Aluminum use for automotive body sheet applications is growing. This growth requires improvement of related joining processes and technology. Resistance spot welding will be one of the major joining technologies used in assembling automobiles.
When spot welding aluminum, electrode tip life is limited by tip erosion and pickup of aluminum on the tip. Increasing weld current improves weld strength (to a limit), however this reduces tip life.
This study examines the control variables in the resistance spot welding process and offers an improved weld schedule to achieve desired weld properties while maximizing tip life. First, the limits of weld parameters where satisfactory welds can be obtained are determined. A window of tip force and weld current is established for a given material and tip geometry. These limits are used to optimize the weld schedule in terms of tip life.
Spot welds fail on the basis of shear strength, button diameter or peel rate. Weld parameters determine the probable failure mode. An analysis of the failure mode is also used to optimize the weld schedule. We will also examine the effects of various surface treatments on weld quality and electrode tip life.