Light Curtains: What Type Do You Need?

Light Curtains
Written by prodigitalweb

Manufacturing and engineering enterprises are inherently and unavoidably dangerous. Interaction with machinery and moving parts can almost invite injury, as indicated by injury statistics shared by the OSHA. There are numerous ways to approach this as a business owner, including direct approaches to improving equipment safety. Light curtains are one such approach.

What are Light Curtains?

First, though, it is essential to revisit the nature and purpose of light curtains as equipment, and in practice. Light curtains, also sometimes referred to as light barriers, are complex sensor arrays; they comprise emitters and receivers, that work together to create a detection field between themselves.

The light path from the emitter points to the receiver, which recognizes the presence of said light. If an opaque object ‘breaks’ that path, preventing light from being detected by the receiver, a signal is sent to a connected machine or system – typically to halt an operation.

Use Cases for Light Curtains

Generally speaking, light curtains or barriers are safety devices. They are used to prevent the injury of workers on given premises, by shutting off dangerous devices and machine operations before they can cause an accident or injury. How this looks in practice depends greatly on the machine, manufacturer, and industry in question.

As an example though, an aperture in an electromechanical instrument might enable the feeding of components or materials into the machine. A light curtain could be calibrated to enable these items to pass into the machine – but if any larger objects entered the aperture, the curtain would be broken and an emergency shut-off process initiated. This larger object could be a body part from a worker operating the machine, or a rogue object destined to disrupt the machine’s internal workings.

What Type to Use?

There are two key types of light curtains available to manufacturers and engineers, Type 2 or Type 4 devices. Type 2 devices are the simpler of the two, being relatively rudimentary sensors, that ‘check’ themselves for faults periodically – making it possible for a fault to develop before the machine is switched off. Type 2 devices are best used concerning machines that offer minor risk to workers.

Type 4 devices are more expensive, more accurate and continuously self-monitoring for sensor faults. They can be calibrated to a high resolution, suiting them for applications requiring the detection of more minute objects. They also have a lower light scatter coefficient, making them more accurate and less prone to error. They are overkill for minor applications, but essential for high-risk equipment.

Whatever equipment you deign to use, installation is relatively simple – and can often be undertaken internally. Brackets are used to affix each side of the curtain to the face or aperture of the instrument in question, and integration into the equipment’s shut-off system is relatively simple to boot.

The Pros and Cons of Using Light Curtains

One of the chief positives to considering light curtains as part of your safety measures is their automatic nature; worker reaction times are not relied upon to adequately meet the severity of a potential injury, and a dangerous incident is avoided or mitigated with millisecond precision.

However, there are teething issues that light curtains can present. For example, if it is installed too close to the machine hazard, the cut-off may be too slow to avoid injury. Light curtains can also give workers a false sense of security, where other hazards relating to a given machine might not be monitored or mitigated as effectively.

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