Metalforming dangers unnecessary
By: Simon Fridlyand
A significant deadline for implementing a power press safety compliance schedule has just passed and those who haven't taken action should do so quickly or face the consequences of Ontario's Occupational Health & Safety criminal negligence bill.
A power press can present serious hazards to its operator. A power press injury can result in the amputation of fingers, a hand or an arm, and can cause many other disabling injuries. Last year alone, the U.S. metalforming industry reported 650 power press-related injuries.
Yet such injuries are preventable and are no longer acceptable in our society.
On poorly safeguarded presses, foot switches or other activating devices can be inadvertently activated while the workers' hands are at the point of operation, resulting in an injury.
The following two factors interact to cause inadvertent machine activation. First, 'unmediated hand movements' are made in response to workpiece and machine problems. In other words, the operator may attempt to correct the placement of a workpiece after the downstroke of the press has been initiated.
Second, out-of-sequence foot or hand movements may be caused by loss of operator balance or by a breaking of the normal task rhythm. The point of operation has to be protected by a reliable control system that will stop the press before an accident can take place.
An important question arises: What constitutes a safe power press?
The simple answer is this -- it is a press that is compliant to current and applicable standards. The Canadian Standards Association published a new edition of its CSA-Z142-02 standard for power presses in 2002. This standard includes additional requirements for compliance for all mechanical, hydraulic and pneumatic power presses.
Control reliability is critical
One of the most significant changes to the standard was the requirement that all safety circuits (electric, hydraulic, pneumatic and muting circuits) be control reliable. For control reliability, all safety control systems must be dual channel with monitoring.
This includes the need for two separate channels that are monitored for faults with every press stroke for all interface, relay and machine control circuits that signal the press to cycle, trip, or allow muting of safety devices such as light curtains.
All programmable electronic systems that are part of the safety control circuit must also be control reliable. Control reliable PLCs include at least two separate, diverse, self-checking processors.
This edition of the standard also has retroactive features. Section 1.3 states: "It is recommended that a schedule be developed and implemented that will ensure compliance with all applicable parts of this Standard no later than two years from the date of its publication."
Deadline has passed
That means the deadline of December 2004 has passed.
Many responsible employers are upgrading their presses as you read this. It makes sense for two main reasons. The first is reducing the liability associated with issues created by Ontario's Bill C-45. C-45 is also known as the Occupational Health & Safety criminal negligence bill.
This law requires that employers take steps to provide a safe workplace for their employees. Employers who fail to do so may face charges of criminal negligence under the amended code.
Criminal negligence occurs when an act or omission of an accused party shows reckless disregard for the safety of others where the accused is under a legal duty to act. Individuals who have been proven guilty may get up to 10 years in prison, and in the event a death has been caused, can receive up to life imprisonment.
Improving productivity a bonus
In addition to increased safety, upgraded presses can also improve operational productivity. Simplified error messaging and troubleshooting allow operators to quickly notice and correct press fault conditions, allowing them to return to the production mode sooner than if there was no total press operations monitoring available.
Another benefit of upgraded press controls is their ability to identify potentially serious mechanical malfunctions early. This allows for preventive maintenance to take place before the occurrence of a major power press breakdown and significant production interruption.
Maintenance consideration important
A press controller is a major component of the upgrade. When selecting a controller, one has to think about repair and maintenance down the road. What would happen to your operation if a component of the controller malfunctioned during the second shift?
Purchasing a system that is easy to fix and maintain would make absolute sense. A relay logic controller is recommended for its simplicity and ease of repair.
Many maintenance people keep a stock of replacement parts (safety relays, for example) and are quite capable of fixing the problem by themselves. However, if the controller is based on chip-board technology, fixing the problem may be very costly (since the entire board has to be replaced and must be supplied by the original board manufacturer) and it may take a while to receive it.
Since the press upgrade relates to electrical and electronic devices which signal the machine to stop, a Pre-Start Health and Safety Review (PSR), as mandated by Section 7 of Reg. 851, also is required in Ontario. In order to avoid additional expenses and startup delays, the PSR has to be coordinated while the press is being upgraded.
Simon Fridlyand, P.Eng., is president of S.A.F.E. Engineering, a Toronto-based company specializing in industrial health and safety issues and compliance. He can be reached at 416-447-9757 or simonf@safeengineering.ca.
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