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TGD-100
Instructions Manual
29 pgs500.75 Kb0
Instructions Manual
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Starr Instruments TGD-100 Instructions Manual

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TGD-100
Ultrasonic Thickness Gauge
Instruction Manual
VER:3.1
3
1 Introduction
v × t H = 2
1.1 Scope of applications
Ultrasonic Thickness Gauge measuring with ultrasonic wave is applicable for measuring the thickness of any material in which ultrasonic wave can be transmitted and reflected back from the other face.
The gauge can provide quick and accurate measurement to various work pieces such as sheets of board and processing parts. Another important application of the gauge is to monitor various pipes and pressure vessels in production equipment, and monitor the thinning degree during using. It can be widely used in petroleum, chemical, metallurgy, shipping, aerospace, aviation and other fields.
1.2 Primary Theory
The primary theory of measuring thickness with ultrasonic wave is similar to that of measuring thickness with optical wave. The ultrasonic wave emitted from the probe reaches the object and transmits in it. When the ultrasonic wave reaches the bounding surface of the material, it is reflected back to the probe. The thickness of the material can be determined by accurately measuring the time of the ultrasonic wave transmitting in it.
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:
Where: H- Thickness of the test piece. v- Sound Velocity in the material. t- The measured round trip transit time.
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1.4 Appearance
THICKNESS GUAGE
Ultrasonic
1.5 Keyboard
Power ON/OFF ☼ LCD backlight on/off
Sound velocity Save data / Browse data
Calibration standard block of 4.00mm Function selector
Adjusting sound velocity and thickness; key for moving menu cursor
Adjusting sound velocity and thickness; key for moving menu cursor
2-point calibration; to be used together with function keys.
1.6 Display symbols
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2 Product Specifications
2.1 Technology parameter
Display: 128×64 LCD with LED backlight. Measuring range: 0.75mm~300.0mm (0.03inch~11.8 inch) Sound Velocity Range: 1000m/s~9999m/s (0.039~0.394in/µs Display resolution: 0.01mm or 0.1mm (lower than 100.0mm)
0.1mm (more than 99.99mm)
Accuracy: ±(0.5%Thickness +0.02)mm, depends on Materials and
conditions
Units: Metric/Imperial unit selectable. Lower limit for steel pipes:
5MHz probe: 20mm3.0mm (0.8 0.12 inch)
10MHz probe: 20mm3.0mm (0.6 0.08 inch)
Power Source: 2pcs 1.5V AA size, batteries.100 hours typical operating
time (LED backlight off).
Communication: RS232 serial port Outline Dimensions: 150mm×74mm×32mm Weight: 238 g Four measurements readings per second for single point measurement, Memory for up to 5 files(up to 100 values for each file) of stored values
2.2 Main Functions
1) Capable of performing measurements on a wide range of material,
including metals, plastic, ceramics, composites, epoxies, glass and other ultrasonic wave well-conductive materials.
2) Transducer models are available for special application, including for coarse grain material and high temperature applications.
3) Probe-Zero function, Sound-Velocity, Calibration function.
4) Two-Point Calibration function.
5) Coupling status Indicator showing the coupling status.
6) Battery information indicates the rest capacity of the battery.
7) Auto sleep and auto power off function to conserve battery life.
8) Optional software to process the memory data on the PC.
9) Optional thermal mini-printer to print the measured data via RS232 port.
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3.3 Setting probe frequency
Press  key to move the cursor to the position as that shown in the following figure. Press to change the frequency setting. LCD will display in
sequence the probe frequency to be set 5M, 7M or ZW.
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3.4 Measurement of thickness
First, set the sound velocity and then coat the coupling agent at the place to be measured, couple the probe with the material to be measured, now you can begin the measurement. The screen will display the thickness of material to be measured. After you remove the probe, the thickness value will be maintained, while the coupling indicator will disappear.
