What are the cleaning scope and methods of precision castings

The process of removing precision castings from the mold, removing excess parts other than the main body, and polishing the inner and outer surfaces of the castings.

De-coring and surface cleaning:

Divided into two types, dry and wet. Dry cleaning is the use of mechanical equipment to clean the castings. The equipment used is simple, the production efficiency is high, it has the advantages of greater adaptability to different types of castings, and can remove the core and effectively clean the surface. The disadvantage is that the equipment is often in operation. Dust is flying, noise is loud, and environment is polluted. Wet cleaning has no dust, but because water is used as a medium, the surface of the casting is easy to rust. A large amount of sewage and cement sand are formed during the operation, which brings about the regeneration of sand and water and sludge treatment.

The dry and wet cleaning methods commonly used in production are:

1. Roller cleaning. Put the casting and star iron into the round drum together. When the drum rotates, the sand inside and outside the casting will be removed due to the collision and friction between the casting, star iron and waste sand. Polishing the surface of the castings can also partially remove the flash and burrs. This type of equipment is suitable for cleaning small and medium-sized castings with simpler appearance and thicker walls.

2. Shot blasting cleaning. The impact force of high-speed steel shot, iron shot, and abrasive flow is used to remove the core, sticky sand, and polish the surface of the casting. In addition, common shot blasting equipment includes shot blasting cleaning table and shot blasting cleaning room, etc. , The shot blasting machinery used for continuous production includes chain plate shot blasting drum, continuous shot blasting cleaning table, suspended continuous production shot blasting cleaning room, etc. The operation and maintenance cost of such equipment is relatively high.

3. Hydraulic sand removal. Shoot high-pressure water through the pipeline from the nozzle of the gun to the cast part to be disposed of, relying on the kinetic energy and scouring action of the water flow to remove the core and casting sand. The hydraulic sand cleaning is usually equipped with an open cleaning chamber composed of section steel and steel plate. The rotary table, the spray gun is installed on the side wall, can move up and down and rotate, so that the high-pressure water can be sprayed to any part except the bottom surface of the casting. Sometimes in order to better improve the efficiency of removing the sand on the surface of the precision casting, the spray gun Quartz sand and other abrasives are introduced into the appropriate position to obtain high-speed water sand flow. This method is usually called water sand cleaning.

4. Water explosion to clear sand. After the casting mold is poured, the casting is boxed when it cools to the specified temperature, and it is immediately immersed in the pool. The water penetrates into the mold through all the gaps and contacts the high-temperature metal quickly and vaporizes and explodes. The shock wave can basically remove the sand attached inside and outside the casting. The water explosion sand cleaning method has the advantages of short working time and high efficiency. It is widely used in steel casting workshops in our country. It is usually used to dispose of steel castings with a carbon content of less than 0.35%.

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