October 4, 2018

By: Jeff Winter, Director, Safety Practice
Grantek Systems Integration

In the Beginning…

With the important goal of assuring safe and healthful working conditions in the United States, the Department of Labor created OSHA in 1971. This set the minimum requirements for the safety of machinery that all employers must follow. Since then, advancements in machine safeguarding really started to take hold. The way engineers designed machines and the way employees interacted with machines was forever transformed, ensuring safety was at the forefront of everyone’s minds.  Since then, fatalities, amputations, and other injuries related to equipment hazards have dramatically decreased to a tiny fraction of what they once were.

The entirety of OSHA’s CFR Part 1910.212 – General Requirements for All Machines, in total, adds up to less than 2 pages when printed out – That’s it!  Without even seeing the content of the regulation, you should be able to quickly gather that the only way for it to be so short is for it to be impressively vague.  Some companies love this vagueness as it allows them to be creative in how they meet the requirements, whereas other companies hate it because they don’t quite know what to do.

No matter which mindset you fall into, OSHA was developed in a technological era where physical guards were the simplest method to make equipment safe while still demonstrating compliance. Physical guards were, and still are, easy for everyone to understand.  You don’t need to be an engineer or a safety specialist to understand how a metal barrier protects you from getting a hand caught in a gear.  Because of this simplicity, safety professionals, engineers, and operations teams have easily been able to work together to create guarding solutions that are not only safe but also are easy to explain to operators and to OSHA.  However, since physical guards by their very nature are designed to make access to the equipment more difficult, they are not always the most production friendly solution. With this, the tug-of-war between safety and productivity starts to really set its roots.

Momentum builds

Fast forward 30 years to the turn of the millennium and the machine safety landscape looked dramatically different.  From a regulatory point of view, the only notable change was in 1989 with the creation of CFR Part 1910.147 – Control of Hazardous Energy.  Since then, employers have been required to develop lockout/tagout programs for servicing and maintenance activities.  However, regulations weren’t where the biggest changes took place – this time they were in industry!

Manufacturers saw an enormous positive impact when newly formed machine safety suppliers started to sprout into existence. These machine safety suppliers had a focus on serving the industry demand for finding ways to make machines safer without impeding productivity. This meant the development of new “safety devices”, which for the first time reliably depended on control circuitry to detect and prevent unwanted behavior from causing harm (e.g. opening a guard door or breaking the beam of a safety light curtain), instead of just physically preventing interaction with equipment through fixed guards.

Both safety and productivity increased dramatically. Operators could now interact with their equipment more easily and freely with assurance of safety than they had been able to in the past, resulting in a noticeable increase in production rates.  Meanwhile, because the systems were simplistic and easy to understand, both engineers and safety professionals were able to work together to ensure that these systems were properly selected, applied, installed, and tested with the appropriate supporting administrative controls.  This gave everyone in the company, especially the safety professionals responsible for protecting employees and ensuring compliance to OSHA, confidence in their new safety solutions – a “win-win” situation.

A revolution takes place

Over time, more safety devices have continually been introduced to the market. These new devices have resulted in a steady improvement in cost, detection capabilities, fault monitoring, reliability, diagnostics, and other feature sets. With each iteration of new safety devices, things incrementally improved, but no major game changers took place.  That is, until Safety PLCs and Safe Motion Control were brought front and center in the early 2010s, forever changing the way we approach the safety of machinery.   Neither of these concepts were terribly new (e.g. Safety PLCs were first introduced in the early 2000s), nor were they conceptually that revolutionary.  PLCs have been around for decades and motion control has become a mature technology.  It would seem as if the safety technology is just catching up to basic automation technology by today’s standards – so what is the big deal? Why is this so important? The Simple answer: Options.

