When does the shot in a shot blasting machine need to be replaced?

In a shot blasting machine, the shot media itself does not usually require periodic replacement. The need for replenishment or replacement is determined by wear, cleanliness, and cleaning efficiency.

Situations requiring shot replacement or replenishment:

**Excessive shot breakdown rate:** When shot fragments and pulverizes due to repeated impacts—reducing the number of effective particles and significantly lowering cleaning efficiency—the mixture should be screened and new shot added.

**Excessive impurities in the shot:** Shot contaminated with scale, sand, oil, etc., affects blasting efficiency or clogs the circulation system, necessitating cleaning or replacement.

**Uneven or excessively fine shot size:** Some shot wears down to an excessively small size, failing to provide the expected cleaning intensity. The shot should be screened and replenished according to specifications.

**Insufficient shot quantity:** If the shot level in the hopper falls below the standard mark (typically recommended at 80% of hopper capacity), thereby affecting continuous operation, timely replenishment is required.

**Significant drop in cleaning efficiency:** Even if other components are functioning correctly, if workpiece surface cleaning fails to meet standards—and wear-related issues (such as worn blades or guide bushings) have been ruled out—the problem may be due to the quality of the shot.