In addition to the above-mentioned reasons, parts of aluminum materials are deformed during processing. In actual operation, the operation method is also very important.
1. For parts with large machining allowance, in order to have better heat dissipation conditions during processing and avoid heat concentration, symmetrical processing should be used during processing. If there is a 90mm thick sheet that needs to be processed to 60mm, if one side is milled immediately, the other side will be milled immediately. Once processed to the final size, the flatness will be 5mm; if repeated feed symmetrical processing is used, each side will be processed twice The final size can ensure that the flatness reaches 0.3mm.
2. If there are multiple cavities on the plate part, it is not advisable to use the sequential processing method of one cavity and one cavity during processing, as it is easy to cause deformation of the parts due to uneven stress. Multiple layers are used for processing, each layer is processed to all the cavity as much as possible, and then the next layer is processed to make the parts evenly stressed and reduce deformation.
3. Reduce the cutting force and cutting heat by changing the cutting amount. Among the three elements of cutting consumption, the amount of back-feeding has a great influence on the cutting force. If the machining allowance is too large, the cutting force of one pass is too large, which will not only deform the parts, but also affect the rigidity of the machine tool spindle and reduce the durability of the tool. If you reduce the amount of back-eating knife, it will greatly reduce production efficiency. However, high-speed milling in CNC machining can overcome this problem. While reducing the amount of back-feeding, as long as the feed is increased accordingly and the speed of the machine is increased, the cutting force can be reduced while ensuring the processing efficiency.
4. Pay attention to the order of cutting. Rough machining emphasizes the improvement of machining efficiency, and the removal rate per unit time is pursued. Generally, reverse milling can be used. That is to cut off the excess material on the surface of the blank at the fastest speed and the shortest time, and basically form the geometric contour required for finishing. The emphasis on finishing is high precision and high quality, and it is appropriate to use down milling. Because the cutting thickness of the cutter teeth gradually decreases from maximum to zero during down-milling, the degree of work hardening is greatly reduced, and at the same time, the degree of deformation of the parts is reduced.
5. Thin-walled workpieces are deformed due to clamping during processing, and even finishing is unavoidable. In order to reduce the deformation of the workpiece to a minimum, the clamping piece can be loosened a little before finishing to reach the final size, so that the workpiece can be freely restored to its original state, and then slightly compressed, as long as the workpiece can be clamped (complete With the feel), this can get the ideal processing effect. In short, the point of action of the clamping force is best on the support surface. The clamping force should act on the direction of the workpiece rigidity. On the premise of ensuring that the workpiece is not loose, the smaller the clamping force, the better.
6. When processing parts with cavity, try not to let the milling cutter directly pierce the part like a drill bit when processing the cavity, resulting in insufficient space for the chip of the milling cutter and unsmooth chip removal, resulting in overheating, expansion and collapse Knife, broken knife and other adverse phenomena. The drill hole should be drilled with a drill of the same size or one size larger than the milling cutter, and then milled with the milling cutter. Alternatively, the CAM software can be used to produce the screw-down knife program.