item research: High-speed impact cutting

3. Feb 2016 item Redaktion

New approaches for the chipless processing of series components.

The specialist mechanical engineering market continues to grow steadily – and the wants and needs of customers, partners and suppliers are also changing. Companies need to tackle these challenges head on and ensure they never stand still when it comes to innovation. We have taken this approach from the start and are determined to continue improving the MB Building Kit System, which is why we are always working on research projects. One such project is a collaboration with the Fraunhofer Institute for Machine Tools and Forming Technology (IWU) in Chemnitz, Germany.

High-speed impact cutting instead of chip forming

The aim of the collaboration was to find a replacement for chip-forming processes to use on series components. The ideal solution was found to be high-speed impact cutting (HSIC) at a speed of 1 ms-1. During the project, the researchers experimented with creating a hole in a steel profile. A previous study had already shown that the process would both be possible and result in high-quality components. However, quantitative studies revealed a different picture: For example, after just a few cutting procedures, cutting punches with PVD-coated and polished surfaces exhibited pronounced adhesive wear, which lead to abrasion and ultimately the breakage of the test tools.

As a result, damage was observed to the cutting edge even before 800 cuts had been performed. Careful scientific investigations into high-speed impact cutting – based on an idea from item engineers – helped resolve this issue. The investigations produced the following conclusions: When the punch penetrates into the sheet material by more than 10 to 50 percent of the sheet thickness, the cut-out section is completely separated from the surrounding area due to the concentration of energy and the “adiabatic effect”, which produces shear bands on a micro scale.

Using HSIC to combat wear

Two conclusions were drawn from this research work. To avoid damage such as this, the shape must first be incised until complete material separation is achieved and then, in a second stage, the separated contour must be ejected by a second punch with a narrower contour. All subsequent investigations were based on this approach and all were successful. Wear was greatly reduced. Despite carrying out several thousand cutting operations, the punch (standard punch, not coated or polished) exhibited only the normal traces of wear associated with conventional processes. The process, which is now patent protected, was also proven to be suitable for use in series production.

The research findings were then used in a collaboration with a renowned plant manufacturer to develop a drive module based on HSIC. This module is designed to ensure the process can be integrated into conventional die cutting technology and state-of-the-art production plants. Our engineers and the specialists from the IWU are currently testing whether this method can also be adopted in other circumstances and for other requirements. It is exciting to think what impact this new technique could have.