TIG Miller Book

215 994 C2012−08 Processes TIG (GTAW) Welding Guidelines For Gas Tungsten Arc Welding (GTAW) Visit our website at www.MillerWelds.com TABLE OF CONTENTS SECTION 1 − SAFETY PRECAUTIONS - READ BEFORE USING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1. Symbol Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2. Arc Welding Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3. Additional Symbols For Installation, Operation, And Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4. California Proposition 65 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5. Principal Safety Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6. EMF Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 2 − PRINCIPLES OF GAS TUNGSTEN ARC WELDING (GTAW) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1. Process Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2. Selecting A GTAW Power Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3. Typical GTAW Welding System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 3 − GAS TUNGSTEN ARC WELDING (GTAW) PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1. Typical GTAW Welding Set-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 4 − SELECTING AND PREPARING A TUNGSTEN FOR DC OR AC WELDING . . . . . . . . . . . . . . 4-1. Selecting Tungsten Electrode (Wear Clean Gloves To Prevent Contamination Of Tungsten) . . . . . . . 4-2. Preparing Tungsten Electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 5 − GTAW WAVEFORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 6 − ARC SHAPING CAPABILITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1. Arc Starting With Different Polarities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2. Balance Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3. AC Frequency Adjustment Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4. Independent Amperage Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5. Frequency Adjustment Control - 60 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6. Frequency Adjustment Control - 200 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 7 − TIG SHIELDING GASES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1. Shielding Gases For TIG Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 8 − GUIDELINES FOR GTAW WELDING (TIG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1. Lift-Arc™ And HF TIG Start Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2. Torch Movement During Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3. Suggested Inverter Power Source Starting Parameters For Various Aluminum Joints . . . . . . . . . . . . . 8-4. TIG Welding Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5. Weld Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 9 − GTAW TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1. Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 1 3 4 4 4 5 5 5 6 7 7 8 8 9 10 12 12 12 12 12 13 13 14 14 15 15 16 17 17 18 19 19 ground. D Do not touch hot parts bare handed. especially children. The input power circuit and machine internal circuits are also live when power is on. use proper tools and/or wear heavy. or another electrode from a different machine. or when there is a high risk of unavoidable or accidental contact with the workpiece or ground. maintain. D Additional safety precautions are required when any of the following electrically hazardous conditions are present: in damp locations or while wearing wet clothing. and protected from hot metal and sparks. 2) a DC manual (stick) welder. constant voltage wire welder is recommended. Only qualified persons should install. The possible hazards are shown in the adjoining symbols or explained in the text. D Frequently inspect input power cord for damage or bare wiring − replace cord immediately if damaged − bare wiring can kill. could result in death or serious injury. Indicates a hazardous situation which. Consult symbols and related instructions below for necessary actions to avoid the hazards. D Do not connect more than one electrode or work cable to any single weld output terminal. if not avoided. The electrode and work circuit is electrically live whenever the output is on. Arc Welding Hazards The symbols shown below are used throughout this manual to call attention to and identify possible hazards. The possible hazards are shown in the adjoining symbols or explained in the text. During operation. state. D Clamp work cable with good metal-to-metal contact to workpiece or worktable as near the weld as practical. D Properly install. D Insulate yourself from work and ground using dry insulating mats or covers big enough to prevent any physical contact with the work or ground. Indicates special instructions. ground it directly with a separate cable. free of oil and grease. and discharge input capacitors according to instructions in Maintenance Section before touching any parts. D Do not touch electrode holders connected to two welding machines at the same time since double open-circuit voltage will be present. 