Internal and External Machining of the Stator Housing

In the pot-shaped version of the motor housing, the stator carrier housing is inserted into the main housing as an intermediate housing. Typical diameters for the thin-walled aluminium part are between 200 and 240 mm on the inside and between 240 and 260 mm externally. Concentricity of the various bearing and mounting diameters is critical to the performance of the electric motor, which requires very precise machining within tight tolerances.

The first of three steps for machining the stator bore is pre-machining with a boring tool. The blank has casting bevels that result in cutting depths of up to 6 mm to be removed. For this purpose, special indexable inserts with a supporting arc shaped land are used to avoid vibrations. This also ensures that small chips are produced, which can be easily removed. In the subsequent semi-finish machining, the complex contour path of the electric motor housing is pre-machined in such a way that the complete fine machining with chamfers and radial transitions can be produced to μm accuracy with the finishing fine boring tool. The tools are individually designed for the respective customer depending on the stock situation, machinery and clamping setup. Different steps in the housing are taken into account with the cutting edge positions of the tools, as are cast-in or pressedin steel bushings for bearings. While the majority of the workpiece is machined with PCD, carbide cutting edges are used for the steel area.