Experimental research of picosecond laser based edge preparation of cutting tools

Abstract

In this study, using ultrafast lasers of 10 ps pulse duration as a precise and efficient method for cutting edge preparation is researched. Cutting edge preparation is an important step within cutting tool manufacturing, while unprepared sharp cutting edges show low stability, which leads to tool failure by high mechanical and thermal loads during the turning processes [C. F. Wyen, W. Knapp, and K. Wegener, Int. J. Adv. Manuf. Technol. 59, 899–914 (2012)]. The rounding of the edges requires laser manufacturing with high precision and minimal heat accumulation; thus, ultrafast lasers have been used in other investigations [M. Stolze, T. Herrmann, and J. L'huillier, Proceedings of ICALEO, Orlando, USA, ICALEO, Orlando, FL, October 23–27 (J. Laser Applications, Orlando, 2011)]. In the authors’ study, the effects of edge roundness on the cutting tool material WC-Co alloy were experimentally investigated. Samples with three different grain sizes and percentages of cobalt were used in the authors’ study. The experiments were carried out on the free surfaces of cutting tools under varying laser parameters including laser wavelength, fluence, and spatial pulse overlap (PO) in air or by using process gases (helium and oxygen). The impact of all these different laser parameters on the various material sorts was investigated. As a result, no reduction of the hardness of the original material was observed that could have a negative effect on the cutting ability of laser rounded cutting tools. By analyzing the surface quality of the ablated areas processed with different laser parameters mentioned above, a surface roughness below Ra = 0,15 μm was generated by using optimal fluence at both wavelengths of 1064 nm (IR) and 532 nm (VIS) and using a 70% spatial PO. Thus, a well-defined cutting edge with radii of 20–40 μm could be prepared.