Safety interlock switches are used as interlock devices that can prevent machine operation or startup in an unsafe situation, such as when a door or guard is open. Interlock devices with a locking function can also prevent doors or guards from being opened while the machine is in operation.
Safety interlock switches (interlock devices) are an important factor in ensuring machine safety, with many relevant safety standards. Two of the most typical standards are ISO and ISO , and safety performance that meets these standards is essential.
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Safety interlock switches are used on safety doors, fences, and guards that physically separate workers from hazards. These devices are essential to ensuring reliable safety precautions.
Sometimes working in dangerous areas is necessary, such as during equipment maintenance or troubleshooting. In such situations, safety interlock switches for doors and movable guards are needed to ensure both worker safety and productivity.
Locking types can also reduce risks while the machine is in operation and prevent the machine from stopping unnecessarily.
Locking-type safety interlock switches are available in power-to-release or power-to-lock models. These types can be used in a variety of ways depending on the situation and hazard.
Power-to-release models use a spring to lock the device, ensuring the device remains locked even when the power is turned off. This means these models are ideal for protection against large robots, rotating objects, and other hazards that cannot be stopped immediately due to inertia. Power-to-lock models, however, use a powered solenoid to lock the device, meaning, the lock is released immediately when the power is turned off. These models are useful in situations where a lock is necessary to protect workers from a hazard that can be immediately shut down if the power is interrupted, or to protect the operation of the machine.
Non-contact safety interlock switches are most commonly used when dust and debris must be avoided to prevent product contamination. These types eliminate any risk of dust and debris because door conditions can be detected with no contact between the sensor and the actuator.
Because non-contact types do not have a locking mechanism, no wear debris is created. This makes these types are ideal for clean environments and food industry settings where a sanitary manufacturing environment is required. The surface of these types is also relatively smooth, preventing foreign particles from adhering to or accumulating on the sensor or actuator. Non-contact types also boast a high enclosure rating (IP65/67/69K), ideal for withstanding the environment and cleaning.
For processing machines, safety precautions are required to detect intrusion into the processing area. Machines require door locks and other measures for quickly responding to the actions of workers, such as when entering the processing area during operation. Additional safety precautions such as slowing down the operation of the machine when working in the processing area are also important.
Power-to-release safety interlock switches (GS-50 Series) are recommended for processing-machine doors. After the machine stops completely, an unlock signal is sent to the safety interlock switch to unlock the door. With a power-to-release safety interlock switch, the door will remain locked even when the power is turned off. This will prevent workers from entering the processing area until the machine’s inertial movements completely stop. Once the worker closes the machine door, the operation can be resumed.
Used in a variety of fields including assembly lines, SCARA robots are known for their space-saving design and high-speed operability. However, because of the limited space used for installation, such as inside cases, the robots can be dangerous if operated while a worker is inside the case with the robot. Workers entering the transfer areas between machines is also dangerous.
A KEYENCE safety interlock switch (GS Series) can be used to monitor the status of doors in such situations. If a door is opened, the robot is stopped and an interlock state is enforced. Once the worker exits the case and closes the door, robot operation can be resumed. Safety light curtains in the transfer area between machines can also be used to turn off the OSSD if a worker is present. This makes it possible to prevent the robot from operating while workers are inside the case.
For large machines with numerous doors, individual controller cables are required, making the wiring for safety devices very complicated. Such situations can also be troublesome due to the limited number of diagnostic methods for troubleshooting, causing the machine to be stopped for unnecessarily long periods and increasing maintenance and repair costs.
KEYENCE’s GS Series Safety Interlock Switches offer cascade connections between contact emergency stop switches and safety interlock switches. This enables a unified safety output for a reduced number of inputs and less wiring. Cascade connections also comply with safety standards such as Category4 and PLe (ISO ‑1). (Up to 30 non-contact types or 25 locking types can be connected.)
