Eberspächer banks on tailored strips

The lighter the vehicle, the lower its level of CO2 emissions. Given the automotive world's increased attention on light-weight design, exhaust specialist Eberspächer is counting on tailored strips (customised steel strips) and on titanium. In the construction of silencers, weight savings of up to 26 percent can be achieved with tailored strips, and with titanium even up to 40 percent.

These are now being used in the rear silencer of the new BMW 730d, thereby contributing to the environmental soundness of this premium model. The company is, for the first time, supplying a rear silencer manufactured with tailored strips tech for a production vehicle. In doing so, the automotive supplier is one of the first suppliers to offer its customers environmentally friendly, weight reducing exhaust systems with tailored strips made of stainless steel.

While driving, individual parts of the BMW rear silencer are subject to differing loads. Up to now, however, stainless steel with a constant wall thickness was used. It was custom-designed to withstand the highest mechanical load, the highest temperature and the strongest corrosion attack that this component is exposed to. Thanks to the innovative steel strips, which are joined by laser welding, material strength and properties of the outside shells can be matched and used exactly to local requirements – in a variety of thicknesses, quality or strength. Even during production, tailored strips have a number of advantages: They improve the malleability of the material in critical areas, thereby placing less stress on the tools than in the past. The tailored steel strips were developed by Thyssen Krupp.

Compared to a conventional silencer (with a consistent wall thickness of 1.2 millimetres), it is possible to realise wall thicknesses of 0.7 or 1.2mm. This in turn helps provide a weight saving of over 700 grams in the rear silencer of the new BMW 730d. What’s more, manufacturing front and middle silencers, pipes or manifolds with tailored strips even reduces the weight of the exhaust system in a medium-class vehicle by up to three kilograms.