The expression automation parts usually identifies an inductive proximity sensor or metal sensor – the inductive sensor is easily the most commonly utilised sensor in automation. You can find, however, other sensing technologies which use the term ‘proximity’ in describing the sensing mode. Some examples are diffuse or proximity photoelectric sensors which use the reflectivity of your object to modify states and ultrasonic sensors that use high-frequency soundwaves to detect objects. Many of these sensors detect objects that are in close proximity for the sensor without making physical contact.
Probably the most overlooked or forgotten proximity sensors currently available will be the capacitive sensor. Why? Perhaps this is due to they have a bad reputation going back to after they were first released years back, while they were more susceptible 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 may detect various types of objects including glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors are often recognized by the flush mounting or shielded face from the sensor. Shielding causes the electrostatic field to be short and conical shaped, similar to the shielded version of the proximity sensor.
Just since there are non-flush or unshielded inductive sensors, in addition there are non-flush capacitive sensors, along with the mounting and housing looks the same. The non-flush capacitive sensors possess a large spherical field that enables them to be used in level detection applications. Since capacitive sensors can detect virtually anything, they can detect amounts of liquids including water, oil, glue or anything else, plus they can detect levels of solids like plastic granules, soap powder, dexqpky68 and just about everything else. Levels can be detected either directly where the sensor touches the medium or indirectly the location where the sensor senses the medium using a nonmetallic container wall.
With improvements in capacitive technology, sensors happen to be designed that may compensate for foaming, material build-up and filming of water-based highly conductive liquids. These ‘smart’ capacitive sensors derive from the conductivity of liquids, plus they can reliably actuate when sensing aggressive acids like hydrochloric, sulfuric and hydrofluoric acids. In addition, these sensors can detect liquids through glass or plastic walls around 10 mm thick, are unaffected by moisture and require little or no cleaning within these applications.
The sensing distance of fanuc parts depends upon several factors like the sensing face area – the greater the better. Another factor is the material property in the object to get sensed or its dielectric strength: the larger the dielectric constant, the greater the sensing distance. Finally, the actual size of the objective affects the sensing range. In the same way with the inductive sensor, the target will ideally be equivalent to or larger in size than the sensor.
Most capacitive sensors have a potentiometer allowing adjustment of the sensitivity in the sensor to reliably detect the objective. The maximum quoted sensing distance of your capacitive sensor is based on metallic target, and thus there exists a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors ought to be utilized for these applications for max system reliability. Capacitive sensors are perfect for detecting nonmetallic objects at close ranges, usually below 30 mm and then for detecting hidden or inaccessible materials or features.