re: kVA computation

admin

Hello peeps!I am a newbie with resistance welding.  Anybody can help me in computing the kVA of the welding transformer with given workpiece specs. eg thickness, material, and no. of sheets.ur help and explanation will be very much appreciated.Thanks and more power!Roy
Reply:A good source may be the Resistance Welding Manufacturing Alliance.http://www.aws.org/rwma/publications.htmlI'm sure this is different than what you're looking at, but my only resistance welding experience was projection welding small studs and tubes.  A stud on the order of 1/4" bolt, would be resistance heated and shoved into an undersized counterbore with about 2000 lbs force and 10,000 amps applied for 5/60ths of a second.  Don't recall what the KVA rating of the machine was.One thing that was somewhat counter intuitive at first was that reducing the force made the stud sink deeper into the counterbore.  But, if you think about it, less force produces a higher resistance and thus higher peak temperature between the stud and counterbore, so the stud is more easily seated.  Also, the relationship between time and current is interesting.  Longer times tend to overheat the electrodes causing mushrooming, so the amount of current is limited and thus the peak temperatue at the joint is lower than a short duration weld at higher peak current.
Reply:thanks pulser,these really are some pieces of helpful information.  hope to see ur reply again in some of my future questions.  thanks!
Reply:Here's another good pamphlet:http://www.millerwelds.com/pdf/Resistance.pdf