The process of die-casting aluminum has many benefits, including the ability to mass-produce castings with high dimensional accuracy in a short amount of time, a wide range of component options, and many different types of alloys to choose from. Because it is difficult to obtain its mechanical properties in rolled aluminum, it is widely used in the manufacturing of mechanical parts. It has always been challenging to carry out surface treatment on die-casting aluminum because the majority of it is an aluminum alloy with a high percentage of silicon, such as ADC10 and ADC12. However, it is now possible to carry out surface treatment, including painting, electroplating, and anodizing, on die-casting aluminum. However, the fact that the pre-treatment of die-casting aluminum is relatively difficult has a significant impact on the surface effect of the finished product. This begs the question: why is the pre-treatment of die-casting aluminum so challenging?Die-casting aluminum is primarily made up of aluminum alloys that have high proportions of silicon and copper.
The amphoteric metal aluminum will dissolve when this type of die-casting aluminum is treated with chemical reagents; however, the majority of China die casting manufacturer the alloy components are difficult to dissolve, and the residual black dirt will adhere to the surface of the aluminum alloy. The vast majority of these contaminants are insoluble substances that are primarily composed of silicon-containing compounds like silicon grain intermetallic compounds. As a result, they will not be removed during the process of removing ash using nitric acid solution in the following step. As a direct consequence of this, the surface treatment film will exhibit poor adhesion as well as peeling, bubbling, and an unattractive appearance. It is difficult to complete the subsequent surface treatment because of the presence of such insoluble dirt, which is produced by the alloy components of die-casting aluminum.
In die-casting aluminum, the molding process involves pressing molten metal into the mold at a high temperature, removing the mold after it has cooled, and then taking the workpiece out of the mold. At this time, a release agent is applied to the mold in advance, which allows for the mold to be demolded smoothly and allows for the production of a smooth and beautiful surface on the aluminum die-casting. However, many surface defects can be attributed to the release agent; consequently, the release agent that is selected as well as the use conditions are very important. The remaining components of these release agents evaporate, and the majority of them adhere to the surface of die-casting aluminum products in a sintered state, making it extremely difficult to clean them off. clean.
Important aspects of how the anodizing process works
Important aspects of how alloy die casting company the anodizing process works.
In most cases, sulfuric acid anodization will use a constant current, and the total current will be determined based on the total anodic oxidation area as well as the current density. Calculating the oxidation area for aluminum materials that contain cavities requires measuring the inner surface area of a section that is between 100 and 300 millimeters in length. In the event that electrolytic coloring treatment is necessary, each hanging material should be of the same specification in order to prevent color differences. Additionally, the contact between the conductive beam and the conductive seat should be in good contact, and the temperature rise should not exceed 30 degrees Celsius. If a single conductive beam is expected to carry more than 8000A, it is recommended that conducting be considered at both ends of the beam.
It is possible to reduce the precipitation of acid gas by using air bags on the cathode plate; however, the circulation of the bath should be increased, preferably to more than three times per hour. The liquid in the tank is agitated at the bottom of the tank in order to ensure that the cold acid solution is added to the tank in an even manner. The circulation volume can be properly reduced by using air agitation, but the agitation needs die casting mold to be even and stable in order to prevent the binding material from becoming more loose. It needs to be washed as soon as possible after the oxidation process is complete. After a power outage, the coloring and sealing will be of lower quality if it is permitted to remain in the oxidation tank for an excessive amount of time. The oxidation state is related to the amount of time the cathode plate will last in service. When the oxidation tank is turned on and off, it poses a risk of causing damage to the cathode plate. It is imperative that the damaged cathode plate be replaced as soon as possible in order to prevent an imbalance in the cathode and anode areas. The voltage rise during anodic oxidation should have a gentle beginning, and the time required for the voltage rise is typically between 10 and 15 seconds.
Anodizing and dyeing aluminum both have specific requirements for the oxide film.
Because the dyeing process is carried out within the film pores of the aluminum anodized film, on the one hand, the film layer needs to have sufficient porosity, and on the other hand, the inner wall of the film hole needs to maintain a certain activity. As a result, not all anodized films can be dyed effectively. The color must be able to fulfill the requirements listed below. Aluminum that has been anodized in a solution of sulfuric acid produces a film that is porous and colorless, making it an excellent candidate for dyeing. However, when AC anodization is used, the following reactions frequently take place: due to the fact that the film layer contains sulfur, despite the fact that it is simple to dye; however, due to the fact that the dye and the sulfur in the film layer form sulfide, even when using the same dyeing solution; DC anodization frequently takes place when the film layer contains sulfur. andThe tone of the anodized film that is obtained through the use of AC treatment is frequently unique.
Consequently, in order to obtain a film of high quality through anodic oxidation, it is necessary to select the process and operating conditions that are appropriate. Other types of anodized films, such as oxalic acid oxide film itself, die casting products have a yellow appearance and can only be dyed into dark colors. The nearly colorless film that was produced as a result of oxidation carried out at 35 degrees Celsius proved to be an effective base for staining. Because it is so thin and has such a small porosity, the chromic acid oxide film is not generally suitable for the process of dyeing. On the other hand, the film has a gray hue and can only be dyed in dark colors due to its composition. The oxide film layer ought to be whole and consistent, devoid of flaws such as scratches, trachoma, and pitting corrosion. In order for the oxide film to be tough, it needs to have specific types of loose pores and adsorption properties.
Some mold materials and steel materials are very good; however, the unreasonable mold structure design, such as thin edges, sharp corners, grooves, sudden steps, thickness disparity, etc. , often results in large deformation of the mold after heat treatment. This can be avoided by using mold materials and steel materials that are of higher quality. Because the thickness of the mold is uneven or there are sharp rounded corners, the thermal stress and tissue stress between the various parts of the mold are different during quenching. This difference in stress leads to a difference in the volume expansion of each part, which in turn causes the mold to deform after quenching. The reason for this is because the thickness of the mold is uneven.
Cautionary measuresWhen designing the mold, the disparity in the thickness of the mold as well as the asymmetry of the structure should be minimized. This is to ensure that the mold can successfully meet the requirements of the actual production. At the point where the mold's thickness meets the mold's thickness, a transition that is as smooth as possible should be adopted as a structural design feature as much as possible. The processing allowance is set aside in accordance with the law of the deformation of the mold to ensure that the mold will not be thrown away as a result of the deformation of the mold caused by quenching. It is possible to use a combined structure to achieve uniform cooling throughout the quenching process for molds that have particularly complex shapes.
