What are the reasons for the blackening and peeling of the casting after shot blasting

What is the reason for the blackening and peeling of the casting after being processed by the shot blasting machine? Today, Qinggong Machinery is here to specifically answer the analysis of the cause of the black surface of the casting after being shot blasted.

First, let's talk about what is called black after shot blasting?

Such as in the conveyor blasting machine, after shot blasting, the overall surface of the casting is black or there are obvious black marks and black spots in some parts. Some can be thrown away, and some have been immersed in the casting matrix. The area and location are not fixed.

Analysis of the reasons for the blackening of the castings after shot blasting:

　　  1. Defects before shot peening brought by the die-casting process:

　　 (1) Too much black oil is used in die casting;

　　(2) The punch oil splashes when the mold is opened;

　　(3) Paint splashes during die casting;

　　 2. The product has been left for too long or the temperature is humid, and the surface is corroded, mildewed or dusty.

　　 3. The dust removal device of the automatic sandblasting machine is invalid, and the steel shot contains more dust.

　　 4. The operator does not wear gloves as required, and directly touches the surface of the casting after shot blasting with his hands, causing fingerprints.

　　 5. After shot blasting, the workpiece will be placed for a long time, there will be dust or splashes of water and oil on the surface, and the environment will be humid and oxidized

Countermeasures for casting blackening after shot blasting:

　　 1. The defect is not all over the surface of the casting. Strengthen control and management by die casting process.

　　(1) is black oil, the color is black;

　　(2) is punch oil, dark red in color;

　　(3) is the paint, the light color of the surface of the casting with different colors;

　　2. After shot blasting, the surface traces of the workpiece are shallow and cannot be removed because it has been immersed in the casting matrix. Strengthen the management of product placement, and it should not be too long. If it needs to be stored for a long time, it must be covered and protected and placed in a suitable environment (dry);

　　3. The surface of the entire casting is black and dull. Replace the filter cartridge of the dust collector and replace the new steel shot;

　　4. The operator must be required to operate according to the operating instructions. Gloves must be worn.

　　5. After shot blasting, the workpiece should be inspected, packed and put into storage in time as soon as possible. If it needs to be stored for a period of time, it must be strictly protected.

QINGGONG MACHINERY， as one of pro blasting supplies, firmly adheres to our commitment towards our customers, honest trade practices & staying at pace with the latest technological advancements. These enable us to cross every hurdle that comes our way and asserts our individuality amongst others engaged in the same business.

Our aim is to position ourselves at the uppermost position by providing our customers with superior quality products & after-sales service & thereby winning their trust.

Last but not least, our never-ending greed for optimal customer satisfaction, keeps us one ahead of our competitors.