A carbide end mill is a type of industrial tool used for cutting and shaping metals and other solid materials. Though its appearance is similar to that of a drill bit, an end mill can cut in all lateral directions as well as axially like a drill bit. End mills are often made from carbide, also called tungsten carbide. Carbide is a very tough and heavy material that can cut metal without breaking or scratching.
The carbide end mill is one of several types of milling tools that are commonly used. End mills are distinguished from other types because they have cutting teeth at one end as well as on the sides. End mills also have one or more “flutes,” meaning deep helical grooves that run up and down the cutter.
The helical shape of the flutes gives two advantages. First, as the teeth cut through the material, chips are pulled away from the cutting surface by the rotation of the flutes. Secondly, the helix shape reduces vibration and gives a more polished finish than if the whole cutting tooth impacted the material at once.
Depending on the material that is being milled, and how the milling is to be done, there are many types of carbide end mill, with different shapes and geometries. For instance, if the material to be cut is a hard metal like stainless steel, shallow flutes and a square cutting edge will be optimal. With a softer metal like aluminum, deeper flutes with sharp cutting edges will be advantageous.
High speed steel was the traditional raw material for end mills, but most are now made of tungsten carbide. This is a highly rigid material that is extremely wear-resistant, giving a carbide end mill a longer life than a steel one. Some of the more impressive properties of carbide include its high melting point, at 5,200 degrees Fahrenheit (2,870 degrees C). It also measures about 8.5 to 9.0 out of 10 on the Mohs scale of mineral harness. By comparison, hardened steel only measures seven to eight.
Because of the precision required in its manufacture, a carbide end mill will usually be made by computerized machines. Inside the machine, the mills are ground by abrasive wheels mounted on spindles. The wheels are made with industrial diamond, one of the few materials on earth that is harder than tungsten carbide. Temperatures in these grinding machines are kept at bay with high-pressure lubricants, which include oils, oil-water emulsions, and sometimes plain water.