Further surface cleaning: After one sandblasting, there may still be some impurities remaining. The second sandblasting can more thoroughly remove the oxide scale, rust, oil stains, old paint layers and other impurities on the surface of the workpiece, making the surface of the workpiece reach a higher level of cleanliness.

Precise control of surface roughness: For some workpieces with extremely high requirements for surface roughness, a single sandblasting may not precisely reach the required roughness range. A second sandblasting can be achieved by adjusting process parameters such as sand particle size, sandblasting pressure, and sandblasting time to make more precise adjustments and controls to the surface roughness, thereby meeting specific process requirements.

Enhancing surface properties: Secondary sandblasting can form a more uniform and dense microstructure on the surface of the workpiece, further improving the hardness, wear resistance, corrosion resistance and fatigue strength of the workpiece surface, and prolonging the service life of the workpiece.

Improving appearance quality: It can eliminate the uneven marks or flaws that may be left by the first sandblasting, making the surface of the workpiece smoother, flatter and more uniform in color, and enhancing the appearance quality of the workpiece. For some products with high appearance requirements, such as automotive parts and electronic product shells, the second sandblasting helps to improve the overall aesthetic appeal and market competitiveness of the product.