In the process of CNC machining metal housing, the choice of clamping method directly affects the positioning accuracy, processing stability and final product quality of the workpiece. Since the shapes, sizes and materials of CNC machining metal housing are different, there are many suitable clamping methods. Reasonable selection of clamping methods can not only ensure the smooth progress of the processing process, but also effectively improve production efficiency and avoid processing errors and safety hazards caused by improper clamping.
Three-jaw chuck clamping is a common and basic method. This clamping method is suitable for circular or nearly circular CNC machining metal housing. Its three jaws can move synchronously to the center and automatically center and clamp the workpiece. The contact surface between the jaws and the workpiece is adjusted by thread to adapt to parts of different diameters. When processing small CNC machining metal housing, the three-jaw chuck can quickly complete the clamping, reduce auxiliary time, and has high positioning accuracy. For CNC machining metal housing with harder materials, the clamping force of the three-jaw chuck is sufficient to ensure that the workpiece does not move during the processing, especially for the processing of rotating surfaces such as outer circles and inner holes. However, this method also has limitations. For irregular or eccentric workpieces, the three-jaw chuck may not be able to achieve stable clamping.
Four-jaw chuck clamping is suitable for CNC machining metal housings with complex shapes, asymmetric or eccentric shapes. Unlike the three-jaw chuck, the four jaws of the four-jaw chuck move independently. By adjusting the position of the jaws separately, the workpiece can be accurately positioned to the required position. When machining square, oval or CNC machining metal housings with special contours, the four-jaw chuck can be clamped according to the shape of the workpiece to ensure that the machining datum is consistent with the design datum. However, the four-jaw chuck clamping has high technical requirements for the operator, and it takes more time to align and adjust, and the uniformity of the clamping force is difficult to control. If the operation is improper, it is easy to cause the workpiece to tilt or deform during the machining process.
Flat-nose pliers clamping is often used for small and medium-sized, flat CNC machining metal housings. The flat-nose pliers drive the movable jaws to move through the screw nut mechanism to clamp the workpiece. When clamping, the workpiece is placed between the jaws. By adjusting the jaw spacing and using auxiliary tools such as shims, the workpiece surface can be ensured to be parallel or perpendicular to the workbench to meet the positioning requirements of different processing directions. For CNC machining metal housings that require plane milling, drilling and other processing, flat-nose pliers are simple and convenient to clamp, and can ensure high clamping accuracy. However, due to the limited clamping force of flat-nose pliers, it may not provide sufficient clamping force for large or heavy CNC machining metal housings. At the same time, its clamping range is also limited by the size of the jaws.
Pressure plate bolt clamping is an effective clamping method for large or irregular shaped CNC machining metal housings. This method uses pressure plates, bolts and shims to fix the workpiece on the workbench. When clamping, according to the shape of the workpiece and the processing part, the positions of the pressure plates and bolts are reasonably arranged, and the pressure plates are tightened by tightening the bolts to clamp the workpiece. The advantage of pressure plate bolt clamping is that it has strong adaptability, can fix CNC machining metal housings of various sizes and shapes, and has a large clamping force to meet the needs of heavy cutting processing. However, this clamping method has a cumbersome clamping process, and it is necessary to repeatedly adjust the position and tightness of the pressure plate and bolts to ensure that the workpiece is accurately positioned and evenly stressed, and at the same time, avoid interference of the pressure plate with the processing part.
Magnetic chuck clamping is suitable for small CNC machining metal housings made of ferromagnetic metal. The magnetic chuck generates suction through electromagnetic or permanent magnetic principles to adsorb the workpiece on the surface of the chuck. When clamping, just place the workpiece on the chuck and turn on the magnetic switch to complete the clamping. The operation is simple and quick, which greatly shortens the clamping time. The advantage of magnetic chuck clamping is that the clamping surface is flat and will not cause indentations on the workpiece surface. It is suitable for CNC machining metal housing processing with high surface quality requirements. But it also has limitations. On the one hand, it can only be used for ferromagnetic metal materials, and cannot be used for non-magnetic materials such as stainless steel and aluminum alloy; on the other hand, the magnetic suction force is limited. For processing procedures with large cutting forces, it may not provide sufficient clamping force, resulting in workpiece displacement.
Special fixture clamping is designed for CNC machining metal housings with specific shapes or mass production. Special fixtures are customized according to the shape, processing requirements and positioning reference of the workpiece, and can achieve fast and accurate clamping. When batch processing CNC machining metal housing, special fixtures can ensure the consistency of the clamping position and posture of each workpiece, thereby improving the consistency of machining accuracy and production efficiency. Special fixtures usually use positioning pins, positioning blocks and other components to position the workpiece, and achieve rapid clamping through pneumatic, hydraulic or manual clamping mechanisms. Although the design and manufacture of special fixtures require a certain cost and time, for mass production, it can significantly reduce the clamping time and scrap rate, and has high economic benefits in the long run.
Combination fixture clamping is a flexible and changeable clamping method, which is composed of a series of standardized and modular components. According to the processing requirements of CNC machining metal housing, fixtures of different structures can be quickly assembled. These components include positioning components, clamping components, support components, etc., which are combined by bolts, pins and other connectors. The advantage of the combination fixture is that it can be reused, and there is no need to design a fixture for each workpiece separately, which greatly reduces the cost and time of fixture manufacturing. For new product development or small batch production of CNC machining metal housing processing, modular fixtures can quickly respond to different clamping requirements and have strong adaptability. However, the assembly of modular fixtures requires certain technical experience. If the components are not combined properly, the rigidity and positioning accuracy of the fixture may be affected.
