Machinery's Handbook, 31st Edition
1584 Gas Metal Arc Welding 30 and 35 volts. With excess voltage, there should be a visible gap between the tip of the electrode and the weld, and the arc sound should be free from crackle. With the sequence shown in Fig. 4, the voltage should now be reduced until a consistent smooth crackle sound is produced. If the voltage is lowered too much, the electrode will run into the weld, making a harsh crackling sound, and the resulting weld expulsion will cause spatter.
VOLTS (too high)
VOLTS (too low)
VOLTS (Correct)
31 32 33
24 25 26
26 27 28
A
B
C
Long Arc Quiet Spray Sound VOLTS
No Arc Noisy Erratic Crackle Spatter VOLTS
Small Arc Length Smooth Crackle Sound VOLTS
A
B
C
Fig. 4. Setting Optimum Voltage for GMAW Spray Transfer Welding Flux-Cored Arc Welding
FCAW welding offers unique benefits for specific applications, but flux-cored consum able electrodes cost more than the solid electrodes used in gas metal arc welding, so users need to be aware of FCAW benefits and disadvantages compared with those of GMAW welding. Generally, flux-cored electrodes designed for use without a shielding gas are intended for welding outdoors. Most indoor FCAW welding is done with gas-shielded FCAW welding electrode wire. Some Standards for gas-shielded FCAW electrodes for various countries are listed in Table 6. Table 6. Standards for Gas-Shielded, Flux-Cored Welding Electrodes Steel Type Country Standard
United States
AWS A5.20 CSA W48.5 JIS Z3313 DIN 8559
Canada
Low-Carbon Steels
Japan
Germany
United States
AWS A5.29 CSA W48.3-M BS 639-2492
Canada
Low-Alloy Steels
United Kingdom
Stainless Steels AWS A5.22 All-Position, Gas-Shielded Electrodes.— The term “all-position” does not necessarily mean that these electrodes are the best choice for all positions. Also, flux-cored elec - trodes may meet all standard specifications, but there will inevitably be subtle differences United States
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online