The process of taking the precision casting out of the mold, removing the excess parts other than the body, and polishing the inner and outer surfaces of the casting.

De-coring and surface cleaning:

It can be divided into dry method and wet method. Dry cleaning is the use of mechanical equipment to clean precision castings. It has the advantages of simple equipment, high production efficiency, strong adaptability to different types of castings, core removal and surface cleaning. The disadvantage is that there is a lot of dust, noise, and environmental pollution. Wet cleaning is dust-free, but with water as the medium, the surface of precision castings is easy to rust. During the operation, a large amount of sewage and cement sand are produced, which brings about problems such as water sand regeneration and sludge treatment.

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

①Drum cleaning. When the barrel rotates, the impact and friction between the casting and the star iron and waste sand can remove the sand particles inside and outside the casting, polish the surface of the casting, and can also partially remove flash and burrs. This equipment is suitable for cleaning small and medium-sized castings with simple shapes and large wall thicknesses.

② Shot blasting cleaning. Using the impact force of high-speed moving steel shots, iron shots and abrasive streams, the castings are cored, sanded and surface polished. In addition, commonly used shot blasting equipment includes shot blasting table and shot blasting room. Shot blasting machines used for continuous production include chain plate shot blasting rollers, continuous shot blasting cleaning tables, suspended continuous production shot blasting cleaning rooms, etc. Such equipment has high operating and maintenance costs.

③Hydraulic sand removal. High-pressure water is injected into the processed casting from the nozzle through the pipeline, and the core and casting sand are removed by the kinetic energy and scouring effect of the water flow. Hydraulic sand cleaning usually has an open sand cleaning room composed of section steel and steel plate, with a turntable at the bottom. The spray gun is installed on the side wall, which can move up and down and rotate, so that high-pressure water is sprayed to any part other than the bottom of the casting. Sometimes in order to improve the efficiency of sand removal on the surface of investment castings, abrasives such as quartz sand are introduced into the appropriate position of the spray gun to obtain a high-speed water sand flow. This method is commonly referred to as water sand cleaning.

④ Water explosion to clear the sand. After pouring, when the casting cools to the specified temperature, the box is opened and the water is immediately immersed in the pool. Water penetrates into the mold through all gaps and comes into contact with the hot metal. The shock wave can basically remove the sand particles adhering to the inside and outside of the casting. The water blast cleaning method has the advantages of short working time and high efficiency, and has been widely used in steel casting workshops in my country. Generally used to process steel castings with simple shapes and less than 0.35% carbon content.