Kamis, 17 Juni 2010

Machine Safety Incorporates Relays, PLCs, Risk Assessment and Standards

What’s in your bottle? The SPF of your sunscreen lotion might protect your hide, but achieving appropriate safety integrity levels (SILs) will protect your operators and machines. This is especially true if you precede SILs with a hazard identification and risk assessment (RA) and follow them with performance requirements, consistent implementation, thorough training and continuous revaluation.

If you don’t apply protection, however, you could wake up at the metaphorical beach with a lobster-red sunburn. Likewise, most machine safety programs are inspired by a painful wake-up call. These events can be deadly serious destructions of life, limb and equipment, or only slightly less serious near misses that could turn tragic next time if changes aren’t made.

Enough Was Enough

After several years of poor safety performance, Goodyear Tire & Rubber's plant in Gadsden, Ala., had two major injuries, which occurred when employees were caught in the facility’s let-off shear machinery in 2006. In one event, a machine had been left in automatic mode, and it seized and injured an operator’s hands when he patted down the roll of rubber on it.

“We had a huge need for improved safety,” says Charles Skaggs, Goodyear’s health and safety manager. “We had 300 new staff this year, and for the past four or five years, we’ve had to tell them that Gadsden was at or near the bottom of all Goodyear plants in terms of safety. After 2006, our corporate management said it wasn’t going to put up with these incidents any more and asked us to study ways for our machines to achieve first-class safety ratings.”

Goodyear’s subsequent study included input from the Rubber Manufacturer Assn, which reported that the most dangerous place in the Gadsden facility—and in most tire-making applications—is the wind-up and let-off areas in their fabric bias cutter and sheet calendar machines. RMA recommended that Goodyear focus on improving the wind-up and let-off safety at all its global facilities. Consequently, Goodyear’s management ordered mandatory safety release (MSR) capabilities, so its machines could attain a Level 1 safety rating, and budgeted $3 million for the project.

To help improve the safety of its machines, many of which were very old, Goodyear used a Rockwell Automation modular kit-based solution that could be implemented and reproduced among multiple machines. Goodyear began installing the presence-sensing equipment and light-activated barriers from August to December 2007. These devices prevent the wind-up and let-off machines from running if an operator puts his or her hand in it. The kit also includes new e-stop equipment, replacing the former safety cables and belly bars, as well as new safety interlocks and fencing.

“Because the kits are modular, we could implement them in 67 wind-up/let-off applications in 20 weeks,” says Skaggs. “The kits were so successful that Goodyear plans to spread them across all of our plants.” Besides completing its MSR project on time, Skaggs reports that Gadsden improved its safety performance and record by 61% in the approximately 12 months that it’s been in place. The plant had 34 fewer OSHA-reportable incidents during the same period, and its safety project also reduced downtime by 34%. The $885,000 worth of safety equipment that Goodyear has installed so far paid for itself in just four months. More specifically, Gadsden’s OSHA-reportable incidents dropped from 148 in 2004 to just 29 in 2007 and 27 as of October 2008.

Skaggs believes the main requirements for a successful safety improvement project include 100% commitment from management, sufficient training and awareness, thorough understanding of the production system and coming to realize that safety is not a technology problem, but is about educating people and overcoming traditional resistance to change.

To further encourage and ensure safety, last year Goodyear started a rapid improvement activity (RIA) program, in which company participants spend one day in a safety class and then go through their facilities and applications, seek out safety-related items that need to be improved and try to complete 80% of those fixes in three days. So far, Skaggs says Goodyear’s employees have found 262 items and have improved 219 of them.

“After doing so badly in 2003-04, Gadsden’s plant management and Goodyear’s corporate management said we just had to do safety differently,” adds Skaggs. “Before that, we just didn’t have enough of a focus on it. So, we revised our whole safety structure and also began to drive more safety responsibility to our safety teams on the plant floors. We also work very closely with our union’s safety representatives, and we have a very good relationship with them because we both have the same goal of no one getting hurt. I think this kind of relationship is something you must have to improve safety and maintain it.”