The term automation parts usually refers to an inductive proximity sensor or metal sensor – the inductive sensor is regarded as the commonly utilised sensor in automation. You can find, however, other sensing technologies which use the word ‘proximity’ in describing the sensing mode. These include diffuse or proximity photoelectric sensors that use the reflectivity of your object to change states and ultrasonic sensors that utilize high-frequency soundwaves to detect objects. All of these sensors detect objects that are in close proximity for the sensor without making physical contact.
One of the more overlooked or forgotten proximity sensors on the market today may be the capacitive sensor. Why? Perhaps it is because there is a bad reputation dating back to to when they were first released yrs ago, while they were more vulnerable to noise than most sensors. With advancements in technology, this has stopped being the truth.
Capacitive sensors are versatile in solving numerous applications and can detect many types of objects including glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors are typically recognized by the flush mounting or shielded face in the sensor. Shielding causes the electrostatic field being short and conical shaped, similar to the shielded version of the proximity sensor.
Just as there are non-flush or unshielded inductive sensors, in addition there are non-flush capacitive sensors, as well as the mounting and housing looks the same. The non-flush capacitive sensors use a large spherical field that allows them to be employed in level detection applications. Since capacitive sensors can detect virtually anything, they may detect degrees of liquids including water, oil, glue and the like, and they also can detect amounts of solids like plastic granules, soap powder, dexqpky68 and just about everything else. Levels might be detected either directly the location where the sensor touches the medium or indirectly in which the sensor senses the medium through a nonmetallic container wall.
With improvements in capacitive technology, sensors are already designed that can make amends for foaming, material build-up and filming of water-based highly conductive liquids. These ‘smart’ capacitive sensors are derived from the conductivity of liquids, and so they can reliably actuate when sensing aggressive acids including hydrochloric, sulfuric and hydrofluoric acids. Additionally, these sensors can detect liquids through glass or plastic walls approximately 10 mm thick, are unaffected by moisture and require little if any cleaning in these applications.
The sensing distance of fanuc module depends on several factors for example the sensing face area – the larger the better. Another factor will be the material property in the object being sensed or its dielectric strength: the higher the dielectric constant, the higher the sensing distance. Finally, how big the marked affects the sensing range. Equally as having an inductive sensor, the objective will ideally be equal to or larger in proportions compared to the sensor.
Most capacitive sensors have a potentiometer allowing adjustment from the sensitivity of your sensor to reliably detect the target. The highest quoted sensing distance of a capacitive sensor will depend on a metal target, and so there is a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors must be used for these applications for maximum system reliability. Capacitive sensors are best for detecting nonmetallic objects at close ranges, usually less than 30 mm as well as for detecting hidden or inaccessible materials or features.