The word automation supplier usually means an inductive proximity sensor or metal sensor – the inductive sensor is the most commonly utilised sensor in automation. You will find, however, other sensing technologies designed to use the word ‘proximity’ in describing the sensing mode. Such as diffuse or proximity photoelectric sensors that utilize the reflectivity of your object to modify states and ultrasonic sensors that utilize high-frequency soundwaves to detect objects. All of these sensors detect objects which are in close proximity on the sensor without making physical contact.
One of the most overlooked or forgotten proximity sensors that you can buy may be the capacitive sensor. Why? Perhaps this is due to these people have a bad reputation going back to once they were first released in the past, while they were more susceptible to noise than most sensors. With advancements in technology, this has stopped being the truth.
Capacitive sensors are versatile in solving numerous applications and will 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 the sensor. Shielding causes the electrostatic field to be short and conical shaped, much like the shielded version in the proximity sensor.
Just seeing 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 a similar. The non-flush capacitive sensors use a large spherical field that enables 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 or anything else, and so they can detect levels of solids like plastic granules, soap powder, dexqpky68 and almost anything else. Levels may be detected either directly the location where the sensor touches the medium or indirectly where the sensor senses the medium through a nonmetallic container wall.
With improvements in capacitive technology, sensors have already been designed that could compensate for foaming, material build-up and filming of water-based highly conductive liquids. These ‘smart’ capacitive sensors derive from the conductivity of liquids, and so 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 virtually no cleaning within these applications.
The sensing distance of fanuc parts depends on several factors for example the sensing face area – the larger the better. Another factor will be the material property in the object to become sensed or its dielectric strength: the greater the dielectric constant, the greater the sensing distance. Finally, the dimensions of the target affects the sensing range. Just like with an inductive sensor, the target will ideally be similar to or larger in proportion in comparison to the sensor.
Most capacitive sensors use a potentiometer allowing adjustment of the sensitivity of the sensor to reliably detect the marked. The highest quoted sensing distance of a capacitive sensor is founded on a metal target, and so you will discover a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors needs to be utilized for these applications for optimum system reliability. Capacitive sensors are perfect for detecting nonmetallic objects at close ranges, usually under 30 mm and then for detecting hidden or inaccessible materials or features.