All about Proximity Sensors & their advantages in the Manufacturing Sector

With enhanced automation of complex production systems, components that are able to acquire and transmit information in regards to the production process become necessary. Proximity sensors are the most basic data acquisition devices in automation that fulfill these requirements by offering information in the form of individual process variables to controllers. They evaluate such variables as length, force, pressure and temperature and identify proximity of an object without any physical contact. They come in several types, each with its exclusive advantages.

  • Inductive Proximity Sensors

Proximity switch inductive sensors comprise an oscillator, coil, detector and output circuit and can be used to identify metallic targets. In their operation, the coil produces a high frequency magnetic field. When in proximity with a metallic target, the object soaks some of the energy, affecting the oscillator field. The object is identified once the oscillation amplitude achieves a particular threshold value. One of the benefits of inductive proximity sensors is that they are exact compared to other technologies. Another is that they have an elevated switching rate. Further, they can work in harsh environmental conditions.

  • Photoelectric Proximity Sensors

Photoelectric sensors can identify both non-metallic and metallic targets. Their primary components are the emitter that sends a beam of light and the detector that identifies it. A target is identified when it comes between the detector and emitter. They have been used in several applications — for instance, in mobile phones and for level sensing. In the iPhone, the sensor deactivates the touch screen as the user brings the device nearer to the face. The benefits are easy installation, low cost, and a more extended sensing range. They have fast switching characteristics and can be organized in harsh conditions.

  • PLC program logic controller

A programmable logic controller or PLC is a computer with a microprocessor but has no keyboard, monitor or mouse. It is basically built to endure very harsh industrial environments. It is a unique form of computer device designed for use in industrial control systems. It has a rigid construction and unique functional features such as ease of programming, sequential control, easy-to-use hardware, timers and counters, and dependable controlling capabilities. The PLC is also regularly used in civil applications such as washing machines and controlling elevators and traffic signals. They are used in several industries to control and monitor production processes and building systems.

  • Ultrasonic Proximity Sensors

These discharge and get sound waves. They use transmitted or reflected ultrasonic waves to detect the presence or absence of a target component. They have several advantages. They can identify a range of objects irrespective of their material properties or surface characteristics. They can detect objects over distances on the order of quite a few feet. Moreover, they can operate effectively in a vast range of operating conditions, including detection in adverse climates.

  • Capacitive Proximity Sensors

These sensors work on the principle of the capacitor. The primary components of the sensor are the oscillator, plate, threshold detector and output circuit. The object and plate act as plates and air as the dielectric. As an object comes close to the plate, the capacitance enhances activating the detector circuit, based on the amplitude output from the oscillator. A benefit of these sensors is that they can detect both non-metallic and metallic targets whose dielectric constant is over air. They are usually low cost and have good stability, resolution, common power usage, and high speed.

Tips for selecting a suitable proximity sensor

Choosing the most appropriate sensor depends on the application and the material to be identified, and if that material is metal, an inductive sensor is most likely the correct choice. Switching alternate sensors on and off and taking alternate reads can be a fast solution to a mutual-interference issue, provided that the application accounts for the corresponding reduction in sensor response time. Equipped with an understanding of sensor operation, available sensor options, and the environmental conditions of the application, designers can choose the inductive proximity sensor that best fits their requirements while delivering optimum performance. 

Proximity Sensors are used in manufacturing and industrial applications extensively, particularly for safety and inventory management applications. In an automated production line, for instance, it is used for positioning, object detection, counting, and inspection. It is also used for part recognition in an industrial conveyor system.

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