Patent ID: 7248042

Claim:
A method for the contactless determination of a thickness of a layer ( 20 ) made of electrically-conductive material applied to a component ( 17 ) made of ferromagnetic material, the following measuring steps taking place with the aid of at least one measuring coil ( 14 ) carrying an alternating current and mounted on a coil form ( 13 ), the change in inductance of which is evaluated: Determine the inductance value L 0,d,f1 of the coil ( 14 ) determined in a measurement carried out exclusively with respect to a component ( 17 ) as the object of measurement made of ferromagnetic material, the coil ( 14 ) being acted upon with a first alternating current frequency f 1 ; the distance between the coil form ( 13 ) and the object of measurement is d Determine the inductance value L 0,d,f2 of the coil ( 14 ) in a measurement carried out exclusively with respect to a component ( 17 ) as the object of measurement made of ferromagnetic material, the coil ( 14 ) being acted upon with a second alternating current frequency f 2 ; the distance between the coil form ( 13 ) and the object of measurement is d Convert the determined inductance value L 0,d,f2 to a dimensionless characteristic value K Convert the characteristic value K with the aid of a distance characteristic into the value of distance d Determine the inductance value L x,d,f1 of the coil ( 14 ) in a measurement carried out with respect to the layer ( 20 ) to be determined, the coil ( 14 ) being acted upon with the first alternating current frequency f 1 ; the distance between the coil form ( 13 ) and the coated component ( 17 ) is d Convert the determined inductance values L 0,d,f1 and L x,d,f1 to a dimensionless measured value M e Convert the measured value M e with the aid of a family of calibration curves with consideration for the determined value of distance d to a layer thickness value a.