Abnormal stress and deformation in aluminum cnc machining milling process

Last week we received a demand order from a customer for aluminum alloy turning and milling CNC processing of aluminum parts. The diameter of the product is 170MM, and the surface needs to have an Apple shell-level effect with an accuracy of 0.02mm. The parallelism of the finished product must be 0.03mm and the roundness should be 0.01mm. This tolerance requirement is a high standard in the CNC processing industry, and more than 95% of factories cannot achieve it!

Due to the structural characteristics of the customer's product, in order to reduce costs, we used national standard 6061 aluminum tubes for processing. During the first turning and milling CNC processing process, the product could not meet the drawing requirements. After many adjustments and material replacements, we found that the pipe had stress deformation during processing.

In order to ensure customer delivery, when the national standard 6061 aluminum alloy pipe material cannot meet the drawing requirements, it is replaced with solid material as soon as possible. After summarizing the experience of the first 6061 aluminum alloy pipe material, when we used the three-dimensional inspection instrument to measure the first piece, there was still a dimensional deviation of 0.002mm;

At this time, we realized that the material stress still existed. The normal process to relieve stress is to leave the product in its natural state for a period of time. This affected our delivery time. We adopted the method of heat treatment of aluminum alloy to relieve stress, which solved the size problem caused by the material. The drawing requirements cannot be met.

After solving the dimensional problem of aluminum alloy CNC turning and milling processing, we have encountered new difficulties. How to solve the cumulative dimensional tolerance and clamping dimensional tolerance of CNC processing. During the SPC analysis of CNC machining, we found that the dimensions of the finished products were unstable. We successively eliminated the instability factors caused by the production process and fixtures. Finally, we found that the positioning reference size tolerance was too large, resulting in the clamping tolerance of each product being too large. . By changing the positioning point of the improved fixture, the unstable abnormality of CNC machining of aluminum alloy turning and milling of precision parts has been solved.