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Milling Cutters: Types, Materials, and How to Choose the Right One

July 26, 2025

Milling cutters are essential tools in machining, designed as sophisticated rotary cutting devices. They combine a cutting body, shank, and cutting edges, enabling precise cutting of various metal materials through rotation and axial movement. This versatility allows milling cutters to be widely used across multiple industrial sectors, including steel production, automotive manufacturing, construction machinery, aerospace, and electronics.

Whether machining flat surfaces or complex curved shapes, milling cutters are known for their efficiency and precision, helping to achieve high-quality and high-efficiency production goals. Therefore, milling cutters are undoubtedly indispensable tools in modern manufacturing.

In this article, we will introduce different types of milling cutters, the materials used in these tools, and guide how to select the right milling cutter for your machining operations. We hope this information will assist you in choosing the appropriate tools for CNC milling.

What is a Milling Cutter?

A milling cutter is a rotary tool designed for milling operations, characterized by one or more cutting edges. It primarily consists of several components, including the shank, cutter head, spindle, cutting surfaces, and body.

During operation, the milling cutter removes the excess material from the workpiece intermittently through its cutting edges. It is mainly used on milling machines or machining centers to process flat surfaces, steps, grooves, contoured surfaces, and to cut off workpieces. As the milling cutter rotates rapidly and moves axially, it produces a variety of shapes and sizes as required by the machining process.

Types of Milling Cutters

Milling cutters come in various types, each designed for specific applications to meet different machining needs, enhance production efficiency, and improve machining quality. Based on functionality, common types of milling cutters include:

1. Cylindrical Cutters

These are primarily used on horizontal milling machines for machining narrow surfaces that are shorter in width than the length of the cutter. The cutting edges are distributed around the cutter’s circumference and can be categorized into straight and helical teeth, as well as coarse and fine teeth. Coarse helical tooth cutters tend to have fewer teeth, providing higher strength and better chip space, making them suitable for rough machining, while fine tooth cutters are ideal for finishing work.

2. Face Mills

These cutters are mainly used on vertical milling machines, end mills, or gantry mills for processing large flat surfaces. They possess teeth on both the end face and the circumference, with a variety of tooth types, including coarse and fine. Face mills can be constructed in integral, insert, or indexable forms. Due to their shorter tool extension and better rigidity, they are often utilized for high-speed cutting, resulting in higher productivity. Their secondary cutting edges provide excellent finishing capabilities, yielding a smooth surface finish.

3. End Mills

One of the most commonly used cutters in CNC milling, end mills have cutting edges on both the circumference and the end face and generally feature spiral teeth, which enhance cutting stability and improve machining precision. They are primarily used for processing grooves, steps, and simple contoured surfaces. Ordinary end mills do not possess cutting edges at the center of the end face, limiting axial feed, though they can be axially fed through the end teeth.

4. Three-Flute Cutters

These can be categorized into straight and staggered tooth designs and are mainly used on horizontal milling machines for creating step surfaces and shallow grooves that are either partially or fully traversing one or both ends. The presence of cutting edges on both the side surfaces and circumference improves cutting conditions and enhances cutting efficiency.

5. Angle Cutters

Designed for milling grooves at specific angles, these cutters come in single-angle and double-angle variations.

6. Saw Blades

Saw blade cutters are used for machining deep grooves and cutting off workpieces. They feature numerous cutting edges around the circumference. To reduce friction during cutting, the teeth are designed with a small clearance angle of about 15’ to 1°.

7. Keyway Cutters

These cutters are specialized for machining keyways on shafts and resemble end mills, but can also cut on the end face. They can facilitate both radial and axial feeding movements. Generally, the diameter of a keyway cutter corresponds to the width of standard keyways.

8. Form Cutters

These specialized cutters are designed with cutting edges that match the specific profiles of the workpieces being machined. They can efficiently produce complex surface shapes on general milling machines while ensuring consistency in shape, particularly beneficial in mass and batch production, with notable applications in turbine blade machining.

