welding + grounding

#1
I posted this on a old thread but I wanted to bump this so people will know.

Remember with grounding always ground as close to your weld area. DCSP and DCRP can destroy bearings and electronics. For example: if you have to weld your shock mount back on your rear axle DO NOT ground on your rim or lug nuts. The current with travel through your bearings and spinder gears. If your using SMAW ( stick ) your using DCRP the current heat it locally at the rod. This is a dangerous issue for bearings. However if your going to run the FCAW ( inner shield flux ) the weld process is DCSP like GTAW ( tig ) current is locally at base metal. This will not cause damage to bearing as quickly than DCRP. Heres a current flow diagram
*DCRP stick <<<< base metal
DCSP wire >>>>> base metal

Also heres a clip form the text book: Currents With direct current the welding circuit may be eitherdc straight polarity (DCSP) or dc reverse polarity(DCRP). When the machine is set for straight polarity,the flow of electrons is from the electrode to the plate,which creates considerable heat in the plate. In reversepolarity, the flow of electrons is from the plate to theelectrode, thus causing a greater concentration of heat at the electrode. The intense heat at the electrode tends to melt off the end of, the electrode and may contaminate the weld. Hence, for any given current, dc reverse polarity requires a larger diameter electrode than dc straight polarity. For example, a1/16-inch diameter tungsten electrode normally can handle about 125 amperes in a straight polarity circuit.However, if reverse polarity is used with this amount ofcurrent, the tip of the electrode will melt off.Consequently, a 1/4-inch diameter electrode will berequired to handle 125 amperes of welding current.*

No one ever really looks at arc marks but under a microscope an arc mark is composed of thousands of cracks. On a frame this wont hurt a damn thing at a microscopic level, but for a bearing this can lead to catastrophic failure. The gap in bearing when electrons pass through them will create arm marks. Always pay attention to your ground points. It would suck to rebuild a engine because of a little welding.
Hope this is some good info for yall happy welding!!
 
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