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Metal processing series
-------Hard refractory metal
Tungsten and Tungsten alloy’s processing character
Usually we called the high melting point metal as hard refractory metal, such as Tungsten, Molybdenum, tantalum, niobium, zirconium, etc with high melting point, high density, stable chemical structure, high activation engery and difficult to process. With the development of the technology, the refractory metal has a wide application in aerospace, mechanical, electrical, mechanical,medical and other industries.
The strong and tough oxide layer of refractory metal will cause the shaking and impact, also cause the drill bit broken.
The chemical activity of refractory metal is high,and strong affinity, which means the cutting chips are easy to stick together, also will increase the wearing capacity of the gun drill bit.
Processing Tungsten
The hardness and strength of Tungsten is very high, so it usually used to be the material of carbide gun drill, and the normal brand number is: YG6, YG8, YS2(YG10H),726.
The pure Tungsten is very fragile,it is easy to broke when deep hole drilling, also decrease the feed volume to avoid gun drilling tools broken.
CBN gun drill bits with high hardness,anti-resistance,but of poor strength but also can process pure Tungsten. When deep hole drilling with CBN gun drilling tools, choose the big cutting speed with small feed volume.
The solution of improving the Tungsten cutting performance
1) There is a hard oxide layer on the surface of Tungsten. Thus before processing, you can sand-blasting the oxide laywer surface at first to remove the oxide layer, then it will reduce the carbide drill bit’s wearing capacity.
2) When the temperature of metal change from one to another, also its chemical performance changed. In order to get a good processing performance, heat the workpiece up to 200℃, then start to drill.
3) Mix some cooper with Tungsten, and after the combination, its chemical performance is similar to 45 steel.
4) Add some Zirconium oxide to the Tungsten, also its processing performance can have a great improvement.
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