Abstract

Although bushing height and wall thickness are crucial issues, cracks and petal formation on bushings affect these outcomes adversely in thermal friction drilling operations. Therefore, in this paper, bushing shapes were investigated both in traditional and mould supported thermal friction drilling of A7075-T651 aluminum alloy, 4 mm in thickness, at 2000 rpm spindle speed and 25 mm/min feed rate. The proportion of the volume cavities (VBC) of the moulds to the volume of the total evacuated material (VE) selected between 16 % and 32 %. Moreover, the gap sizes between the tool and tool proceeding cavity (CDT) were selected at 0.2 mm, 0.3 mm, and 0.4 mm. In conclusion cracks and petal formation were substantially eliminated, bushing height and wall thickness values were able to select, depending on requirements, also homogenous bushing wall thickness for threading, in moulds supporting thermal friction drilling operations.

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