Note: when the probe is coupled with the material to be measured, the instrument will display the coupling indicator; if the indicator flashes or doesn't appear, it means that the coupling is not so good.
3.5 Zero calibration
Select the correct transducer frequency，The sound velocity adjusted to 5900m / s，While the gain is set to use when measuring the gain，Then the probe with the case on 4mm standard test block and displayed good
coupling signs，Zero point calibration by the about the same time, the screen instructions to complete the calibration: calibrate zero done, That the calibration is complete, while calibration data is stored in the instrument, If want to erase the calibration data, please operate according to memory manage,
If the instrument before the keys are not well coupled with the standard test block completion instructions or display calibration is not succeed, the calibration instrument will retain the original value, the screen display process as shown below:
key. Instruments buzzer
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Note: After every change of the probe, probe temperature, ambient temperature changes, etc. After the work environment, or working for some time after the discovery measurement errors should see the standard test block measured value is accurate, if the difference would be larger school Zero operation.
Calibrated display thickness may be bias 4.00 ± 0.02, now only shows the calibration is complete instructions, without further calibration.
3.6 Measurement of sound velocity
The sound velocity of a material can be measured using a test piece with given thickness. First, measure the test piece with caliper or micron micrometer and read the thickness accurately. Couple the probe with the test piece with given thickness till it displays a value, remove the probe, then adjust the display to the actual thickness with or , press , now it will display the sound velocity to be measured. Save the value into current sound velocity memory unit. For measuring sound velocity, one must select a test piece with adequate thickness, and the recommended min. wall thickness is 20.0mm. When measuring the sound velocity, please turn off the min. capturing function.
For example: To measure the sound velocity of a material with a thickness of 25.0mm, the procedure is:
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3.7 Setting alarm thickness limits
The instrument will alarm if the measurement is out of limits. When the measurement is lower than the low limit or higher than the high limit, the buzzer will alarm. The alarming limit is set as follows:
1) Press , move cursor to ALARM.
2) Press display the low and high limit of previous setting, use or
to set the new low or high limit.
3) To exit the Limit Setting, press , , or start to measure.
3.8 Menu option
The setting and function of the instrument be handle in Menu option. Press ,, move cursor to MENU then Press display main menu.
3.8.1 System Setup
1)
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Measurement units: metric and Imperial
2) Receiving gain: LOW and HIGH
1. The LOW is mainly used for measuring coarse material
with high scatter and small sound absorption, such as cast aluminum, cast copper and other metallic parts.
3) Display resolution: 0.1mm(LOW) and 0.01mm(HIGH)
4) Minimum capture measurement OFF and ON
1. To capture min. measurement is to trap the minimum value in a group of measured values. When the probe couples with the work piece, it will display actual measurement, when the probe is taken away, it will display the min. value of measurement carried out a moment ago, and the MIN indicator for the minimum value will flash several seconds. If you continue the measurement when the MIN is flashing, the former measurements will continue to take part in the min. value capturing. If you carry out measurement after MIN indicator stops flashing, the min. value capturing will begin from then on.
2. When the Min. capture function is ON, LCD will have MIN indication
5) 2-Point Calibration: OFF and ON
1. Select two standard samples of the same material with workpiece to be measured, among which, one has a thickness equal to or slightly higher than the tested piece, and the thickness of another test piece is slightly lower than the tested piece.
2. Before carrying out 2-point calibration, please turn off Min. Capture function, perform the Erase CAL Data function in the Memory Manager, and erase the former calibration record.
3. Set the 2-point calibration is ON.
4. Press , key return main display.
5. One can carry out 2-point calibration at any time during measurement.
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6. Press under thickness-measuring state to enter into 2-Point CAL, the screen will prompt to calibrate the thinner piece.
7. Measure the thinner standard test piece, use or to adjust the measurement to standard value. Press ENTER, the screen prompts to measure the thicker piece.
