This paper proposes that laser cutting has potential as a viable alternative to stamping for mass manufacture of thin steel components such as stator and rotor components in the electric automotive sector. Current laser cutting processes are much less efficient than stamping. However, laser cutting is much more flexible and is used for small batches and one-off production. This paper assesses the potential of performing laser cutting operations of multiple sheets or layers simultaneously. This method is referred to herein as polystromata cutting. A numerical model is used to assess the manufacturing performance of stamping, traditional laser cutting and polystromata laser cutting. Polystromata laser cutting is shown to be capable of producing parts at 37% less cost than stamping. However, polystromata remains slower than stamping, taking 79% more time to produce each stator stack. Through this research it has been identified that optimisation of polystromata processes is more complex and performance efficiency varies wildly dependent on manufacturing set-up. This work aims to provide a best practice optimisation methodology for polystromata laser cutting by assessing results using different manufacturing objectives.

With the move away from fossil fuels, the importance of electric machines is increasing. This is particularly the case within major engineering sectors such as the automotive industry. There is therefore a need to further develop processes which will allow for the diverse range of machining operations and large volume manufacture which will be required to overcome the inherent challenges in making this transition. Several critical components of an electric machine, such as the rotor and the stator, are made from electrical grade steel. This is a steel where the composition and processing acts to optimise the magnetic and other properties for the application. The steel is processed as thin sheet laminations and then stacked, to reduce the losses which occur within it due to the generation of eddy currents. The laminations need to be cut to shape, in an operation currently carried out most frequently by stamping from a sheet, but which could be done with greater flexibility by laser cutting (due, for example, to the absence of tooling). In laser cutting the possibility exists to perform cutting operations using what we call here a polystromata method, where several sheets are stacked and then cut simultaneously, increasing the efficiency of the operation. To date there have been few reports on this type of laser cutting process, and none that provide detail on the effect that the number of layers in a cutting stack has on critical parameters, such as the edge quality post cutting and the magnetic performance of the sheets. In this work we perform an experimental study of the process and report data in these measures, quantifying the decrease in performance as the stack increases in number of sheets.