CNC machining parts will undergo deformation during processing, which directly affects the surface quality and machining accuracy of the parts. If the control is not good and even causes the parts to be scrapped, a good solution is to fundamentally prevent deformation of CNC machining parts. So what is the reason for the deformation of CNC machining parts?
1. The influence of material and structure of workpieces on workpiece deformation
The magnitude of deformation, as well as the complexity of shape, length, width, and wall thickness, is directly proportional to the rigidity and stability of the material. Generally, when designing parts, it is necessary to reduce the influence of these factors on the deformation of the workpiece. Especially in the structure of some larger parts, it is necessary to achieve a reasonable structure. During mechanical processing, it is necessary to control defects such as hardness and looseness of the blank to ensure its quality and reduce workpiece deformation.
2. Deformation caused by workpiece processing
During the cutting process, the workpiece undergoes elastic deformation towards the direction of cutting force due to the action of cutting force, which is known as the phenomenon of cutting tools. For similar deformations, corresponding measures can be taken on the tool. During precision machining, the tool should be sharp, which can reduce the resistance formed by the friction between the tool and the workpiece. On the other hand, it can improve the heat dissipation ability of the tool when cutting the workpiece, thereby reducing residual internal stress on the workpiece.
The heat generated by the friction between the cutting tool and the workpiece during processing can also cause deformation of the workpiece, so high-speed cutting is generally chosen. In this type of machining, due to the removal of chips in a relatively short period of time, the vast majority of cutting heat is carried away by the chips, which can effectively reduce deformation.
To ensure the accuracy of the parts, reasonable cutting amounts need to be used during the machining process. When machining thin-walled parts with high precision requirements, symmetrical machining is generally adopted to balance the stress generated on the opposite sides and achieve a stable state. After machining, the workpiece is flat.
3. Deformation caused by workpiece clamping
When clamping the workpiece, it is necessary to select the correct clamping point and select the appropriate clamping force at that position. Therefore, it is necessary to maintain consistency between the clamping point and the support point, so that the clamping force acts on the support. The clamping point should be as close as possible to the machining surface, and the position where the force is less likely to cause clamping deformation should be selected.
When there are several directions of clamping forces acting on the workpiece, the order of clamping forces needs to be adjusted. For the clamping force that makes the workpiece contact the support, it should be applied first and not too large. For the main clamping force that balances the cutting force, it should be applied last.
Secondly, it is necessary to increase the contact area between the workpiece and the fixture, as well as the axial clamping force used. Enhancing the rigidity of the parts is very effective in solving clamping deformation. However, due to the shape and structural characteristics of thin-walled parts, they may have lower rigidity. Under the action of clamping force, deformation will occur.
The entire machining process of CNC machining parts is automatically controlled by the program and is not affected by human factors of the operator. At the same time, there is no hardware such as cams and molds, which eliminates errors caused by wear and tear during manufacturing and use. In addition, the position compensation function of the machine tool, high positioning accuracy, and repeated positioning accuracy result in good dimensional consistency of the processed parts. This is particularly advantageous for batch and mass production.
