1. Optimizing cutting parameters
The reasonable selection of cutting parameters is an important means to deal with the phenomenon of work hardening. In CNC precision metal processing, the three main parameters of cutting speed, feed rate and cutting depth are interrelated and affect the degree of work hardening. Higher cutting speed helps to reduce the contact time between the tool and the workpiece, thereby reducing the depth of the work hardening layer. However, too high a cutting speed may lead to other problems such as increased tool wear, so it is necessary to determine the appropriate range according to the type of metal material and tool performance. In terms of feed rate, an appropriate increase in feed rate can reduce the extrusion of the tool on the workpiece, thereby reducing the degree of work hardening. However, excessive feed rate may affect the processing accuracy and surface quality. The cutting depth also needs to be carefully selected to avoid excessive deformation of the metal due to excessive cutting depth and severe work hardening. Through a large number of experiments and simulations, the best combination of cutting parameters for different metal materials is found to effectively control the work hardening phenomenon.
2. Choose the right tool
The choice of tool is crucial to deal with work hardening. The material, geometry and coating of the tool will affect the stress distribution and metal deformation during processing. First of all, the tool material should have high hardness, high wear resistance and good thermal hardness. For example, carbide tools perform well in many precision metal processing. From the perspective of tool geometry, the reasonable design of tool parameters such as rake angle, back angle, and rake angle can change the direction and size of the cutting force. A larger rake angle can reduce the cutting force, thereby reducing the degree of metal deformation and reducing the possibility of work hardening. In addition, tool coatings can improve the wear resistance and lubricity of tools. For example, tools with TiN (titanium nitride) coatings can reduce the friction between the tool and the workpiece during the cutting process, reduce the generation of cutting heat, and thus reduce the work hardening phenomenon.
3. Use appropriate cooling and lubrication methods
In CNC precision metal processing, cooling and lubrication play an important role in dealing with work hardening. Effective cooling can reduce the temperature of the cutting area and reduce work hardening caused by thermal deformation. For example, using cooling lubricants such as emulsions and cutting oils can absorb and take away a lot of heat generated during the cutting process. At the same time, these cooling lubricants can also play a lubricating role and reduce the friction between the tool and the workpiece. By reducing friction, the cutting force can be reduced, thereby reducing the plastic deformation of the metal and inhibiting the occurrence of work hardening. In addition, the use of micro-lubrication technology (MQL) can accurately spray a small amount of lubricating oil mist to the cutting area, which can not only achieve good lubrication and cooling effects, but also reduce the use of coolant and subsequent processing costs.
4. Reasonable processing sequence
Planning a reasonable processing sequence is also an effective way to deal with the phenomenon of work hardening. For precision metal parts with complex shapes, a step-by-step processing method can be adopted. For example, rough machining is performed first, most of the allowance is removed with a larger cutting allowance, and then semi-finishing and finishing are performed. During the rough machining process, although a certain work hardening layer will be generated, due to the subsequent processing steps, these hardened layers can be removed or their effects can be reduced in the subsequent semi-finishing and finishing. At the same time, during the processing process, some heat treatment processes, such as stress relief annealing, can be appropriately interspersed. Stress relief annealing can eliminate the internal stress generated during the processing, reduce the hardness of the metal, and improve the processing performance of the metal, thereby reducing the work hardening phenomenon in the subsequent processing steps.
