Modern Welding, 12th Edition Page 205 (227 of 928)

Chapter 8 Gas Metal and Flux Cored Arc Welding 205 Copyright Goodheart-Willcox Co., Inc. GMAW Short Circuit Transfer — Stainless Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.030 0.035 0.045 0.8 0.9 1.2 17–22 17–22 17–22 50–145 65–175 100–210 Note: The values shown are based on a mixture of 90% helium, 7 1/2% argon, 2 1/2% CO2. Goodheart-Willcox Publisher Figure 8-16. Approximate machine settings for short circuiting transfer on 300 series stainless steel. GMAW Spray Transfer — Stainless Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.030 0.035 0.045 1/16 3/32 0.8 0.9 1.2 1.6 2.4 24–28 24–29 24–30 24–32 24–32 160–210 180–255 200–300 215–325 225–375 Note: The values shown are based on the use of argon-oxygen shielding gas. The oxygen percentage varies from 1–5%. Goodheart-Willcox Publisher Figure 8-17. Approximate machine settings for spray transfer on 300 series stainless steel. GMAW Spray Transfer — Aluminum Electrode diameter Arc voltage Amperage range inches mm V A 0.030 0.047 (3/64) 1/16 3/32 0.8 1.3 1.6 2.4 19–22 22–28 24–30 26–34 100–150 130–200 160–300 220–450 Goodheart-Willcox Publisher Figure 8-18. Approximate machine settings for spray transfer with 100% argon on aluminum and aluminum alloys. GMAW Spray Transfer — Copper Electrode diameter Arc voltage Amperage range inches mm V A 0.035 0.045 1/16 0.9 1.2 1.6 21–25 22–26 24–28 170–210 200–240 310–400 Goodheart-Willcox Publisher Figure 8-19. Approximate machine settings for spray transfer with 100% argon on copper and copper alloys. FCAW–G—Carbon Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.035 0.045 0.052 1/16 5/64 3/32 1/8 0.9 1.2 1.3 1.6 2.0 2.4 3.2 26–32 24–28 24–28 25–30 26–30 26–32 30–34 150–250 150–250 200–350 225–375 275–450 350–500 400–600 Goodheart-Willcox Publisher Figure 8-20. Approximate machine settings for FCAW–G carbon steel using an E70T-1 electrode and CO 2 shielding gas. Lower values are for out-of-position welding. Higher values are for flat and horizontal fillet welding. FCAW–G—Stainless Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.035 0.045 1/16 0.9 1.2 1.6 23–30 25–30 26–34 90–140 140–260 200–300 Goodheart-Willcox Publisher Figure 8-22. Approximate machine settings for FCAW stainless steel with CO2 shielding gas. When using 75%Ar 25%CO2 shielding gas, lower the voltage by 2 volts. Lower values are for out-of-position welding. Higher values are for flat and horizontal fillet welding. FCAW–S—Carbon and Low-Alloy Steel Electrode type and diameter Arc voltage Amperage r ange inches mm V A E70T-4 (DCEP) 29–36 200–350 5/64 2.0 E71T-11 (DCEN) 16–22 175–350 5/64 2.0 Goodheart-Willcox Publisher Figure 8-21. Machine settings for two FCAW self-shielding electrodes. The values differ significantly because one is designed to work with DCEP and the other with DCEN. Consult the manufacturer’s data sheets for specific recommendations.

