• Weld broke when pulled by hand or when removed from machine
• Weld did not pass nugget size peel test
• Cross wires did not stay welded together
• Welds are weak only once in a while
• Nut did not pass torque test or push out test

If you have weak welds it is because the CURRENT or TIME was not enough. The process is simple but finding the root cause could take up valuable production time and there is probably more than one thing wrong with the machine. It could be a simple settings issue, problem with the timer, or machine problems. The quick fix is to turn up CURRENT by five percent or one to two tap switch settings.

Resistance welding is easy if all the settings are in balance for the application. It is also easy to get the parameters out of balance. You should get some coupons and build a lobe curve for the application and save this information. Make sure the machine is in good working order prior to checking the settings and making the lobe curve. Making a good lobe curve could take as many as 100 weld coupons so if the machine is not in good working order the time will be wasted and the issues will lead you in the wrong direction. Clean all the copper connections first. Do a quick percent heat test. Try the quick fix above and then make your current adjustments. The problem could be from the plant power into the machine so make sure you have good clean power. The problem could also be materials related.

Ninety percent of the time the problem is bad parts, nine percent of the time the problem will be tooling related, and one percent of the time the machine or controller/timer is the root cause.

Nut welding and cross wire welding is much more a problem with too much FORCE and thus an area increase diminishing the current density. Keep the air pressure low, the weld TIME short, and the CURRENT high. For multiple projections and/or cross wires the amperage needed is multiplied by the number of projects and/or wires. The time should increase about one or two cycles, (up to ten extra) per location if other machine conditions are met.

There are a few machines that have made eighteen projections on six weld nuts with one TX and one weld hit. So once things are set correctly it is possible to speed up production with multi-welding arrangements.