1-2. if movement is confined. Symbol Usage DANGER! − Indicates a hazardous situation which. hole-free insulating gloves and body protection. Maintain unit according to manual. use of a DC. Disconnect cable for process not in use. damaged. the wire. Lockout/tagout input power according to OSHA 29 CFR 1910. D Wear a safety harness if working above floor level. wire reel.147 (see Safety Standards). D To handle hot parts.READ BEFORE USING som 2011−10 7 Protect yourself and others from injury — read. Touching live electrical parts can cause fatal shocks or severe burns. D If earth grounding of the workpiece is required. In semiautomatic or automatic wire welding. disconnect input power. and HOT PARTS hazards. and local codes. or lying. D Do not touch live electrical parts. In most situations. D Keep cords dry. watch out. . keep everybody. D When making input connections. or 3) an AC welder with reduced open-circuit voltage. ELECTRIC SHOCK can kill. Repair or replace damaged parts at once. D Always verify the supply ground − check and be sure that input power cord ground wire is properly connected to ground terminal in disconnect box or that cord plug is connected to a properly grounded receptacle outlet. Incorrectly installed or improperly grounded equipment is a hazard. use remote output control if present on unit. ground. do not work alone! D Disconnect input power or stop engine before installing or servicing this equipment. or if there is a danger of falling. and follow the related instructions to avoid the hazard. D Do not use worn.SECTION 1 − SAFETY PRECAUTIONS . D Turn Off inverter. D If AC output is required. MOVING PARTS. D Keep all panels and covers securely in place. SIGNIFICANT DC VOLTAGE exists in inverter welding power sources AFTER removal of input power. and operate this equipment according to its Owner’s Manual and national. The safety information given below is only a summary of the more complete safety information found in the Safety Standards listed in Section 1-5. undersized. D Allow cooling period before working on equipment. And. When you see the symbol. This group of symbols means Warning! Watch Out! ELECTRIC SHOCK. HOT PARTS can burn. D Wear dry. on metal structures such as floors. if not avoided. kneeling. D Do not use AC output in damp areas. or poorly spliced cables. D Do not touch electrode if you are in contact with the work. and repair this unit. D Do not drape cables over your body. will result in death or serious injury. insulated welding gloves and clothing to prevent burns. or scaffolds. 215 944 Page 1 . D Turn off all equipment when not in use. operate. follow. and save these important safety precautions and operating instructions. 1-1. away. when in cramped positions such as sitting. D Use AC output ONLY if required for the welding process. Read and follow all Safety Standards. For these conditions. D Use only well-maintained equipment. use the following equipment in order presented: 1) a semiautomatic DC constant voltage (wire) welder. attach proper grounding conductor first − double-check connections. and all metal parts touching the welding wire are electrically live. drive roll housing. NOTICE − Indicates statements not related to personal injury. gratings. D Insulate work clamp when not connected to workpiece to prevent contact with any metal object. drums. mechanical shocks. and degreasers. D Do not weld on containers that have held combustibles. correct procedures. D If inside. floor. gouging. such as tanks. glare and sparks. they can throw off slag. D Read and understand the Material Safety Data Sheets (MSDSs) and the manufacturer’s instructions for metals. glowing embers. cleaning. WELDING can cause fire or explosion. or pipes unless they are properly prepared according to AWS F4. If this is not possible. lead. D Do not weld in locations near degreasing. D Wear protective clothing made from durable. or fire.0 (see Safety Standards). Sparks fly off from the weld. or while wearing an air-supplied respirator. D Keep cylinders away from any welding or other electrical circuits. open flames. D Wear approved ear protection if noise level is high. Sparks can fly off from the welding arc. D Never drape a welding torch over a gas cylinder. Do not breathe the fumes. Be sure the breathing air is safe. possibly unknown paths and causing electric shock. The coatings and any metals containing these elements can give off toxic fumes if welded. cuffless trousers. The heat and rays of the arc can react with vapors to form highly toxic and irritating gases. a cylinder can explode. warn others not to watch the arc. plasma arc cutting. D Connect work cable to the work as close to the welding area as practical to prevent welding current from traveling long. D Keep your head out of the fumes. D Do not weld where the atmosphere may contain flammable dust. unless the coating is removed from the weld area. and keep a fire extinguisher nearby. physical damage. D Remove stick electrode from holder or cut off welding wire at contact tip when not in use. D Wear an approved welding helmet fitted with a proper shade of filter lenses to protect your face and eyes from arc rays and sparks when welding or watching (see ANSI Z49. heavy shirt. D Wear oil-free protective garments such as leather gloves. Breathing these fumes and gases can be hazardous to your health. sparks. gas. D Be alert that welding sparks and hot materials from welding can easily go through small cracks and openings to adjacent areas. sparks. ELECTRIC AND MAGNETIC FIELDS (EMF) can affect Implanted Medical Devices. D Remove any combustibles. flame-resistant material (leather. D Turn face away from valve outlet when opening cylinder valve. wear an approved air-supplied respirator. Arc rays from the welding process produce intense visible and invisible (ultraviolet and infrared) rays that can burn eyes and skin. consumables. Do not oversize or bypass them. D Protect yourself and others from flying sparks and hot metal. Accidental contact of electrode to metal objects can cause sparks. D Shut off compressed gas supply when not in use. or on closed containers such as tanks. D Read and follow instructions on compressed gas cylinders. ARC RAYS can burn eyes and skin. D Never weld on a pressurized cylinder − explosion will result. associated equipment.1 and AWS A6. D Implanted Medical Device wearers should consult their doctor and the device manufacturer before going near arc welding. regulators. coatings. overheating. high shoes. and flames. and fittings designed for the specific application. or cadmium plated steel. D Use the right equipment. and fire hazards. and while wearing an air-supplied respirator. or induction heating operations. D Install cylinders in an upright position by securing to a stationary support or cylinder rack to prevent falling or tipping. inspect area to ensure it is free of sparks. NOISE can damage hearing. or pipes.7 m) of the welding arc. such as galvanized. D Use protective screens or barriers to protect others from flash. D Work in a confined space only if it is well ventilated. or liquid vapors (such as gasoline). 