Re: [CAD_CAM_EDM_DRO] A bit off topic - resistance welding

At 03:13 PM 10/16/00 -0400, Bertho Boman wrote:<snip>Spot welding clamps
the two pieces together tightly and run sufficiently high current through
the joint to melt the metal, hence

>welding. There are big monster ones used in sheet metal shops and little
>baby ones. Typically just 1 volt or so and hundreds or
>even thousands of amps AC. I have seen them with 1" diameter conductors!

If you do decide to build your own, remember to provide some method of
cooling the electrodes. Almost every spot welder I have seen has the
electrodes mounted on pipes with water pumped through them to cool the
electrodes. With copper electrodes melting steel, stainless, mild or
otherwise, keeping the tips of the electrodes dresses was essential to
obtaining a good spot weld.

Likewise, unless you are going to spot weld ONLY one thickness and/or
composition of metal, three variables need to be provided for:
1.) Voltage. Since spot welding is resistance based, varying the
voltage will adjust the amount of power available at the electrodes.
2.) Pressure. The more pressure the less resistance and hence lower heat.
3.) Time. The longer the current is passed through the joint, the more
heat developed.

Usually you can compensate one of the three by adjusting one or both of the
other three, until you get your ideal spot. Find out more at:

www.kvawelding.com/

click on Reference Documents -> Resistance Welding Overview

Hugh