Solid carbide end mills are long-lasting, efficient at cutting metals, and offer a number of other benefits over HSS, or high-speed steel end mills.
Among these are the fact that many solid carbide end mills are treated with various coatings that improve cutting performance and extend tool life in other ways. We will cover some of these coatings here.
Different Carbide End Mill Coatings
There are many different coatings that are commonly applied to end mills depending on what they will be used for. Some of the more common ones are featured below.
- Titanium nitride (TiN). Titanium nitride-coated end mills are very common, and used for general purpose machining especially of soft metals like mild steel. Titanium nitride is a very hard surface coating that improves permanent dry lubricity and reduces friction. Together, these attributes keep operating temperatures down, reduce thermal stress, extend tool life, and improve chip evacuation rates. This enables TiN coated carbide end mills to be run at faster rates than HSS or other uncoated mills.
- Titanium carbonitride (TiCN). Titanium carbonitride is harder than TiN but otherwise has the same attributes. This makes TiCN coated carbide end mills popular for machining both steels and non-ferrous metals, especially at significantly higher rates. However, high speeds that increase thermal stress cause the hardness of the coating to deteriorate, which counteracts the positive effects. Therefore it is critical to stay within the advisable machining speed operating range for the cutting tool in question.
- Titanium aluminum nitride (TiAlN). Titanium aluminum nitride coated end mills are harder than TiN, but softer than TiCN at normal temperatures. However, at higher speeds and temperatures, TiAlN’s hardness outperforms that of TiCN, making it the preferred choice when the machining process requires high speeds and high levels of thermal stress. It is an effective coating where dry machining will be performed and is commonly used on cast iron, stainless steels, tool steels, and many other metals, except aluminum.
- Aluminum chromium nitride (AlCrN). Aluminum chromium nitride is harder than titanium aluminum nitride and offers among the best hardness ratings and wear resistance of all carbide end mill coatings, even at high temperatures. For these reasons, it is a choice coating when machining challenging metals such as tool steels and titanium, across a wide range of applications.
- CVD diamond. Also known as crystalline CVD diamond, this is a coating in which small diamonds are “grown” right on the surface of the end mill. It results in a remarkably hard coating that dramatically improves tool life by improving tool hardness and wear resistance. However, there is sometimes a small tradeoff as the process of depositing diamond directly on the surface can round off the cutting edges of the flutes, slightly adversely impacting cutting performance.
- Amorphous diamond. Amorphous diamond is a coating in which a diamond coating is physically rather than chemically deposited onto the surface of the tool. This keeps the cutting edges sharp, but reduces the maximum allowable operating temperature. This coating is useful for carbide end mills that will be used to machine abrasive plastics, carbon and aluminum, as these materials incur a lot of wear on end mills.
Keep in mind that the carbide end mill coatings covered here, though they are among the more common, are only a few of those that are out there. If you have any questions about them, or about other end mill coatings, get in touch with us and we will help you out.
Why Coated End Mills?
If you’re wondering what the value is in opting for coated carbide end mills, among the various benefits include:
- Longer tool life
- Higher abrasion resistance
- Higher operating temperatures
- Higher operating speeds
- Superior chip evacuation
- Better workpiece surface finish
- Less rework and fewer scrapped workpieces
Why Carbide End Mills in the First Place?
Whether they’re coated or not, carbide end mills also offer a significant number of advantages over alternatives like HSS, or high speed steel end mills, despite the higher upfront costs. Here are some of the biggest of them:
- Carbide end mills will stay sharper for considerably longer.
- Advanced coatings, as covered here, will improve cutting efficiency, chip evacuation, and improve the finish of the workpiece.
- Carbide end mills offer higher heat resistance than HSS.
- Carbide end mills offer higher cut quality and are more durable overall.
- They’re better for professional shops or others who do a lot of high-volume machining.
Shop Carbide End Mills and Other Metal Cutting Tools Here
Here at TMT Toolbox, we offer a wide range of carbide end mills, including chamfer mills, dovetail mills, and tapered end mills. For more information, check out our full collection, and if you have any questions about end mill specification or need a recommendation, get in touch with us directly at 1-865-724-2516 and we will be happy to assist.
