Non-Destructive Inspection by Infrared Thermography of Resistance Spot Welds Used in Automotive Industry

Abstract

Resistance spot welding (RSW) is one of the main joining technologies of thin sheets in the automotive industry. Key factors affecting the strength of the RSW joint are the nugget diameter, asymmetry, expulsions, intended surfaces, and the presence of cracks. Despite its broad use, the RSW joint quality verification is limited only to destructive testing and a limited number of non-destructive testing (NDT) methods. Most of the testing is done destructively by sampling, which assesses only systematic defects. Ultrasonic Testing (UT) is the most used NDT method to detect non-systematic defects in the RSW joints, however the probability of the defect detection of conventional testing techniques is not fully satisfactory. Other approaches were invented to deal with this situation. The article uses the currently most used NDT approach of the UT testing as a benchmark to evaluate the ability of thermographic testing to detect defective welds of the resistance spot welding in an on-line mode. The article demonstrates that the infrared thermography may find systematic process errors that are not detectable by other NDT methods by an analysis of different temperature drops measured after a constant delay time caused by different cooling dynamics of satisfactory and non-satisfactory weld joints.

Improving Quality Control of Siluminial Castings Used in the Automotive Industry

“…Equal research is currently being carried out on the quality of reciprocating silumin products, including, for example, the improvement of the structure and properties of the material [10][11][12][13], impact of manufacturing technology on the properties of castings [14][15][16][17], evaluation of the dimensional stability of the product [18] or the tribological behavior of the piston alloy [19]. Despite attempts to improve the structure of properties of silumin castings, attention should also be paid to quality control of these castings [6,20].…”

“…The importance of NDT in automotive technology is particularly important also due to the relatively low values of safety factors determined when designing automotive structures [21,22]. The analysis of publications related to the inspection of piston castings indicates that attempts are made to use single non-destructive testing (e. g. The following parameters are available: X-ray [11], ultrasound [20,23,24], infrared thermography [14], eddy currents [25]), depending on the purpose, construction and dimensions of the pistons. Therefore, it is advisable to develop a sequential method to control piston castings.…”

Magneto-Optical Imaging of Arbitrarily Distributed Defects in Welds under Combined Magnetic Field

“…This method has great application prospects and needs to be further studied. At present, the non-destructive testing methods of spot welding are radiographic testing [15], acoustic emission testing [16], ultrasonic testing [17][18][19], infrared thermography testing [20,21], dynamic resistance testing [22,23], eddy current testing [24,25], magnetic flux leakage testing [26,27], and so on.…”