Recently, we received an inquiry from a customer about CBN inserts. What is different this time is that the customer needs CBN inserts with coating.So why do customers have such demand, what is the role of the coating, what are the types of coating?
Advantages of coated CBN tools compared to ordinary uncoated CBN tools：
The coating acts as a chemical and thermal barrier, and the composition of the coated CBN tool reduces the diffusion and chemical reaction between the tool and the workpiece, thereby reducing crescents wear. Coating CBN tool has high surface hardness, good wear resistance, stable chemical properties, heat resistance and oxidation resistance, small friction coefficient and low thermal conductivity characteristics, cutting than uncoated tool to improve tool life 2-3 times more than, improve the cutting speed of 20%~70%, improve processing accuracy 0.5~1 level, reduce tool consumption cost 20%~50%.
However, not all coated CBN tools are better than uncoated CBN tools. When not to choose coated CBN tools?
(1) uncoated CBN tool can meet customer needs, do not need to choose coated CBN tool, after all, the price is higher than uncoated;
(2) not mass production, do not need to improve production efficiency, do not choose coated CBN tool, if only a batch of goods need CBN tool, then choose uncoated can meet the demand.
(3) the uncoated CBN tool itself has no processing problems, there is no severe wear, edge breakage and other problems, do not need to coating PCBN tool to improve durability and collapse resistance, conversely, by coating PCBN tool to improve tool performance.
What are the types of coating?
1. TiN is a universal PVD coating that improves tool hardness and oxidation temperature. The coating can be used in high-speed steel cutting tools or forming tools to obtain good machining results.
2. Titanium nitride carbide coating (TiCN)
The carbon added to TiCN coating can improve tool hardness and obtain better surface lubricity, making it an ideal coating for high-speed steel tools.
3. Aluminum nitride or titanium nitride aluminum coating (TiAlN)
The alumina layer formed in TiAlN/AlTiN coating can effectively improve the high-temperature machining life of the tool. The coating can be used for hard alloy cutting tools mainly used for dry or semi-dry cutting. Depending on the ratio of aluminum to titanium in the coating, AlTiN coating provides higher surface hardness than TiAlN coating, making it another viable coating option for high-speed machining.
4. Chromium nitride coating (CrN)
The good adhesion resistance of CrN coating makes it the preferred coating for the processing of nodules. With this almost invisible coating, the machinability of HSS or carbide tools and molding tools will be greatly improved.
5. Diamond coating
Diamond coatings provide the best performance for machining tools made of non-ferrous metal materials and are ideal coatings for machining graphite, metal matrix composites (MMC), high silicon aluminum alloys, and many other highly abrasive materials. The coatings for hard milling, tapping, and drilling are different and have their specific applications. In addition, multi-layer coatings can be used, which have other coatings embedded between the surface and the tool matrix to further improve tool life.
6. ZrN(Zirconium nitride)
ZrN(zirconium nitride) coating for anti-stick type special coating, coating without Ti and Cr, suitable for processing aluminum, copper, titanium, and their alloys without the product of giving and sticking knife phenomenon.
There are many kinds of coatings, some are suitable for CBN tools and some are not. We need to choose the suitable coating according to the actual processing workpiece material and the situation.
If you need to customize, welcome to inquiry. We will serve you with the most professional attitude.
---EDITOR: Miya Ma
---POST: Cynthia Lee