Safety interlock switches are used to increase machine safety and reduce risks. Machines are generally enclosed by a fence or similar equipment as a basic safety precaution (separation-based safety). However, if it is necessary to get close to a machine for troubleshooting or maintenance, workers must stop the machine to enter the fenced area (stoppage-based safety). Safety interlock switches can be used to check the door status in such situations.
For example, a safety interlock switch can be used to lock the door and keep it from being opened while the device is in operation, preventing accidental operation if a worker opens the door and enters the fenced area without turning off the machine first.
Power-to-lock models unlock when the power is turned off, while power-to-release models remain locked even without power. Because of this, power-to-lock models are used with machines that are not affected by inertia and are able to stop immediately when a door is opened or where a safe distance can be maintained. Power-to-release models use a spring to remain locked even when the power is turned off, so these devices are often used to ensure worker safety with machines affected by inertia, such as rolling machines. Power-to-lock models also unlock immediately in the event of a malfunction because the power to the solenoid is no longer supplied. Power-to-release models, however, will remain locked even after power is no longer supplied. This makes power-to-release models useful to ensure safety in the event of a power failure.
The standard used for designing and selecting interlocking devices such as door switches is ISO , “Safety of machinery — Interlocking devices associated with guards — Principles for design and selection.” This standard defines the following categories (levels) for encoding actuators.
• Low: 1 to 9 coding patterns
• Medium: 10 to coding patterns
• High: or more coding patterns
With specific actuator teaching, the GS Series can support the High encoding level for more than different coding patterns, allowing use with minimal design constraints.
Jonathan Wendt, Director, Global Applications, BQT Solutions looks at the ten critical questions you should be asking before selecting door hardware.
The door lock, once a simple mechanical device to keep a door secured, now stands at the intersection of asset security and electronic innovation.
Security professionals, integrators, specifiers and architects no longer choose ‘just’ a lock, they select a product that will protect assets but also enable seamless access, ensure safe ingress and egress as well as integrate with security systems to track access – and they may want it to look good too.
As someone who’s guided countless security professionals through this decision process, I’ve witnessed how the right hardware choice can make or break a security system.
Whether you’re managing commercial facilities, healthcare institutions or educational campuses, here are ten questions I get security professionals to consider before committing to a door hardware solution.
Not all access points demand equal security. That exterior entrance to your data centre requires significantly different protection than a supply closet.
Is it protecting highly sensitive information, valuable assets or just providing privacy? The security requirements for a rarely used meeting room will differ from those of medicine room in a hospital.
For high-security doors, focus on hardware with robust locking mechanisms featuring strong bolt pins, high lifecycle ratings, high strength and realignment capabilities.
Low-security interior doors might prioritise ease of use and aesthetic over protection. By defining function, you’ll narrow down to hardware that serves its intended purpose.
I’ve encountered hundreds of unique door configurations that demand versatile hardware solutions. Take the RCI YD30 Series from dormakaba, it can be installed vertically or horizontally morticed flush into frames, packed out from frames, wood, aluminium or glass-mounted.
Always choose locks offering multiple application possibilities to avoid installation headaches.
Locks are becoming architectural elements that either enhance or detract from your space’s design.
Ask yourself, or your client: ‘Does this hardware complement our existing aesthetic? Can it be customised with finishes that align with our interior design? Will it maintain a sleek profile or protrude awkwardly from doorways?’ It may not be important to you now, but it might be for a customer down the road.
Having customisable options is always ideal.
A bustling office entrance experiencing thousands of daily uses requires dramatically different durability than a rarely accessed storage area.
For high-traffic zones with heavy usage, select hardware with lifecycle testing exceeding one million cycles.
While lower-traffic areas or medium usage doors (between 500 and 1M cycles) might tolerate less robust options, avoid cheap hardware that fails prematurely; it’s always more expensive in the long run.
Contact us to discuss your requirements of safety door lock switch. Our experienced sales team can help you identify the options that best suit your needs.