9. Mold Cutters

Mold cutters are specifically used for machining mold cavities or forming surfaces. They evolved from end mills and can be classified into three shapes based on their working part: conical flat heads, cylindrical ball heads, and conical ball heads. Carbide mold cutters have extensive applications, allowing not only for the machining of various mold cavities but also for replacing hand files and grinding wheels for finishing castings, forgings, and weld seams, as well as for refining certain contoured surfaces. These cutters can be mounted on pneumatic or electric tools, offering productivity and lifespan improvements compared to grinding wheels and files by factors of tens.

Materials and Characteristics of Milling Cutters

The differences in cutting processes and application requirements necessitate the use of various milling cutter materials. Here are the most commonly used materials for manufacturing milling tools:

1. High-Speed Steel (HSS)

High-speed steel contains alloying elements that enhance heat and wear resistance. While this tool’s lifespan is extended, its cost also increases. It is suitable for machining materials like ordinary steel, cast iron, and brass. Key characteristics include:

High Hardness: With a high content of alloying elements such as tungsten, chromium, molybdenum, and vanadium, HSS can achieve a quench hardness of HRC 62-70 and maintain good hardness even at elevated temperatures around 600°C.
Good Strength and Toughness: It offers excellent edge strength and toughness, making it resistant to vibration, which is beneficial for general cutting speed applications. Even with less rigid machinery, HSS cutters can perform smoothly.
Excellent Machinability: HSS is easier to forge, machine, and grind, allowing for the manufacture of complex-shaped tools.
Poor Wear Resistance: Compared to carbide materials, HSS has lower hardness and is less effective in red hardness and wear resistance.

2. Carbide

Carbide is made from metal carbides (like tungsten carbide and titanium carbide) combined with cobalt-based metal binders through powder metallurgy. This material is harder than high-speed steel and provides better wear resistance, but it has lower toughness, making it more susceptible to cracking and chipping. Carbide cutters excel in machining a variety of metals and non-metals, especially in high-speed and precision machining scenarios. Carbide tools are moderately priced and are the preferred choice in many machining applications. Common carbide types include tungsten-cobalt (YG), titanium-cobalt (YT), and general-purpose carbides. Key characteristics include:

Good Hot Hardness: It maintains excellent cutting performance at temperatures of around 800-1000°C, allowing cutting speeds 4-8 times higher than high-speed steel.
High Hardness: It exhibits high hardness and wear resistance at room temperature.
Low Bending Strength: It has poor impact toughness, which means the cutting edge can chip easily from a fall. It isn’t easy to hone the edge to a very sharp point.

3. Ceramics

Ceramics are harder than carbide but have decreased toughness and increased brittleness, making them sensitive to impact loads. Therefore, they are prone to cracking when used on hard materials or at high temperatures, requiring careful usage. Aluminum oxide and silicon nitride are commonly used to manufacture these ceramics, which are especially well-suited for high-speed cutting and machining hard materials.

4. PCD and CBN

Polycrystalline Diamond (PCD) is a synthetically derived diamond material known for its extreme hardness and wear resistance, making it ideal for machining difficult materials such as aluminum and magnesium alloys. Cubic Boron Nitride (CBN) has similar properties, providing exceptional hardness and cutting performance, and is primarily used for machining high-hardness materials like ductile iron and hardened steel. Both PCD and CBN milling cutters come at a higher manufacturing cost and are recommended for medium-to-small batch production and specialized machining tasks.

How to Choose the Right Milling Cutter?

Selecting the appropriate milling cutter is critical for ensuring machining quality and enhancing efficiency during milling operations. When choosing the right milling tool, several key factors should be considered:

1. Type of Milling Cutter

There are various types of milling cutters, including end mills, roughing mills, peripheral mills, slab mills, and face mills. Each type serves specific purposes and is suited to particular scenarios. For example, end mills are versatile for various drilling operations, while roughing mills are designed for bulk material removal.

