Tool Coatings from TiN to AlCrN and in between
Why Coatings Were Developed
Innovation has been the drive behind the creation of many of our modern tools today and as those tools become more and more efficient, we tend to look at smaller pieces we can add to improve them. One of these such improvements are coatings applied to cutting tools for a variety of reasons.
By adding coatings to tools, you effectively increase the life of the tools without sacrificing the composition of the tools themselves. By 1971 tool coatings had become standard and we begin to see similar end products to what we have today but with significantly less precision and diversity.
The Development of Coatings
As our knowledge of coatings improved so did the diversity in types of coatings and the individual uses that each of them has. Today, you can find hundreds of coatings across various companies, many of them with similar compositions but different names.
The Original: TiN
Titanium Nitride is one of the oldest coatings and was known for its golden appearance when applied. The TiN coating helped protect cutting and sliding surfaces and was often used for medical implants due to its non-toxic exterior. While it does have a wide variety of uses, TiN has become quite outdated and is often left unused in modern machining.
The Front Runners: TiAlN and AlTiN
Titanium Aluminum Nitride (TiAlN) and Aluminum Titanium Nitride (AlTiN) are two of the most commonly used coatings today. Both coatings offer great increases in the lifespan of tools, especially in high heat situations. The main differences between TiAlN and AlTiN stem from their differences in hardness.
AlTiN is a much harder material, making it prone to chipping when cutting harder materials. For this reason, it’s often used for wet milling and drilling with liquid coolants. Conversely, TiAlN is a softer material, allowing it to be used at higher temperatures in dry milling and drilling situations with less chance of chipping.
The Up-And-Coming: AlCrN
Up until now, all of the coatings we’ve talked about have had a single consistent feature, Ti or Titanium. Aluminum Chromium Nitride (AlCrN) is a newer coating with Chromium in place of the Titanium. This coating excels at high speeds and temperatures because the Aluminum adheres to the Chromium more efficiently to help form a protective coating on the tool.
Choosing Your Coating
In general, each coating serves a fairly specific purpose but the true deciding factor should fall on the specific use of your tools. Have a broad use cutter that you need to use in multiple settings; consider using AlCrN.