Sparks and spatter can be a normal and expected part of the resistance welding process. ALWAYS HAVE SAFETY PROTECTIVE GEAR ON WHENEVER MAKING RESISTANCE WELDS! Not all sparks and spatter are bad. Often the best weld quality and the largest lobe window are settings which cause sparks and spatter. This can be a difficult trouble shooting situation and at the end of the day the quality and productivity must come first.
If the RW machine comes down and sparks and/or arcs in the beginning of the weld then either the squeeze time was too short or the cylinder flow control is closed too much( the cylinder too slow, blow-by in the o-rings, or starving for air). There is also a possibly that the electrodes are not set for 2mm overlap without a part in the machine and the machine is not able to get the electrodes to full force prior to welding. This can be quickly adjusted for by increasing the squeeze time. The root cause needs to be determined and fixed.
If there is spitting or a flash in the middle of the weld then the current is probably too high, the force setting too low, or you have a cylinder blow-by causing a poor follow up condition. The main cause is the that the weld nugget is growing too fast causing the weld to spill out from in-between the welds faying surfaces. The quick fix is to turn up the force. Be careful if you go this route because if the pressure gets turned up too much then you will have weak weld conditions.
If the sparks and spatter are near the end of the weld it could be from too much weld time or poor follow up. Make the required adjustment but double check the RW weld quality right away because the weld nugget must have enough time to grow to the correct size.
While having the sparks and spatter stick to the nut and bolt threads is not a good thing, it is better than making a weak weld. Also, in the food industry, spatter that adheres to some surfaces is not acceptable. If the machine is set correctly and with proper upslope this condition can be avoided. However the range for your settings will be more narrow and a careful balance must be found with a machine in good working condition.
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