MITECH MT200 User manual

Ultrasonic Thickness
Gauge
MT200
User’s Manual
MITECH CO., LTD.
www.mitech-ndt.com
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CONTENTS
1 Overview...................................................................................................................................................... 4
1.1 Product Specifications...................................................................................................................... 4
1.2 Main Functions...................................................................................................................................4
1.3 Measuring Principle...........................................................................................................................4
1.4 Configuration...................................................................................................................................... 5
1.5 Operating Conditions........................................................................................................................ 5
2 Structure Feature.......................................................................................................................................6
2.1 Instrument Appearance.................................................................................................................... 6
2.2 Parts of the Main Body..................................................................................................................... 6
2.3 Measurement Screen....................................................................................................................... 7
2.4 Keypad Definitions............................................................................................................................ 8
3 Preparation..................................................................................................................................................8
3.1 Transducer Selection........................................................................................................................ 8
3.2 Condition and Preparation of Surfaces....................................................................................... 10
4 Operation................................................................................................................................................... 10
4.1 Power On/Off................................................................................................................................... 10
4.2 Transducer Set................................................................................................................................ 10
4.3 Probe Zero........................................................................................................................................11
4.4 Sound Velocity................................................................................................................................. 11
4.5 Making Measurements...................................................................................................................12
4.6 Two Point Calibration......................................................................................................................13
4.7 Scan mode....................................................................................................................................... 14
4.9 Resolution.........................................................................................................................................14
4.10 Unit Scale....................................................................................................................................... 14
4.11 Memory Management...................................................................................................................15
4.12 Data Printing.................................................................................................................................. 16
4.13 System Set.....................................................................................................................................16
4.14 System information....................................................................................................................... 17
4.15 EL Backlight................................................................................................................................... 17
4.16 Battery Information....................................................................................................................... 17
4.17 Auto Power Off.............................................................................................................................. 17
4.18 System Reset................................................................................................................................ 17
4.19 Connecting to a Computer.......................................................................................................... 17
5 Menu Operation....................................................................................................................................... 18
5.1 Enter the Main Menu...................................................................................................................... 18
5.2 Enter the Sub menu........................................................................................................................18
5.3 Change the Parameter...................................................................................................................18
5.4 Numeric Digit Input......................................................................................................................... 18
5.5 Save and Exit...................................................................................................................................18
5.6 Cancel and Exit................................................................................................................................18
6 Servicing....................................................................................................................................................18
7 Transport and Storage........................................................................................................................... 19
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Appendix A Sound Velocities..................................................................................................................20
Appendix B Applications Notes..............................................................................................................21
User Notes.................................................................................................................................................... 23
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1 Overview
The Mitech model MT200 is a digital ultrasonic thickness gauge. Based on the same
operating principles as SONAR, the MT200 is capable of measuring the thickness of various
materials with accuracy as high as 0.01 millimeters, or 0.001inches. It is suitable for a variety of
metallic and non-metallic materials.
1.1 Product Specifications
Display：128×64 dot matrix LCD with EL backlight.
Measuring Range：(0.75～300)mm (in Steel).
Sound Velocity Range: 1000~9999 m/s.
Resolution：0.1mm/0.01mm（selectable）.
Accuracy：±（0.5%Thickness+0.04）mm
Units: Metric/English unit selectable.
Four measurements readings per second for single point measurement, and ten per second
for Scan Mode.
Memory for 20 files (up to 99 values for each file) of stored values.
Upper and lower limit can be pre-set. It will alarm automatically when the result value
exceeding the limit.
Power Supply：Two “AA” size, 1.5 volt alkaline batteries. 100 hours typical operating time (EL
backlight off).
Communication：RS232 serial port.
Case：Extruded aluminum body suitable for use under poor working conditions.
Outline dimensions：132mm X 76.2 mm.
Weight：345g
1.2 Main Functions
Capable of performing measurements on a wide range of material, including metals, plastic,
ceramics, composites, epoxies, glass and other ultrasonic wave well-conductive materials.
Four transducer models are available for special application, including for coarse grain
material and high temperature applications.
Probe-Zero function, Sound-Velocity-Calibration function
Two-Point Calibration function.
Two work modes: Single point mode and Scan mode.
Coupling status indicator showing the coupling status.
Battery information indicates the rest capacity of the battery.
Auto sleep and auto power off function to conserve battery life.
Optional software to process the memory data on the PC.
Optional thermal mini-printer to print the measured data via RS232 port.
1.3 Measuring Principle
The digital ultrasonic thickness gauge determines the thickness of a part or structure by
accurately measuring the time required for a short ultrasonic pulse generated by a transducer to
travel through the thickness of the material, reflect from the back or inside surface, and be
returned to the transducer. The measured two-way transit time is divided by two to account for the
down-and-back travel path, and then multiplied by the velocity of sound in the material. The result
is expressed in the well-known relationship:
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2
tv
H 
Where：H－Thickness of the test piece.
v－Sound Velocity in the material.
t－The measured round-trip transit time.
