Experimental study on the effects of feed rate and tool geometries on tool wear in diamond cutting of sinusoidal microstructured surfaces

Tool wear in diamond cutting of sinusoidal microstructured surfaces with a fast tool servo (FTS) may be quite different from that in the conventional diamond turning process, as the depth of cut changes periodically along the contour of the cutting surface and diamond tools with a sharp point tip are used. According to a theoretical analysis of the machining of sinusoidal surfaces, feed rate is a key cutting parameter affecting tool wear. In the current paper, a series of controlled cutting tests of LY12 aluminium alloy with different feed rates was executed on a two-axis bench-type ultra-precision turning machine equipped with an FTS device. The machined surface quality and dynamic cutting forces were measured and analysed. Tool wear patterns were investigated for various feed rates. It is essential to discuss the cutting stress borne by the diamond tool in the cutting of sinusoidal surfaces, since transformation of diamond to graphite induced by high pressure has been proved in previous works. The maximum normal stress acting on the rake face was deduced from measured dynamic cutting forces. Micro-Raman spectroscopy was adopted for analysing materials on tool tips. The experimental results showed that graphite appeared at the tool tip for some feed rates in the cutting of sinusoidal surfaces. The effects of tool geometry on tool wear are also shown.