SPOTWELDS BREAKING ON COATED CRS MATERIALS

[pinchedean]

WAS WONDERING IS ANYONE HAD ANY ADVICE ABOUT SPOTWELDING COATED CRS MATERIAL, I.E. GAX, PAINLOCK, GALVANEAL. WE COMPLETE PULL TEST BEFORE RUNNING PARTS, BUT IT SEEMS HALF WAY THROUGH WE FIND PARTS THAT THE SPOTWELDS START TO BREAK.?

 

[berkshire]

Watch your electrode sizes. The zinc alloys with the copper electrode quite readily. This erodes the tips making them bigger over the course of the welding run. When the tip grows too much your weld density suffers and you end up just melting the zinc and soldering the part instead of welding it. If you have a multistage controller then a short burst on high heat to melt the zinc and squeeze it away from the weld area before the main weld current occurs works best.
Make sure your operators or setup men are dressing the electrodes before weld failure occurs
Also could you please turn your caps lock off before responding, thank you.
B.E.