P M K N S H Explained: Carbide Insert Material Classification Guide

Reading volume: 26111

Release time :2021-12-09

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In CNC machining, choosing the correct cutting tool starts with understanding the workpiece material. Different materials have different characteristics, such as hardness, toughness, thermal conductivity, and cutting resistance, which directly affect tool selection and machining performance.

The ISO P, M, K, N, S, and H classification system is widely used in the cutting tool industry to classify carbide insert applications according to different workpiece materials. These material groups help engineers understand the machining requirements of steel, stainless steel, cast iron, non-ferrous metals, heat-resistant alloys, and hardened materials.

Although originally developed for carbide insert selection, these material classification principles are also useful when choosing other carbide cutting tools, including solid carbide end mills.

By understanding these classifications, engineers can select suitable tool materials, coatings, and cutting geometries for different machining applications.

What Do P, M, K, N, S, and H Mean in Carbide Inserts?

In ISO carbide insert classification, the letters P, M, K, N, S, and H represent different groups of workpiece materials. Each group has unique machining characteristics and requires suitable cutting tool solutions.

P Group: Steel Machining

P group mainly covers steel materials, including carbon steel, alloy steel, and tool steel.

Steel machining usually requires cutting tools with a good balance of wear resistance, toughness, and cutting stability. The selection of carbide grade, coating, and tool geometry plays an important role in machining efficiency and tool life.

For CNC milling applications, suitable  carbide cutting tools  are selected according to steel grade, machining conditions, and required surface finish. Solid carbide end mills are commonly used for operations such as slotting, profiling, and finishing.

M Group: Stainless Steel Machining

M group represents stainless steel materials. Compared with ordinary steel, stainless steel usually has higher toughness, stronger work-hardening characteristics, and lower thermal conductivity, making it more challenging to machine.

When machining stainless steel, cutting tools need stable cutting edges, good chip evacuation, and suitable coating performance to reduce wear and maintain consistent machining quality.

For milling applications, end mills for stainless steel machining  require optimized geometry and tool performance to meet the requirements of materials such as 304 and 316 stainless steel.

K Group: Cast Iron Machining

K group refers to cast iron materials, including gray cast iron and ductile iron.

Cast iron often creates abrasive cutting conditions because of its material structure and hardness variations. During machining, tool wear resistance and edge stability are important factors affecting tool performance.

Suitable cutting tool selection should consider material hardness, machining method, cutting conditions, and required surface quality.

N Group: Non-ferrous Material Machining

N group mainly includes non-ferrous materials such as aluminum, copper, and brass.

Compared with steel machining, aluminum processing requires sharper cutting edges, efficient chip evacuation, and proper flute design to reduce material adhesion and improve surface finish.

For high-speed CNC milling applications, end mills for aluminum machining are commonly selected for stable and efficient cutting performance.

S Group: Titanium and Heat-resistant Alloy Machining

S group includes difficult-to-machine materials such as titanium alloys and nickel-based heat-resistant alloys.

These materials usually have high strength, low thermal conductivity, and strong cutting resistance. During machining, heat can concentrate near the cutting edge, increasing the requirements for tool material and coating technology.

Selecting suitable  titanium alloy end mills  can help improve machining stability and surface quality.

H Group: Hardened Material Machining

H group represents hardened materials, including hardened steel and hardened cast iron.

Machining hardened materials requires cutting tools with excellent wear resistance and sufficient edge strength. Depending on material hardness and machining requirements, carbide tools or advanced tool materials such as CBN may be selected.

For CNC milling of hardened steel, end mills for hardened steel machining should be selected according to material hardness, machining conditions, and finishing requirements.

Carbide Inserts and Solid Carbide End Mills: Different Cutting Applications

Carbide inserts and solid carbide end mills are both widely used carbide cutting tools in modern manufacturing. However, they are designed for different machining methods and applications.

Carbide inserts are commonly used in indexable tooling systems, especially for turning operations and larger milling applications. Solid carbide end mills are mainly applied in CNC milling processes that require high precision, rigidity, and complex machining capability.

The choice between different cutting tools depends on several factors:

• • Workpiece material

• • Machining method

• • Cutting speed and feed conditions

• • Tool material and coating

• • Required accuracy and surface finish

Understanding the relationship between material classification and cutting tool performance helps manufacturers select more suitable solutions for different machining applications.

Factors to Consider When Selecting Cutting Tools

Material classification provides a useful reference when choosing cutting tools, but engineers also need to consider actual machining conditions and production requirements.

1. Workpiece Material

Different materials require different cutting tool properties. A tool designed for aluminum machining may not provide the best performance when used for hardened steel or titanium alloy.

2. Cutting Conditions

Spindle speed, feed rate, depth of cut, machine rigidity, and cooling conditions all influence machining stability, tool wear, and final surface quality.

3. Tool Geometry and Coating

Flute number, helix angle, edge preparation, and coating technology affect chip evacuation, heat resistance, cutting force, and overall machining performance.

Selecting the correct tool design according to material characteristics can help improve machining efficiency, extend tool life, and achieve more stable production results.

For CNC milling applications, DOHRE provides customized carbide cutting tools  designed for different industrial requirements.

For specific machining requirements or customized tool solutions, contact DOHRE to discuss your application requirements.

Conclusion

The P, M, K, N, S, and H material classification system provides an effective reference for understanding machining challenges and selecting suitable cutting tools.

Although these classifications are commonly discussed in relation to carbide inserts, the same material considerations are also important when choosing solid carbide end mills and other CNC cutting tools.

By matching the right tool design with the workpiece material, manufacturers can achieve better machining efficiency, improved surface quality, and more stable production performance.