215 994 Page 2 CYLINDERS can explode if damaged. D Remove all flammables within 35 ft (10. and sufficient number of persons to lift and move cylinders. Compressed gas cylinders contain gas under high pressure. heavy cotton. the area is well ventilated. can cause them to blow up. The flying sparks. Check and be sure the area is safe before doing any welding. D Do not weld on coated metals. and grinding cause sparks and flying metal. FLYING METAL or DIRT can injure eyes. be sure to treat them carefully. and a cap. spot welding. D Wear approved safety glasses with side shields under your helmet. Always have a trained watchperson nearby. D Follow requirements in OSHA 1910. and hot equipment can cause fires and burns. slag. hot workpiece. D Never allow a welding electrode to touch any cylinder. tightly cover them with approved covers. or partition can cause fire on the hidden side. BUILDUP OF GAS can injure or kill. D Watch for fire. Welding fumes and gases can displace air and lower the oxygen level causing injury or death. hoses. maintain them and associated parts in good condition. bulkhead.252 (a) (2) (iv) and NFPA 51B for hot work and have a fire watcher and extinguisher nearby. . explosion. chipping. D Keep protective cap in place over valve except when cylinder is in use or connected for use. and arcs. Noise from some processes or equipment can damage hearing. drums. wire brushing. D Use only correct compressed gas cylinders. from your person before doing any welding. cleaners. Welding on closed containers. As welds cool. such as a butane lighter or matches. D Be aware that welding on a ceiling. D Always ventilate confined spaces or use approved air-supplied respirator. ventilate the area and/or use local forced ventilation at the arc to remove welding fumes and gases. D Protect compressed gas cylinders from excessive heat. D Do not weld where flying sparks can strike flammable material. or wool) and foot protection. D If ventilation is poor. Since gas cylinders are normally part of the welding process. D Wear approved safety glasses with side shields even under your welding helmet. Welding produces fumes and gases. D Use only correct fuses or circuit breakers. D Do not use welder to thaw frozen pipes.1 and Z87. D Welding.FUMES AND GASES can be hazardous. If damaged. and Compressed Gas Association (CGA) publication P-1 listed in Safety Standards. or spraying operations.1 listed in Safety Standards). D After completion of work. D Wearers of Pacemakers and other Implanted Medical Devices should keep away. move. D Follow the guidelines in the Applications Manual for the Revised NIOSH Lifting Equation (Publication No. Have the installation regularly checked and maintained. D WELDING WIRE can injure. D Read and follow all labels and the Owner’s Manual carefully before installing. MOVING PARTS can injure. READ INSTRUCTIONS. Be sure this welding machine is installed and grounded according to this manual. Operation. D Do not use welder to charge batteries or jump start vehicles unless it has a battery charging feature designed for this purpose. industry standards. close together. D Have only qualified persons familiar with electronic equipment perform this installation. D Keep equipment (cables and cords) away from moving vehicles when working from an aerial location. be sure forks are long enough to extend beyond opposite side of unit. using shielded cables. RADIATION can cause interference. D Do not block or filter airflow to unit. To reduce possible interference. D D D D STATIC (ESD) can damage PC boards. stop using the equipment at once. state. D Use proper static-proof bags and boxes to store. and communications equipment. D Reduce current or reduce duty cycle before starting to weld again. or any metal when threading welding wire. panels. the user must take extra measures such as moving the welding machine. and down low. panels. D Use lifting eye to lift unit only. And Maintenance FIRE OR EXPLOSION hazard. NOT running gear. keep spark gaps at correct setting. D Wear a face shield to protect eyes and face. Additional Symbols For Installation. D Electromagnetic energy can interfere with sensitive electronic equipment such as computers and computer-driven equipment such as robots. ARC WELDING can cause interference. rated. D Keep away from pinch points such as drive rolls. BATTERY EXPLOSION can injure. D Do not install unit near flammables. and local codes. If interference still occurs. other people. keep weld cables as short as possible. D Use equipment of adequate capacity to lift and support unit.F.1-3. D Do not overload building wiring − be sure power supply system is properly sized. D Put on grounded wrist strap BEFORE handling boards or parts. FLYING SPARKS can injure. panels. and national. or shielding the work area. D High-frequency (H. D Do not press gun trigger until instructed to do so. covers. or near combustible surfaces. D Perform maintenance and service according to the Owner’s Manuals. operating. Read the safety information at the beginning of the manual and in each section. If notified by the FCC about interference. D Keep away from moving parts such as fans. covers. or servicing unit. and use grounding and shielding to minimize the possibility of interference. MOVING PARTS can injure. H. such as on the floor. gas cylinders. D Do not point gun toward any part of the body. or any other accessories. and body protection. D Use only genuine replacement parts from the manufacturer. and guards closed and securely in place. The user is responsible for having a qualified electrician promptly correct any interference problem resulting from the installation. OVERUSE can cause OVERHEATING D Allow cooling period. 