Shot blasting is the process of putting the projectile material onto the cleaned metal surface at high speed, the impact energy of the projected material is used to remove the surface oxide, rust and other foreign matter, so as to carry out the bottom surface treatment. Among them, the accelerating method of projectile materials can be divided into two kinds. One is to rotate the impeller at high speed and make full use of centrifugal force. The other is to mix the projectile material into compressed air and use the adiabatic change of compressed air to accelerate. Centrifugal acceleration can make the projectile materials project in a wide range, so it is suitable for cleaning large quantities and large workpieces. The compressed air acceleration allows the projectile material to be mixed with the compressed air coming out of the nozzle for concentrated injection, so it is suitable for local cleaning. Compared with compressed air acceleration, centrifugal acceleration has the advantage of a large number of accelerating projectile materials, and the power consumption can also be reduced by 1/2 to 1/5, which can be said to be an energy-saving projection method.
The reason that affects the effect
The cleaning effect, roughness effect and strengthening effect will occur on the metal surface after shot blasting, usually these states can exist simultaneously. There are three main factors influencing the cleaning effect of shot blasting: (1) projectile materials (material, shape, hardness and particle size). (2) treated materials (composition, shape and hardness). (3) conditions for shot blasting cleaning (projectile velocity, projectile density, impact Angle).
One of the important factors influencing the effect of shot blasting is the projectile material. It is very important to choose the suitable projectile material. The shape of projectile materials mainly includes two kinds of particles: spherical granule (called spherical granule) and acute angular granule (called grinding granule). The effect of the two kinds of particles on the surface is different, in which the steel pellet has the effect of tempering, while the abrasive pellet has the effect of grinding.
Generally, the steel pellets with particle size of 120~040 are used to remove oxide skins.