Spot Welding
Questions and Answers
Yes, it could be a power problem. It could be a pressure/force problem also associated with the lack of adequate plant supply. There are many other machine components and schedule issues that should not be overlooked.
These are two articles on related subjects discussed in this blog:
WHY DO WELD NUGGETS VARY DURING A SHIFT?
WHY DO THE FIRST PARTS AFTER A BREAK HAVE UNDERSIZED WELD NUGGETS?
To answer this question, we need to start by defining some words. The question asked appears to be describing extending “HOLD TIME”. This is the time the electrodes remain on the parts exerting force while the part is cooling down.
The word “RETRACTION” is frequently used to describe a cylinder or servo function where the control asks the force device to only open partially to reduce the electrode travel time between welds. More welds can be performed in a short time.
For more information - In this BLOG See:
WHAT IS HOLD TIME IN RESISTANCE WELDING?
WHAT IS A RETRACTION FUNCTION?
A resistance welding schedule has three defined segments. They are:
SQUEEZE
WELD
HOLD
This question comes up frequently. Many look for a formula to set the squeeze and hold time for resistance welding.
Several articles have been written on this subject in this blog:
HOW DO YOU SET THE PROPERSQUEEZE TIME IN A RESISTANCE WEDING SCHEDULE?
IS THERE A FORMULA TO DETERMINE THE SQUEEZE TIME IN RESISTANCE WELDING?
IS SQUEEZE TIME IMPORTANT?
HOW WILL HOLD TIME CHANGE THE RESISTANCE WELD STRENGTH?
Pressure, current and time (PCT) are the basic functions performed by the resistance welder. These functions are controlled or initiated by the weld controller. It initiates each step when told to start the weld process by input from the foot switch or automation PLC. The controller allows time for each step to operate and controls the current amplitude. In simplified form this is Squeeze, Weld and Hold. The squeeze sequence allows the pressure system to build up the force to contain the weld. The weld function is the actual current flow and is totally controlled by the weld controller. It regulates the amplitude and time of current flow. Hold is the period which allows the weld nugget to cool down and solidify under force. The controller regulates this time.
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