How to improve your welding techniques
While the most important technique a converter rebuilder has to learn is how to achieve perfect welds through trial and error and testing. We have a suggestion for how to improve your current welding processes.
Many rebuilders use .035 diameter carbon steel wire. This is available in many grades and individual preferences may be desired. Lincoln-brand and “Murex” are two popular choices of wire. Even more critical is learning correct heat ranges and wire-feed speed for proper weld flow. Along with the correct wire, heat range, and wire-feed speed, the shielding gases need to also be considered. Proper shielding gases will ensure non-contaminated welds.
Starting at the beginning, the diameter of .035 works best with approximately 23-25 volts of electricity and wire-speed of 500 ft./min. By using a gas mixture of 75 percent CO2 and 25 percent Argon, satisfactory results will occur for most low-production rebuilders using a short-circuit method of welding.
For production rebuilders trying to increase productivity, we suggest using .045 diameter wire with 28-29 volts at a speed of 500-600 ft./min. This will allow the operator to increase the turntable speed and cut down production time. When using this combination of wire and voltage, it is recommended to use a gas mixture of 80 percent CO2 and 15 percent Argon and 5 percent Helium. This will provide a hotter, faster weld with outstanding results.
With practice the voltage can be raised using the tri-blended gas, which will cause a desirable spray transfer weld to be achieved. Note the spatter reduction between photos A and B. Photo A is a short-circuit method, while photo B achieves a quality spray transfer. When weld spatter is reduced or eliminated a flawless weld with minimal chance of leakage is accomplished.
Shielding gases play a major role in providing leak-proof welds. According to Tim Snyder, a well-known Miller Welders distributor and welding expert, the voltage should be approximately one half of the wire speed. For example, 24 volts should have wire speed of approximately 480 ft./min. as compared to 28 volts at 560 ft./min. This will always give you a close starting point, allowing you to fine tune your speeds and feeds. Spatter guards are generally not recommended for use on converter welding unless an organic formula of spatter product is used in a well ventilated area.
If excessive silica material is formulated on top of a weld surface, do not be alarmed. Impurities are removed from the convert weld, ensuring a clean welded seam prevails. Silica should be removed after the welding process is complete. This will allow for proper leak inspection. Allow the converter to cool before leak testing to prevent stress or cracks. If bubbles occur in the weld, it is an indication of contaminated gases escaping the weld seam. This problem can be corrected by slightly increasing voltage and/or carefully prepping torque converter components before assembly. All paints and oils need to be removed from the weld area.
With a little practice and following these guidelines, professional welds will be attainable.
Midwest Converters, Rockford, IL
– Found in January 2008 Newsletter