Processing characteristics of stainless steel
As a metal material widely used in various industries, stainless steel has unique characteristics in its processing. These characteristics are closely related to its own physical and chemical properties, and also bring many challenges to the processing technology. First of all, stainless steel has high plasticity and toughness. During cutting, the chips are not easy to break, and often form continuous ribbon-like chips. This will not only wrap around the tool and the workpiece, affecting the continuity of the processing, but may also scratch the surface of the workpiece and reduce the surface quality. For example, when turning stainless steel bars, if the tool angle is not selected properly, the chips will follow the tool like a long “ribbon” and rotate. The operator needs to stop and clean it frequently, which seriously affects the processing efficiency. At the same time, the high plasticity makes stainless steel prone to large plastic deformation during processing, resulting in significant work hardening. That is, the hardness of the processed surface will be significantly higher than the hardness of the substrate. This will increase the difficulty of subsequent cutting processing, require greater cutting force, and also aggravate the wear of the tool.
Stainless steel’s poor thermal conductivity is another notable characteristic of its machining. Compared to ordinary carbon steel, stainless steel’s thermal conductivity is typically only one-third to one-half that of carbon steel. During cutting, the significant amount of cutting heat generated cannot be dissipated promptly through the workpiece and chips. Most of the heat is concentrated in the cutting area and tool, causing the tool temperature to rise sharply. Excessive temperatures can reduce the hardness and wear resistance of the tool material, accelerate tool wear, and even cause thermal deformation of the tool, affecting machining accuracy. For example, when milling stainless steel sheets, if cooling is insufficient, the milling cutter will quickly become dull due to the high temperature, resulting in noticeable tool marks on the surface of the workpiece. To address this issue, effective cooling measures must be implemented during the machining process, such as using a high-pressure cooling system that sprays cooling lubricant directly into the cutting area to reduce cutting temperatures and extend tool life.
Stainless steel contains a high proportion of alloying elements such as chromium and nickel. These elements contribute to its excellent corrosion resistance, but also increase its strength and hardness, increasing its cutting resistance. CNC Machining stainless steel requires significantly greater cutting forces than machining ordinary carbon steel, placing higher demands on the rigidity and power output of the machining equipment. If the machine tool lacks rigidity, the high cutting forces will cause vibration, which not only affects machining accuracy but also increases tool wear. Furthermore, the alloying elements in stainless steel can chemically react with the tool material, forming a bond at high temperatures. This causes the tool surface to adhere to the workpiece material, reducing cutting performance and causing defects such as tearing and strain on the machined surface. Therefore, when machining stainless steel, tool materials with excellent wear resistance and strong adhesion resistance, such as cemented carbide and ceramic tools, are typically used.
Stainless steel requires high surface quality, which is also one of its processing characteristics. Since stainless steel is often used in fields with strict surface quality requirements such as food processing, medical equipment, and chemical containers, its surface must not only have good smoothness, but also avoid defects such as scratches, dents, and oxidation color. During the cutting process, tool wear, cutting parameter selection, and the use of cooling and lubricating fluids will have a direct impact on surface quality. For example, when the tool wears to a certain extent, its cutting edge becomes blunt and will leave obvious scratches on the workpiece surface; if the feed rate is too large, the roughness value of the workpiece surface will increase; insufficient or poor quality cooling and lubricating fluid will cause oxidation color on the workpiece surface. Therefore, in order to ensure the surface processing quality of stainless steel, it is necessary to reasonably select tools and cutting parameters, strengthen cooling and lubrication, and monitor the surface quality in real time during the processing process.
Stainless steel processing technology has poor adaptability, and different types of stainless steel have significant differences in processing performance, which brings certain difficulties to the development of processing technology. For example, austenitic stainless steel has good plasticity and toughness, but severe work hardening and poor thermal conductivity; martensitic stainless steel has high hardness and low toughness, and is prone to cracking during processing; ferritic stainless steel is highly brittle and prone to chipping during cutting. Therefore, when processing different types of stainless steel, it is necessary to develop corresponding processing technologies based on their specific properties, such as selecting different tool materials, cutting parameters, and cooling methods. At the same time, stainless steel processing is also affected by the structure of the part. Stainless steel parts with special structures such as complex shapes, thin walls, and slender structures are prone to deformation during processing, requiring special clamping methods and processing technologies to ensure the processing accuracy and quality of the parts.
