Machine Design

Too little training and the wrong tools led to dough-machine injury

A bakery worker’s hand was injured in the piston of a dough cutter. The worker was cleaning stray dough from the walls of the machine’s hopper at the end of a batch. To do this, he had to reach over the rim of the hopper with a small scraper.

A portable three-step riser permitted access to the hopper from the back of the machine. However it was prone to being bumped by passing forklifts and didn’t provide a good angle for cleaning the hopper. From the top step, workers often climbed onto a flat portion on top of the machine and reached into the hopper.

The rim of the hopper was 14.5 in. above the platform. The moving piston of the cutter created a suction which pulled dough in to form loaves. The moving parts, located about 2 ft below the hopper rim, ran at 30 to 50 rpm.

The worker was standing on the platform, leaning in to scrape dough from the hopper, when his hand was pulled into the piston. He was able to free his hand and run for help, but not before he sustained an injury that kept him from returning to his job.

Investigators learned that machinery operators received on-the-job training from other operators for their assignments.

And although workers said “everyone knew” to turn off machines before cleaning them out, there was no record of the injured employee or anyone else having been instructed in safe maintenance practices.

In addition, the machine lacked clear warning labels indicating pinch points and other hazardous conditions. Investigators also couldn’t find a user manual and had to obtain one from the machine’s manufacturer for their report.

Finally, workers had altered the wiring to bypass some of the machine’s safety provisions. For example, an interlocked control-panel door kept falling off, so the interlock was defeated to let the machine continue running. This bypass also defeated the emergency-stop measure. Someone nearby ran to turn off the machine’s power supply after his coworker was injured.

Investigators recommended a more formal safety program including proper use of lockout/tagout and interlocks. They also suggested a taller hopper or longer scraper as ways to prevent future accidents.

This month’s safety violation comes from the files of Lanny Berke, a registered professional engineer and Certified Safety Professional involved in forensic engineering since 1972.  © 2011 Penton Media, Inc.

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