CSA outlines revised power-press standard
February 23, 2010 by Manufacturing AUTOMATION
Every year, 7,500 workers are injured using machines. Furthermore, one in four workplace deaths involves machines. Ontario’s Workplace Safety and Insurance Board notes that power press injuries often lead to the amputation of fingers, hands, arms or other disabling injuries.
If an injury involves a power press, it will be severe, warns Cory Newton, president of Tekpress Solutions Ltd. and chair of the CSA technical committee responsible for revisions to CSA Z142-02, Code for Power Press Operations. “Whether a power press starts at one tonne or 100 tonnes, getting a hand caught in it will always result in a critical injury,” he says.
Why these injuries happen
U.S. data shows that these injuries seldom are a result of equipment failure; in fact, less than one percent of power press injuries result from electrical control component failures. Instead, the most common causes include:
• disabled safety devices
• improper lockout before conducting maintenance
• failure of die setup or repair personnel to return machine controls to the proper configuration
While these causes sound simple enough, safeguarding power press machines isn’t. Press operations can vary widely, notes Dennis R. Cloutier, co-chair of the ANSI B11.1 Safety Standard for Mechanical Power Presses committee. In an article for Fabricating and Metalworking magazine, Cloutier identified the following common variables:
• size, speed and type of press used
• size, thickness and kind of pieces to be worked
• design and construction of dies; the required accuracy of the finished work
• operator skill
• length of run
• method of feeding, including part and scrap removal
Devising safety procedures to accommodate these variations can be a challenge. Hence, the value of applying CSA’s updated power-press standard.
The current standard specifies requirements for the design, manufacture, installation, maintenance, operation and safeguarding of power presses. The revised standard will have a broader scope, notes CSA project manager Elizabeth Rankin. Among the changes to the 2010 version of the standard include requirements for:
• Direct Drive and Servo Presses. “These presses started appearing in North America in 2000,” Newton explains. He believes the presses now represent 60 percent of new press sales.
• Equipment, Procedures and Training for Safely Pressurizing Hydraulic Tie Rod Nuts. Guidance on how to safely pressurize hydraulic tie rod nuts, sometimes used a last resort to relieve a press stuck on bottom, was recommended by a coroner’s jury following an inquest probing the death of a worker who had been struck in the throat by a section of quick-connect hydraulic coupling he was unscrewing from the port of a hydraulic cylinder. Unknown to the worker, the internal check valve in the coupling had trapped 10,000 PSI of hydraulic pressure behind it. As the worker was unscrewing the coupling, it reached the point where the threads were unable to withstand the force, which transformed it into a high velocity projectile. Tests have since shown that pressure can build up to dangerous levels when the fittings are one turn or less from fully installed.
• New Safety Devices. Injuries often occur when operators bypass safety devices that lack the flexibility required for many jobs. More flexible safety devices reduce the temptation of operators to bypass them, leading to improved safety.
Other changes include:
• A 10-mm per second “slow speed” for use in conjunction with (and only with) laser AOPD guarding devices, adapted from Europe’s prEN12622:2006 hydraulic press-brake standard
• Slide-lock requirements
• Removal of brake monitors as a requirement when not used with safeguarding devices to signal a stop
• Removal of radio frequency devices as acceptable electronic safeguarding devices
• Replacement of the term “control reliable” with “safety circuit performance level,” to ensure compatibility with other standards with equivalent control reliability levels while maintaining the high standard of safety required in the current edition.
Newton attributes the existing standard with creating a safer working environment in many workplaces. “When the standard came out in 2002, there was a big push for training. A lot of workplaces responded, making sure that everybody in the plant has training and is comfortable using the machines,” he says. “The requirement for pre-start health and safety reviews (PSRs) has also made a difference, ensuring that guarding is done properly. In the pre-PSR days, adding guarding devices was often a piecemeal process, just adding an interlocked guard here or a light curtain there. PSRs have changed all that.”
However, Newton continues, he still encounters firms that are unaware of the standard, and of risks that could be avoided. “These firms are not meeting their obligations under the Occupational Health and Safety Act,” he says. “Besides putting workers at risk, they’re making themselves vulnerable to prosecution.”
How does your workplace stack up?
Safeguards, worker training, press maintenance, and inspections are all vital to power press prevention. For a quick assessment of your workplace’s prevention practices, ask yourself these questions, courtesy of the Workplace Safety and Insurance Board:
1. Is guarding in place and used properly?
2. Is machinery in good repair and used properly?
3. Are lockout procedures clear and understandable?
4. Are workers and supervisors trained before work starts on machines?
5. Are written job procedures available to, understood and followed by workers?
6. Is required personal protective equipment in good repair and used properly?
7. Are incidents and injuries investigated to find and eliminate the root causes?
How CSA can help
Z142-10 is expected to be published in March 2010. But you can pre-order the standard today at www.shopcsa.ca/onlinestore/GetCatalogItemDetails.asp?mat=2020838. CSA and IAPA have developed a new course to educate participants about the changes in the standard. Click here for spring course dates and locations.
The changes in the power press standard are among the first in a series of changes to CSA machine safety standards that are intended to harmonize Canadian safety requirements with international standards.
Questions can be directed to Elizabeth Rankin at (416) 747-2011 or email@example.com.