and shielding gas for the application
(See selection chart at the end of section 3)
For (DC-) (most commonly used polarity) con-
nect the TIG torch to the negative dinse plug
connector and the work clamp to the positive
dinse plug connector.
For (DC+) applications connect the TIG torch to
the positive dinse plug connector and the work
clamp to the negative dinse plug connector. In
this mode most of the heat is generated within
the non-consumable tungsten and the heat in-
put into the plate is reduced resulting in lower
penetration depths. (larger tungstens are nor-
mally selected for this application.
Ensure that the process selector switch (3) is
switched TIG.
Ensure that the AC/DC selector switch (4) is set
on DC.
Select 4T2T on the trigger selector switch (5).
Depress the contactor switch on the torch and
hold this down for the entire weld.
Selecting the 2T function will disable the Start
current (9) and the process will immediately
rise to the selected welding current.
For 4T operation, depress the contactor switch
on the torch and release it when welding starts.
Depress the contactor switch again at the end
of the weld.
Selecting the 4T function will enable the start
current (9) and the downslope cycle (12). Both
start current and downslope cycle time must be
manually selected.
Using a remote control device (such as a foot
control, or remote pendant). When using a re-
mote device ensure that the device is properly
fitted by connecting it to the remote control out-
let connector (21). The remote operating con-
trol switch (7) must be set in the on position.
7

11
SECTION 2 KNOW YOUR MACHINE
1 2
3
4
5
Description of the Control Panels
Number Function Description
1 Pre-Flow
2 Start Amp Indicator For TIG welding
3 Upslope Time Indicator Period in TIG welding during which the start amps are increased to the
specified main current.
4 Welding Amps Indicator Main current
5 P.P Current Indicator Pulse Peak Current (1-100%)
6 Downslope Time Indicator Period in TIG welding during which the specified main amps are low-
ered to the final current
7 End Amps Indicator For TIG welding
8 Post Flow For TIG welding
9 Foot Switch Indicator Lights up if foot switch connected
10 Hot Start For MMA welding
11 Arc Force For MMA welding
12 HF Contact Indicator ON/OFF
13 TIG AC Indicator
14 TIG DC+ Welding Indicator
15 TIG DC- Welding Indicator
36
37
5
35 34
33
32
31
30
28
27
29
38
4
3
2 7
1
6
8
10
9
13
12
11
16
15
14
20
19
18
17
24
23
22
21
26
25

12
SECTION 2 KNOW YOUR MACHINE
1 2
3
4
5
Number Function Description
16 Pulse On Indicator
17 Pulse Off Indicator
18 Sine Indicator Sinusoidal waveform indicator
19 OFF Indicator 100% rectangular waveform
20 REC Indicator Rectangular waveform
21 AC Frequency Indicator
22 Set-up Indicator Lights up if under setting status
23
Over Heat Indicator
Save the data
Lights up if the power source overheats (because the duty cycle
has been exceeded) For more information on this see the trouble
shooting section.
It is recommended to save the data
24 2-Step Mode Indicator (2T) Use with foot pedal control
25 4-Step Mode Indicator (4T) Recommended for torch trigger auto on
26 MMA Mode Indicator
27 Mode Button Used to select 2-step mode or 4-step mode or MMA welding (2T /
4T)
28
Gas Test Button Used to set the required amount of shielding gas at the pressure
regulator. After you press this button, gas will flow out for 30 se-
conds. Press the button again to stop the test gas flow before the
30 seconds are up.
29 Parameter Adjusting Knob Used to adjust welding parameter.
30 Balance (-30%/+30%) Used to set the fusing power/cleaning action for TIG
AC welding.
31 Wave Pattern Used to select waveform (Sin, OFF or REC)
32 Pulse Selection Button ON/OFF
33 Process Button Used to select the process depending on the mode that has been
chosen
34 HF Contact Button ON/OFF
35 Store Button Used to store 9 jobs
36 Memory Button Memory display, 1 or 2 or 3 through 9
37 Actual Ouput Amp Display
38 Pre-Set Amp Display

13
SECTION 2 KNOW YOUR MACHINE
1 2
3
4
5
Number Function Description
39 Control Plug 5 pin connection socket for remote control TIG torch or foot pedal
control
40 Output Nozzle Shielding gas output
41 Negative Output
42 Positive Output
43 Power Switch Switching the power source on and off
44 Power Input Cord
45 Shielding Gas Connection
39
43
44
42
45
41
40

14
SECTION 2 KNOW YOUR MACHINE
2.5.2 For DC Pulse TIG Welding SDC welding of
thin material can be enhanced by using the
pulse mode.
When using the pulse mode for DC application
the current will be varied between the welding
current and the set background current. Addi-
tionally the pulse width and pulse frequency
can be adjusted. By adjusting the pulse fre-
quency and width the optimum heat input for a
particular application can be obtained. As a
general rule, increasing the frequency at a giv-
en set of welding and background current the
heat input into the plate will increase.
2.5.3 For AC TIG Welding AC TIG welding is
commonly used for the welding of Aluminum
and Aluminum alloys. The positive half cycle of
the AC current assist in the cleaning action
required for successfully welding Alumi-
num.
Zirconiated tungstens are used for welding and
the size of tungsten depends on the current em-
ployed.
In normal AC sine wave equal time is spent in
the positive and negative cycle of the current.
This delivers a balanced weld with good pene-
tration and a good cleaning action (5).
AC Balance Control
In addition to increasing the welding current in
AC applications, a change in the penetration or
cleaning when welding can be achieved by ad-
justing the AC Balance.
The AC Balance (time spend in the positive
(maximum cleaning) or negative (maximum
penetration) can be adjusted by using the AC
balance control knob (16)
By adjusting the AC balance control knob from
–30 to +30 % (20-80%) progressively increases
the time in the positive side of the AC curve
(higher heat concentration in the non-
consumable tungsten electrode.)
This has the result that the amount of penetra-
tion is decreased.
With the AC balance control set at 20%., higher
currents can be used on thinner electrodes,
resulting in the use of smaller gas cups, there-
fore increasing visibility and reducing gas
flows.
7