94−110) when manually lifting heavy parts or equipment. D Do not install or place unit on. Keep high-frequency source doors and panels tightly shut. FALLING EQUIPMENT can injure. over. safety services. computers. D Keep all doors.F. D Reinstall doors. Locate welding operation 100 meters from any sensitive electronic equipment. D Sparks can cause fires — keep flammables away. or guards for maintenance and troubleshooting as necessary. D Shape tungsten electrode only on grinder with proper guards in a safe location wearing proper face. D Keep away from moving parts.) can interfere with radio navigation. covers. hand. D Be sure all equipment in the welding area is electromagnetically compatible. or ship PC boards. and protected to handle this unit. using line filters. D Have only qualified persons remove doors. or guards when maintenance is finished and before reconnecting input power. D If using lift forks to move unit. D D D 215 944 Page 3 . follow rated duty cycle. Keep head and trunk as far away from the equipment in the welding circuit as possible. is 312-353-2220.org. California Proposition 65 Warnings Welding or cutting equipment produces fumes or gases which contain chemicals known to the State of California to cause birth defects and. from Global Engineering Documents (phone: 1-877-413-5184. Do not place your body between welding cables. Standard for Fire Prevention During Welding. from National Fire Protection Association.org or purchased from Global Engineering Documents (phone: 1-877-413-5184. 1600 Clifton Rd. PA 15250-7954 (phone: 1-866-512-1800) (there are 10 OSHA Regional Offices— phone for Region 5. or using a cable cover.0. Suite 103. then following the above procedures is recommended. and Other Hot Work. CGA Pamphlet P-1. and Allied Processes. Do not work next to. sit or lean on the welding power source. ANSI Standard Z87. and Allied Processes. American Welding Society Standard AWS F4. P.global. pacemakers. Suite 100. 25 West 43rd Street.ihs. NY 10036 (phone: 212-642-4900. Safe Practice For Occupational And Educational Eye And Face Protection. Atlanta. sparky. 3. Safety in Welding. About Implanted Medical Devices: Implanted Medical Device wearers should consult their doctor and the device manufacturer before performing or going near arc welding. Standards Sales. Canada L4W 5NS (phone: 800-463-6727. Arrange cables to one side and away from the operator. plasma arc cutting. If cleared by your doctor.gov/NIOSH). Welding current creates an EMF field around the welding circuit and welding equipment.org). 2. website: www. cancer. 14501 George Carter Way. Cutting. website:www. All welders should use the following procedures in order to minimize exposure to EMF fields from the welding circuit: 1. Safe Practices for the Preparation of Containers and Piping for Welding and Cutting. CSA Standard W117. 6. Occupational Safety and Health Standards for General Industry.global.) This product contains chemicals. 7. GA 30333 (phone: 1-800-232-4636. Subpart J. MA 02269 (phone: 1-800-344-3555. is available as a free download from the American Welding Society at http://www.csa-international. website: www.gov). website: www. website: www. Do not coil or drape cables around your body.nfpa.com).5 et seq. 1-6. website: www.1. restrict access for passers−by or conduct individual risk assessment for welders. Cutting. Ontario. Government Printing Office. Applications Manual for the Revised NIOSH Lifting Equation.ihs.osha. birth defects. Chantilly. from Canadian Standards Association. Pittsburgh.2. from American National Standards Institute. Quincy. American Welding Society Standard AWS A6. from Global Engineering Documents (phone: 1-877-413-5184.org). Do not weld whilst carrying the welding power source or wire feeder.nfpa.ihs. website: www. gouging. OSHA. Code of Federal Regulations (CFR). Title 29. 5060 Spectrum Way.com). website: www. Cutting. Subpart Q. EMF Information Electric current flowing through any conductor causes localized electric and magnetic fields (EMF). Box 371954. Superintendent of Documents. in some cases. spot welding. Connect work clamp to workpiece as close to the weld as possible. 4.ansi. Principal Safety Standards Safety in Welding.cganet. For example. ANSI Standard Z49. Wash hands after use.1-4. NFPA Standard 70. The National Institute for Occupational Safety and Health (NIOSH). (California Health & Safety Code Section 25249.com). known to the state of California to cause cancer. website: www. 1-5. website: www. VA 20151 (phone: 703-788-2700. e. including lead. NFPA Standard 51B.com). Keep cables close together by twisting or taping them. EMF fields may interfere with some medical implants.aws. Protective measures for persons wearing medical implants have to be taken.1. Chicago. National Electrical Code. or induction heating operations.global. 5.1.g. Safe Handling of Compressed Gases in Cylinders. and Part 1926. Quincy. from National Fire Protection Association. Part 1910. New York. from Compressed Gas Association. from U.cdc.org and www. or other reproductive harm. 215 994 Page 4 .S.O. Safe Practices for Welding and Cutting Containers that have Held Combustibles.org). MA 02269 (phone: 1-800-344-3555. In some instances Hydrogen gas may be added to ehance travel speeds. magnesium. D Thickness of materials to be welded. Be sure that proper ventilation is supplied. If ventilation is poor. Keep your head and helmet out of any fumes rising off the workpiece. If filler metal is required to make the weld.No transfer of metal across the arc.Permits pinpoint control of heat input to the workpiece resulting in a narrow heat-affected zone. This will determine whether you require a machine for all weldable metals except Aluminum and Magnesium (DC) or one that is for all weldable metals (AC/DC). No