The word automation parts usually refers to an inductive proximity sensor or metal sensor – the inductive sensor is considered the most commonly utilised sensor in automation. You can find, however, other sensing technologies that utilize the word ‘proximity’ in describing the sensing mode. Some examples are diffuse or proximity photoelectric sensors which use the reflectivity in the object to alter states and ultrasonic sensors that utilize high-frequency soundwaves to detect objects. Most of these sensors detect objects which can be in close proximity to the sensor without making physical contact.
Just about the most overlooked or forgotten proximity sensors that you can buy will be the capacitive sensor. Why? Perhaps this is due to there is a bad reputation dating back to when they were first released in the past, because they were more prone to noise than most sensors. With advancements in technology, this is not really the way it is.
Capacitive sensors are versatile in solving numerous applications and can detect various types of objects like glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors are typically recognized by the flush mounting or shielded face of your sensor. Shielding causes the electrostatic field to be short and conical shaped, similar to the shielded version from the proximity sensor.
Just as there are non-flush or unshielded inductive sensors, there are non-flush capacitive sensors, and the mounting and housing looks exactly the same. The non-flush capacitive sensors use a large spherical field that enables them to be utilized in level detection applications. Since capacitive sensors can detect virtually anything, they may detect levels of liquids including water, oil, glue and the like, plus they can detect quantities of solids like plastic granules, soap powder, dexqpky68 and almost everything else. Levels can be detected either directly in which the sensor touches the medium or indirectly where the sensor senses the medium by way of a nonmetallic container wall.
With improvements in capacitive technology, sensors have been designed that may make up for foaming, material build-up and filming water-based highly conductive liquids. These ‘smart’ capacitive sensors derive from the conductivity of liquids, and they also can reliably actuate when sensing aggressive acids for example hydrochloric, sulfuric and hydrofluoric acids. In addition, these sensors can detect liquids through glass or plastic walls approximately 10 mm thick, are unaffected by moisture and require little if any cleaning over these applications.
The sensing distance of fanuc parts depends upon several factors for example the sensing face area – the larger the better. The subsequent factor will be the material property from the object to be sensed or its dielectric strength: the higher the dielectric constant, the higher the sensing distance. Finally, the dimensions of the target affects the sensing range. Just as with an inductive sensor, the prospective will ideally be equal to or larger in size compared to the sensor.
Most capacitive sensors possess a potentiometer to permit adjustment of your sensitivity in the sensor to reliably detect the target. The highest quoted sensing distance of any capacitive sensor is dependant on a metal target, and therefore you will find a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors needs to be useful for these applications for optimum system reliability. Capacitive sensors are perfect for detecting nonmetallic objects at close ranges, usually lower than 30 mm and then for detecting hidden or inaccessible materials or features.