Background: A manufacturer of large steam turbine nozzle boxes could not fulfill the increase in orders with their current equipment. Each order required 3500 man-hours and had a lead time of approximately 150 days, with forging delivery being the largest component of that lead time.
Situation: A large horizontal boring mill (HBM) was used for four separate machining operations throughout the complex manufacturing process. An order for eight additional nozzle boxes required more HBM hours per month than was available. The client was considering the purchase of another HBM on which to distribute the machining work.
Analysis: A Lean analysis showed that a Vertical Turning Center (VTC) could do much of what had been done on the HBM, and could be purchased and installed far more quickly than another HBM. The economic justification prepared for the client led to quick approval by his management.
Improvement:The VTC was purchased and used for several of the operations previously done on the HBM, freeing up the HBM to be used for unrelated incremental sales.
Result: The new VTC quickly proved to have uses in the nozzle box machining process far beyond what was used to justify its purchase. Man-hours dropped by 19% – 680 hours – per nozzle box and lead time dropped by 19 days. Further Lean improvements were made that within one year resulted in a total man-hour decrease of 27% – 950 hours – per nozzle box and lead time improvement of 40 days – from 150 days to 110. Profit margin increased from 25% to 34%. The plant gained breathing room to handle various contingencies, and was able to fit in additional unscheduled orders.