molten globules of spatter to contend with and no sparks produced if material being welded is free of contaminants. However.Compared to other arc-welding processes like stick or flux cored welding. D Hand-eye coordination is a required skill. D Good for welding thin material. Advantages of GTAW welding: D Concentrated Arc . also known as tungsten inert gas (TIG) welding is a process that produces an electric arc maintained between a nonconsumable tungsten electrode and the part to be welded. zinc. Inert gases. bronze. D Little Smoke or Fumes . D Welds more metals and metal alloys than any other arc welding process. the base metals being welded may contain coatings or elements such as lead. D No Slag . Steel. do not chemically react or combine with other gases. Selecting A GTAW Power Source Your choice of a TIG power source is driven by the type and thickness of the material you will weld. or in other situations may be added using a cold wire feeder. D Equipment costs can be higher than with other processes. stainless steel.). Stainless.SECTION 2 − PRINCIPLES OF GAS TUNGSTEN ARC WELDING (GTAW) 2-1. the molten metal. 215 994 Page 5 .000° F (19. Inert gas (usually Argon) is inactive or deficient in active chemical properties. They pose no odor and are transparent. especially in a confined space. few fumes are produced. Disadvantages of GTAW welding: D Slower travel speeds than other processes. GTAW can also weld dissimilar metals to one another such as copper to brass and stainless steel to mild steel. titanium. D No Sparks or Spatter . 2-2. D Concentrations of shielding gas may build up and displace oxygen when welding in confined areas − ventilate the area and/or use local forced ventilation at the arc to remove welding fumes and gases. and even gold. etc. and nickel that may produce hazardous fumes. D Brighter UV rays than other processes. copper. permitting the the welder maximum visibility of the arc. copper. The torch contributes heat only to the workpiece. therefore no slag to obscure the welder’s vision of the molten weld pool. D Lower filler metal deposition rates. D Good for welding dissimilar metals together. aluminum. D Physical Machine Size − Inverter / Transformer−Rectifier.426° C). and the tungsten electrode are all shielded from atmospheric contamination by a blanket of inert gas fed through the GTAW torch. Items to consider: D Type of metal to be welded . The heat-affected zone. wear an approved air-supplied respirator. GTAW is used to weld steel. The GTAW process can produce temperatures of up to 35.(Aluminum.No requirement for flux with this process. it may be added manually in the same manner as it is added in the oxyacetylene welding process. nickel alloys such as Monel® and Inconel®. brass. Process Description Gas Tungsten Arc Welding (GTAW). such as Argon and Helium. D Package solution that suits the welding application. The shielding gas serves to blanket the weld and exclude the active properties in the surrounding air. D Accessory components that add performance to the system. 804 846-A 1 2 3 Welding Power Source − Constant Current (CC) Foot Control Workpiece 4 5 6 Work Clamp Torch Coolant Out Hose 7 8 9 Coolant In Hose Cooling System Shielding Gas 215 994 Page 6 .2-3. Typical GTAW Welding System 9 8 1 7 6 5 4 3 2 Ref. Typical GTAW Welding Set-Up ! 3 2 Grinding the tungsten electrode produces dust and flying sparks which can cause injury and start fires. Tungsten extension is the distance the tungsten extends out gas cup of torch. Properly dispose of grinder dust in an environmentally safe way. 2 Work Clamp Place as close to the weld as possible. Consider using cerium or lanthanum based tungsten instead of thoriated. Use local exhaust (forced ventilation) at the grinder or wear an approved respirator. Keep flammables away. diameter. Bottom View Of Gas Cup Ref. Wear proper face. Arc length is the distance from the tungsten to the workpiece. 161 892 215 994 Page 7 .SECTION 3 − GAS TUNGSTEN ARC WELDING (GTAW) PROCEDURE 3-1. if tungsten is 1/16 in. 3/16 in. 5 6 The tungsten extension should be no greater than the inside diameter of the gas cup. Thorium dust contains low-level radioactive material. diameter. Guidelines: 10−15° 4 5 6 Direction of Travel 10−25° The inside diameter of the gas cup should be at least three times the tungsten diameter to provide adequate shielding gas coverage. and body protection. gas cup should be a minimum of 3/16 in. 3 4 5 6 Torch Filler Rod (If Applicable) Gas Cup Tungsten Electrode tungsten Select and prepare according to Section 4. Workpiece 4 90° 1 1 Make sure workpiece is clean before welding. 1/16 in. hand. (For example. Read MSDS for safety information. Excellent low amp starts for AC and DC welding. Selecting Tungsten Electrode (Wear Clean Gloves To Prevent Contamination Of Tungsten) . use DC weld output instead of AC weld output.5−2% Lanthanum (Yellow/Blue) 2% Thorium (Red) Pure Tungsten (Green) Application Notes Good all−around tungsten for both AC and DC welding.4 mm) 1/8 in.020 in. not ideal for AC. please refer to manufacturer’s guide for color designation. (6. Not all tungsten electrode manufacturers use the same colors to identify tungsten type. 4-1.8 mm) 1/4 in. B.010 in. Not Recommended for inverters! For best results in most applications use a sharpened cerium or lanthanum electrode for AC and DC welding. (1.Gas Type♦ . (4.4 mm) Up to 25 15-40 25-85 50-160 130-250 250-400 400-500 500-750 750-1000 AC − Argon Balance Control @ 65% Electrode Negative (For Use With Aluminum) Up to 20 15-35 20-80 50-150 135-235 225-360 300-450 400-500 600-800 ♦Typical argon shielding gas flow rates are 11 to 35 CFH (cubic feet per hour).Polarity Electrode Diameter (DCEN) − Argon Direct Current Electrode Negative (For Use With Mild Or Stainless Steel) . Figures listed are a guide and are a composite of recommendations from American Welding Society (AWS) and electrode manufacturers.2 mm) 5/32 in.6 mm) 3/32 in.040 in.SECTION 4 − SELECTING AND PREPARING A TUNGSTEN FOR DC OR AC WELDING gtaw_Inverter_2011-06 Whenever possible and practical. 