Gears manufactured by blanking can be found in many different products like hammer drills or automobiles. Here, only the functional surface, the clean shear, can be used to transmit torque. Therefore, parts in serial production demand a high amount of clean shear, so the required torque can be transmitted with a minimal thickness and part weight. To achieve this, these parts are usually manufactured by fineblanking or related Near-Net-Shape Blanking processes (NNSBPs). Furthermore, the gears are subjected to cyclic loading which can, especially in the highly stressed tooth root, lead to tooth breakage. The effect of different process variants and process parameters on the residual stresses and the fatigue behavior under a pulsating bending load has not been investigated yet. Due to the potential of endurance improvement of blanked gears, this topic is addressed in this paper. To accomplish this, C-shaped profiles are manufactured by five different Near-Net-Shape blanking processes. The investigated processes are fineblanking, precision blanking with and without blank holder, and blanking with a small die clearance with and without a v-ring. The sheet metal material, S355MC (material number 1.0976) with a thickness of 6 mm, is first subjected to a stress relief heat treatment to minimize residual stresses induced by the specimen preparation and to ensure a defined initial residual stress state. After blanking, the residual stresses of the parts are measured. Finally, fatigue strength tests are carried out under a pulsating bending load on the C-shaped profiles with shear-cut edges. The results show that the residual stress state, as well as the part’s fatigue behavior are strongly influenced by the chosen blanking process.

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The longitudinal and transverse beams of trucks are manufactured with a large number of holes to fasten brackets for springs, fuel tanks, batteries etc. The quality of the holes, which is particularly influenced by the manufacturing process, has a major influence on the fatigue strength of the beams and thus the service lifetime of the vehicle. In most cases, the holes are produced using the highly economical shear cutting process. Previous investigations have shown that the fatigue strength of thin sheets can be increased by adjusting the shearing parameters and using a two-stage shear cutting process. This paper discusses the difference between one- and two-stage shear cutting on the hole quality of components made of S500MC (1.0984, thickness 8 mm) and its resulting fatigue strength. The hole quality is characterized by the geometry of the shear cut surface, its roughness, microstructure, and microhardness. It was shown that the two-stage shear cutting process allows producing holes of better quality than the ones manufactured by a one-stage shear cutting process. Furthermore, this resulted in an improved fatigue behavior.

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Especially in the automotive sector, high-strength sheet materials are processed in the manufacturing industry. These steels often show a pronounced sensitivity to edge cracks. Because of this, many edge crack testing methods for a wide variety of stress conditions have been developed to describe the edge crack sensitivity of a material. Only the hole expansion test according to ISO 16630 has been standardized. However, the standardization has some gaps in the process description, which has resulted in test modifications. Another disadvantage is the dependence of the results on the machine operator. In the past, the influence of the shear cutting parameters die clearance, cutting edge geometry, and type of cutting line on the edge crack sensitivity was only calculated for undeformed sheet materials. Not only are shear cutting operations carried out on undeformed sheet blanks in the context of the manufacturing of sheet metal components, but more and more pre-formed sheets are mechanically separated and subsequently further formed. Therefore, it is essential to consider the influence of the type and amount of pre-forming introduced on the sensitivity of a material to edge cracks. The discrete types of pre-forming, uniaxial tension, plane strain, and equi-biaxial stretch forming were introduced to sheet metal blanks using dual-phase steel. The Edge-Fracture-Tensile-Test was used to identify the residual formability of the undeformed and pre-formed specimens. The Edge-Crack-Sensitivity-Factor$${K}_{\mathrm{ec}}$$ K ec , which can be used to predict edge cracks in a finite element forming simulation, was determined from the recorded major strains for selected parameter configurations.