New energy vehicle motor shell, hybrid gearbox shell, battery shell casting process

The development of electric vehicles requires a large number of different new components, which, due to their complexity, are prioritized for design as castings. First and foremost involved are motor housings, battery housings and gas distribution gear covers. Due to the high power density and the increasing integration of functions - sometimes with complex internal cooling units - these components require an extremely high level of production. 

Two-piece motor housings can be produced by die-casting, so special attention must be paid to the quality of the sealing surfaces during development. As an alternative, one-piece solutions are also being promoted for production through the use of complexly shaped inserts. The choice between the low-pressure casting process and the CPS casting process depends on the product complexity and the required throughput. As the integration of electric drives increases, the CPS process offers many attractive possibilities due to its diverse design options. 

Die casting process for two-piece motor housings 

The latest designs for the BMWi3/i8 motor housings are designed for die-cast production. The demands placed on the castings are very stringent. Aluminum-silicon casting alloys with low iron and copper content are used in order to meet component strength and corrosion resistance specifications. Liquid media are used for cooling of the housing. Because so far there is no large-scale mass production applicable production technology that can process with inverted buckle inserts, in order to realize the carefully designed cooling structure around the motor, the shell is designed into two parts (Fig. 1), so as to be suitable for production by die-casting process. Various currently published salt core machining techniques are not able to meet the extremely high demands placed on the inserts inside the motor housing.