Aluminum precision parts and products are popular for their light weight and beautiful appearance, and are widely used in industry and daily necessities. With the continuous progress of science and technology, people's demand for product diversity is increasingly strong. Therefore, the process requirements of aluminum alloy products are higher and higher, and the market demand is also higher and higher. In order to meet people's demand for the diversity and high quality of aluminum alloy shell products, aluminum alloy CNC processing manufacturers summarized the process skills and the problems needing attention in aluminum CNC processing.
1. Select appropriate processing method
Numerical control cutting is a kind of streamline cutting processing method, and is also a common process of aluminum precision processing. I am using an end mill with multi-directional cutting capability, spiral cutting interpolation and contour cutting interpolation. Process fewer holes with fewer tools.
2. Ball end milling cutter can cooperate with spiral interpolation to continuously process taper holes
Ball end mills and screw interpolation drills can be used for boring and chamfering. The end milling cutter can cooperate with contour cutting interpolation for semi finishing of holes and machining of precision parts. The end milling cutter used for thread processing can be used with screw interpolation to process various threaded holes.
Tool interpolation can be used to process high-efficiency aluminum alloy precision parts in precision holes of various sizes. The load on each tooth is relatively light, especially when using a high-speed milling machine. Therefore, the same coated cemented carbide end mills can be used for high-speed and high-precision drilling of a variety of processing materials.
3. Select appropriate cutting amount
Workers can choose which cutting speed to use according to the material being processed, hardness, cutting conditions, material type and cutting depth. These conditions are necessary to effectively reduce machine wear.
4. Select appropriate tools
Rake angle: the rake angle shall be properly selected while maintaining the edge strength. One side can grind sharp cutting edge to reduce cutting deformation, make chip removal more smooth, and reduce cutting resistance and cutting heat. Do not use tools with negative rake angles.
Back corner: the size of the back corner directly affects the wear of the back corner surface and the quality of the machined surface. The cutting thickness is an important standard for selecting the relief angle. During rough machining, the feed rate is large, the cutting load is large, and the heat generation is large. Therefore, the tool is required to have good heat dissipation conditions. Therefore, a smaller rear angle should be selected. When the milling machine is finishing, the edge grinding is required to reduce the friction between the flank and the machining surface and reduce the elastic deformation. Therefore, a larger rear angle should be selected.
Helix angle: the helix angle should be as large as possible to make the milling machine smooth and reduce the force on the milling machine.
Approach angle: properly reducing the approach angle can effectively improve the heat dissipation conditions and reduce the average temperature of the treatment area.
Reduce the number of milling teeth and increase the chip removal space.
Due to the large plasticity of the aluminum alloy material, the cutting deformation is large during processing, the chip space is large, the radius of the bottom of the chip holding groove is large, and the number of teeth of the milling cutter is small. for example φ The milling cutter below 20mm uses 2 teeth, but φ 30~ φ It is preferable to use 3 teeth for a 60mm milling cutter to prevent deformation of thin aluminum alloy parts due to chip blockage.
Fine grinding: the roughness value of tooth edge shall be less than RA = 0.4um. Before using a new knife, the front and back of it should be gently polished with a fine oil stone to remove any burrs or slight serrations left by the grinding. In this way, not only the cutting heat can be reduced, but also the cutting deformation is relatively small.
Strictly control the tool wear standard. With the tool wear, the workpiece surface roughness increases, the cutting temperature increases, and the workpiece deformation increases. Therefore, the wear standard shall not exceed 0.2mm except for the tool materials with good wear resistance. Otherwise, it is easy to produce accumulated debris tumor. During cutting, the temperature of the workpiece shall not exceed 100 ℃ to prevent deformation.
5. Select a reasonable fixture
Parts must fully meet the needs of the machine to reduce unnecessary positioning errors, and special clamping tools shall be selected.
6. Determine reasonable processing route
Try to keep the processing route as short as possible to reduce machine wear.
In high-speed cutting, the machining allowance is large and the cutting is intermittent, so the milling machine will produce vibration during machining, affecting the machining accuracy and surface roughness. Therefore, CNC high-speed machining can generally be divided into rough machining semi finishing, corner cleaning, finishing and other processes.
For parts requiring high accuracy, it may be necessary to perform secondary semi finishing before finishing. After rough machining, the parts are naturally cooled to eliminate the internal stress generated by rough machining and reduce deformation. The allowance left after rough machining shall be greater than the deformation (generally 1-2mm). In the process of finishing, the finished surface of parts shall maintain uniform machining tolerance. 0.2-0.5 mm is generally good. This keeps the tool stable during machining and significantly reduces cutting deformation. Obtain good surface processing quality and ensure product accuracy.