215 994 Page 8 . A. (1 mm) . (1 mm) . (3. Select Electrode Size Amperage Range . Commonly used for DC welding. Select Electrode Composition. Tungsten Type 2% Cerium (Grey *) 1.0 mm) 3/16 in (4. (1 mm) 1/16 in. Contact the tungsten electrode manufacturer or reference the product packaging to identify the tungsten you are using. (2. * Color may vary depending on manufacturer. Properly dispose of grinder dust in an environmentally safe way. Diameter of this flat determines amperage capacity. hand. Read MSDS for safety information. 2 3 Tungsten Electrode Flat A 2% ceriated tungsten is recommended. Use local exhaust (forced ventilation) at the grinder or wear an approved respirator. and body protection. not radial. Consider using tungsten containing ceria. Preparing Tungsten For DC Electrode Negative (DCEN) Welding or AC Welding With Inverter Machines 1 Radial Grinding Causes Wandering Arc Grinding Wheel Grind end of tungsten on fine grit. Wrong Tungsten Preparation 2-1/2 Times Electrode Diameter 2 3 1 4 Ideal Tungsten Preparation − Stable Arc Preparing Tungsten For AC Welding With Phase Control Machines 1 2 Tungsten Electrode Balled End A pure tungsten is recommended. Do not use wheel for other jobs or tungsten can become contaminated causing lower weld quality. Grinding dust from thoriated electrodes contains low-level radioactive material.4-2. lanthana. hard abrasive wheel before welding. Keep flammables away. Ball end of tungsten by applying AC amperage recommended for a given electrode diameter (see Section 4-1). 1 − 1-1/2 Times Electrode Diameter 1 2 215 994 Page 9 . Let ball on end of the tungsten take its own shape. or yttria instead of thoria. Wear proper face. 4 Straight Ground Grind lengthwise. Preparing Tungsten Electrode Grinding the tungsten electrode produces dust and flying sparks which can cause injury and start fires. 0 0. 805 186-A 1 Zero Crossover in the Zero Crossover Area affects the quality of the welding arc.0 20. 805 186-A 215 994 Page 10 . .0 −20.0 −30.0 30.0 Current + 0 Amperage Time 1/60 Second 2 10.0 − Ref. The percentage of time spent 1 Zero Crossover Area + Current 0 − Ref.0 −10.SECTION 5 − GTAW WAVEFORMS 1 2 1 AC Sine Wave Weld Sample Time 40.0 −40. 0 −40.0 −30.0 + 0 − Ref. Less time is spent in zero 1 + Current 0 − Ref. . .1 Squarewave Imposed Over Sine Wave crossover with squarewave output.0 Amperage Current 2 10.0 −20. 805 186-A 1 2 Conventional Squarewave AC Weld Sample electrode positive and electrode negative.0 0.0 −10.0 30.0 20. Faster transition time between 1 Time 40. 805 186-A 215 994 Page 11 . 1 2 Ref. Arc Starting With Different Polarities Electrode Positive Starting Preheats tungsten Repeatable starting Cleans work on starts Can damage tungsten tip Good for AC TIG Electrode Negative Starting Preferred for Precision DC Repeatable starting No cleaning on starts No damage to tungsten Acceptable for AC . AC Frequency Adjustment Control 1 Low AC Frequency Soft. Narrow. Arc shaping capabilities are enhanced by improved balance control. wide arc with shallower penetration. deep penetration.SECTION 6 − ARC SHAPING CAPABILITIES 6-1. 1 2 Ref. Balance Control 1 2 More EP Time More EN Time More Cleaning. and independent amperage control. 805 185-A 6-3. Independent Amperage Control 1 2 More EP Amperage More EN Amperage Wide. 805 185-A 6-4. 2 High AC Frequency Focused arc with deeper penetration. AC frequency control. faster travel speeds. 805 185-A 215 994 Page 12 . 6-2. shallow penetration. 1 2 Ref. Less Cleaning. 6-5. 0 − 1/60th of a second 2 Ref. Frequency Adjustment Control . Frequency Adjustment Control . + Current . Higher AC frequencies create a narrower arc cone.200 Hz 1 2 AC Waveform Weld Sample 1 At 200 Hz the bead is much tighter and penetrated the thicker metal.60 Hz 1 2 AC Waveform Weld Sample 1 At 60 Hz the bead doesn’t quite penetrate the thick aluminum. + Current . 805 186-A 215 994 Page 13 . Lower AC frequencies create a wider arc cone. 805 186-A 6-6. 0 − 1/200th of a second 2 Ref. 804 419-A A.SECTION 7 − TIG SHIELDING GASES gtaw_Inverter_2007-05 7-1. Shielding Gas Comparison CHARACTERISTICS Travel Speed ARGON Reduced travel speeds ARGON/HELIUM MIXES Improved travel speeds over 100% Argon Improved penetration over 100% Argon Cleaning properties closer to Argon Improved arc starting over 100% Helium Improved arc stability over 100% Helium Arc cone shape more focused than w/Helium Arc voltages between 100% Argon and Helium Higher flow rates than Argon Costs higher than Argon HELIUM Faster travel speeds Penetration Cleaning Arc Starting Reduced penetration Good cleaning action Easier arc starting Increased penetration Less cleaning action Difficult arc starting Arc Stability Good arc stability Less low amperage stability Arc Cone Focused arc cone Flared arc cone Arc Voltage Flow Rate Cost 215 994 Page 14 Lower arc voltages Lower flow rates 10-30 CFH Lower cost and greater availability Higher arc voltages Higher flow rates (2 times) Higher cost than Argon . Shielding Gases For TIG Welding 1 Shielding Gas Cylinder Types of Shielding Gases: 1 D Argon (Industry Standard) D Helium D Argon/Helium Mixtures Ref. or to replace the scratch method. Lift Arc Start Method Normal open-circuit voltage is not present before tungsten electrode touches workpiece. or getting contaminated. 1−2 “Touch” Seconds . 1 2 Application: Lift-Arc is used for the DCEN or AC GTAW process when HF Start method is not permitted. Application: HF start is used for the DCEN GTAW process when a non-contact arc starting method is required. Do NOT Strike Like A Match! 