Common Methods of Cleaning and Surface Treatment of Die Castings

Ⅰ. Methods of removing gate and flash from aluminum die castings

1. Manual work: Use simple tools such as mallet, file, pliers and other simple tools to knock and remove redundant parts such as casting pouring system. The advantage is that it is convenient, simple and fast, but the disadvantage is that the incision is not neat, and it is easy to damage the casting and deform. It is not suitable for parts with thick gates, complex parts and large castings.

2. Mechanical operation: Use edge trimmers, punches and dies, band saws and other mechanical equipment. The advantage is that the incision is neat and the cleaning efficiency is high for large and medium-sized castings.

3. Polishing: According to the requirements of aluminum squeeze casting, choose steel grinding wheels, nylon wheels, cloth wheels, flying wing wheels, grinding wheels, etc. for grinding.

4. Automation of the cleaning process: Robots are used to clean the castings to complete the work of removing burrs, grinding and trimming. The result is clean, efficient production.

Ⅱ. Shot blasting cleaning of aluminum die castings

Under the action of the shot blasting wheel, the projectile hits the surface of the casting, causing it to absorb the kinetic energy of the high-speed moving projectile and produce plastic deformation, presenting residual compressive stress, thereby improving the surface strength, fatigue resistance and corrosion resistance of the casting to achieve the purpose of cleaning and strengthening.

Ⅲ. Sandblasting cleaning of aluminum die castings

The purified compressed air strongly sprays the quartz sand flow onto the surface of the casting, and uses the impact force and friction to remove impurities such as burrs, oxide skin, and dirt on the casting. The surface of the casting is cleaned and roughened to improve the bonding force between the coating and the substrate.

Ⅳ. Grinding and polishing of aluminum die castings

Grinding machines, centrifugal polishing machines and other equipment are used by the air ride manufacturers, and grinding stones, abrasives, water, etc. are used to rub against die castings in the process of high-speed vibration to achieve the effect of deburring and polishing the surface.

Ⅴ. Correction of aluminum die castings

When the casting is deformed due to solidification shrinkage, ejection deformation or edge trimming, the deformed aluminum die casting needs to be corrected. The shape correction needs to be corrected manually with a mallet or with a hydraulic press through measuring instruments and fixtures.

Ⅵ. Surface treatment of aluminum die castings

1. Electroplating

Aluminum die castings are subjected to electrolysis in a solution containing the metal to be plated. The casting is the cathode, and the metal to be plated is the anode, so that the surface of the casting can obtain a firmly bonded metal film.

2. Paint

For decoration, protection, signs. Increase or decrease surface friction by painting to hide surface imperfections. The problems that are easy to occur in this process are orange peel, pinholes, matte color, oil accumulation, oil rejection, etc. on the surface of the casting. Therefore, it is necessary to adjust the concentration and coating amount of the paint, the surface of the casting should be clean, and the operation should be strictly followed.

3. Chemical film forming treatment

Treatment with chromate produces a tough film on the surface of aluminum die castings and comes in a variety of colors, improving the corrosion resistance of the castings, providing an aesthetically pleasing surface, and making it easier to paint and color.

4. Electrostatic spraying

A high-voltage electrostatic field is formed between the spray gun, the spray head, and the casting to be coated, so that the atomized paint particles are negatively charged in the high-voltage electric field and fly to the surface of the positively charged casting to form a uniform paint film. Provides a protective layer for castings and a beautiful, smooth surface and provides good corrosion resistance.

5. Impregnation treatment

Under the conditions of vacuum and pressure, the liquid infiltrating agent is infiltrated into the fine holes of the aluminum die-casting parts, and the holes are solidified and blocked to achieve the purpose of sealing.