Safety is a critical factor across the industrial landscape. But while reducing risk on the plant floor has been a constant for more than a century, safety standards have undergone a global transformation in recent years.
“In the converting industry, the changes have been extraordinary,” says Jill Thiede, strategic accounts manager, Paper Converting Machine Company (PCMC) in Green Bay, Wisconsin. “Today, our focus is twofold: making equipment that runs 3,000 ft/min more efficient and enhancing the safety of that equipment.”
To meet this challenge, PCMC, a Barry-Wehmiller company, makes functional safety an integral part of the design process across its portfolio and in upgrades that support legacy equipment (Figure 1).
"Safety has always been an important part of our equipment," says Jason Stover, senior electrical project engineer at PCMC. "However, in the past six years, we have really made some improvements in that area. Ten years ago, we of course had safety on our equipment, but it was what we thought was the best for safety. As we progressed, customers would ask safety questions, and it would be difficult to substantiate our viewpoint. It was one of the challenges we faced."
Because of this, over the past several years, PCMC worked with Rockwell Automation to utilize industry safety standards as the backbone of its equipment. "Now when the customer asks us safety questions, we can clearly articulate why we implemented safety design the way we did, and it is clearly documented," notes Stover. "It's no longer a discussion of whether it is right or wrong, but more of system functionality, which is a lot easier. We know why we do what we do when it comes to safety, which is much better than being in a position where you are not sure of the answer."
Running with safety
With almost 100 years of experience, PCMC designs, builds and services machinery for the tissue-converting, packaging, flexographic-printing and nonwovens industries. Its installed base has an active equipment life that can extend beyond 50 years.
For decades, machine builders approached safety as an add-on. A machine was designed first, and guarding and other safety components were applied later (Figure 2). Still prevalent today, this method enables an OEM to achieve safety compliance, but often at the cost of productivity.
“These installations meet regulations, but oftentimes the entire machine must be stopped to changeover the equipment or perform maintenance,” says Stover.
Also read: How technology is making machines safer
Contemporary functional safety standards, including IEC 62061 and ISO 13849-1, plus the latest control and software capabilities, enable OEMs to design safety into machinery.
“It’s really a change in philosophy,” says Thiede. “Now, we can design an integrated safety system that reduces machine hazards and associated risks and improves overall efficiency and productivity.”
For example, PCMC can divide a complex converting line into safety zones corresponding to specific risks, hazards or functions. The system can be configured to safely remove power and allow maintenance in one zone, while keeping the rest of the line up and running.
"With our equipment , we also design for a fast stop; it's faster than a normal stop, but it is not as fast as an emergency stop," says Stover. "We have normal, fast and e-stop types of stops on our machines. Most of our equipment has guarding around it with locking guard switches (Figure 3). We lock doors and only unlock when zero speed is detected because, if someone opens a guard with the equipment running, it won't stop fast enough. The operator could reach the hazard before it stops, so it must be locked."