This process is using the impact of high-speed sand flow to clean and roughen the metal surface. The surface treatment of aluminum parts in this method can make the surface of the workpiece obtain a certain cleanliness with different roughness, and improve the mechanical process of the workpiece surface, thus improving the fatigue resistance of the workpiece and increasing the adhesion between it and the coating. The adhesion force extends the durability of the coating and is also conducive to the leveling and decoration of the coating. We often see this process in various products of Apple, and it is also more and more adopted by existing TV cabinets or middle frames.