2024/12/27 010｜End Mill Material Theory

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END MILL Material Theory

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[A]--Materials of end mills

Things that we commonly see in the human life circle often have a beginning. For example, the beginning of food is crops in farmland, fish in the sea, cattle and sheep in pasture, etc. The beginning of tableware can be mines, logging sites, and renewable resource fields. Wait until it is polished and produced in the factory, and then reaches the hands of consumers after a long journey, and the end mill of industrial products is no exception.

In particular, the material selection of the mill directly affects the processing performance and life, so in When producing milling cutters, it is necessary to select appropriate materials according to different applications. The following introduces the materials commonly used in end mills, including their acquisition methods, material properties, hardness, composition, origin, application situations and future development trends, to discuss the aspects of milling cutters. It started with those materials.
 

1. High-Speed ​​Steel (HSS, High-Speed ​​Steel)

◼ Acquisition : High-speed steel is mainly manufactured through the steel refining process, including adding a variety of elements, such as carbon, tungsten, chromium, molybdenum, etc., to improve its hardness and heat resistance.
◼ Features : High-speed steel has good toughness and wear resistance, is suitable for medium and low-speed cutting, is easy to grind and reuse, and is relatively economical in price. It can be ground multiple times and is very suitable for general-purpose processing.
◼ Hardness : The hardness is approximately between HRC 60 and 67. It has average high temperature resistance and can maintain stable performance under medium speed operation.
◼ Ingredients : Carbon (about 0.6%-1.5%), chromium (4%-4.5%), tungsten (6%-18%), molybdenum (5%-10%), etc.
◼ Origin : Produced in China, Japan, the United States and other places.
◼ Application : Suitable for processing general steel and less hard materials, such as low carbon steel, medium carbon steel, copper, aluminum, plastic and other soft or medium hard materials. It is suitable for small workshops and economical applications. It is a common and Widely circulated material.
◼ Future development : As the application of hard materials increases, the demand for high-speed steel may decrease, but it still has its market in general processing, especially price-sensitive small and medium-sized enterprises.
 

2. Cobalt Steel

◼ Acquisition : Cobalt steel is made of a mixture of high-speed steel and cobalt elements. Its high cobalt content improves hardness and heat resistance, making it suitable for processing higher temperature and harder materials.
◼ Features : It has higher heat resistance than ordinary high-speed steel and can maintain hardness at high temperatures, so it is suitable for processing materials with medium and high hardness.
◼ Hardness : The hardness is generally between HRC 65 and 70.
◼ Ingredients : The main ingredient is high-speed steel with 5%-12% cobalt added, which gives it high toughness and heat resistance.
◼ Origin : China, Germany, Sweden and other places.
◼ Application : Suitable for processing harder materials such as stainless steel and high-hardness steel, often used in scenarios with medium hardness and high wear resistance requirements.
◼ Future development : Cobalt steel may retain a market in specific applications in the future, but as carbide and ceramic materials become more popular, its demand may gradually decrease.
 

3. Carbide

◼ Obtain : Cemented carbide is mostly made of tungsten powder, tungsten carbide powder and cobalt powder sintered at high temperature through powder metallurgy method.
◼ Features : Extremely high hardness, excellent heat resistance and wear resistance, suitable for high-speed milling and processing of difficult-to-cut materials, and can maintain stability under high temperature conditions, which makes it suitable for CNC automated processing with high precision requirements.
◼ Hardness : The hardness can reach above HRC 75.
◼ Ingredients : Tungsten (about 70%), tungsten carbide (about 20%), cobalt (10%-15%), etc.
◼ Origin : Germany, the United States, and China are the main origins.
◼ Application : Suitable for materials that cannot be processed by high-speed steel, such as hardened steel, stainless steel, aluminum alloys, cast iron, titanium alloys, high-temperature alloys and other medium and high hardness materials, nickel-based alloys, etc., which are widely used in aerospace and automobile manufacturing industries.
◼ Future applications : Cemented carbide has extremely high application potential, especially in industries where the demand for high-strength material processing continues to grow, and it is expected to expand to more industrial fields in the future.
 

4. Ceramic

◼ Obtain : The manufacturing of ceramic materials mainly involves high-temperature sintering of ceramic powders such as alumina, zirconia, and silicon nitride, and the microstructure and hardness are controlled through specialized processes.
◼ Features : Extremely high hardness and heat resistance, suitable for high-speed processing, but brittle and easy to crack.
◼ Hardness : The hardness can reach above HRA 90.
◼ Ingredients : The main ingredients are alumina, zirconium oxide, silicon nitride, etc.
◼ Origin : Mainly produced in countries with advanced material technology such as Japan and the United States.
◼ Application : Ceramic cutting tools are suitable for high-temperature machining and dry cutting. They are often used to process cast iron, heat-resistant alloys, etc., and are suitable for precision and high-speed machining applications.
◼ Future applications : With the development of dry cutting technology, ceramic cutting tools have potential in reducing the use of coolant and improving environmental benefits. It is expected that their applications will be expanded in the aviation and aerospace fields in the future.
 

