Differences in the blade of the square end mill

There are two types of cutting edges for square end mills, and the choice of which one to use depends on the particular machining application. This article provides information to help you choose the appropriate type of cutting edge for your needs.

What is a square end mill?

A square end mill is an end mill with a flat tip. The blade is configured at the outermost diameter and is used for cutting horizontal or vertical surfaces. In addition, since the lower blade of the square end mill is weak, it is better to use ball end mills when performing Z-axis machining.

Types of cutting edges

Features of the sharp type

The ‘sharp corner’ type, or also called ‘sharp edge’, is not treated with a cutting edge. However, when a groove (gash) is added, the corner of the cutting edge is moved backward, resulting in corner residue in the processed area. To remove the corner residue, you can use a sharp type end mill.

The sharp type is used when a shallower depth of cut is desired for the material and the rotation speed needs to be increased. Sharp corner end mills are also used when corner residue removal (pin angle) is required.

Although the chipping resistance is inferior, it has good machining accuracy due to its sharp cutting edge and is suitable for precision finish machining. High-speed steel end mills are mostly sharp types because they have higher toughness than carbide end mills.

Features of the type with a gash

The type with a gash has a groove (gash) on the cutting edge that extends to the outer edge, and the cutting edge is processed to increase the cutting edge strength. This type is also called an atari. The cutting edge corner of an end mill consists of the cutting edge angles of the torsion angle, rake angle, radial relief angle, and end relief angle, and the cutting edge angle is reduced by being driven in from four sides. Vibration and impact occur during machining operations, and the corners may be easily damaged. The type with a gash has a high cutting strength, making it not easily damaged.


Square end mills can perform various types of machining depending on their cutting edges. Please consider these materials when cutting, and select the appropriate one for your machining.