Describe the main operating features of any one of the following: Spot welding machine Rack and pinion mechanism Plastic dip coating tank. - Leaving Cert Engineering - Question i - 2015

The spot welding machine operates using two copper electrodes which apply heat to the sheet metals to be joined.

1. Operation Activation: When the machine is turned on, an electrical current flows from one electrode through the two sheet metal parts to the other electrode.

2. Resistance and Heating: A resistance occurs between the two sheets, causing them to heat up and fuse at a designated point. This is essential for creating a weld.

3. Time and Nugget Formation: The welding process usually lasts a few seconds, forming a nugget at the weld area. This nugget is critical to ensure a strong bond between the metals.