Why Do Laser Cutting Machines Need Sensors?

In the cutting process of laser cutting machine, the distance between the cutting head and the workpiece and the perpendicularity between the nozzle and the surface of the workpiece are two extremely important factors which directly affect the processing quality. Therefore, in order to improve the cutting quality and reduce the generation of scrap, some special sensors need to be installed on the cutting head to ensure that it can produce stable and consistent cutting quality and increase the process safety.
When the shape of the laser cutting head changes and there are uneven obstacles on the surface, the sensors automatically detect this change and automatically adjust the height according to the change so that it is always at the same distance from the surface of the workpiece, thus allowing faster processing of the material without continuous supervision.
Displacement measurement is the most basic measurement task. Depending on whether the sensor is in contact with the workpiece to be measured, displacement sensors can be classified as contact or non-contact. Compared to contact sensors, non-contact sensors can guarantee high resolution while featuring fast dynamic response and small, even zero, hysteresis errors.
Non-contact sensors, sometimes called proximity sensors, were first applied as proximity switches, which give a switching signal when the measured object approaches a certain distance from the sensitive probe. Current proximity sensors have evolved to not only detect the presence or absence of an object, but also give the distance between the object and the sensitive probe, and provide information about the shape and spatial position of the workpiece.
Because it can be used to measure the displacement of a moving object, these sensors are also known as non-contact displacement sensors. Common displacement sensors include hysteresis displacement sensors, eddy current displacement sensors, capacitive displacement sensors and inductive displacement sensors.
Capacitive sensors are highly sensitive and have the following characteristics.
1: good dynamic response, because the electrostatic attraction between the plates is very small, the energy required is very small, the movable part can be made very small and thin, so its inherent frequency is high, the dynamic response time is short. 2: simple structure, adaptable, easy to manufacture, easy to ensure high precision, can be made into a small size sensor to achieve special measurement, can work in high and low temperatures, strong radiation and strong magnetic fields and other harsh environments, and can withstand high pressure, high impact, overload, etc..
3: Small heat generation and small temperature coefficient itself. Since the capacitance value of capacitive sensors is independent of the electrode material, materials with low temperature coefficient can be selected to ensure good stability when the external temperature is stable.
4: The large relative change is only limited by the linear region with values up to 100% or more, which ensures the resolution and measurement range of the sensor.