Calibrations And Measurements; General Instructions For Calibration; Calibration Methods; Saving Calibration Values - Trotec BB 20 Manual De Instrucciones

04 . CALIBrAtIONS ANd MEASurEMENtS

general instructions for calibration

Calibration methods

There are 4 methods of performing calibrations:
1. Basic calibration: recommended for concrete, on
even surfaces and if the measuring object has the
same size and surface structure and is made of the
same material as the zero plate supplied .
2 . Zero-point calibration: recommended if measuring
errors up to ± 3 % of the measured value plus the
constant error value of the sensor are permissible .
(Example of a constant error value: Fe 1 µm; non-Fe
1.5 µm)
3 . Single-point calibration (calibration using a calibration
film): recommended if it is assumed that the mea-
sured values are close to the calibration value and
the permissible sensor error value is max. ± 1% ~
3% of the measured value plus the constant error
value of the sensor .
4 . Two-point calibration (calibration using a set of two
calibration films):
A) Recommended for measurements on rough sur-
faces .
B) Recommended for precise measurements on smooth
surfaces, if the assumed thickness lies between that
of the two calibration films .

Saving calibration values

If the measuring instrument has been calibrated for a
certain purpose, the calibration values can be stored
in the memory until they are changed .
The calibration process should be repeated from the
start if:
• A wrong measurement has been performed.
• A wrong command has been entered.
• T he measuring instrument has switched itself off.

Calibration example

A correctly performed calibration represents the most
important prerequisite for precise measurement . The
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Operating manual – layer thickness measuring instrument BB 20
higher the correlation between the sample and the
product sample, the more precise the calibration and
the subsequent measurement will be .
If, for example, a measurement is to be performed
on a steel cylinder, quality ST37 (standard steel) with
a thickness of 6 mm, the calibration of the uncoated
sample must be performed on a steel cylinder of the
same quality and the same thickness .
The calibration sample must correspond to the pro-
duct sample in the following respects:
• Bending radius
• M aterial properties of the substrate
• T hickness of the substrate
• S ize of the area to be measured
• T he point at which the calibration is performed on
the calibration sample must always be identical to
the measuring point on the product itself, particularly
at the corners and edges of small articles .

High accuracy calibrations

In order to obtain the most precise measured values
possible, we recommend that you measure the calib-
ration values (both the zero values and the calibration
film values) several times in succession . In this way
the measuring instrument determines an average
calibration value within a short time . Find out more
about this subject in the section "Special hints" . This
maximum-precision method of calibration is of great
advantage with uneven surfaces, such as shotblasted
surfaces .

Cleaning the probe tip

The probe tip must be free from oil, grease, pieces of
metal etc . before each calibration . Even the smallest
impurity can influence the measurements and distort
the measured values .

Special calibration hints

The basic calibration, which is already stored in the de-
vice, should only be used for measurements on even
surfaces, i .e . on steel components made of normal
ST37 (structural steel, mild steel) or aluminium parts .
Switch to calibration mode as follows: Menu => Ca-
libration => Enable . The menu automatically jumps
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