How to Classify End Mills
- 1). Check the number of flutes on the end mill to determine what material it will cut. Four-fluted end mills are best for harder materials, such as steel. They are normally run slower than end mills for aluminum, so chip evacuation is not as important. Two- and three-fluted end mills are perfect for aluminum and soft materials, as there needs to be enough space in between flutes to quickly evacuate chips to avoid breakage.
- 2). Check the flute characteristics for classification. There are two basic types of end mills: roughers and finishers. Roughing end mills have ridges on the flutes that run horizontal to help support rough cutting. These bumps break the edge and allow for heavy cuts. Finishing end mills have smooth edges that are very sharp. These edges usually only take off about .010" of material to create a nice finish.
- 3). Classify end mills by their coatings. Roughing and finishing end mills are often coated with different materials to help them stand up to harder material. The most common are TiN, or Titanium Nitride; TiCN, or Titanium Carbonitride; and AlTiN, or Aluminum Titanium Nitride, listed from softest to hardest. The reasons to choose one over another are usually related to price, as they become progressively more expensive the harder they become.
- 4). Determine the material used to make the end mill. End mills are most often made of high-speed steel, cobalt or carbide. Depending on what material you are cutting, there are uses for all three types. Carbide finishing end mills are perfect for finishing steel, and high-speed steel finishers are geared toward applications involving aluminum. Most roughing end mills are made from cobalt, which is an in-between hardness, and are usually coated, which can save you money over using cobalt roughing end mills, which are brittle and tend to snap often under duress.
- 5). Classify specialty end mills in a different category than more standard pieces. Ball-end mills are great for contouring, as they can be run fast and in short lines to create a non-flat surface. Double-ended end mills are useful when you need to economize, as they provide two cutting sides on a single shaft.