Design and testing of an instrumented experimental rig for autogenous friction stir spot welding

Abstract

This report presents the design and testing of an experimental rig, dedicated for testing lightweight alloys in autogenous friction stir spot welding. The rig is capable of accurate measurement of torque and downforce, simultaneously with temperature at several locations in the weld. The objective is to enable investigation of the high temperature deformation behaviour of different materials over a range of friction welding conditions in a controlled setting.

An extensive range of trials explored empirically the sensitivity of the key outputs to variation in the process variables: plunge depth, plunge rate, dwell time, rotational speed, sample thickness and thermocouple arrangement. Four aluminium alloys and one magnesium alloy were tested: wrought Al 6082-T6, 2024-T3, 7449-T3 and cast AlSi10Mg, and cast Mg AM50. The recorded torque showed little scatter and no idling value, improving the quality of the measurements compared to the in-built machine data acquisition system, and allowing for future use with other non-instrumented FSSW machines.