8. Measure the thicker standard test piece, use or to adjust the measurement to standard value.
9. Press , the calibration operation is finished.
6) Auto Down : Power-saving mode ON(default)
7) Baud Rate: 1200;2400;4800;9600
8) Adjusting Display Brightness
1. Press select “Set brightness”:
2. Use or to adjust the display brightness.
3. Press exit setup.
3.8.2 Print function
Connect main unit with micro printer from by the communication
cable, print measured results through menu selection.
When the printing is completed, the buzzer will give out sound, the
display will return to MENU state.
Send data to PC:
Connect main unit with PC by using the communication cable, one can
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send measured results through menu selection.
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3.8.3 Memory Manage
Erase file: Clearing selected files Erase all data: Clearing entire memory Erase CAL data: Clearing calibrating data
4 Data logger operation
4.1 Logging readings into memory
The instrument divides the memory unit into 5 files. Each can save 100 measurement values. Before saving data, Please set file number first. If you select the current file No., you can save the measurement directly by pressing . The procedures for setting file No. are:
1) Use to move the cursor to the position shown in the following
figure:
2) Press , by pressing F1~F5 to display file No.s cyclically. You can exit by
pressing or conducting one measurement.
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4.2
Reviewing stored thickness readings
1) Use to move cursor to the position shown in the following figure:
2) Pressing to brown the contents of memory. Press , erase current
data.
3) Pressing or review stored thickness.
4.3 Clearing current thickness Value
Under the state of Reviewing stored readings, press to erase a saved value currently displayed.
5. Measuring technology
5.1 Cleaning surface
Before measuring, please clean any dust, dirt and rust on the object, and remove any cover such as paint, etc. on it.
5.2 Improving requirement on roughness
Too rough surface will cause error in measurement. Before measuring, please smooth the surface of object by grinding, polishing or filing, etc. or use coupling agent with high viscosity for that.
5.3 Rough machined surface
The regular fine slots on rough machined (by such machines as lathe or planer) surface will also cause error in measurement. The way for compensating that is the same as that in 5.2. In addition, by so adjusting
the included angle between the probe’s crosstalk interlayer plate (the
metallic layer passing through the center of probe bottom) and the fine slots of the object that the interlayer plate is perpendicular or parallel to the fine slots, and by taking the min. value of the readouts as the measured thickness, one can also get better results.
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5.4 Measuring cylindrical surface
When measuring cylindrical material, such as pipes, oil tubes, etc., it is very important to select properly the included angle between the probe’s crosstalk interlayer plate and the axial line of the material to be measured. Briefly to say, first couple the probe with the material to be measured, make the probe’s crosstalk interlayer plate be perpendicular or parallel to the axial line of the object, shake the probe vertically along the axial line of the object, the readouts displayed on screen will change regularly. Select the min. readout from displayed ones as the accurate thickness of the object.
The standard for selecting the included angle between the probe’s
crosstalk interlayer plate and the axial line of the object is depending on
the curvature of it. For a pipe with large diameter, the probe’s crosstalk
interlayer plate should be perpendicular to the axial line of the object; for
a pipe with small diameter, one can measure with the probe’s crosstalk
interlayer plate being both parallel and perpendicular to the axial line of the object, and take the min. readout as the thickness.
5.5 Compound profile
When the material to be measured has a compound profile (such as bend of a pipe), one can use the way described in 5.4 to measure. The exception is that one should have two analyses, get two results when the probe’s crosstalk interlayer plate being both parallel and perpendicular to the axial line of the object, and take the min. readout as the thickness.
5.6 Non-parallel surface
To get a satisfactory ultrasonic response, the other surface of the object must be parallel to or co-axial with the surface to be measured, otherwise, it will cause measuring error or even no display.
5.7 Influence of material’s temperature
Both the thickness and transmitting speed of ultrasonic wave are influenced by temperature. If it has a high requirement on the measuring accuracy, one can use comparison method by test pieces, i.e., use a test piece with same material to measure under same temperature, and get temperature compensation coefficient, and use this coefficient to correct the actual measurement of the object.
