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Air Springs: How to Reduce Manufacturing Costs with Tungsten Carbide


The production of air springs becomes more cost-effective thanks to Argos Surface Technologies.
Today, nearly all heavy vehicles are equipped with front air springs, which have replaced the common leaf springs. Air springs increase comfort for the driver and passengers while reducing stress on the asphalt, which is very important for heavy vehicles in particular.

How air springs work

The essential part of an air spring is the bellows, which is often configured as a so-called folding bellows. At first glance, it looks like a simple rubber cylinder, although it is actually a high-tech product made of elastomers. The base material, rubber, must support high loads for long periods of time without sagging, so it must be resistant to aging and environmental effects such as chemical agents, temperatures and UV rays. The layers of fabric within the rubber affect the behaviour of the spring and its stability and must be adapted to the various fields of application through a targeted choice of materials and correct configuration.

When manufacturing heavy-duty vehicle bellows, rubber hoses and fabric layers are placed on moulds for vulcanization under high temperature and pressure. The moulds are made of hardened steel, but due to the high temperatures and pressures, they wear down in a relatively short period of time. Furthermore, their production is expensive, a problem faced by anyone using moulds to produce air springs.

The Argos solution

As part of a pilot project, we regenerated 200 moulds for a large auto parts supplier.
The moulds were coated with tungsten carbide, a material second only to diamond in terms of hardness. It is also used for cutting reversible knives or for high-load deformation tools.

To make the coating, tungsten carbide is applied to the mould via flame spraying. In this technique, a tungsten carbide wire is expelled from a gun and melted at the tip with a 2000-3000°C flame. The soft material is thus applied to the mould.

At this stage, the material has a temperature of only 150°C, because it cools down very quickly once the flame is turned off.
However, the resulting coating is relatively rough, like a nail file. Since the moulds must have a perfectly smooth surface, an external company took care of the last processing step, grinding.

With a wear-resistant coating based on tungsten carbide, the durability of these expensive moulds increases dramatically, thereby reducing the production costs of air springs.