Sparking spot welds from an older welder : LUSENET : Resistance Welding : One Thread

I Work with spot welders which are over 20 years old,there have a timing switch and a heat switch 1,2,3 e.t.c there are petal operated,l weld 2mm plate together,I use a dome face cap tip on top and a flat tip bottom ,I find it welds ok at first put sparks alot, after awilde it looks like its welded put comes away very easy with out pulling a slug the tips are clean,is it that the welders are just too old, any help on setting spot welders would help ,old ones. thank you billy

-- billy bell (, February 21, 2001


Response to spot welds

You need to give more inforrmation on the machine you are using and the welding timer in the machine.

Things you need to check, the tip diameter should be around 7 - 8mm, the pressure at the tips when welding, if available, you need to put a pressure gauge between the tips, turn the weld off, and cycle the machine you should be looking at having about 2.6 - 3.0 kN of pressure (for 2mm to 2mm plate). In addition to this, you should be able to set the weld time, this should be between 10 - 14 cycles, and the weld current should be around 9 to 13kA. All of which should be checked using a current meter, if you do not have one, contact British Federal in UK, ask for a PWA Weld Analyser.

If you be more specific about the machine and timer I may be able to help further, good luck....

-- gareth bonnell (, February 22, 2001.

Response to spot welds

It sounds like pressure and/or follow-up pressure on the weld is a problem. Older equipment has several things that could cause this. Just a few are as follows. 1. Check for air leaks at the pistonrod packing and cylinder seals. 2. Check for proper operation of the solenoid valve. Is the spool moving fully? 3. Check for mechanical wear and binding

-- Bob Balla (, February 23, 2001.

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