1.4 Configuration
Table 1-1
No
.
Item
Quantity
Note
Standard
Configur
ation
1
Main body
1
2
Transducer
1
Model:
N05/90°
3
Couplant
1
4
Instrument Case
1
5
Operating Manual
1
6
Screwdriver
1
7
Alkaline battery
2
AA size
8
Optional
Configur
ation
9
Transducer: N02
See
Table3-1
10
Transducer: N07
11
Transducer: HT5
12
Mini thermal
printer
1
13
Print cable
1
14
DataPro for
Thickness Gauge
1
For use on
the PC
15
Communication
Cable
1
1.5 Operating Conditions
Operating Temperature: －20℃～＋60℃;
Storage Temperature：-30℃～＋70℃
Relative Humidity ≤90％；
The surrounding environment should avoid of vibration, strong magnetic field, corrosive medium
and heavy dust.
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2 Structure Feature
2.1 Instrument Appearance
1 Main Body
2 Transducer
2.2 Parts of the Main Body
1 Communication Socket 2 Aluminum Case 3 Belt Hole
4 Battery Cover 5 Keypad 6 LCD Display
7 Socket of Transducer (no polarity) 8 Probe zero disc
9 Aluminum Case 10 Label
MT200
M iT e c h
2
1
8. Enter
MiTech Inc. Ltd
5. Switch Selection
6. Save/Delete
7. Exit
3
M iTech
4
8
2. Power On/Off
POWER: 2 X 1.5V
4. Probe Zero
OPERATION GUIDE
1. Plug in the transducer
3. Backlight On/Off
THICKNESS GAUGE
MT200
2
9
5
6
SN:
7
10
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2.3 Measurement Screen
Battery Information: Display the information of the rest capacity of the battery.
Coupling Status: Indicate the coupling status. While the gauge is taking a measurement, the
coupling status should be on. If it is not on, the gauge is having difficulty achieving a stable
measurement, and the thickness value displayed will most likely be erroneous.
Operating Hint: Show hints of current operation
FIL: File selection；
MEM：Memory data viewing；
PRB：Transducer set；
VEL：Change velocity;
CAL：Velocity calibration；
DPC：Dual Point Calibration state；
ZER：Probe zero state
SCA: Indicate that current thickness measurement mode is scan mode, and not single point mode.
File Name: show current file name.
Record No./Count: Indicate current record number while this item is highlighted, or total record
Thickness Reading
Units Label
Battery Info
Transducer Model
Record No./count
File Name
Coupling Status
Operating Hint
Sound Velocity
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counts while it is not highlighted.
Transducer Model: Current transducer model setting in the instrument
Sound Velocity: Current sound velocity setting
Thickness Reading：Display present single time measured value. means exceeding upper
measuring limit. means lower than bottom measuring limit.
Units Label ：When the mm symbol is on, the instrument is displaying the thickness value in
millimeters and the sound velocity value in m/s. When the in symbol is on, the instrument is
displaying the thickness value in inches and the sound velocity value in inch/us.
2.4 Keypad Definitions
Turn the instrument
on and off
Exit from current
selection
Turn on/off the EL
backlight
Enter
Probe Zero
operation
Plus or scroll up
Switch selection
among items
Minus or scroll
down
Data Save or Data
Delete
3 Preparation
3.1 Transducer Selection
The gauge is inherently capable of performing measurements on a wide range of materials,
from various metals to glass and plastics. Different types of material, however, will require the use
of different transducers. Choosing the correct transducer for a job is critical to being able to easily
perform accurate and reliable measurement. The following paragraphs highlight the important
properties of transducers, which should be considered when selecting a transducer for a specific
job.
Generally speaking, the best transducer for a job is one that sends sufficient ultrasonic energy
into the material being measured such that a strong, stable echo is received by the gauge. Several
factors affect the strength of ultrasound as it travels. These are outlined below:
Initial Signal Strength. The stronger a signal is to begin with, the stronger its return echo will
be. Initial signal strength is largely 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 emitting
area. Thus, a so-called “1/2 inch” transducer will emit a stronger signal than a “1/4 inch”
transducer.
Absorption and Scattering. As ultrasound travels through any material, it is partly absorbed. If
the material through which the sound travels has any grain structure, the sound waves will
experience scattering. Both of these effects reduce the strength of the waves, and thus, the
gauge’s ability to detect the returning echo. Higher frequency ultrasound is absorbed and
scattered more than ultrasound of a lower frequency. While it may seem that using a lower
frequency transducer might be better in every instance, low frequencies are less directional than
high frequencies. Thus, a higher frequency transducer would be a better choice for detecting the
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exact location of small pits or flaws in the material being measured.
