Cleaning Scope And Method Of Precision Castings

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

Core removal and surface cleaning:

It is divided into two categories: dry and wet. Dry cleaning is the use of mechanical equipment to clean castings. The equipment used is simple, the production efficiency is high, it has great adaptability to different types of castings and can not only remove the core but also effectively clean the surface. The disadvantage is that the equipment is often dusty, noisy and polluting the environment during operation. There is no dust in wet cleaning, but because water is used as a medium, the surface of the casting is easy to rust. During the operation, a large amount of sewage and cement sand are generated, which brings problems such as sand and water regeneration and sludge treatment.

Commonly used dry and wet cleaning methods in production are:

(1) Drum cleaning. When the drum rotates, it relies on the impact and friction between castings, star iron, and waste sand to remove the sand inside and outside the casting, polish the surface of the casting, and partially remove the flash burr. This type of equipment is suitable for cleaning small and medium-sized castings with simple shapes and thick walls.

(2) Shot blasting cleaning. The impact force of high-speed steel shots, iron shots, and abrasive grain streams is used to remove the core, sticky sand, and polish the surface of the casting. In addition, the commonly used shot blasting cleaning equipment also includes shot blasting cleaning table and shot blasting cleaning room. The shot blasting cleaning machinery used for continuous production includes chain plate shot blasting roller, continuous shot blasting cleaning table, suspended continuous production shot blasting cleaning room, etc. The operation and maintenance cost of this type of equipment is high.

(3) Hydraulic sand removal. High-pressure water is shot from the nozzle to the treated casting through the pipeline, and the core and casting are removed by the kinetic energy and scouring action of the water flow. Hydraulic sand cleaning is usually equipped with an open cleaning chamber composed of steel sections and steel plates, a rotary table is set at the bottom, and the spray gun is mounted on the side wall, which can move up and down and rotate, so that the high-pressure water flow can be shot to any part except the bottom surface of the casting. Sometimes, in order to improve the efficiency of removing the sand on the surface of the precision casting, abrasives such as quartz sand are introduced at the appropriate position of the spray gun to obtain a high-speed water sand flow. This method is generally called water sand removal.

(4) Water blast sand removal. After the casting is poured, the casting is cooled to the specified temperature when the box is made, and it is immediately immersed in the pool, and the water penetrates into the casting mold through all the gaps and contacts with the high-temperature metal to vaporize and explode, and the shock wave can basically remove the sand attached to the casting inside and outside. The water blast sand removal method has the advantages of short operation time and high efficiency, and has been widely used in China's steel casting workshop. Generally, it is used to process steel castings with a carbon content of less than 0.35% and a simple shape.