5.8 Material with large attenuation
For some material such as fiber, with porous and coarse particles, they will cause large scatter and energy attenuation in ultrasonic wave, which
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will cause abnormal readouts even no display (generally, the abnormal readout is less than actual thickness). In this situation, this kind of material doesn't apply to be measured with this instrument.
5.9 Reference test piece
When making accurate measuring for different materials under different conditions, the more the standard test piece is near to the material to be measured, the more accurate the measurement is. The ideal reference test pieces should be a group of test pieces with different thickness made of materials to be measured, the test pieces can provide calibrating factors for the instrument (such as the microstructure of the material, heat-treating condition, direction of particles, surface roughness, etc.). To meet the highest requirement on measuring accuracy, a set of reference test pieces will be critical.
Under most situations, one can get satisfactory measuring accuracy with only one reference test piece, which should have same material and similar thickness with the object. Take an even object, measure it by using a micron micrometer, then it can be used as a test piece.
For thin material, when its thickness is near to the low limit of the probe’s
measuring range, one can use test piece to determine the accurate low limit. Never measure a material with a thickness lower than the low limit. If the thickness range can be estimated, the thickness for the test piece should select the high limit.
When the object is thick, especially for alloy with complex internal structure, please select a test piece similar to the object from a group of test pieces, thus to can have idea of calibration.
For most casting and forging, their internal structures have some direction. In different direction, the sound velocity will have some change. To solve the problem, the test piece should have an internal structure with same direction as that of the object, and the transmitting direction of sound wave in it should also be same as that for the object.
Under certain circumstances, look up the speed-of-sound table for given materials can replace reference test pieces. But this is approximately to substitute some test pieces. Under some situations, the value in the speed-of-sound table will have some difference from the actual measured
values, this is due to difference in the material’s physical and chemical
characteristics. This way is usually used for measuring low-carbon steel, and can only be taken as a rough measurement.
Thickness Gauge can measure sound velocity. Measure the sound velocity
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first, and then measure the work piece with the measured speed.
5.10 Several measuring methods
a) Single measuring way: measurement at one point. b) Double measuring way: measure with probe at one point twice. During
the two measurements, the probe’s crosstalk interlayer plate should be
placed in perpendicular direction, and take the min. readout as the accurate thickness of the material.
c) Multi-point measuring way: make several measurements in a range, and
take the min. readout as the thickness of the material.
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5.11 Selecting probes
Probe
Frequenc
y
Measuring range
Min. area
Application
5P 10
5MHz
1.0mm~300.0mm (steel)
20×3mm
General
Straight probe
5P10/90
General bent probe
7P6 300
7 MHz
0.75mm~25.0mm (steel)
15×2mm
thin work piece
ZW5P10
5 MHz
0.75mm~25.0mm (steel)
30mm
high temperature
2P 14
2 MHz
3．0mm~300.0mm (steel)
20mm
casting work piece
5.12 Changing probe
The wear of the probe’s interlayer plate will influence the measurement.
Please replace probe when the following situation happens.
1. When measuring different thickness, it always displays the same
value.
2. When plugging the probe, it has echo indication or measured value
display without measuring.
5.13 Measuring casting
It has specialty for measuring casting. The crystal particles for castings are
coarse, the structures are not dense enough, plus that they are in gross
state, which makes difficulty in measuring their thickness.
First of all, due to coarse crystal particles and not-so-dense structure, it
will cause large attenuation in sound energy. The attenuation is due to
material’s scatter and absorption of sound energy. The attenuation
degree is closely relative with the size of crystal particle and ultrasonic
frequency. Under the same frequency, the attenuation will increase with
the crystal diameter, but it has a high limit, when it reaches to this limit, if
the crystal diameter increases, the attenuation will tend to be a fixed
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value. For attenuation under different frequencies, it will increase as the
frequency.
