KS Huayu AluTech GmbH, a venture between Germany's Rheinmetall Automotive and China’s Huayu Automotive Systems, has developed a casting process that will be implemented at a new facility in Guangde, which is well-suited for fabricating complex engine block geometries and electric motor housings.

Engineers merged various casting processes to deliver high-quality, highly robust engine Source: Rheinmetall Automotive blocks that can be cast in short cycle times. The new sand casting solution is currently being used for a four-cylinder in-line engine with cast-over gray cast iron liners. The liners are cast over a few millimeters toward the cylinder head to avoid the milling tool negotiating a variety of materials during the subsequent machining process. Such a design would not be viable in conventional low-pressure permanent-mold casting.

The exacting tolerances of the positioning of the liners in the sand proved to be a major challenge. The liners must be heated in the fully assembled core package after they have been centered exactly between 22 sand cores of the package when cold.

Chill castings are likewise required in the area of the bearing bulkhead most stressed during engine operation. Since cooling is not active as in permanent-mold casting, the required heat extraction must be controlled by the mass of the chill castings. In this way, desired material tensile and yield strength properties are achieved with increased elongation.

The process provides maximum design flexibility with undercut geometries and all shapes of channels. In addition, less material is used and weight savings of 3% to 5% can be achieved. Due to the extremely low heat conduction of sand, low wall thicknesses can be obtained with the same filling speed and melt temperature compared to permanent-mold casting. Instead of a cycle time of up to eight minutes as with low-pressure permanent-mold casting, the new process requires a quarter of this time.