The surface pretreatment of enameled cast iron is different from that of enameled steel plate. If the enameled cast iron adopts the pickling method, the acid and cast iron are prone to produce hydrogen gas, and bubbles or other enamel defects will occur during firing. Therefore, the pretreatment of enameled cast iron is annealed. Or sandblasting (shot blasting).

Before enameling, the enamel factory must blast the enameled cast iron to remove surface inclusions, mold sand, iron scale, rust spots, oxides, etc. If it is a small-sized enameled casting, chemical degreasing can also be used. method to clean the surface.

There are two sandblasting methods for enameled cast iron. The first is to pressurize with an air compressor, and the airflow sprays wear-resistant particles on the surface of the casting. The second is to use mechanical sandblasting, such as using centrifugal force to make the wear-resistant particles impact the casting. surface.

When blasting enamel cast iron, the enamel factory should pay attention to the following points:

1. The shape of the sand used for sandblasting should be irregular and angular, the hardness of the cast steel and quenched cast iron sand should be above HV650, and it has good edge stability and wear resistance, so it is mostly used for sandblasting on the surface of cast iron. deal with. Brittle sand such as quartz sand, zircon sand, corundum, etc. can also be used, but it is necessary to avoid the use of plastic metal particles or projectiles, which are easy to form balls and strengthen the surface of cast iron, thereby sealing the inner grains and wrapping impurities. Blistering on the surface of the enamel caused by enamelling;

2. Strictly control the particle size distribution of blasting to ensure uniform cleaning of the casting surface, especially the cleaning of depressions. The particle size distribution and grade of blasting depends on the type of blasting equipment and blasting;

3. During the sandblasting process, all burrs on the workpiece should be eliminated, and the radian of the curved part of the workpiece should not be less than 6.5mm;

4. It is best to use the cleaned workpiece immediately. If sandblasting is used after long-term storage, it needs to be annealed.

The above is the relevant content about the pretreatment of enamel cast iron. Nolifrit is a supplier of enamel frit, providing one-stop service for our customers. If you have any technical or product related questions, please contact us!