Secondly, due to coarse crystal particle and if coarse out-phase structure
exists, it will cause abnormal reflection, i.e. the grass-shaped echo or
tree-shaped echo, so that the measuring will have error reading, and
cause wrong judgment.
Thirdly, as the crystal particle is coarse, the anisotropy in flexibility in
metal’s crystallizing direction will be obvious, which results in difference
in sound velocities in different directions, and the max. difference can
even be up to 5.5%. What’s more, the compactness in different positions
of the work piece is different, which will also cause difference in sound
velocity. All of these will produce inaccuracy in measurement. Therefore,
one must be very careful in measuring castings.
During measuring castings, please pay attention to the following points:
1. When measuring casting with un-machined surface, please use engine
oil, consistent grease and water glass as coupling agent.
2. Calibrate the sound velocity for the object with a standard test piece
having the same material and measuring direction as that for the object
to be measured.
3. If necessary, take 2-point calibration.
6 Preventing errors in measurement
6.1 Ultra-thin Material
For any ultrasonic thickness-gauge, when the thickness of object is less
than the low limit of the probe, it will cause measurement error. When
necessary, measure the min. limit thickness by comparing with the test
pieces.
When measuring ultra-thin object, sometimes error called “double
refraction” may occur, its result is that the displayed readout is twice of
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the actual thickness. Another error result is called “pulse envelop, cyclic
leap”, its result is that the measured value is larger than the actual
thickness. To prevent these kinds of errors, please repeat the
measurement to check the results.
6.2 Rust, Corrosion and Pit
The rust and pit on the other surface of the object will cause irregular
change in readouts. In extreme situation, it will even cause no readout. It
is very difficult to find small rust. When one finds a pit or is in doubt, he
should be very careful in that area. In such situation, one can orient the
probe’s crosstalk interlayer plate in different directions to have multiple
measurements.
6.3 Error in Identifying Material
When calibrates the instrument with one material, and then uses it to
measure another material, error will occur. Please be careful in selecting
correct sound velocity.
6.4 Wear of Probe
The surface of the probe is allyl resin, after long time of usage, its
roughness will increase, and the sensitivity will drop. If the user can be
sure that this is the reason for error, he can grind the surface with sand
paper or oilstone to make it smooth and has good parallelism. If it is still
not stable, the probe must be replaced.
6.5 Overlapped Material and Compound Material
It is impossible to measure uncoupled overlapped material, because the
ultrasonic wave can’t pass an uncoupled space. Since the ultrasonic wave
can’t transmit in compound material in even speed, it is not applicable to
use ultrasonic thickness-gauge to measure overlapped material and
compound material.
6.6 Influence of Oxidation Layer at Metal’s Surface
Some metals can produce dense oxidation layer on its surface, such as
aluminum, etc. The layer is closely contacted with the substrate, and it
has no obvious interface, but the ultrasonic wave has different
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transmitting speed in these two materials, which will cause error. In
addition, different thickness in oxidation layer will cause different error.
Please be careful in this. One can make a reference piece from a batch of
objects by measuring with micron micrometer or caliper, and use it to
calibrate the instrument.
6.7 Abnormal Readout of Thickness
The operator should be able to identify abnormal readout. Generally, the
rust, corrosion, pit and internal defect of the object will cause abnormal
readout. For the solution for that, please refer to chapter 4 and 5.
6.8 Utilization and Selection of Coupling Agent
The coupling agent is for transmitting high-frequency energy between the
probe and the object. If the type of agent is wrong, or the utilization is
wrong, it will cause error or flashing coupling indicator, and it will be
impossible to measure. The coupling agent should be used in proper
amount and be coated evenly.
