The Paton Welding Journal, 2015, №08



2015 №08 (04)

DOI of Article 10.15407/tpwj2015.08.05

2015 №08 (06)

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The Paton Welding Journal, 2015, #8, 26-30 pages
 

Analysis of the copper-chromium based electrode deformation during resistance spot welding process

C. Nachimani

Department of Mechanical Engineering, Faculty of Engineering, University of Malaya. 50603, Kuala Lumpur, Malaysia. E-mail: nachicharde@yahoo.com
 
 
Abstract
This research presents an experimental investigation of the RMWA class two (Cu-Cr) electrode caps in resistance spot welding of carbon and stainless steels. A pair of equal-size circled-electrode caps 5 mm diameter is committed to weld up to 900 welding processes. The electrode caps are sharpened once in the meantime and are replaced using electrode dresser after underwent approximately 400 weld attempts. The degrading factors of Cu-Cr electrodes have directly influenced the weld geometries on carbon and stainless steels while affected the bonding strength implicitly. The electrode caps that performed up to 900 weld attempts have been underwent the microstructural analytical observation, and several cracks in its internal structure were found. The internal cracks are only appeared in the movable-upper electrode cap due to continuous heating and hitting effects by pneumatic pressures, to compared with static-lower electrode in the 75kVрA spot welder. Mushroom growth of electrode cap tips is another threat to weld surfaces as it reduces the process resistances during welding. In this experiment, the mushroom growth is seemed to be higher on upper side electrode than the lower side one. With increased diameter of electrode tip areas due to mushrooming effect, the weld geometries become odds which lead to inconsistency in its appearances and pave the way for expulsions. 21 Ref., 9 Figures.
 
Keywords: spot welding, electrode mushroom, electrode degrading, electrode deterioration
 
Received:                27.04.15
Published:               13.10.15
 
 
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