The word 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 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 improve states and ultrasonic sensors that use high-frequency soundwaves to detect objects. Many of these sensors detect objects that are in close proximity towards the sensor without making physical contact.
Probably the most overlooked or forgotten proximity sensors that you can buy is definitely the capacitive sensor. Why? Perhaps it is because they have a bad reputation going back to after they were first released years back, as they were more prone to noise than most sensors. With advancements in technology, this is no longer the truth.
Capacitive sensors are versatile in solving numerous applications and can 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 to become short and conical shaped, just like the shielded version in the proximity sensor.
Just as there are non-flush or unshielded inductive sensors, there are also non-flush capacitive sensors, and the mounting and housing looks a similar. The non-flush capacitive sensors have a large spherical field that allows them to be used in level detection applications. Since capacitive sensors can detect virtually anything, they may detect levels of liquids including water, oil, glue and the like, plus they can detect quantities of solids like plastic granules, soap powder, dexqpky68 and all sorts of things else. Levels may be detected either directly where the sensor touches the medium or indirectly in which the sensor senses the medium by way of a nonmetallic container wall.
With improvements in capacitive technology, sensors happen to be designed that may make amends for foaming, material build-up and filming 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 including hydrochloric, sulfuric and hydrofluoric acids. Moreover, these sensors can detect liquids through glass or plastic walls approximately 10 mm thick, are unaffected by moisture and require little or no cleaning within these applications.
The sensing distance of fanuc parts is determined by several factors for example the sensing face area – the larger the better. The following factor is the material property in the object to be sensed or its dielectric strength: the greater the dielectric constant, the higher the sensing distance. Finally, the dimensions of the prospective affects the sensing range. Just like by having an inductive sensor, the objective will ideally be similar to or larger in proportion than the sensor.
Most capacitive sensors have got a potentiometer to permit adjustment from the sensitivity from the sensor to reliably detect the marked. The highest quoted sensing distance of your capacitive sensor is based on a metal target, and so you will discover a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors should be useful for these applications for optimum system reliability. Capacitive sensors are ideal for detecting nonmetallic objects at close ranges, usually lower than 30 mm and also for detecting hidden or inaccessible materials or features.