It is very important to select proper coupling agent. When it is used on a
smooth surface, you’d better use an agent with low viscosity (such as
coupling agent provided along with the instrument and light engine oil,
etc.). When it is used on a coarse object surface, or vertical surface and
top surface, one can use agent with high viscosity (such as glycerin grease,
consistent grease and lubricating grease, etc.).
Various coupling agents with different components are available
everywhere.
7. Attention
7.1 Cleaning the Test Piece
Since the test pieces supplied along with the instrument will be coated
with coupling agent when being used for inspection, so please prevent it
from rust. After the measurement, the test pieces should be cleaned.
When the weather is hot, never stick any sweat on the pieces. If the
pieces are not to be used for a long time, please paint them with some oil
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to prevent rust. When one wants to use them again, first clean them, then
he can have normal operation.
7.2 Cleaning the Instrument’s Case
Alcohol will corrode the case, especially the LCD of the instrument.
Therefore, when you clean the instrument, you can do that just with some
clean water and clean it slightly.
7.3 Protecting the Probe
The surface of the probe is allyl resin, which is very sensitive to the heavy
scratch from the coarse surface. Therefore, during operation, Please press
it lightly. When measuring coarse surface, please minimize scratch on the
working surface of the probe.
When measuring under normal temperature, the temperature of the
surface to be measured should not be more than 60C, otherwise the
probe can’t be used.
The oil and dirt will age and break the probe line, so please remove dirt on
the cable after operation.
7.4 Replacing Batteries
When indication for low voltage occurs, please replace batteries on time :
Turn off the instrument
Open the battery chamber
Take out the batteries, put in new ones. Please note the polarity.
If the instrument will not be used for a long time, please take out the
batteries to avoid leakage, and corrosion in the battery chamber and pole
piece.
7.5 Absolutely avoid collision and moisture.
8. Maintenance
8.1 When the error of measurement is too large, please refer to chapter 6,
7.
8.2 If the following problems occur, please contact the dealer or
manufacturer:
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9. Operation to restore the factory parameters
Actual use, if the measured value of the error or deviation is too large,
may be operator error or other causes within the parameters of the
machine error, the best approach is to restore the factory parameters, as
follows:
Press , move cursor to MENU then Press display main menu.
use or to select About Software , Press into About Software.
Then press
key the machine will all the parameters back to factory
settings, while the machine automatically shut down.
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10.Configuration
No
ITEM
QUANTITY
NOTE
Standard configuration
1
Main Unit
1 2
Transducer
1
3
Couplant
1
4
Instrument case
1
5
Operating Manual
1
6
1.5V battery
2 7
Optional Configuration
1
Transducer:N02
2
Transducer:N07
3
Transducer:HT5
4
Mini Thermal printer
5
Print cable
6
“DataPro” Software
7
Communication cable
8
9
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Material
Sound velocity
(m/s)
(inch/µs)
Aluminum
6320-6400
0.250
Zinc
4170
0.164
Silver
3607
0.142
Gold
3251
0.128
Tin
2960
0.117
Steel, common
5920
0.233
Steel, stainless
5740
0.226
Brass
4399
0.173
Copper
4720
0.186
Iron
5930
0.233
Case Iron
4400-5820
0.173-0.229
Lead
2400
0.094
Nylon
2680
0.105
Titanium
5990
0.236
SUS
5970
0.240
Epoxy resin
2540
0.100
Ice
3988
0.222
Plexiglass
2692
0.106
Gray Cast
4600
0.180
Porcelain
5842
0.230
Glass (quartz)
5570
0.220
Polystyrene
2337
0.092
PVC
2388
0.094
Quartz glass
5639
0.222
Rubber, vulcanized
2311
0.091
Teflon
1422
0.058
Water
1473
0.058
Sound velocity for Different Materials
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Certificate of approval
Products Name::_Ultrasonic Thickness Gauge
_
Products Type:
Main unit No:___________________________
The product accords with the technical criteria and is
allowed to sell.
QUALITY CONTROL ENGINEER:_________________
Inspection date:_____________
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