IJSRP, Volume 4, Issue 8, August 2014 Edition [ISSN 2250-3153]
Aravinthan Arumugam and Abdul A Baharuddin
Resistance Spot Welding (RSW) is a process that is widely used in the automotive industries. The parameters that are used to develop a spot weld are the welding current, weld time and electrode force. Electrode force was not used as a control parameter due to the use of pneumatic system to actuate the welding electrode. The pneumatic system does not allow the development of closed loop control system; therefore electrode force was not used to control the growth of the spot weld nugget. This reported work looks into the ability to control electrode force dynamically during welding by using servomechanism. Force profiles were introduced in this work and the electrode force during welding was controlled to follow these force profiles. Based on the findings, the developed controller was able to control the electrode force during welding to follow the given force profiles. Decreasing the electrode force during welding facilitates the initiation of spot weld growth earlier in the weld cycle which in turn produces bigger weld diameter and stronger weld strength. The opposite was noticed when electrode force was increased during the weld cycle. Furthermore decreasing the electrode fore during welding produced a button pull-out failure and increasing the force produced an interfacial weld failure.