In CNC machining of precision parts, workpiece vibration is a key factor affecting machining quality. Vibration not only leads to out-of-tolerance surface roughness and reduced dimensional accuracy, but can also cause accelerated tool wear and increased machining noise, severely restricting the machining quality of precision parts. Therefore, taking effective measures to prevent workpiece vibration is crucial for improving the level of CNC machining of precision parts.
The rigidity of the workpiece itself is an important factor affecting vibration. If the workpiece rigidity is insufficient during CNC machining of precision parts, it is prone to vibration under cutting forces. To enhance workpiece rigidity, the workpiece structure can be optimized, such as by adding reinforcing ribs and rationally arranging the positions of holes, so that the workpiece can better maintain its shape stability under stress. Simultaneously, when clamping the workpiece, it is essential to ensure good contact between the workpiece and the fixture, increasing the contact area. This can be achieved by adding auxiliary supports and using soft jaws, providing more stable support for the workpiece during machining and reducing vibration caused by insufficient rigidity.
The selection and design of the fixture plays a crucial role in preventing workpiece vibration. A suitable fixture can accurately position and firmly clamp the workpiece, effectively transmit cutting forces, and prevent workpiece displacement or vibration during machining. In CNC machining of precision parts, a dedicated fixture or a customized fixture should be selected based on the workpiece's shape, size, and machining requirements. For example, for thin-walled parts with complex shapes, a vacuum chuck fixture can be used to uniformly fix the workpiece using vacuum suction, reducing vibration caused by uneven clamping forces. For shaft parts, a three-jaw self-centering chuck with a center can be used to improve the workpiece's clamping rigidity and stability.
Proper setting of tool parameters is also crucial for preventing workpiece vibration. Tool geometry parameters, such as rake angle, clearance angle, principal cutting edge angle, and secondary cutting edge angle, directly affect the distribution and magnitude of cutting forces. In CNC machining of precision parts, appropriately increasing the tool rake angle can reduce cutting deformation and cutting forces, lowering the likelihood of vibration. Properly selecting the principal and secondary cutting edge angles can improve the working conditions of the cutting edge, making the cutting process smoother. Furthermore, the wear condition of the cutting tool also affects vibration. Severely worn tools experience increased cutting forces, easily leading to vibration. Therefore, worn tools should be replaced promptly to ensure they are in good cutting condition.
The selection of cutting parameters has a significant impact on workpiece vibration. A proper combination of parameters such as cutting speed, feed rate, and depth of cut can control the magnitude and variation of cutting forces. In CNC machining of precision parts, excessively large cutting parameters are generally not advisable, as excessively high cutting speeds and feed rates will cause a sharp increase in cutting forces, leading to intensified workpiece vibration. Appropriate cutting parameters should be determined through experimentation and experience based on the workpiece material, tool material, and machining accuracy requirements to effectively suppress workpiece vibration while ensuring machining efficiency.
The performance of the CNC machine tool itself also has a significant impact on preventing workpiece vibration. The rigidity and dynamic characteristics of the machine tool determine its stability during the cutting process. A highly rigid machine tool structure can better withstand cutting forces, reducing the impact of machine tool vibration on the workpiece. Simultaneously, the accuracy and stability of the machine tool's transmission system, spindle system, etc., are also crucial. Regular maintenance of machine tools, including inspection and adjustment of all components, ensures they are in good operating condition and helps reduce the likelihood of workpiece vibration.
In CNC machining of precision parts, preventing workpiece vibration requires a comprehensive and systematic approach, considering factors such as workpiece rigidity, fixture design, tool parameters, cutting parameters, and machine tool performance. Only in this way can workpiece vibration be effectively reduced, improving the machining quality and production efficiency of precision parts, and meeting the requirements of high-precision machining.
