Sand blasting uses compressed air as the power to form a high-speed jet beam to spray the spray material (copper ore sand, quartz sand, emery sand, iron sand, sea sand) to the surface of the workpiece to be processed at high speed, so that the appearance or shape of the workpiece surface changes. Due to the impact and cutting effect of the abrasive on the surface of the workpiece, the surface of the workpiece is given a certain degree of cleanliness and different roughness, and the mechanical properties of the surface of the workpiece are improved, so the fatigue resistance of the workpiece is improved, and it and the coating are increased. The adhesion between them prolongs the durability of the coating film, and is also conducive to the leveling and decoration of the coating.