In this article, we will discuss the method to evaluate processing effect of shot blasting machine. That will be shown with both texts and pictures comparasion. At same time, processing effect is not only determined by shot blasting machine, but also abrasive and suitable operation.

Right shot blasting machine + Right abrasive + Rright operation = Ideal processing effect

All following descriptions about rust grades and blast-cleaning grades are quoted from ISO 8501-1:2007.

>> Rust Grades <<

Grade A
Steel surface largely covered with adhering mill scale but little, if any, rust.

Grade B
Steel surface which has begun to rust and from which the mill scale has begun to flake.

Grade C
Steel surface on which the mill scale has rusted away or from which it can be scraped, but with slight pitting visual under normal vision.

Grade D
Steel surface on which the mill scale has rusted away and on which general pitting is visual under normal vision.

Rust Grades IS08501-1 2007 20210224

>> Blast-cleaning Grade <<

Sa1 – Light blast-cleaning
When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from poorly adhering mill scale,rust, paint coatings and foreign matter. See photographs B Sa1, C Sa1 and D Sa1.

Sa2 – Thorough blast-cleaning
When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from poorly adhering mill scale,rust, paint coatings and foreign matter.Any residual contamination shall be firmly adhering. See photographs B Sa2, C Sa2 and D Sa2.

Sa2-1/2 – Very through blast-cleaning
When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from poorly adhering mill scale,rust, paint coatings and foreign matter.Any remaining traces of contamination shall show only as slight stains in the form ofspots or stripes. See photographs A Sa2-1/2, B Sa2-1/2, C Sa2-1/2 and D Sa2-1/2.

Sa3 – Blast-cleaning to visually clean steel
When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from poorly adhering mill scale,rust, paint coatings and foreign matter.It shall have a uniform metallic colour. See photographs A Sa3, B Sa3, C Sa3 and D Sa3.