5. Diamond Coating

◼ Obtain : Diamond coating deposits a micron-sized diamond film on carbide tools through chemical vapor deposition technology (CVD).
◼ Features : It has extremely high hardness and wear resistance, can easily handle extremely hard materials, and is suitable for cutting difficult-to-machine materials such as carbon fiber and composite materials. Due to the high cost, diamond-coated knives are mostly used for processing high-precision and high-value-added materials. And maintain extremely high cutting accuracy.
◼ Hardness : The hardness can reach above HRA 90, which is close to natural diamonds.
◼ Ingredients : The main ingredient is pure carbon, coated in the form of artificial diamond.
◼ Origin : Japan, Switzerland and other high-precision manufacturing powers.
◼ Application : Suitable for processing super-hard and brittle materials such as carbon fiber, ceramics, and glass, and used in precision processing and electronic product manufacturing.
◼ Future applications : With the popularization of high-tech materials, the demand for diamond-coated cutting tools may increase, especially in advanced manufacturing such as 5G equipment, solar energy and LED industry applications.
 

Summary--

The common advantage of high-speed tool steel is that it is cheaper and easier to buy than carbide, but high-speed tool steel is more sensitive to heat and more flexible than carbide, so it wears faster and the machining accuracy is slightly lower, etc. Material differences will be adjusted due to end mill processing material requirements, speed requirements and cost-effectiveness considerations. In the future, with the development of emerging materials and manufacturing technologies, especially the increase in the application of green manufacturing and high-hardness materials, cemented carbide The market demand for , ceramic and diamond-coated cutting tools is expected to continue to grow.

[B]--Three common materials

Currently, among end mill materials, the three most commonly used materials are high-speed steel (HSS), carbide (Carbide) and ceramic (Ceramic). Each of these three materials has different characteristics, advantages and application scenarios, and is suitable for different processing needs. The following is their comparison and analysis :
 

1. HSS, High-Speed ​​Steel

Features : High-speed steel has good toughness and impact resistance, is easy to regrind, and is relatively affordable. Although its wear resistance and heat resistance are not as good as carbide, it performs stably in low to medium speed processing.

◼ Advantages :
☐ Low cost and suitable for mass production.
☐ It can be re-sharpened multiple times to extend the service life of the tool.
☐ High toughness, suitable for processing soft materials.

◼ Disadvantages :
☐ Limited heat resistance and hardness, not suitable for high-speed processing.
☐ When machining harder materials, tool life is shorter.
☐ Scope of application: Suitable for processing soft materials such as low carbon steel, copper, aluminum alloys, etc., especially suitable for small and medium-sized workshops and scenarios with high cost control requirements.

2. Carbide

Features: Carbide end mills have high hardness, good wear resistance, and can maintain stable cutting performance at high speeds and high temperatures. They are currently the most widely used milling cutter material in industry.​

◼ Advantages:
☐ Extremely high hardness and wear resistance, suitable for high-speed and high-precision processing.
☐ It can process hard materials such as stainless steel, titanium alloy, etc., and has good high temperature stability.
☐ High processing efficiency, suitable for high output and automated processing.

◼ Disadvantages:
☐ Its toughness is not as good as high-speed steel and it is brittle, especially under heavy load or strong impact conditions.
☐ The price is higher and the initial investment cost is large.
☐ Scope of application: Suitable for high-speed processing of stainless steel, hardened steel, aluminum alloy, high-temperature alloy and other materials. It is widely used in automobiles, aerospace and other industrial fields that require high processing accuracy and efficiency.

3. Ceramic

Features: Ceramic cutting tools have extremely high hardness and heat resistance and are suitable for high-speed cutting at high temperatures. However, they are brittle and susceptible to impact damage. Suitable for use in dry cutting without coolant.​

◼ Advantages:
☐ High temperature resistance, suitable for high-speed cutting, and can maintain good performance even without the use of coolant.
☐ High hardness, suitable for processing cast iron, heat-resistant alloys and other materials, and can provide high-precision cutting.

◼ Disadvantages:
☐ Poor toughness and low tolerance to vibration and impact.
☐ The price is relatively high and not suitable for the processing needs of general materials.
☐ Scope of application: Often used for processing high-hardness materials such as heat-resistant alloys and cast iron, and suitable for high-precision applications in high-demand industrial fields such as aerospace and precision manufacturing.
 

