Session:

Manufacturing Modeling and Dynamic Systems
Monday March 01, 2004, 17.55 – 18.15

Session Chair:

Fatima Rateb

Paper Title:

Studying the Quality of Resistance Spot Welding Joints Using Self-Organising Maps

Author(s):

H. Junno, University of Oulu, Finland
P. Laurinen, University of Oulu, Finland
L. Tuovinen, University of Oulu, Finland
J. Röning, University of Oulu, Finland

Abstract:

Resistance spot welding is used to join two or more metal objects together, and the technique is in widespread use in, for example, the automotive and electrical industries. The quality of the welding joint is estimated by destructive or non-destructive tests. In this work, a method was developed that can be used to study the quality of a welding spot without destroying the joint. In this paper, the quality of the welding spot is analysed by using the diameter as a measure of quality. The relations between the diameter of the welding spot and certain features extracted from the welding signal curves are studied by dividing the signal curves into ten parts of equal length and using their averages as training parameters. Self-organising maps are also trained by using the most dissimilar features of the feature set. The relations between the diameter and the other features can be easily seen from the respective maps. According to the results, compression force has a notable influence on the size of the diameter. Two general rules of spot welding were confirmed by our study, which indicates that large values of diameter co-occur with small values of compression force and vice versa. Also, small values of current and small values of some features of voltage correlate with small values of diameter. This dependency naturally only holds true within reasonable limits of maximum current (to prevent splashing) and minimum force. The results also show that the quality of the welding spots can be inferred from data on other welds.