Advances in proximity sensors
Inside machines, proximity sensors: Inductive, magnetic, ultrasonic are among the technologies used for proximity sensing, and small sizes and extended ranges are among features in recently announced proximity sensors.
When a sensor is needed to sense proximity to an object, then distance, material, and other variables may dictate the technology or features required for the application. AutomationDirect, Carlo Gavazzi, Pepperl+Fuchs, Sick, and Telemecanique (part of Schneider Electric) recently announced proximity sensing products. Details follow.
Longer distance prox sensors
AutomationDirect offers the Contrinex DW-series of extended and triple-distance proximity sensors in 3 mm to 30 mm cylindrical and 20 mm rectangular styles. With 10 to 30 V dc operating voltage and sensing distances ranging from 1 mm to 40 mm, cylindrical sensors are available in shielded and unshielded models with nickel silver, nickel silver/chrome, chrome-plated brass, or stainless steel housings. DW-series 3 mm proximity sensors are fitted with a two-meter axial cable; other sizes offer two-meter axial cable, M8, or M12 quick disconnects. DW-series proximity sensors are designed with an LED status indicator and are available with NPN and PNP, as well as normally open or normally closed outputs. The DW series proximity sensors have an IP67 protection rating and provide overload protection.
Miniature inductive proximity sensors
AutomationDirect’s miniature inductive proximity sensors range in sizes from 4 mm to 8 mm and feature stainless steel shielded housings. Offered as NPN (negative positive negative) or PNP (positive negative positive) models and with normally open or normally closed outputs, sensors are available with standard sensing distances of 0.8 mm or 1.5 mm; available extended distance models have either 1.5 mm or 2 mm sensing ranges. The miniature sensors are IP67-rated, are equipped with a 360-degree-visible yellow output LED, and come with built-in overload protection. Models are offered with an attached 2-m axial cable or with an M8 connector; axial and right angle zinc-plated mounting brackets are also available. The new miniature inductive proximity sensors are CE-, RoHs-, and Reach-compliant.
Magnetic proximity sensors
AutomationDirect’s M-series cylindrical magnetic dc proximity sensors are available in 8, 12, and 18 mm sizes. With 10 models available, the magnetic sensors feature stainless steel shielded housings, are offered as NPN or PNP models with normally open or normally closed outputs, and are available with standard sensing distances of 0 to 70 mm. M-series sensors are IP65/IP67 or IP68/IP69K-rated and come with built-in overload protection. Models are offered with an attached 2-m axial cable or with an M8 or M12 connector; proximity sensor damping magnets also are available.
Longer range inductive proximity sensors
Carlo Gavazzi expanded its ICB Series Inductive Proximity Sensors to include new "Extra Extended" range sensors, providing up to three times the sensing distances of standard inductive proximity sensors. By extending the sensing range up to 10 mm (M12), 20 mm (M18), and 40 mm (M30), a broader range of applications are possible. A microprocessor-based design allows calibration after the assembly, enabling greater temperature stability, reliability, and repeatability. The microprocessor design also simplifies original equipment manufacturer (OEM) customization requests, such as special output types, switching frequencies, and timing functions. A diagnostic LED is easily viewed from any direction and provides status, set-up, short circuit, and overload indication. With up to 2,000 Hz operating frequency, the new ICB Series is useful for high-speed counting and monitoring rotational speed. Permanently legible laser-engraved part number, cULus and CE marks, and serial number are readily visible on the front face of the sensor.
All ICB Series sensors are cULus listed and rated for operation from -25 to +70 °C (-13 to +158 °F). A range of 3-wire dc inductive sensors are available in M12, M18, and M30 housings. Single, extended and extra extended sensing distances are available. Long or short nickel-plated brass housings, for flush or nonflush mounting, are available, either normally open (NO) or normally closed (NC) PNP or NPN outputs. Connection options include either a 2-m PVC cable or M12 disconnect plug.
Small-sized ultrasonic sensors
Smaller than a match box, these acoustic sensors from Pepperl+Fuchs come offering high-end features; F77 series ultrasonic sensors are designed to fit in tight spaces, can be used for dirty and dusty application environments, and are adept at handling color variations or transparent targets. Because these miniature sensors can detect objects within an area rather than being restricted to sensing only what is directly in front of them, the F77 series is suitable for applications where the pin-point accuracy of a photoelectric beam is too focused to accurately sense the target.
The sensors are insensitive to color, provide reliable clear object detection, and ignore target holes and ridges, "resulting in a coverage area that is more forgiving than that of most photoelectric sensors," said Marcel Ulrich, product manager, Pepperl+Fuchs. "This is particularly significant, for example, in a printed circuit board application where cuts and holes in the board and shiny copper tracks on a dull background would result in false readings for optic-based products."
The sensors also are highly immune to acoustic interference and have minimal deadband, important characteristics for sensors mounted on machinery with noisy pneumatic cylinders.
With a housing size of 31 mm x 11 mm x 23 mm, the sensors fit in space-restricted applications and provide up to 50 Hz switching frequency for fast response times. High visibility LEDs provide an at-a-glance status indication. Intuitive range adjustments make it easy to make on-the-fly changes.
The IP67-rated sensors can be used in temperatures ranging from -25 to 70 °C (-14 to 158 °F). A 4-pin Nano-style M8 connector makes installation easy. The sensors provide one PNP, NO (normally open) or NC (normally closed) switch point output, use inexpensive discrete programmable logic controller (PLC) inputs, offer high- or low-frequency options, and deliver a 2 Hz/mm maximum resolution. They are available in diffuse (up to 400 mm sensing range), retroreflective (up to 400 mm sensing range), and through-beam models (up to 800 mm sensing range).
Inductive adaptability in a proximity sensor
A new sensor from Sick features four-corner LEDs, a rotating sensor head, and application-specific, integrated circuit (ASIC) technology for reliable detection even in harsh environments; the Sick IQG inductive proximity sensor provides reliable detection in a wide variety of applications and fit into most brackets for easy replacement and less downtime. With the lowest manufacturing tolerances on the market, the customer or OEM no longer needs to readjust the sensor during replacement, which saves time. In addition, the four corner LEDs enable straightforward status monitoring, regardless of mounting position. Together, these features simplify installation and monitoring.
The sensor head can be rotated in five directions, allowing the sensor to easily be adapted to suit a wide range of applications. Using a proprietary Sick ASIC, the IQG inductive proximity sensor features ambient temperature range from -25 to 85 °C, excellent resistance to shock and vibrations, and electromagnetic compatibility. The IQG sensors now have IP68 and IP69K enclosure ratings for operation in harsh environments.
Cost-effective prox with improved performance
Telemecanique Sensors (part of Schneider Electric) have a renewed basic range of cylindrical inductive sensors, available in flush and nonflush versions in 12 mm, 18 mm, and 30 mm diameter. They feature a new cable design, improved waterproofing, internal LED, and laser tagging. The sensors provide great performance in noisy environments and a high switching frequency for fast detection.
The inductive proximity line is called OsiSense XS, for noncontact sensing of metal objects with extended offerings up to 60 mm, and the capacitive proximity line is OsiSense XT for noncontact sensing of any material up to 20 mm. They comply with international standards and have an IP69K rating. Full stainless steel and plastic versions work for dedicated food and beverage applications, with cubic and full stainless steel cylindrical for automotive including welding applications.
Telemecanique Sensors (part of Schneider Electric)
– Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering, firstname.lastname@example.org.
- Varied sensing technologies serve as proximity sensors
- Smaller sizes and extended ranges are among advances
- Different configurations suit many applications.
Is it time to rethink some proximity sensor applications, given longer ranges and other expanded options?