CHANGES IN EMISSIVITY OF THE ELECTRODES FOR RESISTENCE SPOT WELDING DUE TO THEIR WEAR

1 FOREJTOVÁ Lucie
Co-authors:
2 ZAVADIL Tomáš 1 KOLAŘÍK Ladislav 1 KOLAŘÍKOVÁ Marie 3 SOVA Jan
Institutions:
1 Czech Technical University in Prague, Faculty of Mechanical Engineering, Technická 4, Prague, Czech Republic, EU, Lucie.Forejtova@fs.cvut.cz
2 Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Břehová 7, Prague, Czech Republic, EU
3 WORKSWELL, Libocká 653/51b, Prague, Czech Republic, EU, jan.sova@workswell.cz
Conference:
28th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 22nd - 24th 2019
Proceedings:
Proceedings 28th International Conference on Metallurgy and Materials
Pages:
657-662
ISBN:
978-80-87294-92-5
ISSN:
2694-9296
Published:
4th November 2019
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
29 views / 9 downloads
Abstract

Resistance spot welding is one of the most used welding technologies for joining of thin, deep drawn steel sheets in automotive industry. The condition of electrodes may have significant impact on the resulting weld quality, therefore it is necessary to check the electrodes´ wear that otherwise may cause creation of specific defects in the weld joints. One of the possibilities is utilization of infrared thermography. In order to perform the testing correctly it is essential to know the expected emissivity of the electrodes. This article deals with the changes in emissivity due to wear. It demonstrates that the emissivity of new electrodes is significantly different in comparison with worn electrodes. The biggest change is observed between the first and 25th weld. With increasing number of performed welds the emissivity drops slightly with increasing number of welds. The increased temperature caused significant drops when temperature is elevated up to 40 °C, but it is virtually constant for temperatures above 40 °C. It concludes that a mean „operational emisivity of the electrodes operated at higher temperatures (i.e. 40 °C +) is a suitably accurate factor to be used during the weld inspection on defects.

Keywords: automotive, resistance spot welding, thermography, ultrasonic testing
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