Machine guarding and economic value: Wired safety versus safety automation

Over the past 10 years machine safety has experienced probably the greatest transformation since the advent of machine control technology. In my opinion, the recent adoption of “safety automation” has outpaced the original adoption of PLC technology in the early 1970’s. It was in the early 1970’s that machine safety was mandated by industry standards to be “hard wired.” At this time, PLC technology had just been introduced, and its reliability paled in contrast to the robust PLC reliability of today. See graph illustrated below.


Machine safety has experience probably the greatest transformation over the past 10 years since the advent of machine control technology. In my opinion, the recent adoption of “safety automation” has outpaced the original adoption of PLC technology in the early 1970s. It was in the early 1970s that machine safety was mandated by industry standards to be “hard wired.” At this time PLC technology had just been introduced and its reliability paled in contrast to the robust PLC reliability of today. Just take a quick glance at the conceptual graph illustrated below.

Graph explaining the growth of general automation versus machine safety technology along with downtime. Courtesy: J.B. Titus 

I experienced the introduction of automation technology lead by PLCs as a young engineer in an automotive plant. After a slow start, automation technology took off like a rocket experiencing wide spread adoption and application to machine control. The advantages of diagnostics reduced wiring, increased machine up-time, reduced panel space, easier trouble shooting, etc. drove acceptance as research and development drove technological improvements and inherent reliability. At the same time, however, machine safety was required to be hard wired and could not enjoy these advantages or technological improvements.

JB Titus, CFSEIn my opinion, this created a safety layer in the machine control architecture interfacing the safety related electromechanical components to the machine control automation technology. The unintended consequences resulted in a rather stagnant level of technology innovation for the safety layer in comparison to the automation technology. This gap of technology helped drive a new metric called “unplanned downtime.” Plant operation personnel became used to the diagnostics and other advantages of the automation technology and conversely became frustrated by the lack of diagnostics, intermittent downtimes, and other disadvantages of the safety layer. Thusly, many of us experienced occasions where “quick fixes” were made to get machines back into production to meet schedule demands.

To make a long story short, folks in my era have experienced the changing landscape of machine control to once again see the unified machine control architecture of “integrated automation with safety” in innovative technology. Machine safety can once again be designed in vs an after-thought. Of course, direct wiring of safety components is still a viable option. However, for larger more complicated machines integrated safety is now available. Most importantly the economic values of increased productivity can drive increased profits which in turn can provide a competitive advantage.

What experiences have you had along this changing landscape evolution?

Your comments or suggestion are always welcome so please let us know your thoughts. Submit your ideas, experiences, and challenges on this subject in the comments section below. Click on the following text if you don't see a comments box, then scroll down: Machine Guarding & Economic Value – wired safety vs safety automation

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