Proper Risk Assessment Will Keep You in Compliance

The RIA R15.06 machine-guarding standard that took effect last month has important implications for manufacturers. 

Assessing risk has always been an important safety consideration when developing and implementing industrial machinery. Thanks to the passage of the Robotic Industry Association (RIA) R15.06 standard in 2013, risk assessments just became even more important: They are now mandatory. But while the standard officially took effect January 1, 2015, many professionals responsible for plant safety have long conducted risk assessments for increased safety as a matter of practice.

The basics of machine-guarding risk assessment

Understanding and assessing these risks—and ensuring compliance—is not a simple task. The OSHA machine-guarding standard, which includes robotic welding (29 CFR 1910.212), consistently falls in the top 10 most frequently cited OSHA standards violated in any given year. Considering the many regulatory changes now taking effect, there is a real potential for confusion and uncertainty.

The first step for facility/safety professionals is to identify and understand all codes and regulations applicable to their facility and operation. They should next examine the prevailing machine-guarding choices for those applications in order 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 set of unique challenges and associated risk. 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 would 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.

This new RIA R15.06 standard references ISO 10218-1 & 2, which addresses robots, robot systems and integration. It requires superior hazard identification accounting for not only robot motion, but the task being performed. Additionally, it requires validation and verification of the safety systems employed, and of the designs that incorporate protective measures for the robot cell and the operator. Because every robot system is different, requiring risk assessments is an important step in protecting employees.

An automated barrier door or roll-up curtain can be a good way to reduce risks posed by robotic welders. These arrangements eliminate exposure to dangerous machinery movements and hazards like smoke or debris from the welding process.

Risk assessments and safety-rated motion

Some of the biggest changes we will see with this industrial robot standard have to do with safety-rated motion and allowing for advanced programmable safety devices to be utilized. This means software will now be 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 in that programmable safety controls were not allowed.

Thanks to technological advances in safety controls, these long-overdue applications can now safely be implemented. In the past, engineers designing these systems guarded for the maximum space, speed and load of the robot. With these changes, the physical footprint of new robot cells should shrink. Coupled with the proper point-of-interaction safety devices, significant floor-space savings can be realized.

More quantitative regulations

The change in RIA R15.06 is part of a larger movement toward more quantitative regulations being implemented in the U.S. and across the world. This started several years ago with the move from EN 954-1 to ISO 13849-1 and EN 62061.

Essentially, ISO 13849-1 provides 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 the old EN 954-1. It applies common sense and forces facility managers to validate their safety systems, whereas EN 954-1 was conceptual and only required facilities to apply safety devices (controls) properly specifying non-programmable, 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 processes all require considerable attention to assure those processes can proceed efficiently and safely. ISO 13849-1 is making for a much safer manufacturing environment because it accounts for the regulatory gaps that were starting to show in the older standards.

Because every robotic system is different and has its own set of guidelines, it’s important to understand those guidelines before a system is implemented. Specifications such as space and cycles need to be known. Integrators of new robotic systems will be required to perform these risk assessments in an attempt to identify potential dangers and ways to limit and eliminate them.

Guarding point-of-operation

When performing a proper risk assessment, point-of-operation guarding is probably the most involved aspect. It is 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 operating the machine.

Point-of-operation is where things get tricky. Many details must be considered, including process layout, system limits, and the need to identify the hazards to be eliminated and risks reduced. Once the severity of a potential hazard has been determined, the frequency or duration of exposure and the possibility of eliminating or limiting exposure can guide the choice of the proper machine-guarding device. Also, using the distance formula identified in OSHA guidelines can help in this selection. Per this formula, the safeguarding device has a prescribed location based on several factors, including secondary hazards that might harm a machine operator.

Presence-sensing devices and barrier doors

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. The automated process ceases once the safety device’s infrared beam is tripped. In many instances these devices provide acceptable safety. However, they’re not always the best choice in all applications, especially after a risk assessment is performed.

While light curtains can limit exposure to the hazard, a fast-acting automated barrier door or roll-up curtain may be a better choice. This is because they can eliminate exposure to both the dangerous movement of the machine and secondary hazards produced by the process, such as smoke, flash, splash, mist or flying debris associated with automated welding operations. Coupled with safety interlocks, automated barrier doors and roll-up curtains provide safeguarding that can be seen (unlike the invisible infrared beams of presence-sensing devices), thus reducing the opportunity for accidental work stoppage. The physical separation they provide is a clear visual indicator that the machine operator needs to be on task.

Due to the nature of a properly interlocked automated barrier door, certain aspects of OSHA’s safety distance formula become moot because there is no depth penetration factor, thus allowing the safeguard to be placed closer to the hazardous area. That means less space dedicated to a “safety zone,” which, in turn, can reduce the manufacturing cell’s footprint. The smaller safety zone may also make for a better ergonomic situation for the machine operator by limiting required motion and help increase productivity.

Regardless of the safety device selected for machine-guarding, facility managers need to remember to perform a proper risk assessment to keep their workers safe and to remain in compliance with RIA R15.06. MT

This article was prepared with information supplied by Eric Esson, Rite-Hite Machine Guarding, Milwaukee, WI. The information is provided without warranty as a general reference only regarding the use of the noted product(s).