Views: 12 Author: Site Editor Publish Time: 2020-07-09 Origin: Site
The cemented carbide is made of tungsten carbide powder as a matrix, and is pressed and sintered with cobalt powder as a binder. Usually contains 94% tungsten carbide and 6% cobalt. Because of its high hardness, it is very wear-resistant and has a certain strength, suitable for high-speed cutting. But the toughness is poor and very brittle. In order to improve the performance of cemented carbide, some use chemical vapor deposition of a layer of 5-7 microns of ultra-hard titanium carbide (TIC) or titanium nitride (TIN) on the carbonized substrate to make it Has a higher hardness. Some use ion implantation technology to inject titanium, nitrogen, and carbon into their substrate to a certain depth, which not only improves the hardness and strength, but also these implanted components can migrate in when the drill bit is reground. There is also a physical method to generate a layer of diamond film on the top of the drill bit, which greatly improves the hardness and wear resistance of the drill bit.
Bit material selection
According to the processing characteristics of the material, the drill bit is required to have the following characteristics: the hardness of the drill bit must be greater than the hardness of the workpiece to be processed; because the drill bit is subjected to a large torsional and axial force when processing the workpiece, it must have sufficient strength and toughness; Due to the good toughness of the processed material, the cutting edge must be sharp enough during cutting, so the tool material must have sufficient wear resistance to reduce work hardening; due to the high chemical properties of the workpiece, the tool material and the titanium alloy are required to have poor affinity In order to avoid the spread of the stroke and cause the phenomenon of sticking the knife and breaking the drill.
At present, there are a wide variety of materials suitable for making tools, including tool steel, cemented carbide, and super hard materials.
At first, try to use ordinary high-speed steel drill bit for coating test. The ordinary high-speed steel drill bit is cheap. When the coating technology is used, the friction coefficient between the tool and the workpiece can be significantly reduced and the tool life can be improved. However, due to the high speed of the machine tool, the strength of the drill bit used is not enough, and the drill bit is broken during the processing process, and the effect is not ideal.
Cemented carbide is a newly developed tool material suitable for rough finishing of most materials, including steel, cast iron, special materials and plastics. It has been the first choice of drilling jobs.