THE EFFECTS OF ASPECT RATIO, GEOMETRY AND SCALE ON LINEAR FRICTION WELDING PARAMETERS WHEN WELDING 7000 SERIES ALUMINIUM

This presentation will discuss the data extracted from recent linear friction welds performed on the MTI LF35-75 linear friction welding machine using a 7000 series Aluminium. The research program objective was to quantify the effect that variations in the weld interface size and geometry had on the application of energy per unit area (friction power density) during the steady state phase of the weld cycle.

During this research program, two experiments were conducted where firstly, the weld interface aspect ratio in respect to the direction of oscillation was progressively increased while the weld interface area remained the same. In the second experiment, the cross-sectional area of the weld interface was progressively increased while the aspect ratio of the weld remained the same. Consistent weld parameters for velocity (amplitude and frequency) and specific load were maintained for both experiments.

The results of the above experiments have led to a fundamental rethinking of how the linear friction welding process is applied to 7000 series Aluminium component geometry/applications and may apply to other materials. This includes how parameters are calculated to compensate for the variation in friction power density across the weld interface as a result of changes in interface scale and aspect ratio.

While it has been established that Aluminium alloys used in the construction of modern commercial and military aircraft are more susceptible to variations in post weld performance as a result of changes in weld interface characteristics, the same behaviour has been observed in other materials such as Titanium and steels. This renders a “one size fits all” static parameter set for velocity and specific load questionable when applied to variations of geometry and scale.

The presentation will also provide an update on the most recent developments in Low Force Friction Welding.