A worker’s finger was amputated while he was troubleshooting a plastics dryer that he had not de-energized.
How did it happen?
Kevin Patterson (not his real name), was a temporary employee who had worked the night shift as an assistant material handler for five months. Patterson and another employee were operating a plastics dryer that sorted and dried a thermoplastic elastomer – a rubber-like material that can be formed into parts – before it was sent to an injection molder.
The elastomer was stored in a 55-gallon drum; a hose attached to the drum was connected to a hopper above the injection molder and a pneumatic hose was connected from the hopper to a vacuum under the dryer. A device on the dryer – called a programmable logic controller, or PLC – monitored how much of the elastomer entered the hopper from the 55-gallon drum.
Both Patterson and the other employee noticed that the vacuum was not drawing enough elastomer from the drum. They thought the problem might be due to a clog somewhere in the equipment.
Patterson opened a compartment under the dryer and felt for an obstruction with his finger. However, he didn’t disconnect the pneumatic hose that triggered a piston under the dryer; the piston, which created the vacuum necessary to move the product into the hopper, suddenly sprung up and cut off the tip of his right index finger.