Hot metal stamping allows weight reduction in automotive industry, according to last studies. Warm and hot forming is the main topic of the Forming Technology Forum (FTF 2014) settled in the University of Twente campus, Holland. One of the up-and-coming technologies which will be discussed at the conference is the hot stamping of special boron-alloyed steels, which circumvents the fact that high-strength steels generally have poor formability properties. The University of Twente is focusing on this new technology working for Volkswagen to dicrease cars weight.
Hot stamping entails heating sheet metal to a temperature of 900°C, after which it is pressed into a cooled die. During forming, the metal is still hot and easily formable, but immediately afterwards, the metal is quenched as it remains in the cold die. As a result of this rapid cooling, a hard martensitic microstructure is created which lends the product its remarkable strength. The technology is highly suitable for high production speeds. If stronger types of steel are used, thinner sheets can be opted for. By applying this technology, the automotive industry is capable of accomplishing great weight reduction. Several car manufacturers, such as Volvo Cars, Volkswagen AG, Audi and Opel which were present at the FTF 2014.
Other aspects of warm metal forming will also be discussed. The properties of the work piece used are highly dependent on the temperature the work piece is exposed to. In consequence, the work piece can take on a completely different microstructure influencing the strength of the final product. The constant friction between the tool and the work piece also depends on temperature and can change drastically depending on the type of lubricant used. Forming processes and temperature greatly influence each other. Therefore, simulations are always made up of wholly linked thermo-mechanical calculations.
“The quality of the products highly depends on the exact degree and order of forming and on the temperature during production”, explains Professor Ton van den Boogaard. Van den Boogaard organises the FTF 2014 event on behalf of the Nonlinear Solid Mechanics department. “Simulating the process is of great importance to reach optimum process conditions. The research fits in with the activities of the Faculty of Engineering Technology’s department of Mechanics of Solids, Surfaces and Systems, which is conducting research for the manufacturing industry.”