Tungsten carbide Cutter Tips, also known as tungsten carbide coal Cutter Tips, are a cutting tool for coal mining machines and other construction machinery composed of tungsten carbide parts brazed with structural steel, with excellent thermo mechanical and chemical properties, mainly in terms of high hardness, high strength, good anti-wear, good heat resistance and excellent corrosion resistance.
During the coal bed mining process, the carbide cutter tips cut in an impact rotary mode and are therefore subjected to both high pressure stresses and shear bending stresses, which are cyclical and alternating. During the excavation process, the cutter tips also experience intense friction with the coal seam, which generates frictional heat. In addition, throughout the excavation process, the cutter tips may show various mechanical behaviors such as local yielding, contact fatigue, corrosion and fracture.
It is worth to be mentioned that in the process of coal bed excavation, the carbide cutter bit often crumbles due to the effect of impact load. This is mainly due to the uncertainty of the coal bed geology which leads to the inability of the cutter head to make complete contact with the coal bed, and the coal bed also contains gangue(waste rock) and other impurities, which is one of the reasons for the poor contact between the cutter head and the coal bed. Under the action of alternating load, the cutter bit is easy to have crack of impact fatigue and thermal fatigue and thus damaged.
In order to improve the failure of carbide cutter tips, we can adjust the grain size, composition and formula of tungsten carbide to improve its performance. Specifically, the cobalt content in the carbide can be increased appropriately (8%~13%) ，as cobalt can effectively improve the thermal fatigue resistance, plasticity and relaxation stress of the carbide; the suitable grain size and ratio of tungsten carbide (WC) powder can be selected. Generally speaking, the smaller the grain size of WC powder is, the larger the surface area is, which will improve the average free range of cobalt, which is equivalent to the increased cobalt content and is beneficial to improve the toughness of the carbide. In addition, in order to enhance the effect of cobalt phase, appropriate heat treatment can be applied to the carbide cutter tips.
