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. There are actually, however, other sensing technologies that use the expression ‘proximity’ in describing the sensing mode. Such as diffuse or proximity photoelectric sensors that use the reflectivity from the object to alter states and ultrasonic sensors that utilize high-frequency soundwaves to detect objects. Many of these sensors detect objects which can be in close proximity towards the sensor without making physical contact.
Probably the most overlooked or forgotten proximity sensors that you can buy is the capacitive sensor. Why? Perhaps it is because there is a bad reputation dating back to to whenever they were first released years back, as they were more vulnerable 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 many types of objects such as glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors are typically recognized by the flush mounting or shielded face from the sensor. Shielding causes the electrostatic field to be short and conical shaped, much like the shielded version of the proximity sensor.
Just as there are non-flush or unshielded inductive sensors, there are also non-flush capacitive sensors, along with the mounting and housing looks exactly the same. The non-flush capacitive sensors possess a large spherical field that allows them to be utilized in level detection applications. Since capacitive sensors can detect virtually anything, they may detect amounts of liquids including water, oil, glue and the like, plus they can detect amounts of solids like plastic granules, soap powder, dexqpky68 and all sorts of things else. Levels may be detected either directly the location where the sensor touches the medium or indirectly the location where the sensor senses the medium through a nonmetallic container wall.
With improvements in capacitive technology, sensors have already been designed that can compensate 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 they also can reliably actuate when sensing aggressive acids including hydrochloric, sulfuric and hydrofluoric acids. Moreover, these sensors can detect liquids through glass or plastic walls as much as 10 mm thick, are unaffected by moisture and require little or no cleaning in these applications.
The sensing distance of fanuc module depends on several factors such as the sensing face area – the larger 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 greater the sensing distance. Finally, the dimensions of the marked affects the sensing range. In the same way with an inductive sensor, the target will ideally be comparable to or larger in size compared to sensor.
Most capacitive sensors possess a potentiometer allowing adjustment of your sensitivity of your sensor to reliably detect the target. The maximum quoted sensing distance of a capacitive sensor will depend on metallic target, and consequently you will discover a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors should be used for these applications for maximum system reliability. Capacitive sensors are best for detecting nonmetallic objects at close ranges, usually under 30 mm as well as for detecting hidden or inaccessible materials or features.