A vacuum pump can continue running while its effective pumping speed or attainable vacuum deteriorates. Forming response becomes progressively slower, receiver recovery takes longer, and performance may worsen as the pump reaches operating temperature.
The pump should first be tested at its inlet with the production circuit isolated. Ultimate vacuum, pump-down time, motor current, operating temperature, noise, and oil condition should be compared with the manufacturer’s service data. A good isolated test followed by poor system performance points to downstream leakage, restriction, or excess volume rather than the pump.
Filters, separators, oil, vanes, seals, belts, and cooling provisions must be serviced according to pump type. Process contamination should not be allowed to reach the pump. Increasing the forming dwell or reducing production speed may conceal the loss temporarily, but it does not restore the pressure-time performance required by the tool.