Squeeze is the first segment of the weld schedule. It’s function is to apply force on the work pieces to bring them together. This pressure under the face of the electrode in turn makes good electrical contact and controls and contains the resultant weld nugget during the weld and hold portion of the weld cycle. If current is applied prematurely before the proper force has been reached these functions will be compromised and expulsion and poor nuggets should be expected.
Offset holders are designed to allow one to reach into or over something on the part. They are designed to withstand most welding forces with very little flexing. Offset holders should be used in machines and set ups to minimize any other bending forces.
Squeeze time is the first sequence of a weld schedule. It is designed to allow the electrodes to close and build up full force on the parts before current is applied. If squeeze time is too long it does not hurt the welding operation but it does increase the cost of the total operation by increasing the total time of the weld schedule and thus fewer parts per shift.
Edge distance is a very important design criteria in resistance welding. Any weld on an edge can expel metal and or result in a partial weld nugget. This type of weld is considered deficient in quality programs. Edge welds should be avoided in all design and set up situations.
Part fit up is very important in determining the quality of resistance welds. All weld schedules call out a force value with the purpose of holding the part together, containing the weld nugget and performing a little forging as the weld cools. If the part does not fit up properly then part of this force is used to force or form the part into place and is not available to contain and forge the weld nugget.
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