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How Are Photoelectric Fork Sensors Different from Normal Thru-Beam Sensors?

Posted by Tom Corbett on Fri, Aug 26, 2016

Fork sensors—when one housing is better than two

Fork sensors, also called fork type sensors or slot sensors, have a unique U shape similar to that of a tuning fork. But don’t be fooled by their name or shape—these are photoelectric sensors that work with light rather than sound. A photoelectric fork sensor is a type of thru-beam sensor with an emitter and receiver facing each other. But instead of the emitter and receiver existing apart from one another as two separate sensors, they are both contained together in the same housing. This one-piece design aligns the optical axis, and with the emitter and receiver perfectly aligned, you get higher switching speeds and better reliability. Finally, since this housing needs only one electrical connection instead of two, the sensor is simpler to install and more cost-effective.

Why would I want to use a fork sensor instead of a regular thru-beam sensor?

Fork sensors can detect objects within fractions of a millimeter of accuracy. They excel at sensing small parts over short distances. Because they consist of only one part rather than two, fork sensors are quicker and easier to set up than normal thru-beam sensors. Their design vastly improves repeatability and precision.

A closer look at the right size

Normal thru-beams work just fine for detecting the kind of objects that typically move along a conveyor belt. However, when you need to sense parts that are so small that using a conveyor belt would be impractical, nothing beats the fork sensor. The smaller the gap in the fork, the greater the accuracy of the fork sensor. When it gets down to brass tacks (or whatever else you want to detect), we have sensors that can provide extremely precise measurements with 0.3 mm accuracy or better.

What applications are photoelectric fork sensors good for?

Fork sensors are great at small part detection and counting. One of the most common applications is detecting nuts, bolts, washers, or other small parts as they pass through a clear tube made of glass or plastic. Other applications include label detection and counting, edge guidance, and end of travel / object positioning.

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