Air logic breeds safety
Automating operations, of course, increases productivity by increasing cycle times. And when done properly, says Jim Ruthemeyer, manufacturing engineering manager at OPW, automation improves safety and ergonomics of an operation as well. "We have four highly-skilled toolmakers within our Advanced Manufacturing Engineering Group who were instrumental in coming up with clever and effective ways to automate our operations. Personnel from our shop floor helped bring these ideas to fruition."
A common application of air logic at the OPW plant are twohand, no-tie down controls. These controls are used whenever a reasonable potential exists for a machine to injure a worker — typically presses and clamps. The twohand,no-tie down control works by requiring an operator to actuate a pair of air switches simultaneously.
Logic of the two-hand, no tiedown control requires the operator to press both switches at the same time — or at least within a narrow time period. If only one switch is pressed, or too long a time passes before the second is pressed, the machine cannot be operated until the control is reset and both switches pressed within the prescribed time period. Likewise, both switches must be released before the machine operation can be repeated.
This setup ensures safety by preventing the simultaneous twohand operation requirement from being defeated. This could be done by securing one switch in the depressed position.
Ruthemeyer says the two-hand, no-tie down control reduces workplace accidents because if operators must use both hands to operate machine controls, their hands cannot get in the way of potentially dangerous areas — within the range of presses or gripper jaws. "Obviously, our top priority is preventing workers from getting hurt. But from a business stand-point, injuries hurt productivity. If a machine would injure a worker, that machine could not be used until investigations — usually lengthy — were completed. Even then, machine modifications and subsequent testing would usually have to be performed."
Ruthemeyer says management also must consider the actual cost of injuries, which can be in the form of Workers' Compensation payments, insurance premiums, and direct compensation. So reducing or eliminating workplace injuries not only benefits workers, but helps keep a lid on manufacturing costs by reducing machine downtime and labor costs.
How much have these pneumatic machine controls improved safety? Ruthemeyer says that since OPW's safety team implemented these controls and other improvements-over a 7-yr period, workplace-injuries have been reduced from 24 injuries per 200,000 hr of work to less than two — more than a 90% reduction!