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Chapter 8 Gas Metal and Flux Cored Arc Welding 205 Copyright Goodheart-Willcox Co., Inc. GMAW Short Circuit Transfer — Stainless Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.030 0.035 0.045 0.8 0.9 1.2 17–22 17–22 17–22 50–145 65–175 100–210 Note: The values shown are based on a mixture of 90% helium, 7 1/2% argon, 2 1/2% CO2. Goodheart-Willcox Publisher Figure 8-16. Approximate machine settings for short circuiting transfer on 300 series stainless steel. GMAW Spray Transfer — Stainless Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.030 0.035 0.045 1/16 3/32 0.8 0.9 1.2 1.6 2.4 24–28 24–29 24–30 24–32 24–32 160–210 180–255 200–300 215–325 225–375 Note: The values shown are based on the use of argon-oxygen shielding gas. The oxygen percentage varies from 1–5%. Goodheart-Willcox Publisher Figure 8-17. Approximate machine settings for spray transfer on 300 series stainless steel. GMAW Spray Transfer — Aluminum Electrode diameter Arc voltage Amperage range inches mm V A 0.030 0.047 (3/64) 1/16 3/32 0.8 1.3 1.6 2.4 19–22 22–28 24–30 26–34 100–150 130–200 160–300 220–450 Goodheart-Willcox Publisher Figure 8-18. Approximate machine settings for spray transfer with 100% argon on aluminum and aluminum alloys. GMAW Spray Transfer — Copper Electrode diameter Arc voltage Amperage range inches mm V A 0.035 0.045 1/16 0.9 1.2 1.6 21–25 22–26 24–28 170–210 200–240 310–400 Goodheart-Willcox Publisher Figure 8-19. Approximate machine settings for spray transfer with 100% argon on copper and copper alloys. FCAW–G—Carbon Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.035 0.045 0.052 1/16 5/64 3/32 1/8 0.9 1.2 1.3 1.6 2.0 2.4 3.2 26–32 24–28 24–28 25–30 26–30 26–32 30–34 150–250 150–250 200–350 225–375 275–450 350–500 400–600 Goodheart-Willcox Publisher Figure 8-20. Approximate machine settings for FCAW–G carbon steel using an E70T-1 electrode and CO 2 shielding gas. Lower values are for out-of-position welding. Higher values are for flat and horizontal fillet welding. FCAW–G—Stainless Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.035 0.045 1/16 0.9 1.2 1.6 23–30 25–30 26–34 90–140 140–260 200–300 Goodheart-Willcox Publisher Figure 8-22. Approximate machine settings for FCAW stainless steel with CO2 shielding gas. When using 75%Ar 25%CO2 shielding gas, lower the voltage by 2 volts. Lower values are for out-of-position welding. Higher values are for flat and horizontal fillet welding. FCAW–S—Carbon and Low-Alloy Steel Electrode type and diameter Arc voltage Amperage r ange inches mm V A E70T-4 (DCEP) 29–36 200–350 5/64 2.0 E71T-11 (DCEN) 16–22 175–350 5/64 2.0 Goodheart-Willcox Publisher Figure 8-21. Machine settings for two FCAW self-shielding electrodes. The values differ significantly because one is designed to work with DCEP and the other with DCEN. Consult the manufacturer’s data sheets for specific recommendations.

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204 Modern Welding Copyright Goodheart-Willcox Co., Inc. Warning When setting up the GMAW or FCAW station, look for all potential safety problems. Spatter from GMAW or FCAW can cause a fire. All flammable materials must be removed from the welding area. 8.4.1 Setting Up a GMAW/FCAW Power Source In order to produce acceptable welds, a GMAW/ FCAW power source must be properly adjusted for the material being joined and the desired metal transfer method. Before setting up the power source, the fol- lowing information must be known: • The type of base metal to be welded. • Base metal thickness. • The type and diameter of welding wire. • The type of transfer method to be used. • The type of shielding gas to be used. Once this information is known, the welding machine can be properly set up. Only a few controls must be set prior to welding. See Figure 8-13. First, adjust the voltage setting. The voltage deter- mines the arc length and helps determine the metal transfer method. Other factors also affect the transfer method, as discussed in sections 8.2.1 through 8.2.4. Second, adjust the wire feed speed. When the wire feed speed is adjusted, the machine’s welding amper- age is also adjusted. Figure 8-14 through Figure 8-22 list the voltage and amperage settings for welding different base metals using both short circuiting transfer and spray transfer. 5. Connect the workpiece lead to the welding machine. Both the welding gun cable assembly and the workpiece lead should be checked for any signs of wear or cuts. Wear or cuts on the outside of these items may indicate damage to the leads. 6. The workpiece clamp should be checked. The clamp should be clean so it can make a good electrical connection. 7. If a water cooler is used, connect it to the welding machine or to the gun according to the manufacturers’ recommendations. The welding machine, wire feeder, or welding gun is connected to the outlet on the water cooler. This way, cool water flows from the cooler to the gun. Warm water returning from the gun is connected to the inlet on the water cooler. GMAW Spray Transfer — Carbon Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.030 0.035 0.045 1/16 3/32 0.8 0.9 1.2 1.6 2.4 24–28 24–28 24–30 24–32 24–33 150–265 175–290 200–315 275–500 350–600 Note: The values shown are based on the use of argon with 2%–5% oxygen for mild and low-alloy steel. Goodheart-Willcox Publisher Figure 8-15. Approximate machine settings for spray transfer on carbon or low-alloy steel. GMAW Short Circuit Transfer — Carbon Steel Electrode diameter Arc voltage Amperage range inches mm V A 0.030 0.035 0.045 0.8 0.9 1.2 15–21 16–22 17–22 70–130 80–190 100–225 Note: The values shown are based on the use of CO 2 for mild steel and argon CO2 for low-alloy steel. Goodheart-Willcox Publisher Figure 8-14. Approximate machine settings for short circuiting metal transfer on carbon and low-alloy steel. Gun cable connection Gun trigger connection Voltage adjustment Wire feed adjustment Jog switch Purge switch Voltage and current meters Power on/off Miller Electric Mfg. Co. Figure 8-13. A GMAW/FCAW power source.

