Views: 7 Author: Site Editor Publish Time: 2020-07-13 Origin: Site
Aluminum is an important industrial raw material. However, due to the low hardness and large thermal expansion coefficient, it is easy to deform when processed into thin-walled and thin-plate parts. In addition to improving the tool performance in advance and eliminating the internal stress of the material, some steps can be taken to reduce the deformation of the material in aluminum CNC machining as much as possible. Please follow us to find out.
The following knowledge points are listed below:
Stratified multiple machining
Select an appropriate cutting parameter
Optimize ability of cutting tools
Two-times compression of thin-walled parts
Drilling and milling
For cnc aluminum machining parts with large machining allowance, it is necessary to avoid excessive heat concentration to produce better heat dissipation and reduce thermal deformation. The method that can be taken to achieve this is called symmetric processing.
Imagine, for example, a 90 mm thick aluminum plate needs to be ground to 60 mm thick. If the milling side is immediately transferred to the other side, because each surface is processed to the final size and the continuous machining allowance is large, this will cause problems with the heat concentration and the flatness of the alloy plate can only reach 5 mm.
But if the method of symmetrical processing on both sides is repeated, each surface can be processed at least twice until the final size is reached, which is conducive to heat dissipation and the flatness can be controlled at 0.3 mm.
When there are multiple cavities on the aluminum alloy plate, due to the uneven force, it is easy to twist the cavity wall. The best way to solve this problem is to use a multi-layer processing method, which is to process all the cavities at the same time.
Not all cnc aluminum machining parts are completed at once, but the parts can be divided into several layers and processed to the required size layer by layer. The force applied to the part will be more uniform and the possibility of deformation will be less.
By selecting appropriate cutting parameters, cutting force and cutting heat can be reduced. In the machining process, if the cutting parameters are greater than normal, the cutting force will be too large, which will easily cause deformation of the parts and affect the spindle rigidity and tool durability.
Among the influencing factors of cutting parameters, the biggest influence on the cutting force is the size of the back cutting depth. However, while reducing the number of tools is beneficial to ensure that the parts are not deformed, the processing efficiency will also be reduced.
The material and geometric parameters of the tool have an important influence on the cutting force and cutting heat. Therefore, the correct selection of tools and tool parameters is very important to reduce the machining deformation of cnc aluminum machining parts.
Rough cutting and finishing require different methods. Rough machining requires cutting the excess material on the surface of the blank with the fastest cutting speed in the shortest time to form the geometric profile required for finishing. The focus here is on processing efficiency and material removal rate.
Precision machining puts forward higher requirements on machining accuracy and surface quality. The focus should be on milling quality. When the cutting thickness of the cutter teeth is reduced from the maximum value to zero, the work hardening phenomenon can be greatly reduced, and the deformation of the cnc aluminum machining parts can be suppressed to a certain extent.
When processing cnc aluminum machining parts, the clamping force will cause deformation. In order to reduce the deformation of the workpiece caused by clamping, before the final size is completed, the pressed piece should be released and the pressure should be released to restore it to its original state, and then the second pressure should be applied.
The second pressing point is best on the support surface, and the clamping force should be in the direction of maximum rigidity. If everything is correct, the compression force should be able to keep the workpiece from loosening. This method requires experienced operators, but can ensure that the deformation of the processed cnc aluminum machining parts is minimal.
Processing cnc aluminum machining parts with cavities has its own problems. If the milling cutter is applied directly to the part, the cutting chips will not be smooth due to insufficient fragmentation space of the milling cutter. This results in the accumulation of a large amount of cutting heat, which expands and deforms the cnc aluminum machining parts, and may even cause damage to the part or tool.
The best way to solve this problem is to drill first and then mill. This includes first drilling a tool that is no smaller than the milling cutter, and then inserting the milling cutter into the hole to start milling.