4. Comparison and Summary

5. Analysis

The three materials of high-speed steel, cemented carbide and ceramics meet different market needs : 

◼ High-speed steel is an economical choice, suitable for small and medium-sized enterprises and ordinary steel processing, and suitable for workshops with cost control.
◼ Carbide provides high-speed, high-precision machining performance and is widely used in industries with high efficiency and precision requirements. It is currently the most commonly used end mill material in industry.
◼ Ceramic cutting tools are potential players in the fields of dry cutting and high-temperature-resistant and high-hardness material processing in the future. As the demand for high precision and environmental protection grows, they may become an important choice for specific high-end applications.
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In the future, these materials will expand their applications based on technological advancements and changes in industry needs.

[C]--The influence of CNC

1. High speed steel

Influence on CNC machining :
◼ Cutting speed : Due to limited heat resistance, high-speed steel milling cutters are not suitable for high-speed cutting in CNC and are usually used for medium and low-speed machining.
◼ Processing accuracy : It can achieve medium precision, but the tool wears quickly, so it is suitable for occasions with low demand for one-time large-volume processing.
◼ Tool life : Tool life is relatively short and is prone to wear especially when processing materials with higher hardness.
 

2. Carbide

Influence on CNC machining :
◼ Cutting speed: Carbide can support higher cutting speeds and feed rates, improve the efficiency of CNC machining, and is suitable for high-speed and precision machining.
◼ Machining accuracy: Carbide cutting tools can maintain stable cutting performance, are suitable for high-precision processing, and are not easily deformed in high-temperature environments, making them suitable for a variety of automation and mass production scenarios.
◼ Tool life: Carbide has a long life and is suitable for long-lasting machining, especially on high-hardness materials. However, it is sensitive to vibration and requires stable CNC settings.

3. Ceramics
Influence on CNC machining :
◼ Cutting speed: Suitable for ultra-high-speed cutting, which can significantly shorten processing time. Due to its high temperature resistance, it can reduce the use of coolant, especially in dry cutting.
◼ Processing accuracy: Suitable for high-precision and smooth processing, but it is relatively brittle and requires stable CNC equipment and avoidance of strong impact.
◼ Tool life: When machining hard materials or heat-resistant alloys, ceramic tools have a longer life, but are more brittle and easy to break, so they are usually used in stable, low-vibration CNC machining.
 

4. Diamond Coating

Influence on CNC machining :
◼ Cutting speed: Supports extremely high cutting speed and feed rate, with high processing efficiency.
◼ Processing accuracy: Extremely high surface finish and precision can be achieved when processing composite materials.
◼ Tool life: The tool life is extremely long, especially in the processing of extremely hard materials, but care must be taken to avoid large impacts and strong vibrations.
 

5. Material influence in CNC machining

In CNC machining, choosing the appropriate tool material can directly affect the processing speed, accuracy, surface quality and tool durability. When processing workpieces with higher hardness, tool materials with high hardness and strong heat resistance are suitable; while when processing soft materials, materials with lower cost and better toughness can be used.

Additionally, material selection affects CNC settings such as feed rates, depth of cut, and coolant usage. For example, when using ceramic tools, you can choose dry cutting to reduce costs; when using high-speed steel tools, moderate cooling is required to extend tool life. In general, the selection of milling cutter materials needs to be based on the workpiece material, processing conditions and accuracy requirements. Decision, choosing the appropriate tool material can greatly improve the production efficiency and finished product quality of CNC machining.
 

D. Conclusion, the influence of materials on milling cutters

1. Surface treatment technology of tool materials

Different coatings affect the heat resistance, wear resistance and friction coefficient of milling cutters.

2. Adaptability of tool geometry and material

Geometric design (such as cutting angle, helix angle, number of cutting edges) will further affect the machining effect.

3. Matching of materials and processing conditions

Such as cutting speed and feed rate, coolant, durability and hardness, etc., as well as the material being processed.

4. The relationship between milling cutter material and workpiece surface quality

The performance of tool materials not only affects cutting efficiency, but also directly affects the surface finish of the workpiece.

5. Digitization and intelligence of cutting tools

Embedded sensors monitor tool wear and processing conditions in real time to improve the accuracy and efficiency of automated processing. Develop an AI-based tool selection and processing parameter optimization system.

6. Environmental protection and sustainable development

Develop tool materials with low environmental impact and reduce the use of rare metals such as cobalt.
Develop reusable or recycled tools to reduce production costs and resource waste.

7. Conclusion

The selection of milling cutter materials is a multi-dimensional consideration. In addition to the hardness, heat resistance and toughness of the cutter itself, the material of the workpiece to be processed, cutting conditions and final processing requirements also need to be comprehensively considered. At the same time, technological progress and attention to the environment are promoting continuous innovation in tool materials and processing technology, which provides more possibilities for improving processing efficiency and quality in the future.