What’s your safety system strategy?

A safety system is essential for protecting machine operators and other workers on the manufacturing floor from hazardous machine motion.

Another less obvious benefit of machine safety technology is that it can help achieve improvements in overall equipment effectiveness (OEE). Manufacturers are starting to take advantage of their safety systems’ ability to help keep machines running and lower the frequency of unplanned stoppages.

Technologies that form part of the Industrial Internet of Things (IIoT) are the driving force behind this trend towards using the safety system to enhance OEE, since they reduce wiring, simplify troubleshooting and help gather machine data.

As it turns out, manufacturers are employing these technologies in two seemingly opposing ways: either to create modular safety systems that enhance flexibility or to bring an entire plant’s machinery under a single, all-encompassing safety solution.

Some companies seek to achieve the best of both worlds.

Using IIoT-enhanced machine safety for equipment availability

Traditional machine safety technology requires that all safety devices on a machine be individually wired back to the safety controller, creating a variety of potential failure points. In this situation, a faulty connection could create an error on the system that would result in time-consuming troubleshooting activities.

By using an IIoT safety network instead, manufacturers can reduce wiring requirements and also acquire important diagnostic information. The reduction in the overall number of wires also simplifies installation and cuts costs.

The reduction in wiring and resulting improvements in flexibility and data collection have prompted manufacturers to adopt strategies that garner the most value from IIoT safety applications.

Depending on its particular business model, a company may opt for centralized control to simplify hardware and optimize the use of data coming from smart sensors and other networked devices or may instead put flexibility first and foremost with a modular system.

The case for centralized safety systems

Some manufacturers are currently building comprehensive safety solutions that use just one programmable logic controller (PLC) and one safety controller for an entire production line.

When there are multiple safety controllers, there are more opportunities for variation and errors within safety programs. Each controller might be programmed a little differently from the next, which delays troubleshooting.

This gives them centralized control over safety-related data, simplifies troubleshooting and lowers hardware and training requirements. In the automotive industry, for example, some manufacturers are now bringing the entire panoply of robots on a weld line under one PLC and one safety controller, whereas they used to have a PLC and safety controller for every sub-line.

These large-scale safety systems shorten troubleshooting time by making it easier to arrive at the “single source of truth” – that is, the root cause of failure resulting in unplanned downtime.

When there are multiple safety controllers, there are more opportunities for variation and errors within safety programs. Each controller might be programmed a little differently from the next, which delays troubleshooting.

The case for modular safety systems

Traditional safety guarding defined around a specific machine doesn’t allow for much in the way of flexibility. In the past, when manufacturers would build a process line and expect to run it for the next 20 years or so, this strategy worked just fine.

Nowadays, companies are producing smaller lots in order to meet the demand for a wide variety of customized products.

Moving to an IIoT solution opens up more options for machine configurability and allows for automated changes to things such as muting zones and robot working envelopes depending on the particular product coming down the line.

This need is leading to a trend in which manufacturers seek to incorporate smaller safety systems dedicated to one specific cell or piece of equipment that can still network with the larger plant-wide system.

Essentially, they want to plug modular safety pieces together as needed in order to meet the demands of flexible manufacturing. This trend is largely facilitated by safety networks and smart safety devices.

This need is leading to a trend in which manufacturers seek to incorporate smaller safety systems dedicated to one specific cell or piece of equipment that can still network with the larger plant-wide system.

Using safety networks and IIoT devices, manufacturers no longer need to laboriously rewire each safety device and then manually reprogram their safety programs when they want to reconfigure a production line.

Instead, they can simply connect devices and subsystems to the local safety network. Some automation suppliers enable automatic detection of networked safety devices and offer the ability to automatically create safety programs on safety PLCs. Production line reconfiguration can then be completed with a few mouse clicks.

Aiming for the best of both worlds

Choosing between a modular approach and a centralized approach generally has to do with the degree of flexibility that a manufacturer aspires to. For contract manufacturers and packagers that need a highly variable line with retooling or reconfiguration taking place regularly, a modular approach works best.

Large automotive OEMs, on the other hand, tend to benefit from a centralized approach when they plan to produce a particular body style for several years.

Some large OEMs are trying to achieve a combination of modular and centralized safety that maximize both flexibility and data omniscience. Going back to the weld line example, this would involve having a single PLC for the entire line containing multiple robots – let’s say 100 or so – while retaining the ability to work with just part of the system whenever necessary.

The centralized computing system would allow them to visualize all the goings-on in that 100-robot system, and when something goes down, they’d be able to delineate the hazard zones of the system and allow specific portions of the line to continue running while troubleshooting the affected area.

Several of the current IIoT developments support both strategies and even help move towards the “best of both worlds” ideal. Whether a manufacturer is using a centralized or modular safety system, having a single integrated development environment for the whole system is a powerful strategy, thanks to the “single source of truth” concept discussed above.

Several of the current IIoT developments support both strategies and even help move towards the “best of both worlds” ideal.

A single integrated development environment (IDE) can gather and monitor safety data, define the necessary safety measures, and provide visibility to the entire system, no matter the degree of flexibility.

Additionally, advances in safety programming software have given rise to automated program verification, which is essentially a sort of “truth table” function that confirms whether the design intent of the safety program has been met. This program verification provides a critical step in demonstrating due diligence and taking “every precaution reasonable in the circumstances” to protect workers – a legislated duty of employers in Canada.

Ultimately, IIoT technologies in a safety system serve to simplify installation and maintenance, minimize potential failure points, and reduce the amount of effort required for troubleshooting. Whether a manufacturer is leaning towards a flexible, modular system or a more centralized one, these benefits are within reach.

Sophisticated data collection and easy reconfiguration come in handy in any application, whether it’s a high-mix, low-volume production line or a high-throughput, single-product one.

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Michael Joaquin, P. Eng, Pam Horbacovsky Klancewicz, FS Engineer (TÜV Rheinland), and Todd Mason-Darnell, Ph.D, are safety services specialist, safety product manager, and marketing manager for services and safety, respectively, at Omron Automation.

This article originally appeared in the October 2020 issue of Manufacturing AUTOMATION. Read the digital edition here.