Abstract:

In the present study, hole drilling was performed by using the friction drilling method on AZ31B Mg alloy at a constant speed and feed rate under minimum quantity lubrication (MQL) environment. In the experiments, the effects of MQL application times on axial force, temperature, surface roughness, bushing profile, and thread pull-out strength was investigated. The test results revealed that MQL applications reduced the temperature in the process region and caused an increase in axial force. During the friction drilling process, it was observed that the axial forces occurred in 7 different zones while the temperature consisted of 2 different zones.The increasing MQL application times were positively affected to hole surface quality and reduced the formation of the material adhesion on the hole wall. Three different bushing profiles were obtained as a parabola, linear, and binary linear depending on the generated heat exchange because of the MQL application times. The test results revealed that the hole surface quality has no effect on the thread pull-out strength, and the combination of the bushing profile and bushing length was decisive. The lowest thread pull-out strength was measured under dry drilling conditions, while the highest thread pull-out strength achieved by 10 seconds of MQL application. 

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