No abstract

Advanced materials, like nickel-based alloys, gain importance in turbomachinery manufacturing, where creating complex surfaces constitute a major challenge. However, milling strategies that provide high material removal rates at acceptable tooling costs demand optimized tool geometry and process parameter selection. In this paper, a description of circular milling is given, focusing on resulting engagement conditions. Regarding this, a test bench was designed to investigate the chip formation process in an analogy milling process. Furthermore, the methodology for the approach in the analogy process was developed. Results of a first test run in Inconel 718 verify the presented approach.

In this experimental study, the cutting performance of ball-end mills in high-speed dry-hard milling of powder metallurgical steels was investigated. The cutting performance of the milling tools was mainly evaluated in terms of cutting length, tool wear, and cutting forces. Two different types of hardened steels were machined, the cold working steel HS 4-2-4 PM (K490 Microclean/66 HRC) and the high speed steel HS 6-5-3 PM (S790 Microclean/64 HRC). The milling tests were performed at effective cutting speeds of 225, 300, and 400 m/min with a four fluted solid carbide ball-end mill ( = 6, TiAlN coating). It was observed that by means of analytically optimised chipping parameters and increased cutting speed, the tool life can be drastically enhanced. Further, in machining the harder material HS 4-2-4 PM, the tool life is up to three times in regard to the less harder material HS 6-5-3 PM. Thus, it can be assumed that not only the hardness of the material to be machined plays a vital role for the high-speed dry-hard cutting performance, but also the microstructure and thermal characteristics of the investigated powder metallurgical steels in their hardened state.