The impending onset of electrified motor vehicles is setting new challenges for the automotive supply chain – and in particular, cutting tool manufacturers.

Mapal already offers a wide range of innovative machining solutions for manufacturing individual parts and components in electric vehicles. However, the challenge is an ongoing one that Mapal is continuing to meet.

High precision for large diameters using ultralight tools

One of the core challenges in electrified automotive powertrains is the high-precision machining of the main bore in the stator housing. Presenting a challenge for the tool and machine, all other steps in the production of the stator housing can be carried out on machines with a HSK A63 spindle configuration. However, in most instances the main stator bore requires machining with HSK A100 spindle. This is down to two factors: firstly, the high cutting torque requirements of up to 500Nm; and secondly, the maximum permissible tool weight and tilting moment.

Cost-effective manufacturing with short cycle-times calls for a solution whereby complete machining can be carried out on a single machine with small spindle connections. This is because these machines are characterised by their high spindle speeds, lower investment and operating costs, as well as lower energy consumption. In order to meet these demands, Mapal has developed a fine boring tool with an ultra-light design. The low weight of around 10kg meets the precondition for use on machines with smaller spindles. In addition to the weight reduction, Mapal has also optimised the cooling channels, introducing a special back-flushing system that ensures a far more effective removal of the chips. This prevents chips from scratching the machined surface.

Chatter-free machining of complex, thin-walled battery housings

Mapal offers the necessary tools with the optimum strategy for the different variants of the battery housing. It is here that polycrystalline diamond (PCD) is applied as a cutting material and minimum quantity lubrication (MQL) technology is introduced for maximum cost-effectiveness. Different milling technologies are employed to reduce the cutting forces and this depends upon the required stock removal, machining application and component.

The SPM milling cutter from Mapal is ideally suited to this application. Thanks to its high positive cutting-edge geometry and its optimised chip flutes, the cutting force is reduced by up to 15% compared with conventional milling cutters. If deep pockets are to be machined, Mapal employs special PCD milling cutters whose cutting edges are arranged with both positive and negative axis angle. In combination with the trochoidal milling strategy, the cutting force is kept very low during the machining operation.

Spiral forms with tolerances in the micron range

Aside from the drive and the energy storage systems being affected by the electrification of the modern vehicle, many auxiliary units and peripheral parts are also impacted by this relentless vehicle development. One example is the electric refrigerant compressor. At the heart of an electric refrigerant compressor are two nested aluminium spirals, the scroll stator and scroll rotor. The efficiency of the electric refrigerant compressor depends essentially on how precisely these parts are manufactured.

The demands on form and positional tolerances lie in the range of a few microns. A particular challenge here is the machining of the “screw”. A defined rectangularity of less than 0.04mm and a surface roughness (Rz) in the single-digit micron range are essential. Despite these demands, the thin walls and the depth of the part, finishing has to be carried out in a single pass.

Mapal has developed an SPM milling cutter with a finishing geometry and highly positive rake angle for this application. It ensures low-vibration cutting and has an additional chamfer on the diameter. It can perform the machining of base, wall and chamfer in a single step. As a result, the close tolerances for rectangularity and surface finish can be reliably achieved.