Cause cause of milling cutter tatty more complex, but substantially or basically can divide two kinds: (1) mechanical wear: The flexibility that machines the surface by face of the knife before cutting bits and cutting tool, workpiece is out of shape cause with the acuteness attrition between face of the knife after cutting tool wear away, call mechanical wear. It is when cutting temperature is not quite high, the mechanical abrade that by this kind attrition causes is cutting tool tatty main reason. (2) heat wears away: When cutting, the heat in metal cutting that because acuteness plasticity of the metal is out of shape,arises with attrition place, make the hardness of edge is reduced and lose what cutting function place causes to wear away, call heat to wear away. Besides afore-mentioned two kinds outside wearing away, still the following kinds wear away: Below high temperature high pressure, felt phenomenon can appear between cutting tool and workpiece material, material of one part cutting tool is cut bits is taken away, make cutting tool produces felt to wear away. Below higher temperature, the certain element in cutting tool material (wait like tungsten, cobaltic, titanium) will to workpiece material inner diffusion, make the chemical composition of surface layer of cutting tool cutting part is changed thereby, also reduced cutting tool intensity and wearability, make cutting tool generation diffuses wear away. To high-speed steel cutting tool, below higher cutting temperature, the metallographic organization of cutting tool surface layer can produce change, make hardness and wearability are reduced, will appear to change wear away. Every tooth of milling cutter is periodic discontinuous cutting, tooth arrives by light locomotive trip enter cutting, the metabolic range of temperature is very big, can say to enter cutting to get every time thermal shock. Hard alloy cutting tool, below thermal shock, bit interior can produce very great stress, cause craze, cause cutting tool hot tearing to wear away. Because milling cutter is discontinuous,undertake cutting, turning of cutting temperature unlike is so tall in that way, cause cutting tool tatty main reason is the mechanical wear that mechanical attrition causes commonly. CNC MillingCNC Machining