FISCHER DELTASCOPE DMP30 - Calibration

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Calibration DMP30 / DMP40
9 Calibration
The term "calibration" is used in this Operator's Manual as a general term for deter-
mining the deviation from a reference value, adjustment and correction: calibration
of the gauge using calibration standards to adapt the measuring system (gauge and
probe) to the measuring application at hand.
The calibration sets the difference between nominal and actual value to zero.
A calibration is a reference measurement during which the material properties and
geometric shape of the specimen are recorded and stored in a calibration file in the
connected probe, separate from the batch. During the reference measurement, the
influencing variables are recorded using an uncoated reference piece and one or two
calibration standards in order to compensate the influences for future measure-
ments.
 Uncoated reference piece, the material of which has the same properties as the
base material of the specimen. Needed for adjustment to the base material (ze-
ro = zero point).
 Calibration standard, available in different versions:
• Calibration foil, plastic foil, hard paper foil or metal foil with a certain thick-
ness, characterized by the nominal value that simulates a coating thickness
during the calibration process. An adjustment to the corresponding coating
thickness value is performed for each calibration foil thickness.
• Calibration standard, coated reference piece whose base material and
coating material have the same properties as the coated specimen and
whose coating thickness has been determined using the most accurate
alternative measurement method possible (nominal value of the calibration
standard).
In order to measure, it is absolutely essential that a calibration suitable for the mea-
suring application has been assigned to the batch.
The coating thickness measurement is mainly influenced by the following variables:
 Physical properties of the base material of the specimen, such as magnetizabil-
ity (permeability) or electrical conductivity
 Geometric shape of the specimen, such as the thickness of the base material
or the curvature of the specimen (e.g. cylindrical shape)