215 994 Page 15 .SECTION 8 − GUIDELINES FOR GTAW WELDING (TIG) 8-1. or hand control. foot control. Hold electrode to workpiece for 1-2 seconds. sticking. and turns on whenever arc is broken to help restart arc. The solid-state output contactor does not energize until after electrode is touching workpiece. HF Start High frequency turns on to help start arc when output is enabled. Arc is formed when electrode is lifted. only a low sensing voltage is present between electrode and workpiece. High frequency turns off when arc is started. Lift-Arc™ And HF TIG Start Procedures Lift-Arc Start 1 2 TIG Electrode Workpiece Touch tungsten electrode to workpiece at weld start point and enable output and shielding gas with torch trigger. This allows electrode to touch workpiece without overheating. and slowly lift electrode. Type of power source and output polarity may affect when high frequency turns off after arc is started. Form Pool 2. Tilt Tourch 15° 3. Tungsten With Filler Rod 75° Welding direction 1. Add Filler Metal 4. repeat steps 3−5. 162 002-B 215 994 Page 16 . Move Tourch in front of Pool. Move Tourch to front of Pool. Travel at a consistant speed. Form Pool 2.8-2. Torch Movement During Welding Tungsten Without Filler Rod 75° Welding direction 1. Travel at a consistant speed. Remove Rod 5. Tilt Tourch 3. repeat steps 2−3. 1/8 in. 3/32 in. 1/8 in. hold a short arc. 3/32 in. although tilting it ahead (in the direction of travel) will be helpful. 1/8 in. travel at a uniform speed. practice running beads of weld metal on flat plates using a full electrode. and feed the electrode downward at a constant rate as it melts. TIG Welding Techniques Butt Joint After learning to start and hold an arc. 70° 20° 20° 162 003 / S-0792 215 994 Page 17 . Torch Position For Making a Butt Joint 90° . hold a short arc. and feed the electrode downward at a constant rate as it melts. 3/32 in. 1/8 in. To produce the best results. Hold the electrode nearly perpendicular to the work. T-Joint . Argon Argon Argon Argon 15-20 CFH 15-20 CFH 15-20 CFH 15-20 CFH 90-120 100-125 90-110 80-90 65-75% 70-75% 70-75% 65-70% 60-120 Hz 100-200 Hz 100-150 Hz 100 Hz 8-4. Suggested Inverter Power Source Starting Parameters For Various Aluminum Joints Weld Joints Butt Joint T-Joint Lap Joint Corner Joint Amperage Balance Frequency Base Base Filler Filler Tungsten Tungsten Shielding Gas Flow Material Material Rod Alloy Type Diameter Gas Alloy Thickness Diameter 6061 6061 6061 6061 1/8 in. 1/8 in. 70° 20° 162 003 / S-0792 Hold the torch 70 degrees to the work. 5356 5356 5356 5356 2% Ceriated 2% Ceriated 2% Ceriated 2% Ceriated 3/32 in. 1/8 in. To 40° Torch Position For Making a T-Joint produce the best results. travel at a uniform speed.8-3. 1/8 in. A good weld bends over but does not break. Weld Test 3 3 2 To 3 in. the arc length was probably too long. If the weld breaks. (6. and feed the electrode downward at a constant rate as it melts. (51-76 mm) 2 1 S-0057-B 1 2 3 Vise Weld Joint Hammer the cause. If the weld contains bits of slag. Strike the weld joint in the direction shown. (51-76 mm) 1/4 in. To 70° produce the best results. This may happen on a V-groove joint made in several layers and calls for additional cleaning between layers. travel at a uniform speed. If the weld is porous (many holes). the arc may have been too long or the electrode was moved incorrectly which allowed molten slag to be trapped in the weld.4 mm) 2 1 2 To 3 in. hold a short arc. hold a short arc. If the original beveled surface is visible the material was not fully melted which is often caused by insufficient heat or too fast a travel speed. To produce the best results. TIG Welding Techniques (Continued) 40° Lap Joint Torch Position For Making a Lap Joint Hold the torch 70 degrees to the work. and feed the electrode downward at a constant rate as it melts. examine it to determine 215 994 Page 18 . 70° 20° 30° 162 003 / S-0792 Corner Joint 90° Torch Position For Making a Corner Joint Hold the torch 70 degrees to the work. . travel at a uniform speed.8-4. . 20° 162 003 / S-0792 8-5. check to make sure circulator is turned on then check coolant flow. If using pure tungsten. Remedy Problem: Shielding Gas Probable Causes Inadequate or too much gas flow or wrong gas type. Improper size tungsten for current used. Change tungsten . Touching tungsten to weld puddle. Use argon gas 100 percent.SECTION 9 − GTAW TROUBLESHOOTING 9-1. If machine has Balance Control. and torch are not restricted or the tank is not out of gas. Remedy Check to be sure hose. Gas flow should typically be set at 15 to 20 CFH. Check for empty cylinder or closed shut−off valve. Defective gas hose or loose connection. or pin holes. Check flow rate (15 to 20 CFH) and gas type. Replace gas hose and check connections for leaks. change to ceriated or lanthanated. 215 994 Page 19 . Tungsten oxidation during cooling. DC). Use ceriated (AC. cuts. Adjust flow rate as necessary. Raise the torch so that the tungsten is off of the work piece 1/16 to 1/8in.General purpose tungsten size is 3/32 in. Air-cooled torches get very warm. gas valve. Check for gas flow at end of torch. Excessive heating in torch body. If using a water-cooled torch. Inadequate or too much gas flow. Keep tungsten from contacting weld puddle. Coolant flow may be restricted or coolant may be low. Switch to electrode negative (DCEN). Problem: Porosity and Poor Weld Bead Color Probable Causes Condensation on base metal. Metals stored in cold temperatures will condensate when exposed to warm temperatures. Tighten fittings on torch and all hoses. Tungsten melting back into cup (AC). thoriated (DC). Increase Tungsten size -Tungsten diameter may be too small for the amount of current being used. Use of gas containing oxygen or CO2. Troubleshooting ! Turn off welding power source and disconnect power before troubleshooting. diameter at a maximum of 235 amps. Remedy Problem: High Frequency Present . Remove all condensation from base metal before welding. No shielding gas. or lanthanated tungsten.No Arc Power Probable Causes Incomplete weld circuit. Problem: Burning Through Tungsten