Pepperl+Fuchs Blog

Ask an Expert Industrial Sensors - Episode 19

Posted by John Appleson on Fri, Jul 22, 2016

This episode of Ask an Expert for industrial sensors examines and provides answers to interesting sensing questions we've received from customers just like you. We explore and answer these questions:

1. Can the inductive sensor NJ6-F-N operate at -40 °C?
2. How far can a target reflector move sideways before a photoelectric sensor can't read it anymore?
3. Do you have distance sensors compatible with EtherNet/IP and ControlLogix Safety PLC?
4. What sensors could sense plastics and metals through a plastic tray?

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Topics: Inductive Sensors, Capacitive Sensors, Photoelectric Sensors, Ask an Expert, Laser Sensors, Distance Sensors, Positioning Systems

What’s the Big Deal about Discrete Outputs on a 2-D Laser Scanner?

Posted by Colton Rentsch on Fri, Apr 15, 2016

What is a 2-D laser scanner?

A 2-D laser scanner consists of a light beam that’s rotated or fanned around a circular path in order to detect anything that is in the plane of the light beam. The light beam emitted will measure both the distance and the angle to the given object in the plane of view.

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Topics: Laser Sensors, Distance Sensors

Is Environmental Heat Getting the Better of Your Optical Sensors?

Posted by Tom Anderson on Thu, Sep 24, 2015

Ed. Note: This guest blog post is by Tom Anderson, General Manager of PSI Technics, LTD. and is cowritten with Ann Zecha of WordSpark, LLC.

Radiant heat from manufacturing processes in high-temperature environments can present a challenge for optical sensors used in automated production facilities. Excessive heat in melting, pouring, or similarly demanding industrial applications that exceeds a sensor’s temperature specifications can degrade the measurement quality, damage sensor diodes, and cause unwanted disruption to production. Usage statistics show that for every 18 °F (10 °C) increase in temperature, the diode lifespan of optical sensors is reduced by up to 50%.

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Topics: Applications, Distance Sensors

Laser Sensors that Measure the Distance!

Posted by Amanda Blakeman on Thu, May 07, 2015

You read that right.  Now with Pulse Ranging Technology (PRT), laser sensors can determine the distance to an object by emitting short, high-energy light pulses over a given distance.

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Topics: Laser Sensors, Distance Sensors

Photoelectric Sensors Use Time-of-Flight Measurement

Posted by Tom Corbett on Tue, Feb 04, 2014

Not just distance measurement, but customized detection!

You may already know that pulse ranging technology (PRT) is Pepperl+Fuchs’ advanced time-of-flight measurement used in photoelectric sensors like the popular VDM28 distance sensor. PRT provides continuous measurement of a target’s distance by using the speed of light as a constant, sending out extremely short but very powerful pulses of light, and calculating the duration between the time a pulse is sent and the time it is received.

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Topics: Photoelectric Sensors, Distance Sensors

Measurement Displacement Sensors – How Can They Help Me?

Posted by Sean Miller on Tue, Apr 23, 2013

Measurement displacement sensors are used when you need to know a continuous distance that the sensor is from a selected target. There are two primary output types that can give distance.

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Topics: Ultrasonic Sensors, Photoelectric Sensors, Laser Sensors, Distance Sensors

5 Sensors that Detect Differences in Aerosol Caps

Posted by Jeff Allison on Fri, Feb 22, 2013

Aerosol cans are ubiquitous in the modern household. Look at the cleaning products under a kitchen sink or at the spray paint on a basement workbench, and you are likely to find an aerosol can or two.

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Topics: Applications, Photoelectric Sensors, Laser Sensors, Distance Sensors

Speaking the Language of Laser Distance Measurement

Posted by Jeff Allison on Thu, Nov 08, 2012

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Topics: Terminology, Laser Sensors, Distance Sensors

3 Front-Runners of Distance Based Photoelectric Sensing

Posted by Jeff Allison on Fri, Aug 10, 2012

As anyone who has bought or sold real estate can attest, the three most important things about a property are often location, location, and location.

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Topics: Applications, Photoelectric Sensors, Distance Sensors

Hot off the Press: Laser sensor detects presence of hot steel

Posted by Jeff Allison on Tue, Jun 05, 2012

It’s always nice to find a new use for a tool, but it’s even better when you can save some cash doing it.

I talked to one of our Pepperl+Fuchs account managers after he spent an afternoon testing a sensor at a customer site that manufactures steel. Sensing hot steel has always been a challenge. Using an inductive prox sensor or mechanical limit switch is just not going to happen, because a slab of steel at 1400 °F will render them useless at less than an inch away. Having a puddle instead of a sensor doesn’t do anyone much good, right?

Using infrared (IR) radiation detectors is great… as long as the slab doesn’t stop on the line too close to the detector, as prolonged exposure to the high-temperature slab could melt the detector. But the main problem with them is their cost. IR detectors are usually housed in heavy-duty housings, are water-cooled, and cost thousands of dollars.

A regular photoelectric sensor can be problematic if the hot metal is radiating all kinds of its own light. When that happens, the reflected light from the sensor that makes it back to the sensor’s receiver gets drowned out by the “noise” of the metal’s radiated light, making it difficult to sense the metal.

This application is located at a hot-strip mill in the Midwest. Simply put, the process involves taking a slab of steel that is six- or seven-inches thick, reheating it, and running it through a series of rollers to change the shape and thickness of the slab to meet customer requirements.

Engineers at the mill were looking for a way to detect the presence of the strip or slab of steel at certain points of the process between the roughing mills, which start shaping the roll, and the finishing mills, which complete the process.

They tested our new VDM28-15 laser measurement sensor. Because it operates based on Pulse Ranging Technology (PRT), it emits extremely high bursts of light periodically rather than a continuous emission of lower light energy. Those high-energy bursts of light are emitted from the sensor to the steel and reflected back to the sensor at long distances, which reduces the ambient temperature at the sensor’s location. Using this technology, the VDM28-15 laser sensor reliably detected the hot slab of steel at temperatures of 600 °F to 1400 °F.

Another headache for hot steel detection is slag. Slag is the black scale that can appear on a section of hot metal as the metal corrodes. Sensors that reflect light off the steel see a drop in the reflected light signal with dark black slag, as it absorbs light, and the sensor sees less light energy reflected back to it. But the VDM28-15 was able to detect the black slag or hot metal both consistently—no difference in performance, due to its use of PRT.

Also, because the VDM28-15 has a laser light spot less than 0.5 inches in diameter, it can easily detect the thin edge of a slab of steel. Non-lasers, with their larger light beams, would be hard-pressed to do that.

The laser sensor was tested about six feet away from the metal, and the customer is going to install a metal shield in front of the sensor with an aperture of about 0.5 inch diameter for the laser beam to pass. A single VDM28-15 is a fraction of the cost of the IR detectors they were using. Instead of paying thousands of dollars, they’re looking at hundreds of dollars.

And, because this sensor is a distance measurement sensor, if they want, they can not only detect presence of the steel roll, but measure its thickness.

Thanks to the account manager, now I know a reliable way to detect hot steel at a fraction of the cost of conventional methods. After all, sensing 1400 °F metal is just something I couldn’t have really tested myself in the office.
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Topics: Photoelectric Sensors, Laser Sensors, Distance Sensors

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