Influence of experience level on determining weld diameter in resistance spot welding

Abstract

The weld diameter is the most important quality criterion in resistant spot welding and is unsually determined after destructive testing. Several standardized destructive testing methods are available for this purpose. The determination of the spot weld diameter is influenced by numerous factors. These include the measurement conditions, such as the lighting conditions, the measurement equipment used, and the person performing the measurements. The human aspect is influenced by experience and is therefore subjective. To manually evaluate a resistance spot weld, the weld diameter can be measured according to ISO 17677-1, AWS D8.1M, or DVS 2916-1, among others. The challenge here is that the statistical variation in the destructive evaluation of the spot weld diameter due to human experience is still insufficiently researched. In addition, the results of destructive testing are not statistically validated or are questioned in many scientific publications. The suitability of the destructive test methods used is often not justified or compared with other test methods. The purpose of this contribution is to statistically evaluate the human experience on manual weld diameter measurements and give recommendations, that should be taken into account in the future of some kind of issues. For this purpose, more than 180 spot welds were destroyed by torsion testing and the weld diameters were measured by 20 different participants with different levels of experience. The results show that the measurements are influenced by a number of factors, including the level of experience of the participants, the size of the weld diameters measured, the failure mode, and the duration of the measurements on a sample.