The term automation supplier usually describes an inductive proximity sensor or metal sensor – the inductive sensor is easily the most commonly utilised sensor in automation. There are actually, however, other sensing technologies that utilize the term ‘proximity’ in describing the sensing mode. Some examples are diffuse or proximity photoelectric sensors that utilize the reflectivity of the object to alter states and ultrasonic sensors which use high-frequency soundwaves to detect objects. Many of these sensors detect objects which can be in close proximity on the sensor without making physical contact.
Just about the most overlooked or forgotten proximity sensors on the market today will be the capacitive sensor. Why? Perhaps it is because they have a bad reputation dating back to to after they were first released in the past, because they were more susceptible to noise than most sensors. With advancements in technology, this is no longer the case.
Capacitive sensors are versatile in solving numerous applications and will detect many types of objects including glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors can be identified by the flush mounting or shielded face of your sensor. Shielding causes the electrostatic field being short and conical shaped, just like the shielded version in the proximity sensor.
Just seeing as there are non-flush or unshielded inductive sensors, there are non-flush capacitive sensors, as well as the mounting and housing looks the identical. The non-flush capacitive sensors have a large spherical field that enables them to be employed in level detection applications. Since capacitive sensors can detect virtually anything, they are able to detect degrees of liquids including water, oil, glue or anything else, plus they can detect amounts of solids like plastic granules, soap powder, dexqpky68 and just about everything else. Levels may be detected either directly the location where the sensor touches the medium or indirectly in which the sensor senses the medium via a nonmetallic container wall.
With improvements in capacitive technology, sensors have already been designed that could make amends for foaming, material build-up and filming water-based highly conductive liquids. These ‘smart’ capacitive sensors are derived from the conductivity of liquids, plus they can reliably actuate when sensing aggressive acids such as hydrochloric, sulfuric and hydrofluoric acids. Additionally, these sensors can detect liquids through glass or plastic walls around 10 mm thick, are unaffected by moisture and require little if any cleaning in these applications.
The sensing distance of fanuc parts depends upon several factors including the sensing face area – the greater the better. Another factor may be the material property of the object to become sensed or its dielectric strength: the better the dielectric constant, the higher the sensing distance. Finally, the size of the objective affects the sensing range. Just as with an inductive sensor, the marked will ideally be similar to or larger in dimensions compared to sensor.
Most capacitive sensors possess a potentiometer allowing adjustment of the sensitivity of your sensor to reliably detect the objective. The maximum quoted sensing distance of any capacitive sensor is founded on metallic target, and so you will find a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors ought to be useful 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.