Electronic Products & Technology

Evolving force guided relays for Industry 4.0

By Christian Netsch, product manager at TE Connectivity   

Automation / Robotics Electronics automation industrial Industry 4.0

Automated manufacturing processes are the foundation to eventually integrate digital technologies

Industry 4.0 is not possible without increasing the rate of automation in industrial facilities, ranging from synchronized machine operations, robot movements and material flows in between. Automated manufacturing processes are the foundation to eventually integrate digital technologies. A more technical definition refers to the interoperability of machine-to-machine capabilities, deep learning from manufacturing processes and greater control over technology. While there are countless benefits to automation — including faster production, decreased human labor, and workplace efficiencies — how does it impact safety?

As rates of automation increase and Industry 4.0 demands become greater, the need for automated processes require risk mitigation plans and implementing safety protocols into the logic controls.

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Safety prerequisite

Force guided relays are central to any conversation regarding functional safety — as their inherent function is to enable safe operation – even if the relay has a malfunction. The critical role played by force guided relays has been around since their invention in the mid 1970s, but their application uses have evolved with Industry 4.0. Force guided relays provide assurance that an application will move into a safe state, protecting humans and equipment from harm in case of error.

This is accomplished with antivalent contacts, which perform executive opposites of each other. One contact is normally open and the other is normally closed — both cannot be open or closed at the same time and always the relay must enable a min. of 0.5mm (0.20 inch) contact gap of the antivalent contacts. This forces technology to perform the correct movement, otherwise it will not be allowed to move, thereby protecting the equipment and everything around it.


Depending on the logic used by the end customer, relays force applications to shut down completely or pause or slow down into a degraded motion path, both defined as a safe state. The complexity of the application determines the number of input and output channels the relays need. Ultimately, force guided relays ensure safety in industrial contexts by preventing technology from moving against pre-programmed logic.

Evolving Industry 4.0 needs

This smart electromechanical principle makes force guided relays an optimal safety solution for industrial applications and has not changed since its invention 45 years ago. However, the way a force guided relay today is being designed and produced is constantly developing. For example, their reliability in monitoring circuits with a low signal voltage level has been improved. Also, the component design and processes to minimize particles inside the relays have changed over time, which is nowadays reducing the risk of contact welding, if dust is accidentally coming near the working air gaps.

The decentralized controls and work centers of the factory of the future often require miniaturized product designs and are driving also for force guided relays the need for smaller form factors. Energy saving is not just environmentally friendly, but inventing relays with lower coil power consumption to drive the relay allow better heat dissipation and therefore higher PCB component density. Which is beneficial, if more sensors are being used to monitor a process, but the available space for the now more complex safety relevant controls is smaller.

Global safety standard

Besides technology, also the safety awareness and the duty to mitigate risks has changed. Driven by obligatory safety standardization for machinery, elevator or robotic applications, its proliferation in many dangerous processes has sped up the usage of force guided relays over the last 30 years. Starting mostly as European standards, functional safety is today globally mandatory for designing and exporting industrial machinery and robotics, which provides a positive outlook for the demand and further need for force guided relays.




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