Start with risk assessment to enhance safety
Automated barrier doors create safer workflow
By John Ritter
Look before you leap. This sage advice holds true in today's manufacturing world, especially as it pertains to machine guarding. That is why it is always a good idea to perform a proper risk assessment before installing or upgrading new equipment. Understanding all of the possible dangers associated with new operations can help a facility protect against hazards before an accident occurs.
And yet, according to the Occupation Safety and Health Administration (OSHA), "machine guarding," which pertains to machine general requirements for general industry (29 CFR 1910.212), consistently falls in the top ten most frequently cited OSHA standards violated in any given year. The multitude of robotic applications and the growth of robot use and automation in all industries seemingly make ensuring safety more difficult. But facility managers who start with a risk assessment need not be troubled by these advances in technology.
Unfortunately, understanding and assessing these risks-and ensuring compliance-is not a simple task. Let's break it down by starting with risk assessments, before diving into possible machine guarding solutions, and then ending with a brief history lesson on some of the industry's changing safety standards.
The first step for facility and safety professionals is to identify and understand all codes and regulations that are applicable to their facilities and operations. For managers who have stayed up to date, this is not a difficult task. For those who have not, this might not be quite so simple.
The second step is to examine the prevailing machine guarding choices for those operations to validate their safety system and its components. Although many guarding methods and products are available, not all can be applied universally. Every machine guarding application has its own unique challenges and associated risks. The choices a facility manager makes for one application might not be the same-or appropriate-for the next.
In most cases, safety-conscious managers would not guard an industrial robot the same way they guard other equipment, because the risk associated with each differs greatly. Risk may even vary between similar operations, depending upon employee exposure and other factors.
Conducting a thorough risk assessment is the best way to maintain a safe work environment, especially when adding new automated processes. Proper risk assessments are not just good practice, however. When RIA R15.06-2013 went into effect several years ago, they became mandatory.
Creating a safe environment for workers near robotic equipment.
When it arrived earlier this decade, the RIA R15.06 standard made life easier for manufacturers and end users by being compliant with international standards already in place in Europe. RIA R15.06-2013 references ISO 10218-1 & 2, which addresses robots, robot systems, and integration. This standard requires better hazard identification related not only to robotic motion, but also to the task being performed. Additionally, it requires validation and verification of the safety systems employed and requires designs that incorporate protective measures for the robot cell and the operator.
Some of the biggest changes with the RIA R15.06 industrial robot standard have to do with safety-rated motion and allowing advanced programmable safety devices to be used. This means software is allowed "safety-rated" control of various aspects of the robot's function, limiting the area in which the robot operates and the speed of robot motion. This is a departure from older standards, which did not allow programmable safety controls.
As mentioned earlier, risk assessments are required as part of this standard. Many professionals responsible for plant safety have been conducting risk assessments to increase safety as a matter of practice; the new regulations mandate them.
When performing a proper risk assessment, point-of-operation guarding is probably the most involved aspect. It is relatively easy to place perimeter guarding around the entire process. However, in most situations, a machine operator needs to interact with the process by loading or unloading materials (such as metals to be welded) and "running" the machine.
Point-of-operation guarding is where things get tricky. Many details must be considered when it comes to this area, including the layout or design of the process and the limits of the system. Also, facilities must properly identify all associated hazards and devise methods for hazard elimination and risk reduction.
Once the severity of the potential hazard has been determined, the frequency or duration of exposure and the possibility of eliminating or limiting exposure should be considered before making any machine guarding decisions. Also, using the distance formula identified in OSHA guidelines can help in this analysis. Per this formula, the safeguarding device has a prescribed location based on a number of factors, including secondary hazards that might harm a machine operator.
Light curtains, laser scanners, and other presence-sensing devices are a commonly used and widely accepted method of machine guarding in manufacturing facilities-from tier 1 automotive to small machine shops and fabrication facilities. With presence sensing, the automated process ceases once the safety device's infrared beam is tripped.
These devices often provide acceptable safety. However, they are not always the best choice in all applications, especially after a risk assessment is performed.
Physical barriers offer more protection
Although light curtains may be the right choice in some applications, a fast-acting automated barrier door or roll-up curtain may be the better choice. They restrict workers' access into hazardous areas and can eliminate exposure to both the dangerous movement of the machine and secondary hazards produced by the process, such as smoke, flash, splash, mist, and flying debris. Thus, they more comprehensively diminish the potential risk and the severity of exposure.
Another benefit to physical barriers is that they take up a much smaller footprint than presence-sensing devices. This is because barriers with properly integrated safety interlocks (up to PLe per EN ISO 13849-1) render certain aspects of OSHA's distance formula moot. With no depth penetration factor, automated barriers can be placed much closer to the hazardous area. This reduced safety zone allows workers to be much closer to the automated process, which saves floor space.
ISO 13849-1 and EN 62061 emerge
The move from EN 954-1 to ISO 13849-1 and EN 62061 represented one of the largest regulatory shifts in decades. While approval of this harmonized standard was a hotly contested fight 10 years ago, all has been well since it went into effect in 2012.
At its core, ISO 13849-1 is a clearly defined set of rules to follow when designing the safety system as applied to industrial machine control systems. Officially defined as "safety of machinery, safety-related parts of control systems, general principles for design," this regulatory shift was made necessary by advances in technology for safety control systems and methodology.
The ISO 13849-1 standard is more quantitative than EN 954-1. It applies common sense and forces facility managers to validate their safety systems. Previously, EN 954-1 was conceptual and only required facilities to apply safety devices (controls), properly specifying nonprogrammable, out-of-date technology.
Increasingly complex manufacturing processes require more complex systems to monitor their safe operation and keep machine operators safe. Automated processes, robotics, and even time-tested operations all require considerable attention to ensure they are both efficient and safe. EN ISO 13849-1 is ultimately making a much safer manufacturing environment, because it accounts for the regulatory gaps that were starting to show in the older standards.
RIA R15.06 is similar to ISO 13849-1 in that it takes on a quantitative approach to hazard identification. A functional safety requirement of D (performance level [PL] "d") will be required of all robotic systems, as well as structure category 3 (dual channel), unless a risk assessment determines otherwise. PL safety and category ratings will offer a much more measurably reliant way to gauge safety.
Safety begins with a proper risk assessment
As regulations like RIA R15.06 and EN ISO 13849-1 are adopted, it is important to adopt the latest and greatest safety technologies available to match the right product to the right process, taking not only potential machine hazards into consideration, but the task being performed. Advances in design and available technology make automated barrier doors an option to guard the machine and protect operators, ultimately increasing productivity and the level of safety for years to come.
Regardless of the safety device selected for machine guarding, facility managers need to remember to perform a proper risk assessment. Although they can be tricky, this process will ultimately make a facility safer for workers and stay in compliance with RIA R15.06.