Experimental Evaluation of the Feasibility and Reproducibility of a Novel Multi-step Forming Process for Cu-OFE Micro Gear Manufacturing Compared to Macro-scale Forming

Abstract

The increasing miniaturization of technical systems leads to a rising demand for micro components. Miniaturized drive systems with geared micro parts or micro gears are applied in various industries. Due to the demand for high production volumes, productive and resource-efficient fabrication is of major importance. Compared to industrially applied manufacturing methods like cutting and metal powder injection, cold forming provides technological, economic and ecological potential for the mass production of micro gears. It enables high productivity and advantageous mechanical properties of the gears. In the macroscopic size range, forming processes are well established in series production of gears. However, in micro-scale, according to the current state of the art, cold forming of modules m<0.2mm is not possible due to size effects, high tool loads and handling problems. Within this contribution, a multi-stage forming process for the fabrication of micro gears with a module of m=0.1mm is introduced and compared with a conventional forming process on macro-scale with a module of m=1.0mm. The use of coil material provides potential for easy handling of the micro parts in a progressive die for the potential application in a high-speed press. In addition, the multi-stage forming achieves a grain alignment, which enhances the formation of the micro gear profile. Based on the comparison between micro- and macro-scale, the performance of the micro process is analyzed with regard to deviations of process force as well as gear quality and possible size effects are identified. The results prove the feasibility of the process chain and the achievement of equivalent part quality and reproducibility compared to macro-scale forming.