The three major types of coatings used today
A list of the three main coatings used today:
Titanium nitride (TiN) TiN-coated carbide end mills must be run at speeds and feed rates close to that of uncoated carbide end mills. However, the TiN coating provides a better wear and lubricity to the end mill.
Titanium carbon nitride (TiCN) TiCN coatings are perfect for slow feeds and speeds, however it is often the choice coating for high-speed steel end mills. For carbide tools coated with TiCN, you can run at speeds approximately 80 % faster than uncoated solid carbide end mills. However, TiCN is prone to failure under extreme heat, which is why it is often used in slower feed and speed applications.
Titanium aluminum nitride (TiAlN) or Aluminum titanium nitride (AlTiN) TiAlN- or AlTiN-coated end mills are becoming increasingly popular. The aluminum in both coatings helps to create a gaseous aluminum oxide layer at the cutting edge that can reach temperatures greater than 1800-degrees. This layer of aluminum oxide gas protects the carbide in the tool from the damaging effects of heat. This is why these two coatings have become popular for high-speed and hard milling, especially in dry cutting. Aluminum titanium nitride contains greater amounts of aluminum than titanium aluminum nitride.
There are other coatings available on the market today, however, they are variations of the main three. When machining nonferrous materials, aluminum, brass, and plastics non-coated carbide end mills that have polished flutes are recommended in order to prevent edge buildup. These materials require finely keen edges and end mills that are coated don’t allow as sharp an edge.
These are only a few of the factors to consider using carbide end mills. Other factors include the specific geometries of the end mill, rake angles, gash lands, relief angles, as well as programs, and the machine. Understanding the process as well as the material that will be machined is only the first step in deciding which end mill should be selected for the application.
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