At a particular manufacturing plant, a high-profit line experienced a particular breakdown about once every six months. The repair procedure required two electricians to conduct lockout/tagout, unwire a 40-hp motor, remove the motor, and wait for the mechanics to pull a complex assembly. The next set of steps took nearly three hours, after which time the electricians would re-energize the system and start the motor.
Because the downtime was so expensive, there was a focus on how to get the mechanics to perform their repairs faster. The failure was always one of two bearings, so great attention was paid to becoming more proficient at taking the mechanism apart to get at those bearings. And, indeed, some improvement was realized.
What didn’t happen until a particular expert got involved a determination of the root cause of the bearing failure. Given the position of each bearing, the most likely cause was a hard jarring lateral thrust. But where would such thrust come from? It turned out that operators were starting the line under conditions of unbalanced load. The real repair for this failure was to install a variable speed drive for smooth “ramp-up” starting.
