Shot blasting refers to the technology of mechanically projecting shot (steel shot or sand) onto the working surface at a high speed and angle, allowing the shot to impact the working surface, and then cleaning the shot inside the machine through the airflow of the matching vacuum cleaner, recovering the shot and the cleaned impurities separately, and making the shot reused. The shot blasting machine is equipped with a dust collector, which can achieve dust-free construction. Shot blasting machines can be divided into three types according to their walking form: hand-push type, vehicle-mounted type and self-propelled type.

The main factors affecting the strength of the shot blasting machine are as follows:

① Shot blasting speed When the shot blasting speed increases, the shot blasting strength also increases, but when the speed is too high, the amount of shot blasting damage increases.

② Shot blasting hardness When the shot blasting hardness is higher than the part hardness, the change in its hardness value does not affect the shot blasting strength; when the shot blasting is softer than the part, if the shot blasting hardness value decreases, the shot blasting strength also decreases.

③ Shot blasting size The larger the shot blasting, the greater the impact kinetic energy, the greater the shot blasting strength, but the coverage of the shot blasting is reduced. Therefore, while ensuring the strength of shot blasting, smaller shots should be used as much as possible. In addition, the shot blasting size is also limited by the shape of the parts. When there are grooves on the parts, the shot blasting diameter should be less than half the radius of the inner circle of the groove. The shot blasting particle size is usually selected between 6 and 50 meshes.

Almost all steel castings, gray castings, malleable castings, ductile iron castings, etc. need to be shot blasted. This is not only to clean the oxide scale and sand sticking on the surface of the casting, but also an indispensable preparation process before the quality inspection of the casting. For example, the casing of a large gas turbine must be strictly shot blasted before non-destructive testing to ensure the reliability of the flaw detection results. In general casting production, shot blasting is a process to find surface defects of castings such as subcutaneous pores, slag holes, sand sticking, cold shut, peeling, etc. In addition to cleaning the oxide scale and finding the surface defects of the castings, the main purpose of the surface cleaning of non-ferrous metal castings, such as aluminum alloys and copper alloys, is to clean the burrs of die castings and obtain a surface quality with decorative significance by shot blasting to obtain a comprehensive effect. In metallurgical steel production, shot peening or pickling is a process for mechanical or chemical combined removal of phosphorus scale to ensure high productivity in mass production of steel. In the production of silicon steel sheets, stainless steel sheets and other alloy steel sheets and strips, shot peening or pickling is performed after annealing during the cold rolling process to ensure the surface roughness and thickness accuracy of the cold-rolled steel sheets.