Multi-piece forging of aluminium alloys for automotive wheels

Multi-piece forging of aluminium alloys for automotive wheels

One-piece forging requires the cutting of a large number of redundant dimensions, which can be costly and time-consuming. In order to achieve mechanical properties comparable to those of one-piece forged wheels, while reducing machining time and costs, some automotive wheel brands have adopted the multi-piece forging process. Multi-piece forged wheels are available in two or three pieces, the former consisting of spokes and rim and the latter consisting of a front piece, rear piece and spokes. The three-piece car wheel aluminium alloy is also sealed after assembly to ensure air tightness due to the joints. There are currently two main ways of connecting the spokes of multi-piece forged wheels to the rim: one is a special bolt/nut connection; the other is welding. Although the cost of a multi-piece forged wheel is lower than that of a one-piece forged wheel, it is not as light in weight.

Aluminium alloy extrusion casting for automotive wheels

The forging process facilitates the machining of intricately shaped parts, and the forging process gives the parts better mechanical properties. In this process, liquid metal is poured into an open container and subsequently pressed into a mould by a high-pressure punch, which is filled, shaped and cooled to crystallisation. This processing method effectively ensures that the wheel is internally dense and that the mechanical properties are close to those of a one-piece forged automotive wheel aluminium alloy, while requiring less residual material to be cut. A significant proportion of wheels in Japan already use this processing method, and due to the high degree of intelligence, many companies are using extrusion casting as one of the production directions for automotive wheels.