Position Sensors

Motion control applications frequently require position sensors. Depending on the application, the specs might dictate small size, ruggedness or special approval ratings. A complete motion control system may employ other sensors, such non-invasive ultrasonic or cylinder position sensors. The six sensors in this section meet tight performance specs as well as one or more of the trends of rugged, smaller and easy to use.

PHOTOELECTRIC PROXIMITY SWITCH

Providing one of the industry's smallest photoelectric form factors, SICK's W2 and W4-3 series have extremely narrow, flat or sugar-cube housing options. The W2 series through-beam and photoelectric reflex and proximity switches have long ranges as well as high performance. With background suppression, the laser-like light spot switches offer high precision and resistance to interference. This is particularly beneficial when positioning handling systems or during circuit board detection. The scanner detects reflective and transparent objects meeting user's high EMC, vibration immunity and impact demands based on the switches' unique narrow and flat shapes and optics design. The W4-3's sugar-cube photoelectric switch design is capable of detecting small objects in ranges of up to 4m. An interface IC permits fieldbus connections via IO Link and provides background suppression and electronic scanning distance adjustments. Using precision LEDs, black objects are detected with spill-over reflections prevented for highly repeatable readings.

METAL SLOT SENSORS

Industrial applications that require high-speed counting, level monitoring or edge detecting now have a new option from Banner Engineering Corp. The SLM Series Metal Slot Sensors offer opposed-mode sensing of objects as small as 0.30 mm that pass between its fixed-distance opposed-mode emitter and receiver. The sensors have a fast response time of 500 µsec, a rugged metal housing rated IEC IP67, NEMA 6, and are available in slot widths of 10, 30, 50, 80, 120 and 220 mm. With the receiver and emitter integrated in the fixed arms of the housing, there is no need to align opposed-mode emitter and receivers. The new series includes a 2 or 9m attached cable, with a 4-pin Euro-style or 3-pin Pico-style quick disconnect. Operating on 10 to 30V dc, the units have bi-colored indicator lights that provide ongoing sensor status. The sensors are available with current sinking (NPN), bipolar (one NPN and one PNP) output or current sourcing (PNP) and offer solutions for printing, material handing, pharmaceutical packaging and automotive industries.

ULTRASONIC LEVEL SENSOR

Providing level liquid detection through metal containers, TURCK Inc. levelprox sensors have received FM approval for Class I, Division 2 applications when used with lockfast devices and approved mounting brackets. The standard 30-mm barrel M30 and 316L stainless steel housing T50 models are both approved for Class I, Division 2 applications. Levelprox is a non-invasive ultrasonic sensor that measures the signal through a metal container's walls using a high frequency pulse and compares it to easily programmed full and empty conditions. The sensors target hygienic, hazardous or high-pressure applications as well as hard to solve level applications.

RUGGED PHOTO ELECTRIC SENSOR

Extended range sensors like ifm efector's OG Basic Line offer increased protection against mechanical damage in harsh applications by allowing the sensor to be located farther away from the target. For added ruggedness, the industry-standard M18 threaded housing uses 316 stainless steel. The photoelectric sensor has an integrated polymethyl methacrylate (PMMA) lens for sensing ranges from 4m for polarized retro-reflective to 250 mm for diffuse background suppression with a potentiometer adjustment for precision and 20m for thru-beam applications. The 3-wire dc OG Basic sensors have an LED indicating operating or switching status and use a standard M12 cable assembly. With PNP units available in either dark-on or light-on modes, the photoelectric sensors target rugged industrial automation applications and environments.

INDUCTIVE POSITION SENSOR

Distributed in North America by Everight, Precision Technologies Corp., Positek's X111 intrinsically-safe linear variable inductive transducer position sensors are offered in the 50 to 800-mm measurement range. The units are ATEX certified to EEX ia IIC TA standards (TA = -40 to 80C), which is equivalent to US Class 1, Div 1, Groups B, C and D. Used as a system with Positek BX Series galvanic barriers, the sensors provide either a 0.5 to 9.5V dc or a 4 to 20 mA analog output of absolute position immediately on power up. With no wearing contacts, built-in EMC protection and stainless steel housings sealing between IP65 and IP68, the inductive transducers have a reliable, long life even in rugged environments and maintain output stability over a wide temperature range. Positek X Series Sensors target use in oil and gas production, transportation and exploration, as well as factory automation applications and heavy equipment.

CYLINDER POSITION SENSOR

Able to continuously monitor the piston's position in a pneumatic cylinder within a range of 50 mm, Festo's new SMAT electronic position sensor is independent of magnet polarization, mounts in a size 8 cylinder slot and offers an analog output of 0 to 10V or 4 to 20 ma proportional to the piston's position. The integrated out-of-range (OOR) detector indicates when the piston exceeds the monitored area. Easily installed, the units mount directly in a space-saving T-slot and lock into place with an Allen key. The position transmitter SMAT cylinder sensor targets work piece changing, force fitting, gripping, clamping and part-selecting tasks in process monitoring applications in sheet metal handing and production, as well as wear monitoring and quality inspection.