2. Material and Hardness

The choice of milling cutter should also consider the type and hardness of the material being machined. For example, when machining steel, a cutter with a higher hardness is appropriate, while softer materials can be processed with cutters of lower hardness.

3. Machine Type

The machine used for milling can influence cutter selection. Cutters for CNC machining centers are typically made from solid carbide, while conventional milling machines can use high-speed steel. Right-hand cutters are suitable for counterclockwise (CCW) rotating machines (viewed along the spindle direction), while left-hand cutters are suitable for clockwise (CW) rotating machines.

4. Cutter Diameter and Specifications

The diameter and specifications of the milling cutter must be considered based on the equipment’s capabilities and the dimensions of the workpiece.

Face Mills: The diameter chosen should ensure that the required power of the tool is within the power range of the machine, typically following the formula D = 1.5d (where d is the spindle diameter). In high-volume production, a cutter diameter of 1.6 times the workpiece cutting width may also be used.
End Mills: The diameter should primarily reflect the workpiece’s dimensional requirements while ensuring that the tool’s power needs are within the machine’s rated capability. For small-diameter end mills, it is also crucial to check if the machine’s maximum spindle speed can achieve the minimum cutting speed (60 m/min).
Slot Mills: The diameter and width selection should be determined based on the size of the workpiece, ensuring that the cutting power remains within the machine’s allowable range.

5. Rake Angle and Geometry

The rake angle and geometry of the milling cutter significantly influence the cutting performance. Negative rake angle cutters are suitable for roughing, while positive rake angle cutters are more suitable for finishing.

6. Cutting Edge Strength and Chip Removal Capability

The strength of the cutting edge and its ability to remove chips are also vital considerations when choosing a milling cutter. The chip removal space on the milling cutter is determined by the number and design of the flutes. More flutes help achieve higher feed rates, but can increase the overall diameter of the cutter, reducing chip space. The spiral angle dictates the cutting speed based on the spindle’s rotation, with steeper angles being more effective for softer materials.

7. Blade Selection

Finishing: For finishing operations, it is best to choose ground blades, which offer higher dimensional accuracy and better cutting edge positioning, resulting in improved machining precision and surface finish.
Roughing: Pressed blades are preferable for roughing, as they have slightly lower dimensional accuracy and edge sharpness but better edge strength, allowing them to withstand larger depths of cut and feed rates.
Sharp Large Rake Angle Blades: These can be used for machining sticky materials like stainless steel. The sharp edges reduce friction between the blade and workpiece material, allowing for faster chip removal from the cutter’s front.

8. Tooth Count Selection

The number of teeth and their spacing will determine how many cutter teeth engage in the cutting process simultaneously, which affects the stability of the cut and the requirements placed on the machine.

Coarse Tooth Cutters: Primarily used for roughing, these have larger chip removal spaces and are suited for removing significant amounts of material. They can effectively process when the spindle hole specifications are smaller (e.g., R-8, 30#, 40# taper holes), reducing the power requirements for the machine.
Fine Tooth Cutters: Typically used for finishing, they have shallower depths of cut and can achieve better surface quality. For larger and more rigid spindle specifications, fine-tooth cutters can also be applied for roughing operations.

Summary

In conclusion, milling cutters come in a wide variety of types and applications. When selecting a cutter, it is essential to consider specific machining requirements, equipment specifications, and workpiece dimensions. Milling tools play a crucial role in any milling process, as they are used in milling machines to remove or cut materials into different shapes for various operations. A good choice of milling cutter leads to higher feed rates, resulting in shorter cutting times and lower costs.

At JIAHUI, we have a team of experts ready to meet all your manufacturing needs, including CNC milling services, CNC turning, 3D printing, quick prototyping, and more. With 20 years of machining experience, our engineers will help you choose the right milling cutter for your parts, ensuring high quality and high standards in your products.