Weldbonding of Aluminum Automotive Body Sheet

This paper presents the results of an investigation into the material variables that influence the weldbonding of aluminum. The four major variables that were considered in this study were the aluminum alloy, type of adhesive, the presence of a forming lubricant, and the metal surface treatment. To maximize the amount of information gained from this study, a statistical design of experiments was used. The particular design used here is an example of a screening design, in which a relatively small number of variable combinations is investigated to identify those variables that have a strong impact on the measured responses. The responses in this experiment consist of both quantitative measurements and qualitative judgments that must be taken together to interpret the experimental results. The “quantifiable” responses included weld parameters (current and percent heat); nugget diameter; weld quality ratings (based on a subjective rating system); and tensile strength. The strictly qualitative responses of electrode wear and micrograph evaluations were also considered.

Considering all of these responses as a whole the single largest influencing factor was the aluminum alloy. Adhesive was also significant, with each adhesive offering different advantages. The impacts of lubricant and surface treatment were smaller, and were largely present in interactions with alloy and adhesive.