In the field of machining industry, we often contact with the processing of aluminum alloy parts. Here is a brief introduction of the difficulties in processing aluminum alloy parts
In the process of machining, due to the influence of machining deformation on the dimension, form and position tolerance of parts, the machining method of high speed, low feed and low cutting depth is used to complete the machining of all associated dimensions of parts through one clamping, so as to reduce the deformation caused by excessive cutting force in the machining process and avoid the error caused by the non coincidence of machining datum and design datum, Improve the dimensional accuracy and shape and position accuracy of parts.
Problem: parts in the machining process, often due to internal stress and deformation, especially non-ferrous light metals such as aluminum, magnesium alloy processing. The frequent occurrence of warping, side bending and distortion caused by internal stress will seriously affect the processing quality and efficiency of parts, especially for thin-walled and thin-walled parts. How to minimize or eliminate the deformation of parts, ensure product quality and production efficiency, has been our processing technology topic!
Cause analysis: in the process of production and processing, in order to improve the processing and use performance of aluminum alloy, it is necessary to improve the strength through heat treatment (quenching treatment + aging treatment) before processing. The internal stress of the material produced in the quenching process is very large, and the aging process can not completely release the internal stress produced in the quenching process. In the subsequent machining process, new cutting stress is generated. With the continuous removal of materials, the balance state of internal stress is broken, and the internal stress is redistributed until the new balance process is reached, resulting in deformation, which makes the parts lose their due machining accuracy. Moreover, when the stress on the surface of the part exceeds the strength limit of the material, cracks will occur.
Solution: in view of the above reasons, the “nesting” method is used for processing thin-walled and thin-walled aluminum alloy parts“ The “nesting” method is a processing method that the parts are taken out from the blank after all dimensions are processed in one clamping. The process of raw materials includes milling upper surface, rough milling inner cavity, rough milling shape, finish milling shape, finish milling inner cavity, finish milling bottom surface, point (drill) hole, cutting and so on. Because the whole process is completed in one clamping, before cutting off, because the part is connected with the bottom of the blank material, the internal stress will not cause large deformation of the part, and the size of the part is stable in the whole process. When cutting, it is necessary to make the blank material and the part material have 0.1 mm adhesion on the bottom surface, so as to ensure that the part has enough strength to resist the cutting stress generated in the whole “nesting” process.
After the mechanical parts are cut from the blank, although the parts are deformed due to the stress release, the relative dimensions of the parts will not change. It only needs to increase the correction process to level the bottom surface, and all the dimensions and shapes can be restored to be correct.
The above is the knowledge of aluminum alloy processing technology. In the future processing, it can not only improve the processing efficiency and product quality, but also avoid the error caused by the non coincidence of design benchmark and process benchmark, avoid the compression of tolerance due to the conversion of dimension chain, and simplify the process of making process specification and parts processing.
ken. tang@chengcg.com