Geometry of the transducer. The physical constraints of the measuring environment
sometimes determine a transducer’s suitability for a given job. Some transducers may simply be
too large to be used in tightly confined areas. Also, the surface area available for contacting with
the transducer may be limited, requiring the use of a transducer with a small wearface. Measuring
on a curved surface, such as an engine cylinder wall, may require the use of a transducer with a
matching curved wearface.
Temperature of the material. When it is necessary to measure on surfaces that are
exceedingly hot, high temperature transducers must be used. These transducers are built using
special materials and techniques that allow them to withstand high temperatures without damage.
Additionally, care must be taken when performing a “Probe-Zero” or “Calibration to Known
Thickness” with a high temperature transducer.
Selection of the proper transducer is often a matter of tradeoffs between various
characteristics. It may be necessary to experiment with a variety of transducers in order to find one
that works well for a given job.
The transducer is the “business end” of the instrument. It transmits and receives ultrasonic
sound waves that the instrument uses to calculate the thickness of the material being measured.
The transducer connects to the instrument via the attached cable, and two coaxial connectors.
When using transducers, the orientation of the dual coaxial connectors is not critical: either plug
may be fitted to either socket in the instrument.
The transducer must be used correctly in order for the instrument to produce accurate,
reliable measurements. Below is a short description of the transducer, followed by instructions for
its use.
Left figure is a bottom view of a typical transducer. The two semicircles of the wearface are visible,
as is the barrier separating them. One of the semicircles is responsible for conducting ultrasonic
sound into the material being measured, and the other semicircle is responsible for conducting the
echoed sound back into the transducer. When the transducer is placed against the material being
measured, it is the area directly beneath the center of the wearface that is being measured.
Right figure is a top view of a typical transducer. Press against the top with the thumb or index
finger to hold the transducer in place. Moderate pressure is sufficient, as it is only necessary to
keep the transducer stationary, and the wearface seated flat against the surface of the material
being measured.
Table 3-1 Transducer Selection
Model
Freq
MHz
Diam
mm
Measuring
Range
Lower limit
Description
N02
2.5
14
3.0mm～
300.0mm（In
Steel）
40mm (in Gray
Cast Iron
HT200)
20mm
for thick, highly
attenuating, or highly
scattering materials
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N05
5
10
1.2mm～
230.0mm（In
Steel）
Φ20mm×
3.0mm
Normal Measurement
N05
/90°
5
10
1.2mm～
230.0mm（In
Steel）
Φ20mm×
3.0mm
Normal Measurement
N07
7
6
0.75mm～
80.0mm
（In Steel）
Φ15mm×
2.0mm
For thin pipe wall or
small curvature pipe
wall measurement
HT5
5
14
3～200mm（In
Steel）
30mm
For high temperature
(lower than 300℃)
measurement.
3.2 Condition and Preparation of Surfaces
In any ultrasonic measurement scenario, the shape and roughness of the test surface are of
paramount importance. Rough, uneven surfaces may limit the penetration of ultrasound through
the material, and result in unstable, and therefore unreliable, measurements. The surface being
measured should be clean, and free of any small particulate matter, rust, or scale. The presence of
such obstructions will prevent the transducer from seating properly against the surface. Often, a
wire brush or scraper will be helpful in cleaning surfaces. In more extreme cases, rotary sanders or
grinding wheels may be used, though care must be taken to prevent surface gouging, which will
inhibit proper transducer coupling.
Extremely rough surfaces, such as the pebble-like finish of some cast iron, will prove most
difficult to measure. These kinds of surfaces act on the sound beam like frosted glass on light, the
beam becomes diffused and scattered in all directions.
In addition to posing obstacles to measurement, rough surfaces contribute to excessive wear
of the transducer, particularly in situations where the transducer is “scrubbed” along the surface.
Transducers should be inspected on a regular basis, for signs of uneven wear of the wearface. If
the wearface is worn on one side more than another, the sound beam penetrating the test material
may no longer be perpendicular to the material surface. In this case, it will be difficult to exactly
locate tiny irregularities in the material being measured, as the focus of the sound beam no longer
lies directly beneath the transducer.
4 Operation
4.1 Power On/Off
The instrument is turned on by pressing the key. When the gauge is initially turned on, the
model type, the manufacture information and the serial number will be displayed prior to entering
into the main measurement screen.
It is turned off by pressing the key when it is on. The tool has a special memory that
retains all of its settings even when the power is off.
4.2 Transducer Set
The model of the transducer should be pre-set to the instrument before measuring operation.
This enables the user to select the transducer type among supported transducers according to
frequency and diameter depending on application requirements. Use the following steps to select
your transducer model：
1. On the measurement screen, press the key multiple times to activate the 【Transducer
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