The expression automation parts usually identifies an inductive proximity sensor or metal sensor – the inductive sensor is considered the most commonly utilised sensor in automation. You will find, however, other sensing technologies which use the phrase ‘proximity’ in describing the sensing mode. Some examples are diffuse or proximity photoelectric sensors which use the reflectivity of the object to change states and ultrasonic sensors designed to use high-frequency soundwaves to detect objects. Every one of these sensors detect objects that are in close proximity for the sensor without making physical contact.
One of the most overlooked or forgotten proximity sensors available today is the capacitive sensor. Why? Perhaps it is because they have a bad reputation dating back to whenever they were first released years back, while they were more susceptible to noise than most sensors. With advancements in technology, this is not the situation.
Capacitive sensors are versatile in solving numerous applications and may detect many types of objects for example glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors are often identified by the flush mounting or shielded face of your sensor. Shielding causes the electrostatic field being short and conical shaped, much like the shielded version from 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 identical. The non-flush capacitive sensors use a large spherical field that allows them to be utilized in level detection applications. Since capacitive sensors can detect virtually anything, they could detect amounts of liquids including water, oil, glue and so forth, and they also can detect degrees of solids like plastic granules, soap powder, dexqpky68 and almost everything else. Levels might be detected either directly in which the sensor touches the medium or indirectly where the sensor senses the medium via a nonmetallic container wall.
With improvements in capacitive technology, sensors are already designed that can make up for foaming, material build-up and filming of water-based highly conductive liquids. These ‘smart’ capacitive sensors are based on the conductivity of liquids, and they can reliably actuate when sensing aggressive acids like hydrochloric, sulfuric and hydrofluoric acids. Additionally, these sensors can detect liquids through glass or plastic walls as much as 10 mm thick, are unaffected by moisture and require little if any cleaning during these applications.
The sensing distance of fanuc module is dependent upon several factors like the sensing face area – the greater the better. Another factor is definitely the material property of the object to be sensed or its dielectric strength: the better the dielectric constant, the higher the sensing distance. Finally, how big the prospective affects the sensing range. Just as with the inductive sensor, the marked will ideally be comparable to or larger in proportions in comparison to the sensor.
Most capacitive sensors use a potentiometer allowing adjustment from the sensitivity from the sensor to reliably detect the marked. The maximum quoted sensing distance of any capacitive sensor is based on a metal target, and thus you will find a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors needs to be employed for these applications for max system reliability. Capacitive sensors are fantastic for detecting nonmetallic objects at close ranges, usually less than 30 mm and then for detecting hidden or inaccessible materials or features.