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Basic knowledge of End mills (1) What is an End mill?

Dec. 23. 2021

Previously, we have explained the basic knowledge of drills. This time, we will explain the basic knowledge of end mills. Although there are few materials and information on end mills than on drills, end mills play a major role in the cutting process. We would like to write a series of articles that are as easy to understand as possible and we hope that will be helpful to you.

What is an End mill?

End mills are multi-functional tools that have cutting edges on the tip and periphery and are rotated to perform side cutting, front cutting, groove cutting, and hole drilling of work material.

The most suitable end mill differs depending on the application and the shape of the workpiece, and a wide variety of end mills with different shapes are manufactured.


Types of End mills

As we mentioned earlier, end mills come in a wide variety of shapes depending on the application, but here are some of the most common types.



Solid end mill: An end mill in which the tip, body, and shank are made of the same material. There are many variations from small to large diameters. Most are made of HSS (High Speed Steel) or cemented carbide. Capable of side cutting, groove cutting, and hole drilling.


Head exchangeable endmill: An end mill with an interchangeable head. The tip part is made of cemented carbide and the shank part is made of HSS (High Speed Steel). When worn out, only the tip needs to be replaced, which is low cost if re-grinding is not considered. Side cutting is not possible. 


Brazed endmill: An endmill with a cutting edge brazed with cemented carbide. In the case of large-diameter end mills, the cost would be high if all the parts were made of cemented carbide, so only the cutting edge is made of cemented carbide and the other parts are made of HSS (High Speed Steel) to reduce the cost. Due to its structure, it is impossible to manufacture small diameter products.


Insert end mills: End mills that use inserts for the cutting edges. However, due to its structure, it can only be used for end mills with large diameters.


Bottom Flute Shape

Square end mill: The most common type with a straight bottom edge. Can be used for frontal cutting, side cutting for cornering, grooving, and hole cutting. The disadvantage is that a large load is placed on the outermost edge and it wears out easily.


Radius endmill: An endmill with a radius on the edge of the bottom flute. It can be said to be a type that strengthens the outermost edge, which is a drawback of square end mills. It is used for side cutting with a corner radius, groove cutting, hole drilling, and uncomplicated 3D machining.


Ball end mill: An end mill with a spherical bottom flute. It is used for machining of complex 3D shapes. The disadvantage is that the cutting area is small and the pick-feed cannot be large (more machining passes). 


Peripheral shape

Straight (general): The most common type. The cutting edge has the same diameter from the tip to the shank side.


Ruffing: An end mill with an uneven outer edge. Since chips are easily broken up and cutting coolant can easily enter through the gaps, it is effective in reducing cutting resistance and preventing thermal deformation, so it is used for rough machining. It is also effective in reducing cutting resistance and preventing thermal deformation, so it is used for rough machining. It is not suitable for finishing because the side cutting surface becomes rough.]


Taper: Used for tapered side machining and for securing rigidity when cutting only with the tip.


Neck: The shank side is thinner than the outer cutting edge. It is used for deep hole drilling.


Total mold: An original shape created to perform complex side machining in a single operation.


Number of Flutes

End mills are available in variations from single flute to 2, 3, 4, 10, and so on. End mills with a small number of flutes have the advantage of a large cutting volume and are often used for rough machining. Those with many cutting edges have a small cutting volume but improve the surface roughness of the machined surface, so they are often used for finishing.

In addition, some blades are divided unequally to prevent chattering and resonance during machining.



The twist angle of an end mill ranges from 0° to 60°, but the standard angle is about 30°. Some have a gradual change in twist angle between the tip and shank side, and some have both left- and right-hand twist.


This is a general description of end mills. In the next article, we will explain in more detail.


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