Advances in process modelling and monitoring at the University of Sheffield Advanced Manufacturing Research Centre with Boeing could open the way to rapidly developing machining strategies that cut the cost and improve the quality of aerospace components made from everything from titanium and nickel based superalloys to composites.

Reducing the time needed to make components by increasing material removal rates is one key way of cutting costs, but with the added risk of distortion and high machining induced tensile residual stresses resulting in increased scrap rates and reduced service life.

Making a component within specified distortion limits and with acceptable surface integrity has only been possible following extensive and expensive laboratory trials. Moreover, the introduction of newer, advanced aerospace materials has often forced the manufacturer to start the process from the beginning again.

Recent work at the AMRC aims to use simulation models to predict the behaviour of component material during machining process.

Tools like Finite Element Analysis are being combined with a range of advanced, non-destructive measurement techniques, including X-Ray Diffraction, Digital Image Correlation, Ultrasonic and Thermal Imaging to study and predict the effect of machining on the component distortion and surface integrity.

Research at the AMRC is also filling in gaps in generating the material data for high strain rates at elevated temperatures, to increase the accuracy of the finite element models developed.

"Simulation is increasingly becoming important, especially for tailoring the surface integrity of the machined component to acceptable limits," says Krunal Rana, from the AMRC's Process Modelling Group.

"All the more so if aerospace component manufacturers are interested in exploring the trends that are likely to emerge if they change a machining strategy and tooling, rather than seeking absolute values."

With the increasing use of composites, the AMRC is also developing advanced predictive models and measurement techniques to understand the effect of varying fibre orientations on surface delamination and tool wear when machining composites.

As simulation's capabilities increase, along with real time monitoring technologies, the prospect of achieving the ultimate vision of using feedback mechanisms to optimise machining strategies and adapt the machining process in real-time moves ever closer.