Update on press and press brake safety standards
Metal fabricators take note: Harmonized safety upgrades on the way
Updates to the ANSI standards are meant to harmonize press and press brake safety standards from all parts of the world. Once accomplished, a manufacturer can feel confident that its plants meet the latest safety standards no matter where those facilities are in the world.
The American National Standards Institute (ANSI) B11 press and press brake standards were first issued in 1971 (B11.1). Currently all three are being updated, with B11.1, which applies to mechanical presses, just completed in fall 2009, and updates for B11.2 (hydraulic presses) and B11.3 (press brakes) in process and targeted for completion this year.
Even though previous versions of these standards called for dual-channel control reliability of all safety monitoring devices on presses and press brakes, many in the industry, including some inspectors, believe that less than half of these powerful pieces of equipment have been retrofitted to meet these safety requirements. Unfortunately, serious accidents continue to happen. To avoid those dreadful scenarios, all safety-related devices and motion-related components on presses and press brakes need to be monitored continuously with dual-channel redundancy. These include Category 4 light curtains, interlock gates, ram block plugs, air pressure, and stopping time all tied into real-time monitoring by an advanced press control that monitors and reacts to stop the dangerous motion of the press to prevent injury. (Category 4, as defined by the European EN 954-1 machine safety standard, dictates that no single fault should lead to a loss of safety and the single fault should be detected when it occurs.)
A manufacturer’s reluctance to invest in safety upgrades becomes more evident as further upgrades are recommended in new safety standards. For example, consider the new changes included in this summary of the new version of ANSI B11.1:
- Protection and monitoring are recommended for moving bolsters and related pinch points, scrap chutes and all openings, and tandem lines and transfer presses.
- Removal of overrun cams and replacement with stop signals are encouraged. A mechanical cam commonly was used to monitor a press’s crank to ensure it didn’t overshoot top dead center. Today’s newer presses and retrofits have replaced these cams with encoder monitoring that generates a stop signal to halt the crank before it overshoots top dead center.
- Servo presses have been addressed. Because servo presses are direct-drive and have no clutch, brake, or flywheel, no stopping monitors are required. However, a 90-degree stopping distance is still a requirement for these types of presses because, as with other crank-style presses, 90 degrees is the most severe position at which to initiate stopping of the ram. Servo presses also must have continual monitoring of the reverse motion encoder for each initiation of motion because they have the potential for instantaneous reverse motion due to electronic component failure.
- An emphasis is placed on the use of slide locks because of their reliability when compared to safety blocks.
- Additional requirements were issued for control technology used to keep workers safe.
Although the details related to changes in store for ANSI B11.2 and B11.3 are not yet available, you can be sure that they will take into account safety recommendations from other parts of the world. In fact, one of the purposes of these updates is to bring about a harmonization of U.S., Canadian, and European standards, giving the manufacturers of press and press brake equipment confidence that the safety designed into their products ultimately will meet the standards on a global basis. So whether it is the ANSI standards described previously, the CSA Z142-10 in Canada, or the BS EN 692 in Europe, recent revisions have moved these effectively to a much closer level of harmonization when it comes to the major safety features of the equipment.
Once this level of harmonization is achieved, it is hoped proactive equipment manufacturers will take measures to ensure that upgrade solutions are developed and readily available for their equipment already in the field and new presses.
For those companies looking to proceed with a retrofit of their own equipment, dual-channel, control-reliable units can be installed rapidly on all types of presses and press brakes. This approach may be especially attractive to those companies with facilities in many countries that are looking for similar safety commitments for all of their press and press brake users, no matter where they might work. For a management primer on what these standards require from the perspective of senior management, visit http://bit.ly/press_safety.
The fact that these safety requirements now are expanding and being harmonized in a number of global markets is a sign that perhaps every piece of press and press brake equipment sold, regardless of where it was originally manufactured, will have the latest safety tools to keep operators safe. It is only in this way that companies can deliver the safest environment for their employees.
The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.