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206 Modern Welding Copyright Goodheart-Willcox Co., Inc. Globular transfer voltages and amperages fall in the range between those shown for short circuiting trans- fer and spray transfer. Pulsed spray background volt- age settings are slightly higher than the values shown for short circuiting transfer. The peak current must be above the transition current. The currents shown for spray transfer are above the transition current. Figure 8-23 shows a welding machine on which welding variables are set and stored in electronic memory. The welding machine has a microprocessor inside. A microprocessor can be considered a small computer. The manufacturer programs the micropro- cessor with a set of welding values. The microproces- sor determines the best settings or parameters for the welding application based on a set of input data about a weld. The welding machine determines the welding parameters as well as the type of transfer. A welder using a microprocessor-equipped weld- ing machine enters information about the weld to be made, which includes welding wire type, wire diam- eter, type of shielding gas, and metal thickness. The microprocessor sets the voltage, wire feed speed, and possibly the slope, thus determining the type of metal transfer used. Standard welding values are prepro- grammed into the welding machine. Special welding parameters can also be saved as a program in the machine. This program, or any preset values, can be recalled at any time in the future. Because the welding values are stored electronically, the welding machine is set up exactly the same way each time. Some power sources allow the slope to be changed. Many machines have a preset value for the slope. Power sources that have the ability of pulse spray transfer have additional controls to set up. These con- trols include an on-off switch, a background voltage adjustment, a peak amperage adjustment, and some- times a “pulses per second” adjustment. The back- ground voltage is set relatively low, in the globular transfer range. The peak amperage is fairly high to cause spray transfer to occur. This peak amperage must be above the transition current. The pulses per second adjustment is used to set the number of times per second the current pulses from the low value to the high value. 8.4.2 Setting Up the Wire Feeder Wire feeders use a 24V–40V DC or a 115V AC supply. Figure 8-24 shows a complete wire drive unit with four drive rolls. Figure 8-25 shows a two-roll wire drive system. Two mated gears are located in the wire drive unit. One gear is driven by an electric variable- speed motor. A roll is attached to each gear. In a four- roll wire feeder, two rolls are driven. See Figure 8-26. The Lincoln Electric Company Figure 8-23. A microprocessor-controlled power source with a built-in wire feeder and digital displays. Electrode spool mount Drive rolls Welding gun connection The Lincoln Electric Company Figure 8-24. A complete wire feeder.

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Page 2Part 1 Welding Fundamentals click to expand contents

Page 102Part 2 Shielded Metal Arc Welding click to expand contents

Page 168Part 3 Gas Metal and Flux Cored Arc Welding click to expand contents

Page 240Part 4 Gas Tungsten Arc Welding click to expand contents

Page 300Part 5 Plasma Arc Cutting click to expand contents

Page 320Part 6 Oxyfuel Gas Processes click to expand contents

Page 484Part 7 Resistance Welding click to expand contents

Page 534Part 8 Special Processes click to expand contents

Page 718Part 9 Metal Technology click to expand contents

Page 766Part 10 Professional Welding click to expand contents

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