KERN & SOHN TN 300-0.01US - Manual (Page 3)

Sauter GmbH
Tieringerstr. 11-15
D-72336 Balingen
E-Mail: [email protected] Tel: +49-[0]7433- 9976-174
Fax: +49-[0]7433-9976-285
Internet: www. sauter.eu
Instruction Manual
TN_US
TN_US-BA-e-1112 3
1 Coupling status: Indicates the coupling status. While
measurements are taken, the coupling status should be
on. If it isn’t or if it isn’t stable, the instrument has got
difficulties in achieving stable measurements and the
thickness value displayed will most likely be erroneous.
2 Unit: Current unit system. MM or IN for thickness value.
M/S or IN/µS for sound velocity.
3 Battery information: Displays the rest capacity of the
battery.
4 Information Display: Displays the measured thickness
value, the sound velocity and shows hints of the current
operation.
2.2 Keypad definition
Turn the
instrument on/off Sound velocity
calibration
Turn on/off the
EL backlight Enter
Zero operation Plus;
Turn on/off
Scan mode
Unit switch
between Metric
and Imperial
system Minus;
Turn on/off the
beep mode
Data Save or
Data Delete
3. Preparation
3.1 Transducer selection
With this instrument it is possible to measure a wide range
of different materials, started from various metals to glass
and plastics. These different types of material require the
usage of different transducers. Choosing the correct
transducer is the most important thing to perform accurate
and reliable measurements. Generally speaking, the best
transducer for an operation is the one that sends sufficient
ultrasonic energy into the material to be measured in the
way that a strong, stable echo is to be received in the
instrument. There are several factors that affect the
strength of the traveling ultrasound. They are described as
followed:
Initial signal strength: The stronger a signal is at the
beginning, the stronger its echo will return. Initial signal
strength is mainly a factor of the size of the ultrasound
emitter in the transducer. A large emitting area will send
more energy into the material being measured than a small
one. Thus, a so-called “1/2 inch” transducer will emit a
stronger signal than a “1/4 inch” transducer.
Absorption and scattering: As the ultrasound travels
through a material, it is partly absorbed. If the material has
got any grain structure, the sound waves will start
scattering. Both of these effects reduce the strength of the
waves and thus the instrument’s ability to detect the
returning echo. Ultrasound of higher frequency is absorbed
and scattered more than ultrasound of lower frequency.
While it may seem that using a lower frequency transducer
is better in every instance, it should be mentioned that low
frequencies are less directional than higher ones. Thus, a
higher frequency transducer is a better choice for detecting
the exact location of small pits or flaws in the material to be
measured.
Geometry of the transducer:
The physical constraints of the environment sometimes
determine a transducer’s suitability for an operation. Some
transducers are simply too large to be used in a confined
area. If the available surface area for contacting with the
transducer is limited, the usage of a transducer with a
small surface is required.
Measurements on a curved surface, in example an engine
cylinder wall, will require a transducer with an adapted
surface.
Temperature of the material: If exceedingly hot surfaces
are to be measured, high temperature transducers must be
used. These transducers are built with special materials
and techniques that allow them to withstand high
temperatures without being damaged. Additionally, care
must be taken if a “Zero adjustment” or a “Calibration to
known thickness” is being performed with a high
temperature transducer.
The selection of a proper transducer is often a matter of
tradeoffs between various characteristics. Sometimes it is
necessary to experience with a variety of transducers in
order to find the one that works well for a special
operation.
The transducer is the “business end” of the instrument.
It transmits and receives ultrasonic sound waves which the
instrument uses to calculate the thickness of the material
being measured. The transducer is connected to the
instrument via the attached cable and two coaxial
connectors. The transducer has to be installed correctly to
get reliable measurement results. Each plug must be fit
into the adequate socket in the instrument.
Below there are shown two photos and a short description
of the instruction use of a transducer.
The upper figure is a bottom view of a typical transducer.
The two semicircles are visibly separated in the middle of
the surface. One of the semicircles is conducting the
echoed sound back into the transducer. When the
transducer is placed against the material being measured,