In the foundry industry, castings often emerge with thick layers of scale and molding sand. Shot blasting machines are commonly used to remove these, but because such castings are extremely hot and the operating conditions are unique, specific process requirements must be followed to protect both the equipment and the workpieces.
First, strictly control the temperature of the workpieces; never feed red-hot or high-temperature castings directly into the shot blasting chamber. High-temperature workpieces can cause steel shot to deform, which impairs cleaning efficiency. Furthermore, the intense radiant heat can damage equipment components—such as sealing strips, dust collector filter bags, and rubber parts—thereby accelerating equipment wear and aging. Always allow castings to cool naturally to ambient temperature before subjecting them to shot blasting.
Second, for thick layers of molding sand or scale, opt for steel shot or grit with higher hardness and larger particle size to enhance impact and cutting force. Extending the shot blasting duration as needed will ensure the complete removal of sand and scale. For large castings, use a hook-type shot blasting machine, while for small to medium-sized castings, a tumble-belt (crawler-type) machine is more appropriate.
Since residual molding sand and debris can easily enter the abrasive circulation system—placing an extra burden on the separator and dust collector—it is advisable to shorten the intervals for abrasive screening and dust collector cleaning to ensure that waste residue is removed promptly.
Additionally, because foundry environments contain higher levels of dust and impurities, equipment liners and blast wheel blades will wear out more quickly; therefore, the frequency of inspections for these vulnerable parts should be increased. Adhering to these operational guidelines will ensure high-quality cleaning of the castings while effectively extending the service life of the shot blasting machine in a foundry environment.
