Material Selection for Cutting Tools
The main materials for cutting tools are high speed steel, tungsten carbide,CBN and cermets etc.The material for cutting tool must have the performances such as wear-resistance,anti-shocking.The cermets has high hardness ,but its transverse rupture strength and anti-shocking strength are low, which is unsuitable for heavy-turning with uneven allowance ,meanwhile the CBN is as same problem as cermets. However ,the tungsten carbide with low friction coefficiency which could reduce cutting temperature in process and improve high temperature resistant strength significantly, which is suitable for heavy and rough machining high hardness materials. The tungsten carbide is divided into WC-Co(YG),WC-TIC-Co(YT) and WC-TiC-NC-TaC-Co(YW) etc series.When machine steel materials,YG series tungsten carbide with good transverse rupture strength and toughness ,but its high temperature hardness and toughness is bad ,meanwhile the plastic-deformation is big in heavy-turning with serious friction coefficiency and high cutting temperature ,consequently ,the YG series tungsten carbides are rarely used in heavy-turning machining work .YT series tungsten carbide with high hardness ,wear resistance ,heat resistance,anti adhesion ,diffusion and oxidation performances are the main cutting tools materials for heavy-turning work, which are capable for machining steel., however,in the slow-speed turning process,the YT series tungsten carbide inserts would be flaked due to its bad toughness in unstable process ,especially machining some materials with high toughness ,the YT series tungsten carbides are unavailable to accommodate actual needs due to its short service life . Under this condition ,the selection for YW,fine or untra-fine tungsten carbide cutting tools is recommended The fine grain size tungsten carbide with good wear-resistance is much more suitable for machining chilled cast iron ,its working efficiency is 1 time than the YW series tungsten carbide .
The cutting speed for heavy-duty turning is increased significantly ,which is one of the keys to improve the productivity ,as well as the favorable factor to shorten producing cycle .With other cutting tools materials ,the process is finished by several steps ,each step with very small cutting depth ,however the cutting speed is improved dramatically by means of tungsten carbide .
