Wear of cemented tungsten carbide (WC) router cutters during oak wood milling

摘要

The WC-based (WC-Co) hard alloys were patented in 1923 in England and in the USA. They were started to be used for manufacture of blades of various cutting tools [1], Different tests of wear of cutting tools revealed that the cutting edges made of WC are more resistant to wear, while compared with blades made from stellites, high-speed steel, high-alloyed or alloyed tool steel [2], The diamond cutting edge in average four times harder than the cutting edge made of WC, but four times weaker in case of bending strenght, moreover, it is characterized by low toughness [3], The hardmetal is the alloy of various metal carbides - tungsten (W), titanium (Ti) and/or vanadium (V) bonded with elastic binder. WC was used in wood processing industry for the first time in 1929 [3], Usually the hardmetal used in wood industry consists of 80 - 90% W and 20-10 % cobalt (Co)[3].The cutting edge of tools used in composite wood processing contains approx. 2.5 - 4% Co and are the most resistant to wear. These tools are recommended for processing of wood based materials with homogeneous structure, which induce abrasive wear[4].When the wood composite materials are processed, the cutting edge of tools is working more intensively than in case of processing solid wood [1-4]. More intensive wear of tools' cutting edge appear when tools are used to process wet wood or wood based materials [3,4], During cutting thermal, electric, and chemical factors affects the wear of WC tools' blades [5-11 ]. The wear of cutting edge (change in the micro-geometry of the cutting edge) is the main factor that restricts the efficiency of tools [4, 6, 12]. According to the tests, the wear of the tool's cutting edge depends on the cutting length or processing duration, tool's material, cutting mode, and main characteristics of the processed solid wood or wood composites [3,4, 13, 14], The wear of the tool's cutting edge might be divided into three stages: initial, monotonic and emergency [5, 6, 13]. The wear of the cutting edge leads to continuous decreasing of quality of the processed surfaces [15-17]. The surface unevenness is formed due to the peculiarities of mechanical processing. The size of unevenness depends on the processing mode, microgeometry of the tool blade cutting edge (nose), cutting direction, and of the cutting and feed speeds [18-20].