Choosing the Right End Mill Coating for Each Application

by startoolinc | Last Updated: December 19, 2019

Since the development of the original Titanium Nitride (TiN) coating, the use of coatings for industrial cutting applications such as carbide end mills has become widespread. Hundreds of different coatings have been developed over the last decades, along with the corresponding rise in popularity, yielding a dizzying array of options currently available in the market. As a result, it’s no small feat to understand and wade through the differences and eventually settle on the end mill coating that is truly best suited for your situation.

For high-performance cutting tools, arguably, the two best PVD coatings available on the market today are Titanium Aluminum Nitride (TiAlN) and Aluminum Chromium Nitrite (AlCrN). These two, in particular, outperform others in a majority of uses and provide the benefits that operators of cutting tools will be looking for in their industrial applications.

So what makes the TiAlN and AlCrN coatings particularly useful, and when should you use each one?

Titanium Aluminum Nitride (TiAlN) Coating

TiAlN coating is a prevalent option for use with carbide end mills today and for a good reason. At a basic level, the mix of titanium and nitride resists the formation of built-up edges (BUEs). BUEs occur when materials gradually stick to the cutting edge of the tool and peel away the coating layer over time, causing the rake face of the cutting tool to separate from the chip. 

TiAlN coating is widely used in applications where excessive heat is generated. The added aluminum serves as a thermal insulator, providing stability and heat resistance at extremely high temperatures. This layer of aluminum on the tool surface not only prevents further oxidation but provides a hardness that resists chipping that may otherwise occur on other coatings.

You might notice TiAlN bears the same chemical components as AlTiN. Despite this similarity, AlTiN comprises more aluminum and, therefore, much harder coating material, which can result in increased chipping when used to cut equally hard materials. TiAlN, alternatively, is softer and can be used more effectively in higher temperature dry milling environments.

Aluminum Chromium Nitrite (AlCrN) Coating

AlCrN coating further improves upon TiAlN coating by ditching titanium and instead substituting chromium in its place. Since aluminum adheres to chromium, more aluminum can be added, thereby improving the hardness and oxidation resistance of the cutting tool. 

The inclusion of chromium ensures that the coating will perform even better under high-speed and high-temperature milling environments. While AlCrN is viewed as an improvement over TiAlN for that reason, it is also a more flexible coating overall and can be used in a variety of settings.


We hope this brief overview has helped help you understand the different tool coating options that are available and why we choose to offer the TiAlN and AlCrN options for end mill coatings.