Welding Data

Resistance spot welding (RSW) is the most common technique employed in joining metal sheets for mass production. In this process, two overlapping galvanized steel sheets are joined without the use of any filler material. The so-called dynamic resistance curve (DRC) shows how the electrical resistance between the pieces of metal being joined changes during the welding operation, providing a technological signature of the metallurgical development of a spot weld. Anomalous conditions, such as excessive welding current and insufficient electrode pressure, cause expulsion in the welding joint. Expulsion is the ejection of molten metal from either the interfaces of metal sheets or the interfaces between metal sheets and electrodes, resulting in a serious defect that destroys the welding strength. It also reduces the electrode life. Given these detrimental effects, detecting expulsion is paramount for ensuring consistent welding quality in production lines. The dataset consists of n = 115 DRC curves measured in milliohm, collected for five spot welding points made by the same welding machine. The total number of variables is p=750, and expulsion occurred in parts of 70 curves. The first column of the data matrix contains a binary variable indicating whether expulsion occurred.