How to Select a Safety Curtain for a Machine? A Practical Guide

What is a safety curtain?

A safety curtain (optoelectronic) is a system consisting of a transmitter and a receiver that create an invisible barrier of light beams. Breaking this barrier immediately stops the machine.

This solution is widely used in:

* presses,

* industrial robots,

* production lines,

* assembly stations.

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1. Determine the risk level (the most important step)

Before selecting a safety curtain model, you must conduct a risk analysis in accordance with applicable standards (e.g., PN-EN ISO 13849-1).

Pay attention to:

* possibility of contact with moving parts,

* machine speed,

* downtime,

* frequency of operator access.

👉 The analysis result will determine the required safety level (PL — Performance Level).

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2. Select the safety curtain resolution

The resolution determines what the safety curtain detects.

Typical values:

* 14 mm – finger protection,

* 20–30 mm – hand protection,

* 40 mm and above – body protection.

📌 If the operator can reach the hazard zone with their hand, the choice is simple: a high-resolution safety curtain (e.g., 14 mm) is required.

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3. Determine the height of the protection zone

The curtain must protect the entire access area.

Consider:

* machine height,

* possible bypass (e.g., from above or sideways),

* operator position.

📌 A curtain that is too low = false safety.

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4. Calculate the minimum mounting distance

The curtain must be mounted at the appropriate distance from the hazard zone.

Why is this important?

Because the machine needs time to stop.

The calculations take into account:

* curtain response time,

* machine stopping time,

* operator movement speed.

📌 If the curtain is too close, the system will not have time to react.

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5. Select the curtain type

Various solutions are available on the market:

Standard curtains

* basic protection,

* most commonly used.

Curtains with muting

* allow for material transport (e.g., on pallets),

* eliminate false stops.

Curtains with blanking

* enable the ignoring of selected beams,

* used in more complex applications.

📌 The selection of functions depends on the technological process.

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6. Environmental Conditions

Not every curtain will perform well in all conditions.

Pay attention to:

* dust,

* humidity,

* temperature,

* presence of oil or mist.

📌 In harsh environments, choose models with a high ingress protection class (e.g., IP65/IP67).

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7. Integration with the control system

The curtain must be compatible with the machine's control system.

Check:

* output type (OSSD),

* compatibility with safety relays,

* ability to connect to a safety PLC.

📌 Poor integration = non-compliance with standards.

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Common mistakes when selecting a safety light curtain

* selecting too high a resolution "just in case,"

* failing to analyze the machine's downtime,

* neglecting the possibility of bypassing the safety device,

* ignoring environmental conditions,

* selecting solely based on price.

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Summary

Choosing a safety light curtain is a technical process that requires analysis and experience. It's not just about purchasing the device, but about ensuring real operator protection and compliance with regulations.

If you're unsure, it's worth consulting a specialist – mistakes at this stage can cost much more than the light curtain itself.

Posted in: Sample Category