Burr Formation in Microstructuring Processes

Due to high form accuracy and flexibility concerning the structure geometry, cutting is predestined to produce structures in the micron range. At the Institute of Production Engineering and Machine Tools (IFW), a fly-cutting process is used for manufacturing microstructures. These structures are used to improve the tribological performance of thermo mechanically highly stressed surfaces. The structures thus produced are able to hold some lubricant and can also be used to increase the hydrodynamic pressure built up between the friction partners already at low sliding speeds.

When machining the small structures, material of the compression zone in front of the cutting edge is squeezed in the direction of the free lateral surface areas and causes burrs. For an unrestricted functionality of the structured surface and for avoiding down-stream finishing processes, these burrs have to be minimized. In this paper, the basic relationship between the cutting edge geometry and the burr formation in machining ductile materials with depths of cut below 50 μm will be investigated. In particular, the influences of the material, the tool cutting edge radius and the tool cutting edge angle on the cutting forces and burr formation will be described. Based on these correlations, a special cutting edge microgeometry will be developed which prevents material flow in the direction of the lateral free surface areas.