According to the national standard GB8923-88 "Steel surface modification grade and rust removal grade before painting", the rust removal level of shot blasting machine is divided into four grades, which are represented by the letter Sa.
1. Sa1 grade mild spray or projectile rust removal
There is no visible dirt, grease, and weakly attached oxide scale, paint coating, rust, and impurities on the surface of the workpiece just now.
2. Sa2 level, thorough sandblasting and rust removal
There should be no visible grease, dirt, scale, rust, paint coating and impurities on the surface, and the residue should be firmly attached.
3. Sa2.5 level very thorough sandblasting and rust removal
There are no visible grease, oxide scale, dirt, paint coating and impurities on the surface, and the residue traces only show striped slight stains or dots.
4. Sa3 grade, sandblasting and rust removal until the steel surface is clean
There is no visible grease, dirt, oxide scale, rust, paint coating and impurities on the surface, and the surface has a uniform metallic color.