This study shows how we increased pump builds from 1.5 pumps to 3 pumps per week, increasing capacity and reducing cost by eliminating unnecessary tasks.
100% of pump rotor builds required re-machining because heat shrunk impellers were “oversize” after cooling onto their intended shaft. This re-work added “shock” load to the machine shop and stalled pump assembly until the rotor was returned.
An internal review highlighted; - The shrink calculation on all engineered drawings for shrink fit components was incorrect. This caused all component bore sizes to be machined marginally smaller and this prevented them shrinking back to size when fitted to their corresponding shaft.
The reason for re-machining the rotor went unchallenged for several years. Instead, the needless task of “skim” was added to their processes. This became normal practice and included in assembly training for new recruits.
When the build process was finally challenged, and the shrink calculation corrected, all components returned to their design size after fitting. This eliminated the shock load in the machined shop and allowed all pump builds to be completed without interruption.
NB: The company built approximately 150 pumps per year. This action saved valuable time, space and cost in a very busy factory.
Summary: All companies (SME or larger) lose their way from time to time. Periodically reflecting on process and procedure can save valuable time and cost in any organisation, improving competitive costing or profitability.