How To Evaluate The Quality Of Shot Blasting

Visual inspection: No rust spots, scales or dirt on the surface, it is required to reach the grade Sa2.5-Sa3 of the grading table: "completely remove rust and scale, without leaving any tiny marks, the steel surface is uniform silver-white metallic luster." Due to the heat treatment process, the workpiece shows a slight oxidation color after shot blasting.

After the blasting is completed, the blasting and derusting parts should be thoroughly inspected first, and the cleanliness and roughness of the base steel surface should be inspected. It is important to check the parts that are not easy to spray, and the rust parts of manual or power tools can be appropriately reduced. When checking the cleanness and roughness of the base steel surface, first, it is strictly forbidden to touch by hand; second, it should be carried out under good scattered sunlight or under artificial lighting conditions with comparable illuminance to avoid missing detection.

After sandblasting and derusting, the cleanliness of the surface of the metal structure should reach Sa21 / 2, and it should be compared with the photos provided in "Steel Surface Rust and Derusting Levels Before Coating". There should be at least one comparison point every 2m2.

After sandblasting and derusting, the surface roughness of the metal structure should reach Ry60-100um. According to the technical requirements, the corresponding roughness model should be taken and compared with a magnifying glass of at least 7 times magnification. There should be a comparison point at least every 2m2. When directly measured with a surface roughness meter, there must be at least one evaluation point for every 2m2 surface, and the evaluation length is 40mm, and 5 points are measured within this length range, and the arithmetic mean value is taken as the surface roughness value of this evaluation point.