Types of end mills

This article will explain what an end mill is and break down its various components. In addition, we will also introduce various end mills that are available under the MonotaRO original brand.

What is an end mill?

An end mill is a tool called a mill used in milling machines that also has a blade at the end (tip). The shape of an end mill is similar to that of a drill, but whereas the drill drills a circular hole in the direction of the tip, the end mill generally widens the hole vertically by means of the side blades, making it a tool for finishing products with high surface accuracy. In addition, since there is a cutting edge at the tip, it is possible to drill a hole horizontally in the direction of the tip as with a drill, but in this case, a pre-drilled hole should be first made with a drill or the like.

A unique feature of an end mill is that it can cut very hard materials such as steel, stainless steel, and aluminum into a variety of shapes including holes, grooves, flat surfaces, and three-dimensional curved surfaces.

Components of the end mill

The structure of the end mill can be roughly divided into two main parts: the first is the shank, which is the part that attaches the end mill to a part called the holder, which exists between the milling machine and the end mill.

The second is the part used for cutting, called the body.

The body has a groove called a tip pocket, which plays the role of draining chips generated during processing to the outside. In JIB B 0172, the size of an endmill is expressed as follows: outer diameter x blade length x overall length x size of the shank (shank length), the diameter of the blade is the outer diameter, the length of the blade is the blade length, and the entire length of the end mill is the overall length. 

Types of end mills

Square end mill


Purpose: For side machining and finishing of metals such as high-alloy steel and castings.

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

Roughing end mill


Purpose: For rough machining

Short, medium, and long types are available depending on the length of the cutting blade. Roughing end mills are designed for roughing, but depending on the product, they are capable of machining as well as semi-finishing. Most of them are made of cobalt high-speed steel. Carbon steel, alloy steel, stainless steel, and aluminum alloys can be machined.

Ball end mill


Purpose: For machining curved surfaces and other shapes

Since the cutting edge is spherical, it is very useful for machining curved surfaces, such as R-milling and 3D machining. It should be noted that the tip of the cutting edge makes it difficult to eject chips, and since the cutting edge is R-shaped, pressure is particularly applied to the tip, resulting in severe spills and abrasion.

Radius end mill


Purpose: For corner milling and pick-feed machining

End mills usually have cutting edges on both the periphery and the bottom, of which the corners of the bottom edge are rounded. With radius end mills, the corners of the cutting edges are rounded off, so the materials can be machined into relatively smooth shapes.

Taper end mill


Purpose: Used for grooving and finishing of dies, etc.

A cutting tool with a tapered blade that is composed of multiple cutting edges with torsion formed on the periphery of the tool body. It is installed in machine tools such as machining centers. Various innovations have been made to the tapered cutting edge in order to achieve stable cutting by increasing rigidity and improving chip evacuation.


End mills can perform various types of machining depending on their cutting edges and shapes. Please consider these materials when cutting, and select the most suitable cutting tool for your application.