Inspection Detail

Inspection: 300059490 - Camaco Columbus Manufacturing

Inspection Information - Office: Omaha Area Office

Investigation Summary

Employee #1 and a coworker were operating a Cleveland part-revolution power press. They were running the 110 ton press in the dual operator mode, where there are two separate sets of controls. To initiate a cycle, both operators must activate their two-hand controls simultaneously. Employee #1 and the coworker completed a cycle and the coworker moved forward to remove a completed part from the left side of the die when the brake mechanism of the press failed. He realized the press was coming down and moved his hand away from the danger area. Employee #1 was also reaching into the machine when the die lowered on his right hand with enough force that he could not remove it from between the upper and lower dies. The coworker notified a supervisor of the accident and contacted a maintenance person who was in the area. The maintenance person had other employees block the press so that the die could not move down any further. The maintenance person then reversed the power to the press motor so that it would cycle in the opposite direction. He then actuated the press in the "inch" mode so that he could control its movement. The maintenance worker was able to move the press ram upwards and free Employee #1's hand. He suffered numerous small lacerations and severe bruising, but doctors predicted a complete recovery within two weeks. Subsequent inspection of the press revealed that all safety devices were operating correctly. The brake mechanism is actuated pneumatically and springs keep the brake in contact with the brake plate until air is injected into the brake piston. This causes the brake/clutch plate to move into contact with the flywheel, cycling the press. In the event the air pressure is too low to move the brake piston, the press will not cycle. The press is designed so that a power or air failure will not cause it to cycle erratically. In this case, the O-ring which maintains pressure in the brake cylinder had disintegrated and become trapped in the piston sleeve. This caused the brake/clutch plate to jam between the flywheel and the brake pads, leaving the machine stuck in a state of limbo. There was no power transfer to the press so it did not cycle, nor was there any pressure against the brake pads to stop the press from rolling over, thus allowing the press to close. This is not something that can be routinely inspected. To examine the O-ring that failed takes a maintenance worker between 10 and 12 hours. The press had been inspected by a qualified maintenance worker within 42 hours before the accident, and no deficiencies were noted.

Keywords: POWER PRESS, EQUIPMENT FAILURE, TWO-HAND CONTROL, CAUGHT BETWEEN, POINT OF OPERATION, PRESS OPERATOR, HAND, PRESS, CONTUSION