Tool-life criteria and wear behavior of single-edge ultra-small micro end mills

Abstract

Prototypes of microfluidic systems are often produced via micro milling, and the thermoplastic commonly used as substrate is polymethyl methacrylate (PMMA). A key challenge when manufacturing those systems is the confection of the micro tools, whose geometric design is limited by the current lack of knowledge about the process itself, especially for applications requiring micro tools with diameters D ≤ 50 μm. In terms of productivity, the tool-life capability is restrained by the machining conditions and the finish quality. Typical requirements for the manufacture of microfluidic structures with ultra-small micro mills are structures with Ra < 60 nm on the groove bottom and a top burr overhang h0 < 3 μm. This paper studies the tool-life capability, including an analysis of the wear behavior of micro tools with diameters D ≤ 50 μm, providing the correlation between machining force signal, machining results (e.g. roughness or burr formation) as well as tool's characteristics before and after machining.