What Is an End Mill?
An end mill is a cutting tool used in industrial milling applications. It is known for its ability to produce minimal chips during cutting and is particularly effective in machining threads in soft materials. The strength of the threads produced is high, and the effective diameter variations are well-controlled.
End mills come in various designs, some featuring a groove to enhance the supply of cutting fluid.
Uses of End Mills
End mills are commonly used for soft materials like aluminum. While there are end mills designed for steel, they are less effective for harder materials. They are typically used in machine tools rather than by hand due to the high torque required during machining. They are particularly effective for machining stop holes where chip production is a concern.
Various manufacturers provide end mills for machining materials like iron, low carbon steel, low carbon alloy steel, and stainless steel.
Principles of End Mills
End mills work by forming threads through plastic deformation, making the size of the pre-hole crucial for the final thread shape. High-precision control of the pre-hole is essential. For instance, while a M10 x 1.5 thread machined with a spiral or point tap might require a Φ8.5 pre-hole, an end mill would require around Φ9.2.
Using a precise carbide drill is key to achieving high-precision pre-holes. For small-diameter holes with strict dimensional control, high-precision drills are recommended.
For achieving stable, high-precision drilling, using end mills for contouring or boring after pre-drilling with a drill is effective.
It is important to note that end mills are specific to either through-hole or stop-hole drilling and are not interchangeable. Rigid tapping, as opposed to using a tapping collet, is necessary due to the high torque required, ensuring stable thread depth.