Too often, I see decision-makers fixate on initial price while overlooking long-term costs. Lock prices range, from budget-friendly manual options to premium electromechanical solutions costing thousands.
The critical question isn’t, “how much does this cost now?” but rather “what value am I protecting and is this investment proportionate?” When evaluating total cost of ownership, consider first that installation complexity directly impacts labour costs.
Second, maintenance requirements vary: Premium solutions may need minimal servicing over decades, while budget options often require frequent adjustment and component replacement.
Energy consumption represents another hidden cost that compounds over time. Consider the RCI YD30’s efficiency, drawing just 40mA of current versus a typical maglock’s 750mA.
At 12VDC, that’s roughly $0.71 annually per door compared to $13.40 for a standard maglock. Not staggering numbers in isolation, but for an enterprise with 500 doors, that’s an annual difference of $6,345 in electricity costs alone.
Finally, quality hardware typically delivers more operational cycles before failure, reducing replacement frequency and associated downtime.
The RCI YD30 Series has been cycle tested to over one million, so you know you’re installing a durable product.
When factoring these considerations together, premium hardware often emerges as the more economical choice in the long run.
Over the last decade or so, I’ve noted standalone locks are becoming obsolete as modern facilities demand solutions that communicate with access control systems, surveillance networks and building management platforms.
While these solutions can be very smart and complex, locks that are system agnostic ensure the act of controlling that lock is a simple process.
A lock that requires only power and a switch input allows for flexibility and control for any access system.
The ability to retrofit is equally important. Can this solution work with legacy systems during phased upgrades? Will it require extensive modifications to existing infrastructure? The YD30 Series excels here, designed for smooth retrofitting across architectures.
It communicates effectively with many access control systems, minimising integration hurdles. This adaptability ensures your investment remains viable through multiple systems and upgrades, extending its lifespan.
This critical decision balances security against life safety. Fail-safe locks unlock during power failures, prioritising emergency egress but potentially compromising security.
Fail-secure options remain locked, maintaining security but potentially impeding evacuation. Your choice should reflect both code requirements and risk assessment.
The RCI YD30 offers field-configurable operation modes, eliminating the need to stock different hardware types.
Misalignment and warping are issues that can affect door security and function. Misalignment occurs when a door no longer fits properly in its frame; warping happens due to moisture or temperature changes, leading to gaps and improper seals.
These issues can make it easier for intruders to bypass security, strain hardware and expose the door to environmental damage.
A poorly aligned door can also fail to close properly, reducing overall security. The RCI YD30 Series from dormakaba addresses these problems with its precise re-alignment capabilities of ±8mm (±5/16”) – the YD30 ensures smooth operation and long-term security by pulling the door in tight, helping to maintain functionality and protect property.
Real-time feedback to the control panel is crucial for monitoring door status and ensuring security. The YD30 Series provides continuous feedback, alerting the control panel to critical changes in door and lock pin status.
This ensures you can quickly address issues and maintain optimal security without delays or manual checks, improving operational efficiency and peace of mind.
Every access point has unique security requirements based on threat assessments. Strength/holding force is perhaps the most critical or often asked question I get about any lock.
When evaluating strength requirements, consider both intended and unintended scenarios. How much force might be applied during normal operation? What about during emergency situations or attempted breaches?
For exterior doors or those securing restricted areas, seek electromechanical locks with holding force ratings of at least 1,000kg (2,200lb). Another question I often get asked about though is side load.
It’s important to be able to get out that door quickly in case of an emergency. This is where the YD30 is in a league of its own.
With a collapsing mechanism, the YD30 Series is engineered to release when requested even under significant sideload pressure of up to pounds.
It’s crucial to understand that ‘strength ratings’ typically reflect ideal laboratory conditions. In real-world installations, factors like improper mounting and door alignment issues can reduce effective holding strength.
This is why premium hardware solutions include precise installation templates and will realign that door to perfection.
By asking these questions, you’ll select door hardware that not only meets security needs but delivers long-term value and performance.
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