What Is an Electromagnetic Film Thickness Gauge?
An electromagnetic film thickness gauge is a device that measures the thickness of a thin film using the principle of electromagnetic induction. The thickness can be measured by placing a coil close to the measurement area and measuring minute inductive electromotive force. It is used to measure the thickness of thin films and coatings that cannot be measured with calipers.
There are other types of film thickness gauges, such as eddy current, ultrasonic, and reflection spectroscopy, and they can be used according to the object to be measured. An electromagnetic film thickness gauge can instantly and accurately measure thickness, but has the disadvantage that it cannot measure well if the film is magnetic.
Applications of Electromagnetic Film Thickness Gauges
Electromagnetic film thickness gauges are used to measure a wide variety of thin films. For example, they can be used to measure the thickness of food films and protective films for precision equipment. When thin films are several micrometers or nanometers thick, it is difficult to measure them visually with a ruler or calipers. An electromagnetic film thickness gauge is used to check if the film is thick enough. It is also used to check the thickness of paints and coatings. If it is too thin, it will not function, but if it is too thick, it will be a waste of raw materials. Checking the thickness is indispensable in order to form an appropriate thin film.
Principle of Electromagnetic Film Thickness Gauges
An electromagnetic film thickness gauge uses the principle of electromagnetic induction to measure thickness. The structure consists of a probe containing an electromagnet, which is placed in contact with the surface to be measured. When an electric current is applied to the electromagnet, electromagnetic induction occurs, attracting the magnetic material behind the thin film. The voltage of the coil changes according to the distance between the electromagnet and the magnetic material, and this is used to measure the film thickness. Like calipers, it does not need to be clamped from both sides, and it can measure minute thicknesses that cannot be measured visually.
In addition, an electromagnetic film thickness gauge can instantly and accurately measure thickness, and is easy to operate and can be handled by anyone. It is not possible to measure the film thickness if the underlying material is nonmagnetic. The thickness can be measured only when the underlying substrate is a magnetic material, such as metal, and the object to be measured is a non-magnetic material. For example, non-magnetic metal plating, paint, or resin film can be measured. Furthermore, since the electromagnet must be in close contact with the surface, it is not possible to measure objects accurately with uneven surfaces.