Protecting Workers from Automated Machine Operations
Plan ahead by providing proper machine guarding equipment sooner rather than later; if not to prepare for future regulations, do it to keep employees safe.
- By Eric Esson
- Dec 01, 2016
In the ever-evolving industrial world, new technologies are constantly putting old safety rules out of date. Even old-fashioned processes such as stretch wrapping have become more technologically advanced and are often automated today. While OSHA doesn’t currently have a specific standard referencing automated stretch wrapping operations, broader OSHA regulations should apply.
Perhaps it is no surprise that "machine guarding" (specifically, 29 CFR 1910.212) consistently falls into the top 10 of most frequently cited OSHA violations on a yearly basis. When new safety regulations are introduced every year, it is easy to understand why this commonly misunderstood topic is more confusing than ever. The multitude of robotic applications and the growth of robot use and automation in all industries only enhance the challenge.
Automated Processes Increase the Danger
Simple stretch wrap machines are nearly as ubiquitous to loading dock areas as dock levelers, seals, or shelters. As with almost all other industrial processes, what began as a manual operation (the arduous task of bending, pulling, and moving stretch wrap around a pallet) is now commonly automated.
While most dock employees are happy about this, this particular aspect of plant operation has long been overlooked as a hazard—and its dangers are increasing. As more and more facilities automate the palletizing and stretch wrapping process, it becomes increasingly important to protect employees and pedestrians from coming into contact with the moving parts of those machines. And as suppliers add more automated functions to their floors (such as intelligent conveyors, AGVs, and AS/RS systems), it’s critical that the safety methodology is similar to that of other robotic cells and is compliant with current standards.
Right now in the United States there aren't OSHA guidelines specific to the simple basic stretch wrap machines, other than the OSHA B1910 standards. As a rule of thumb, companies want to ensure safety of their employees, and the OSHA General Duty Clause stipulates the following:
(a) Each employer:
(1) Shall furnish to each of his employees employment a place of employment which is free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees; and
(2) Shall comply with occupational safety and health standards promulgated under this Act.
(b) Each employee shall comply with occupational safety and health standards and all rules, regulations, and orders issued pursuant to this Act, which are applicable to his own actions and conduct.
To ensure stretch-wrapping equipment is safe, it should be guarded or contained per 29 CFR 1910.212(a)(3)(ii), General Requirements of All Machines. The rule states, "The point of operation of machines, whose operation exposes an employee to injury, shall be guarded. The guarding device shall be in conformity with any appropriate standards therefore, or, in the absence of applicable specific standards, shall be so designed and constructed as to prevent the operator from having any part of his body in the danger zone during the operating cycle."
Unfortunately, these safeguards are either grossly inadequate or completely ignored, removed, and not even considered.
The Growth of Robotics in Stretch Wrap Processes
Stretch wrapping operations in warehouses and manufacturing facilities tend to be stand-alone processes and keep trending toward automated versions. More and more suppliers (OEMs) are incorporating robots into the wrapping process, allowing the robots to do the heavy work of handling the items to be palletized.
Additionally, intelligent conveyors, AGVs, and in some cases AS/RS systems are responsible for the movement of the pallets to and from the pallet wrapping machines. These process suppliers (integrators and OEMs) must ensure that the palletizers can communicate with AGVs and conveyor systems and the robotic processes being performed, tying the control systems and safety requirements into the process.
Clearly, safety methodologies similar to those used with other robotic applications need to be devised and implemented in this scenario. This safety methodology needs to be compliant with the latest standards, referencing the new RIA and EN ISO standards, while adopting a more sophisticated approach employing those technologies. Luckily, this safety approach doesn’t have to deter efficiency, if done properly.
Start with a Machine Guarding Risk Assessment
Before implementing new robotic or automated equipment into a stretch wrapping process, a risk assessment must be performed. While this has always been a best practice, it became mandatory when RIA 15.06-2013 went into effect in 2015. This rule harmonizes existing international regulations and requires better hazard identification related not only to robotic motion, but also 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.
Understanding and assessing these risks—and ensuring compliance—is not a simple task. The first step for facility/safety professionals is to identify and understand all codes and regulations that are applicable to their facility and operation. Next, they should 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.
Determining Risk
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, as in automated stretch wrapping operations or in robotic welding. This point of operation is where things get tricky. Many details must be considered when it comes to this area, including the layout or design of the process, the limits of the system, and properly identifying all associated hazards, as well as devising 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 can assist in choosing the proper machine guarding device. Also, using the distance formula as identified in OSHA guidelines can help in this selection. 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.
Presence-Sensing Devices Offer Some Protection
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 devices, 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.
Limiting Hazard Exposure Even Further
While curtains may be the right choice in some applications, a fast-acting automated barrier door or roll-up curtain may be the better choice 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, and flying debris, thus further diminishing the potential risk and the severity of exposure.
Coupled with safety interlocks (up to PLe per EN ISO 13849-1 when integrated properly), automated barrier doors and roll-up curtains offer an increased level of protection for point-of-operation guarding.
For example, they restrict access to automated processes, such as stretch wrapping, where inertia causes machine parts to continue moving after it has been shut off. They also contain those secondary hazards mentioned above by placing a barrier between machine operators and machine movement. These types of guards are an ideal alternative to light curtains and other presence-sensing devices in many situations.
Stay Ahead of the Curve: Guard All Automated Processes
Regulations are still playing catch-up with new technologies. Just because there is an operation that is under-regulated today doesn't mean there won’t be a regulation in the future. Automated stretch-wrap operations will have their own set of safety rules soon enough.
Advances in design and available technology make automated barrier doors an ideal option to guard the machine and protect operators, ultimately increasing productivity and the level of safety for years to come. Plan ahead by providing proper machine guarding equipment sooner rather than later; if not to prepare for future regulations, do it to keep employees safe.
This article originally appeared in the December 2016 issue of Occupational Health & Safety.