In machining aluminium alloys, here is what will help manufacturers reduce unit costs and achieve process reliability. Article by Walter AG.
A few years ago, chassis components made of aluminium were still reserved for the premium segment in the vehicle market. Steering knuckles, suspension arms and wheel carriers for medium-class and small cars were predominantly made of cast iron or forged steel. This has changed in the last few years.
Since then, significantly reducing the CO2 emissions of a vehicle has become a top priority in vehicle construction. One way to do this is reducing the vehicle weight. A reduction in weight of 100 kg means 0.3 l to 0.4 l less fuel consumption.
Even with electromobility as an alternative to the combustion engine, the weight of the vehicle is a key factor—the lighter the car, the higher the battery range. Materials like forged wrought aluminium alloys or ductile cast aluminium alloys with a low silicon content can therefore increasingly be found in all vehicle classes.
With the changeover to other materials, the challenges in machining also change. Machining aluminium alloys requires different machining strategies compared to existing materials in use, especially under the conditions of high cost pressure and strict machining quality and process reliability requirements. The machining tools used are an important factor here. Many automotive suppliers already count on machining specialist Walter AG for this.
“Aluminium alloys are the optimal material for the automotive industry. The alloys are light, with sufficiently high strength, and can be machined at speeds that are very different from those of traditional cast iron or steel materials. However, this does not mean that they are easy to machine. Above all, the long chips are a risk factor when it comes to a stable process. In addition, build-up on the cutting edge can quickly form on the cutting edges of the tools. It then soon becomes difficult to comply with the specified tolerances when it comes to the fit sizes and the surface quality. In this respect, users are dependent on the quality of the machining tool and the right technology,” says Fabian Hübner, Component and Project Manager for Transportation at Walter.
Creating Complex Bores
Above all, the integration of solid bores represents a technical and economic challenge in the production of chassis components made of aluminium alloys. While pre-forged recesses are often bored with larger bores, such as the wheel hub bore on the wheel carrier, smaller bores such as on the suspension arm are, in contrast, created in the solid material. The often high complexity of the contours to be drilled and the very strict requirements of the accuracy of the bore and of the surface quality also need to be considered.
Mostly, the smaller bores act as adaptors for plain bearings and dampers. This requires more than simply setting a bore. For example, defined end faces or chamfers must also be fitted, in order to allow you to fit bearing bushings or damping elements in the next production step. Consequently, up to five machining steps per bore quickly follow.
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