Reduction of Burr Formation for Conventional Shear Cutting of Boron-alloyed Sheets through Focused Heat Treatment

Conventional shear cutting is the most commonly used manufacturing process in sheet metal working. Due to its good automation capacity it is high productive and therefore it has a significant economic importance. However, the occurence of burr is still a remaining issue of the conventional shear cutting process. The burr has to be removed as they pose a high risk for functional and ergonomic aspects. Deburring requires additional processing steps in the production line, which are expensive and time-consuming. In the case of automotive industry components, the removal costs make up 15 % to 20 % of production costs. When it comes to precision components, such as engine parts, the cost equals even up to 30 %. Thus, it is worthwhile to aim for the avoidance or at least the reduction of burr formation. In this work, different heat treatment methods were applied to 4 mm thick 22MnB5 sheets, in order to increase the strength of the material and thereby reduce burr formation. For this purpose, the heat treatment methods case hardening, flame hardening, and plasma nitriding were studied. After punching the hardened sheets, the characteristic cutting surfaces were determined by tactile measuring. The results of the different heat treatment methods were compared regarding the resulting burr and evaluated by means of Vickers hardness measurements and microstructural analysis.