How to Spot Weld Aluminum:
Spot welding is a procedure in which two metal surfaces are melted jointly to form a weld. A couple of electrodes at the same time clamps the work pieces jointly and delivers the electrical current wanted to make the weld. The two electrodes focus the current onto a small spot, which is where the term "spot welding" comes from. Aluminum spot welding is becoming more common as aluminum replaces steel in many applications where weight is main, such as automobiles.
1). Use three phase electrical energy to spot weld aluminum. This type of electrical power is wanted for the big output current that spot welding requires. Spot welding typically brings current for 0.1 seconds or less, so the current must be very high. Spot welding machines typically deliver 150 amps per phase draw on a 440 volt system.
2). Choose capacitor discharge welders. These welders use a capacitor to store and distribute the extremely high current necessary to do spot welding. The main advantage of capacitor discharge welders is that they need a smallest power draw, which allows lesser plants to perform spot welding without upgrading the electrical supply. This allows assembly lines to use spot welding on thicker pieces without the lights flickering.
3). Think the physical properties of aluminum when performing spot welds. Aluminum conducts electrical energy and warmth very easily, so it has to be welded faster than steel to avoid overheating the work pieces. Aluminum typically needs two to three times the current and one quarter of the weld time that steel does. The very high current and short weld times mean that the electrodes have to be water cooled.