Causes of tool wear

1) Abrasive wear

There are often some extremely hard small particles in the processed material that can scratch grooves on the surface of the cutting tool, which is called abrasive sanding damage. Abrasive wear exists on all surfaces, with the front blade surface being the most obvious. Moreover, hemp material wear can occur at various cutting speeds, but for low-speed cutting, due to the lower cutting temperature, the wear caused by other reasons is not significant, so abrasive wear is the main reason. The lower the hardness of the cutting tool, the more severe the abrasive damage.

2) Cold welding wear

During cutting, there is significant pressure and strong friction between the workpiece, cutting, and the front and rear cutting surfaces, resulting in cold welding. Due to the relative motion between the friction pairs, cold welding will cause fracture and be carried away by one side, resulting in cold welding wear. Cold welding wear is generally more severe at moderate cutting speeds. 

According to experiments, brittle metals have stronger resistance to cold welding than plastic metals; Multiphase metals are smaller than unidirectional metals; Metal compounds have a smaller tendency towards cold welding than elemental compounds; The B group elements in the periodic table of chemical elements have a low tendency to cold weld with iron. Cold welding is more severe during low-speed cutting of high-speed steel and hard alloy.

3) Diffusion wear

In the process of cutting at high temperature and Contact process between the workpiece and the tool, the chemical elements of both sides diffuse each other in solid state, changing the composition and structure of the tool, making the surface of the tool fragile and increasing the wear of the tool. The diffusion phenomenon always maintains the continuous diffusion of objects with high depth gradients towards objects with low depth gradients.

For example, cobalt in hard alloys rapidly diffuses into chips and workpieces at 800 ℃, while WC decomposes into tungsten and carbon, which diffuse into steel; When PCD tools are used to cut steel and iron materials, when the cutting temperature is above 800 ℃, the carbon atoms in PCD will transfer to the surface of the workpiece with great diffusion strength to form new alloys, and the tool surface will be graphitized. Cobalt and tungsten diffuse more severely, while titanium, tantalum, and niobium have strong anti diffusion capabilities. 

Therefore, YT type hard alloys have good wear resistance. When cutting ceramics and PCBN, diffusion wear is not significant at temperatures as high as 1000 ℃ -1300 ℃. Due to the same material of workpiece, chip and tool, thermoelectric potential will be generated in the contact area during cutting. This thermoelectric potential has the effect of Facilitated diffusion and accelerating tool wear. This type of diffusion wear under the action of thermoelectric potential is called "thermoelectric wear".