15
SECTION 2 KNOW YOUR MACHINE
2.6 Technical Specifications
7
Model PowerTig 210EXT PowerTig 320EXT
Power Voltage (V) 240V 1 phase 220V, 380V & 460V 3 phase (depending on
Country)
Frequency (Hz) 50/60 50/60
Fuse Rating (A) 32 32
OutPut Current (A) Stick 10-160 Stick 10-320
DC TIG 5-210 DC TIG 5-210
AC TIG 10-210 AC TIG 10-320
No-Load Voltage (V) 62 62
Duty Cycle 40% @ 210A 320A
Power Factor 0.95 0.95
Protection Grading 1P23 1P23
Weight (lbs) 37.4 59.4
Dimensions (in) 17x8.5x16.5 19x10x19

16
SECTION 2 KNOW YOUR MACHINE
2.7 .1 Schematics PowerTig 210EXT
7

17
SECTION 2 KNOW YOUR MACHINE
2.7.2 Schematics PowerTig 320EXT
7

18
3.1 INTRODUCTION
The Tungsten Inert Gas, or TIG process
uses the heat generated by an electric arc
struck between a non-consumable tung-
sten electrode and the workpiece to fuse
metal in the joint area and produce a mol-
ten weld pool. The arc area is shrouded in
an inert or reducing gas shield to protect
the weld pool and the non-consumable
electrode. The process may be operated
autogenously, that is, without filler, or filler
may be added by feeding a consumable
wire or rod into the established weld pool.
3.2 PROCESS
Direct or alternating current power
sources with constant current output char-
acteristics are normally employed to sup-
ply the welding current. For DC operation
the tungsten may be connected to either
output terminal, but is most often connect-
ed to the negative pole. The output charac-
teristics of the power source can have an
effect on the quality of the welds produced.
Shielding gas is directed into the arc area
by the welding torch and a gas lens within
the torch distributes the shielding gas
evenly over the weld area. In the torch the
welding current is transferred to the tung-
sten electrode from the copper conductor.
The arc is then initiated by on of several
methods between the tungsten and the
workpiece.
3.3 PROCESS VARIABLES
DCEN
When direct-current electrode –negative
(straight polarity) is used:
 Electrons strike the part being welded
at a high speed.
 Intense heat on the base metal is pro-
duced.
 The base metal melts very quickly.
 Ions from the inert gas are directed to-
wards the negative electrode at a rela-
tively slow rate.
 Direct current with straight polarity
does not require post-weld cleaning to
remove metal oxides.
Use of DCEN
For a given diameter of tungsten electrode,
higher amperage can be used with straight
polarity.
Straight polarity is used mainly for welding
 Carbon steels
 Stainless steels
 Copper alloys
The increased amperage provides
 Deeper penetration
 Increased welding speed
 A narrower, deeper weld bead
DCEP
The DCEP (reverse polarity) are different
from the DCEN in the following ways:
 High heat is produced on the electrode
rather then on the base metal.
 The heat melts the tungsten electrode
tip.
 The base metal remains relatively cool
compared to the sing straight polarity.
 Relatively shallow penetration is ob-
tained.
 An electrode whose diameter is too
large will reduce visibility and increase
instability.
Use of DCEP
 Intense heat means a larger diameter
of electrode must be used with DCEP.
 Maximum welding amperage should be
relatively low (approximately six times
lower than DCEN)
GAS TUNGSTEN ARC WELDING (GTAW/TIG)
SECTION 3

19
(continued)
Alternating Current with High Frequency
Welding with alternating current
Welding with alternating current combines
both direct-current characteristics:
 In the positive phase, cleaning action
occurs in the weld puddle.
 During the negative phase, heat is con-
centrated in the weld puddle.
 The above causes increased penetra-
tion.
GAS TUNGSTEN ARC WELDING (GTAW/TIG)
SECTION 3

20
3.4 SHIELDING GAS SELECTION
GAS TUNGSTEN ARC WELDING (GTAW/TIG)
SECTION 3
Material Sheilding Gas Benefits
Aluminum Alloys Argon 1) Used with high frequency AC:
good stable arc; good cleaning ac-
tion
Argon/Helium 1) Used with high fequency AC:
good cleaning action; higher weld-
ing speed; increased penetration
Aluminum Bronze Argon Reduces penetration during surfac-
ing minimising dilution
Brass Argon Stable arc; low fume
Cobalt-based Alloys Argon Stable and easy to control arc
Copper-nickel (Monel) Argon Stable and easy to control arc; can
be used for copper-nickel to steel
Deoxised Copper Helium Increased heat imput; Stable arc;
Good penetration
Helium(75%) Stable arc
Argon(25%) Lower penetration
Nickel Alloys (Inconel) Argon Stable arc; Manual operation
Helium High speed automated welding
Steel Argon Stable arc; Good penetration
Helium High speed automatic welding;
Deeper penetration; Small concen-
trated HAZ
Magnesium Alloys Argon Used with continuous high frequen-
cy AC; Good arc stability; Good
cleaning action
Stainless Steel Argon Good penetration; Good arc stability
Helium Deeper penetration
Titanium Argon Stable arc
Helium High speed welding