Which material is the most difficult to CNC machine?

In the field of CNC machining, there are a variety of metal materials. Some materials, due to their unique physical and chemical properties, will bring great challenges to the machining process. To determine whether a material is difficult to CNC machine, it is necessary to comprehensively consider multiple factors such as its hardness, strength, toughness, thermal conductivity, chemical activity, and performance during machining. Among the many metal materials, several materials have attracted much attention due to their extremely high difficulty in machining.

Titanium alloys are widely used in aerospace, medical equipment and other fields, but their CNC processing is extremely difficult.

From the perspective of physical properties, titanium alloys have high strength and can still maintain high strength at high temperatures, which greatly increases the cutting force during processing and puts a huge load on the tool. At the same time, its thermal conductivity is very poor, only 1/5 of steel and 1/10 of aluminum. The heat generated by cutting is difficult to dissipate. A large amount of heat is concentrated in the cutting area, which will cause the tool temperature to rise sharply and accelerate tool wear.

Moreover, titanium alloys have strong chemical activity and are prone to chemical reactions with tool materials at high temperatures, resulting in tool sticking, which not only affects the surface quality of the parts, but also further aggravates tool wear. For example, when processing high-strength titanium alloys such as TC4, the tool life is often very short, the processing efficiency is also low, and the rigidity and stability requirements of the processing equipment are also very high.

High-temperature alloys are mainly used for parts in high-temperature working environments such as aircraft engines and gas turbines, and their processing difficulty can be described as "hard core".

High-temperature alloys have excellent high-temperature strength and oxidation resistance, but this also makes them have high hardness and strength at room temperature, and have high cutting resistance during processing. Its plasticity and toughness are also very good, and it is easy to produce large plastic deformation during processing, resulting in increased deformation resistance in the cutting area.

In addition, the work hardening phenomenon of high-temperature alloys is extremely serious, and the hardness of the processed surface will be much higher than the hardness of the matrix, which will make subsequent cutting more difficult and increase tool wear. At the same time, its thermal conductivity is poor, and the cutting heat is concentrated at the tip of the tool, which can easily cause the tool to overheat and fail. For a typical nickel-based high-temperature alloy like Inconel 718, the tool wear rate during processing is several times that of ordinary steel, and there are extremely demanding requirements for the selection of tool materials and cutting parameters.

Ultra-high strength steel is widely used in fields with extremely high strength requirements, such as automotive safety parts and aerospace structural parts, but its CNC processing also faces huge challenges.

This type of steel has extremely high hardness and strength. The hardness of some varieties can reach HRC50 or above. The cutting force during processing is very large, which places extremely high requirements on the hardness and wear resistance of the tool. Moreover, ultra-high strength steel has good toughness, and it is easy to produce continuous chips during cutting, which is difficult to break, affecting the smooth progress of processing and the surface quality of parts.

The large amount of heat generated during the processing is also difficult to dissipate, which can easily cause the tool to overheat and reduce the service life of the tool. At the same time, due to the excessive hardness of the material, vibration is easy to occur during processing, affecting the processing accuracy, and the processing equipment needs to have sufficient rigidity and vibration resistance.

As a new type of high-temperature structural material, titanium-aluminum intermetallic compounds have broad application prospects in the aerospace field, but their CNC processing is more difficult than expected.

This material has high high-temperature strength and oxidation resistance, but it is brittle at room temperature and has a high hardness, which makes it easy to crack during processing. Its thermal conductivity is worse than that of titanium alloy, and it is more difficult to dissipate cutting heat, resulting in a huge heat load on the tool.

Moreover, the fracture toughness of titanium-aluminum intermetallic compounds is low. When subjected to cutting force during processing, it is easy to crack, which not only damages the parts, but also causes a huge impact on the tool, making the tool extremely easy to break. At present, the processing technology for this material is still being explored and improved.5. Key strategies for dealing with difficult-to-process materials

In the face of these difficult-to-process materials, there is no way out. Targeted strategies need to be adopted from multiple aspects:

• Tool selection: Select tool materials with high hardness, good wear resistance, high temperature resistance and strong chemical stability, such as ultra-fine grain cemented carbide, cubic boron nitride (CBN), ceramic tools, etc., and select appropriate tool geometry parameters according to material properties.

• Cutting parameter optimization: Use lower cutting speed, appropriate feed rate and cutting depth to reduce cutting heat generation and tool wear. At the same time, through cooling and lubrication systems, such as high-pressure cooling and oil mist lubrication, the temperature of the cutting zone can be effectively reduced and the cutting conditions can be improved.

• Processing technology improvement: For parts with complex shapes, process methods such as step-by-step processing and high-speed processing can be used to reduce vibration and deformation during processing. In addition, proper heat treatment of parts to improve the processing performance of materials can also reduce the difficulty of processing.

• Equipment guarantee: Use CNC processing equipment with good rigidity, high precision and strong stability to meet the high requirements of difficult-to-process materials for processing equipment.

Although these difficult-to-process materials bring many challenges to CNC machining, they play an irreplaceable role in high-end fields such as aerospace and auto parts. If your project involves these difficult-to-process materials, or you have questions about the difficulty of processing a certain material, please feel free to contact us. We have rich experience in CNC machining of difficult-to-process materials, advanced processing equipment and a professional technical team. We can provide you with customized processing solutions to help you overcome processing problems and smoothly advance your project.