How to optimally configure steel shots for casting cleaning

Selection of steel shot

The level of density is directly related to the life of steel shot. If the density of the steel shot is low, it indicates that there are more pores and cracks inside the steel shot. Or it has a high carbon content and is easily broken during use. For good steel shot, the surface of the steel shot peels off layer by layer during the cleaning process, the steel shot gradually becomes smaller, and the composition of the steel shot particle size of the whole system will gradually become smaller. Therefore, it is best to replenish the steel shot continuously to ensure that the quantity and particle size composition of the steel shot remain unchanged, thereby ensuring a stable cleaning quality.

During the shot blasting process, the change of the supplementary method and particle size of good steel shot will also have a greater impact on the cleaning efficiency. On the one hand, during the process of the steel shot being accelerated on the blade, the steel shot with large particles leaves the blade first, and the steel shot with small particles leaves the blade later. If the particle size composition of the steel shot remains unchanged, the hot spot of the throwing head remains unchanged. If the shot size changes and the hot spot moves away from the workpiece, the cleaning efficiency will be reduced. On the other hand, cleaning efficiency is not only related to impact force, but also related to coverage. Large-grained steel shot has great impact and good effect. But the number of particles per kilogram is limited and the coverage is low. The cleaning efficiency is not the highest and results in a rough surface. The impact force of the steel shot with small particles is small, and the cleaning effect of each steel shot is poor. However, the number of particles per kilogram of steel shot is large, so the coverage rate is high. And can clean to the subtleties, so that the surface roughness value is reduced.

in conclusion

(1) The surface roughness of the castings cleaned by shot blasting is closely related to the particle size of the abrasive used and the ejection velocity. The larger the particle size, the higher the surface roughness life value; the higher the projectile velocity, the higher the surface roughness value; the graded steel shot has a lower surface roughness value than the single-sized steel shot.

(2) The application of graded steel shot has a great influence on reducing the surface roughness of castings and cleaning efficiency, and can improve the cleaning efficiency of castings.

(3) The feeding method has a great influence on cleaning efficiency and surface roughness. Replenish the material in time and keep the steel shot gradation unchanged, so as to ensure that the cleaning efficiency does not decrease and the surface quality of the casting is stable.

(4) The shot blasting time has a certain influence on the surface roughness of the casting. With the extension of time, the surface roughness value of the casting tends to a certain value.