Safety Light Curtains
Safety light curtains are safety devices that create a virtual barrier around a hazard. These devices meet the highest safety standards of Type4, SIL3, Category4, and PLe. Integration is efficient and easy with the minimal footprint, durable housing, and options for reduced wiring. Each model achieves the high enclosure rating of IP65/IP67.
A safety light curtain is a sensing device designed to protect personnel from injury. These devices are most commonly used in factory automation for machine safeguarding. Unlike typical photoelectric sensors, safety light curtains monitor themselves through redundant signals and will stop the hazard (ex. machine) if an internal fault is detected.
How do Safety Light Curtains work?
A safety light curtain uses an array of photoelectric sensors that, when interrupted, will send a signal to stop a machine or hazard if an area is breached. Unlike typical photoelectric sensors, safety light curtains monitor themselves through redundant signals and will stop the hazard (ex. machine) if an internal fault is detected.
What is a Safety Light Curtain used for?
Safety light curtains are designed to protect personnel from injury, most commonly in a manufacturing setting. In addition to protecting personnel, safety light curtains can also safeguard machines from damage. Both of these applications are most often referred to as "machine guarding."
Benefits of Safety Light Curtains
KEYENCE safety light curtains meet Type 4 requirements established by the IEC 61496-1 / UL 61496-1 safety standards. As such, these devices offer superior safety performance for use as electro-sensitive protection equipment (ESPE).
Designed to meet IEC 61496-1/2 requirements, KEYENCE safety light curtains have been evaluated and certified by a third party as offering superior safety performance. Such standards require devices to have a self-diagnosis function for detecting an internal fault.
Light curtains that meet Type 4 requirements are recognized as offering the highest safety performance possible. In particular, the self-diagnosis function is always enabled, and in the event of a malfunction, the curtain enters an error state to ensure the safety of personnel and equipment.
Installation and alignment of safety light curtains are easy thanks to the slim design and wide range of mounting brackets. Light curtains are also more flexible than safety fences or hard guarding and require less effort to open/close. This makes safety light curtains ideal for ensuring safety on machines that require frequent access.
To prevent workers from entering a hazardous area, safety precautions typically involve using safety fences or guards around machines. However, opening and closing these devices may hinder efficiency if the machine is frequently accessed for tooling changes, loading/unloading products, etc.
Safety light curtains allow users to access machines quickly, safely, and efficiently. The slim design, wide variety of mounting brackets, and built-in alignment make installation easy. This means curtains can be installed in a wide range of locations and easily adapted to layout changes.
With safety light curtains offering non-contact monitoring, they commonly have a much longer service life than mechanical door switches or other devices that require opening/closing. Unlike similar products, these devices provide superior safety and reliability over longer periods of time.
Safety light curtains are generally installed at equipment openings, exposing them to dirt/debris, liquids, and even direct impact. KEYENCE light curtains, however, incorporate a robust, environmentally resistant design for greater reliability even in harsh environments.
With a safety light curtain, detection is not possible if the transmitter and receiver are not aligned. Detection issues can arise after installation stemming from direct impact or equipment vibrations. This means both the safety light curtain and the mounting bracket must be robust enough to prevent damage. KEYENCE safety light curtains are not only compliant with the IP65/67 enclosure protection specifications established by IEC 60529 but are also resistant to water, oil, or other liquids.
The large, high-power lenses also help prevent malfunctions even if the detection surface is exposed to water or oil splashes for safe use even in harsh manufacturing site environments.
Safety Light Curtain Case Studies
Safety precaution for presses
In factories where stamping presses are used, safe operation needs to be ensured throughout the facility by providing appropriate health and safety training, appointing supervisors, and conducting targeted voluntary inspections. Even then, however, the possibility of work-related injuries around presses cannot be completely eliminated.
Safety precautions for presses involve installing safety light curtains at the press break. If the safety light curtain is blocked, the press is stopped and the machine cannot restart until the light curtain is clear, thereby guaranteeing worker safety.
Safety precautions for SCARA robots (horizontal multi-joint robots)
Because of their compact design and high operating speed, SCARA robots are commonly installed in manufacturing facilities. However, due to limited installation space, the robots can be dangerous if operated while a person is inside the enclosure. Workers entering transfer areas between machines can also be a safety concern.
Safety precautions for SCARA robots involve stopping the robot and preventing accidental startup. Safety interlock switches can be used to monitor the status so that the robot stops if the door is opened. Safety light curtains can monitor transfer areas between equipment and stop the transfer if a worker enters the area.
Safety precautions for 6-axis robots
Understanding the range of a 6-axis robot in motion can be incredibly difficult, making approaching the robot dangerous. Conducting equipment maintenance near a robot is particularly risky. To minimize this risk as much as possible, multiple safety precautions are needed.
If a worker opens a door or blocks a safety light curtain, the robot is stopped. Safety laser scanners can also be used to detect the presence of workers within the safety zone.
In such situations, robot operation will be possible only after the worker has left, the door is closed, and the light curtain is no longer blocked. Even after all these requirements are met, workers should still perform a safety check from outside the enclosure before restarting the machine.
Frequently Asked Questions About Safety Light Curtains
The GL family of light curtains provide a variety of options. The high-powered GL-R Series includes a wide selection of pre-assembled mounting brackets as well as built-in alignment indicators. The compact design of the GL-S Series allows for installation in narrow and tight spaces.
Three wiring systems are available. Our optical synchronization and one-line systems offer reduced wiring while wired synchronization offers additional functionality when needed.
Conventional light curtains require regular maintenance to prevent stoppages and other problems due to decreased received light intensity. Such decreases can be caused by misalignment (due to impact or vibration) or by contamination from oil or dust.
Either scenario can reduce the amount of received light enough to trigger the light curtain to stop the machine.
The robust design of the GL-R Series light curtain prevents misalignment while also ensuring stable detection even when oil or dust adheres to the lens. Not only does this help prevent unexpected stoppages but also the need for frequent maintenance.
There is a critical difference between area sensors that are not safety rated and a safety light curtain. If an internal fault/error occurs in a safety light curtain, the self-diagnosis function detects the problem and the safety light curtain will enter an error state and stop the machine. Area sensors do not generally have a self-diagnosis function, so even if a fault/error occurs in the device, the sensor could still allow the machine to operate creating a dangerous situation. KEYENCE recommends safety rated devices, such as safety light curtains, in any situation where there is a chance of injury.
This guide introduces the main features of GL-R, GL-S, and SL-V Series safety light curtains as well as advice on selecting the right model—a must-read for anyone looking to purchase safety curtains. Browse KEYENCE’s wide variety of safety light curtains to find a model that best meets your needs.
This guidebook introduces a wide range of safety information, including machine safety standards (for manufacturing equipment and other machines), the Performance Level (PL) classification used for defining risk assessment and safety factors, and specific safety devices.