Fast Probable Causes Inadequate gas flow. Problem: Tungsten Contamination Probable Causes Tungsten melting into weld puddle. Check all cable connections. Use less current or larger tungsten. Keep shielding gas flowing 10-15 seconds after arc stoppage (one second for each 10 amps of weld current). Remedy Line should be purged with Argon for a few minutes. Remedy Check work connection. Loose fittings in torch or hoses. Gas flow should typically be set at 15 to 20 CFH. Operation on electrode positive (DCEP). Gas flow should typically be set at 15 to 20 CFH. adjust setting towards Max Penetration (70-90 percent). or moisture from filler metal. grease. Match tungsten size and cup size to joint being welded. Clean and sharpen tungsten. Improper tungsten size or cup size. Adjust the torch so that the tungsten is off of the work piece 1/8 to 1/4 in. 100 to 180 Hertz is acceptable. use pointed tungsten. oil. oil. Keep tungsten from contacting weld puddle. oil. Remedy Lower the torch so that the tungsten is off of the work piece 1/16 to 1/8 in. Improper shielding gas. Point will eventually round off after welding. Remove paint. Incorrect arc length. Base metal is contaminated. and dirt (including mill scale) from base metal. increase frequency to give proper arc stability and directional control. Improper gas flow. Select DCEN (Direct Current Electrode Negative). grease. Tungsten is contaminated. Remedy Check polarity switch on welder. thick aluminum. Problem: Arc Wanders While DC Welding Probable Causes Improper arc length/tungsten in poor condition. . Inadequate post flow. Set at 10 to 15 seconds. diameter and 8 cup. Problem: Porosity and Poor Weld Bead Color (Continued) Probable Causes Base metal is contaminated. Tungsten is contaminated. Remove paint. 215 994 Page 20 Grind marks should run lengthwise with tungsten. Lower torch so that the tungsten is off of the work piece no more than 1/16 to 1/8 in. Arc too long. General purpose tungsten size is 3/32 in. Remove 1/2 in. Remove 1/2 in. Gas flow should typically be set at 15 to 20 CFH. grease. Gas flow should typically be set at 15 to 20 CFH. Shorten arc length. Remedy Remove paint. On welders with adjustable AC frequency. Add filler metal. Frequency set too low. when welding on 3/8 to 1/2 in. and dirt (including) mill scale from base metal. Increase post flow time. oil. Base metal is contaminated.In some cases. Use correct arc length. Improperly prepared tungsten.Probable Causes Contaminated or improper filler metal. not circular. Problem: Unstable Arc While DC Welding Probable Causes Weld circuit polarity is incorrect. of tungsten and repoint tungsten. 120 Hz is recommended. Remove 1/2 in. Use proper grinding method and wheel. Light gray frosted appearance on end of tungsten. Check tungsten type or size. Remedy Check filler metal type. Incorrect shielding gas or mixture. of contaminated tungsten and repoint tungsten. Change shielding gas . of contaminated tungsten and repoint tungsten. Use argon gas. Problem: Unstable Arc While AC Welding Probable Causes Excessive rectification in arc. Raise the torch so that the tungsten is off of the work piece 1/8 to 1/4 in. With Squarewave and inverter machines. Improperly prepared tungsten Remedy Increase travel speed. and dirt (including mill scale) from base metal. Increase balance control toward Max Penetration. Tungsten contamination. Argon/Helium is used. Check tungsten type or size. Problem: Yellow Powder or Smoke on Cup − Tungsten Discolor Probable Causes Shielding gas flow rate too low. Remedy Increase flow rate. Remove all grease. The higher the frequency. Gas flow should typically be set at 15 to 20 CFH. Remove 1/2 in. Frequency set too low. grease. General purpose tungsten size is 3/32 in. of contaminated tungsten and repoint tungsten.90. Notes MATERIAL THICKNESS GAUGE 215 994 Page 21 229895 . Increase balance setting toward Max Penetration. Tungsten is contaminated. Remove paint. Increase AC frequency on machines so equipped to stabilize and direct the arc. Increase balance toward Max Penetration. Improper tungsten size and type.Problem: Arc Wanders While AC Welding Probable Causes Improper tungsten preparation. Select proper size and type. use pointed tungsten. Remedy With Squarewave and inverter machines. Point will eventually round off after welding. Increase travel speed. Improper shielding gas flow. Base metal is contaminated. diameter and ceriated or thoriated. and dirt (including mill scale) from base metal. Incorrect balance control setting. Add filler metal. oil. the narrower the penetration profile. Excessive rectification in arc. Normal Balance Control setting is 70 . WI 54914 USA International Headquarters−USA USA Phone: 920-735-4505 Auto-Attended USA & Canada FAX: 920-735-4134 International FAX: 920-735-4125 For International Locations Visit www. Co.com Contact the Delivering Carrier to: File a claim for loss or damage during shipment.MillerWelds.com or call 1-800-4-A-Miller Miller Electric Mfg. Co. ORIGINAL INSTRUCTIONS − PRINTED IN USA © 2012 Miller Electric Mfg. Contact your Distributor for: Welding Supplies and Consumables Options and Accessories Personal Safety Equipment Service and Repair Replacement Parts Training (Schools. For assistance in filing or settling claims.) For Service Contact a DISTRIBUTOR or SERVICE AGENCY near you. 2012−01 . Books) Technical Manuals (Servicing Information and Parts) Circuit Diagrams Welding Process Handbooks To locate a Distributor or Service Agency visit www.millerwelds. An Illinois Tool Works Company 1635 West Spencer Street Appleton.Owner’s Record Please complete and retain with your personal records. Model Name Purchase Date Distributor Address City State Zip Serial/Style Number (Date which equipment was delivered to original customer. Always provide Model Name and Serial/Style Number. contact your distributor and/or equipment manufacturer’s Transportation Department. Videos.