Safety PLCs allow engineers freedom to design custom systems that can be optimized for difference pieces of equipment or different applications.  In addition, Safe Motion Control allows for a shift in mindset over what is considered “safe”.  IEC 61800-5-2 spells out more than a dozen different safe motion functions that can be applied to servo drives other than the conventional approach of just removing power.  Examples of these safe conditions include Safe Operating Stop (SOS), Safe Limited Speed (SLS), Safe Limited Torque (SLT), Safe Direction (SDI), etc.  If applied properly, Safety PLCs and Safe Motion can revolutionize how companies evaluate and apply safeguarding solutions on equipment. Safety will no longer be viewed as a separate activity from engineering – they will be intertwined and fully integrated. Imagine robot systems where employees can safely interact with the Robot without needing it to stop. How much would that help productivity?  Imagine being able to safely clear jams, safely sanitize a machine, or safely conduct a quality inspection all without stopping the equipment? We are now at a time where the limitation of safety systems is less about the technology and more about the creativity and expertise of the engineer designing the system.

Avoiding the Illusion of Safety

When you change from only having a few combinations of options for safety system design to essentially a world of limitless possibilities, you find your systems becoming more complex.  With increased complexity comes increased confusion and a higher likelihood for oversights or mistakes in design.  Unchecked, this engineering freedom can easily result in the unintended consequence of a more unsafe machine than people realize, creating an “illusion of safety”.

There are two primary factors that can lead to an illusion of safety when utilizing this newer programmable and configurable safety technology:

1. Engineers are not traditionally trained on how to properly design safety systems for machinery.  It requires an entirely separate set of skills and knowledge to correctly design and program safety systems compared to the skills needed to design a machine control system. This means that engineers can easily design a safety system that is inadequate or incorrect for the application.  In addition, the steps required for proper verification and validation become much more complex.  Testing the proper functionality of a safety system is not the same thing as testing the proper functionality of the general machine controls.  Machine controls need to work correctly for a machine to function, whereas a safety system is generally just hiding in the background and never used unless something goes wrong.
2. Most safety professionals who are responsible for ensuring machines are safe and compliant do not have a background in engineering or system design.  That is perfectly ok!  When safety systems were simple and limited to a single function, an engineering background wasn’t really required to understand how it worked and how it protected people. Think about an Emergency Stop, you don’t have to be an engineer to quickly learn that pushing the button removes all power from the machine. However, once safety systems start to be “engineered” to optimize productivity, it can be quite difficult for that safety professional to understand how exactly that system is protecting the employees.  And if safety professionals don’t fully understand how a system works, how successful do you think the supporting safety programs (safe work procedures, safety training, inspections, etc.) will be at ensuring the systems are used and serviced correctly?

So, before running out and immediately upgrading equipment with the newest and coolest technology, make sure your organization is mature enough to do it right.  Make sure your engineers are well familiar with the current design and application standards for safety and make sure your safety professionals are familiar with functional safety.  The goal is to ensure safety professionals and engineers (whether internal at a company or external contractors) can talk to the same language.  The last thing you want is to think you are getting a safe machine, when you really aren’t.

This article was originally published by the International Society of Automation (ISA) for the benefit of their members. To learn more about the ISA or to become a member, visit: www.isa.org

 

About the Author: Jeff Winter is the director of Grantek Systems Integration’s Safety Practice, where he leads a team of engineers in developing and delivering machine safety services across North America. With over 10 years of experience working for several different safety product manufacturers, he has a unique experience in bridging OSHA regulatory compliance and safety standards interpretation with engineering requirements and corporate safety strategy. Throughout his career he has been a leader in educating the industry on the benefits of machine safety through hosting best practice industry events, participating in speaking engagements, developing white papers, and writing technical articles. Jeff is currently the Machinery Chair of the Safety and Cybersecurity Division of the International Society of Automation (ISA). Jeff is also a TÜV Functional Safety Engineer, Board Certified Safety Professional, voting member of the ANSI B11 Accredited Standards Committee, and member of the American Society of Safety Engineers Three Rivers Chapter.