Surface treatment of hard aluminum parts before cold extrusion

Surface treatment before cold extrusion of aluminum parts Meiling Group Anhui Dongfeng Machinery General Factory (Hefei City) Zhou Hong Introduction To improve the cold extrusion process, overcome the shortcomings of poor prospects of duralumin, especially to reduce the friction between the rough or semi-finished duralumin parts and the mold It can reduce the extrusion force of processing and increase the service life of the mold. Before cold extrusion, the blank or semi-finished product of the part needs to be annealed and surface lubricated. "Art process (hard aluminum parts rough or semi-finished products) degreasing, alkaline oxidation, hot water washing, drying, saponification, drying, drying, and cold extrusion processing. The process of degreasing and degreasing depends on the oil contamination of the workpiece. It may not be carried out when there is less oil contamination. Alkaline oxidation is directly carried out for degreasing, because the alkaline oxidizing solution also has a certain degreasing ability. If the work piece is seriously stained, in order to prevent oil stains from contaminating the alkaline oxidizing solution and improve the effect of alkaline oxidation, organic solvents should be used for degreasing. Oil. The more scientific one should choose tetrachloroethylene or a mixture of tetrachloroethylene and trichloroethylene as the degreasing agent. Duralumin alloys should not be used to remove waves and high-concentration alkaline solutions for degreasing. And process parameters (industrial grade). (Industrial grade) called temperature and time operating specifications. After magnetic oxidation, the hard aluminum alloy has a gray to light black oxide film crystal on the surface, forming the same wet layer as the ferrous metal phosphating film. What we need is exactly this film. The thickness of the film is related to the temperature of the solution and the length of the oxidation time. The solution temperature is high, the oxidation time is too long, and the oxide film is thick. Thicker oxide film has a certain effect on the subsequent saponification. However, the longer the oxidation time, the greater the change in the size of the workpiece. Therefore, the length of the oxidation time should depend on the specific conditions. The workpieces after magnetic oxidation should avoid collisions with each other to prevent the oxide film from falling off. Hot water washing Hot water washing requires water temperature τ

It is to wash away the reduced liquid adhering to the alkaline oxide film. If the hot water washing is not sufficient and the lye is not washed clean, the film reduction will prevent the oxide film from fully adsorbing soap during saponification, thereby reducing the quality of saponification. At the same time, too much alkaline substances are brought into the soap solution, which increases the magnetic properties of the solution, making it difficult for the workpiece to obtain a thicker saponified film. Therefore, the production process should pay attention to the hot water washing process. The purpose of drying is to drive off the moisture in the pores of the alkaline oxide film, and the bonding force between the strong alkaline oxide film and the substrate. At the same time, the saponification can be accelerated, and the binding force of the saponified film and the oxide film can be increased. Saponification solution formula and process parameters Soap (ordinary laundry soap) temperature and time operation specifications In actual operation, special attention should be paid to temperature. If the temperature of the solution is too high, it is difficult to form a thicker saponification film; if the temperature is low, the saponification solution will condense back, and it is difficult to penetrate the pores of the alkaline oxide film, and the saponification film formed on the surface of the workpiece is uneven. The better way is to release the workpiece when the temperature is the upper limit, and remove the workpiece when the temperature is the lower limit.

Generally speaking, the upper limit of the soap content is better. After saponification, the workpiece must be dried before drying. The purpose of drying is to make the saponified film more uniform, and it is difficult for the workpiece to not drip the saponification liquid for the length of time. In order to nationalize the saponified film, the dried workpiece needs to be dried again. When drying, the starting temperature of the oven should be around, and then gradually rise to. If the starting temperature is too high, the saponified film will easily flow off the surface of the workpiece. The baking degree is so high that the film does not touch your hands. Bake at the temperature for too long, it will harden the saponified film and affect the lubricating effect. Conclusion The production practice of our factory for many years has proved that this process has a high use value and has a good effect on extending the service life of the mold and avoiding the strain of the hard aluminum parts during the cold extrusion process.