What is an ultrasound test?
Ultrasonic non-destructive testing, also known as ultrasonic NDT or simply UT, is a method of characterizing the thickness or internal structure of the measured object by using high frequency sound waves. The frequency used for ultrasonic testing, or the slope many times higher than the limit of human hearing, is generally in the range of 500 KHz to 20 MHz.
What kind of materials can be tested?
In industrial applications, ultrasonic testing is widely used in metals, plastics, composite materials and ceramics. The only common engineering materials that are not suitable for ultrasonic testing with conventional equipment are wood and wooden paper products. Ultrasound technology is also widely used in biomedical fields for diagnostic imaging and medical research.
What are the advantages of ultrasound testing?
Ultrasonic testing is completely non-destructive. The test piece does not need to be cut, broken, or used destructive chemicals. Only need to enter one side, unlike the use of mechanical thickness measurement tools, such as calipers and micrometers. There is no potential for mechanical detection using ultrasound, and I don't want radiography. When a test is properly set up, the results are highly repeatable and reliable.
How does it work?
High-frequency sound waves are very directional. They propagate through a medium (like a piece of steel or plastic) until they encounter the boundary of another medium (like air), at which point they emit back to their source. By analyzing these reflections, it is possible to measure the thickness of the test piece, or find signs of cracks, or other hidden internal defects.
What are the potential limitations of ultrasound testing?
Ultrasonic defect detection requires a trained operator who can set up a test with appropriate reference standards and appropriate results. It can be challenging to detect workpieces with complex geometries. Ultrasonic thickness gauges must be calibrated on the basis of respecting the material being tested. Applications require a wide range of thickness measurements or acoustically different material measurements that require multiple settings. Ultrasonic thickness gauges are much more expensive than mechanical measuring equipment.
What is an ultrasonic testing instrument?
An ultrasonic thickness gauge is a device that generates acoustic pulses in the test piece. It measures very accurately the time interval when the echo is received. The sound velocity of the tested material has been programmed. The instrument uses the sound velocity information and the measurement time interval to calculate the thickness through a simple relationship. [Distance] is equal to [sound velocity] times [time].
What is an ultrasonic probe?
A probe is any device that converts one form of energy to another. An ultrasonic probe converts electronic energy into mechanical vibration (sound waves), and sound waves into electronic energy. Typically, they are small, hand-mounted, and have a variety of frequencies and types for special testing needs.
How accurate are ultrasonic testing instruments?
Under optimized conditions, commercial ultrasonic instruments can achieve an accuracy of up to +/- 0.001 mm (0.00004 "), which is +/- 0.025 mm (0.001") in most commonly used engineering materials, or may be higher. Factors that affect accuracy include consistency with the speed of sound of the material being measured, the degree of sound scattering and absorption, surface conditions and accuracy, and pay attention to what needs to be calibrated for the upcoming application.
Who uses ultrasonic instruments?
The main application of ultrasonic instruments is to measure the residual thickness of corroded tubes or boxes. The measurement is carried out quickly and simply without entering the inside or requiring the tube or tank to be exhausted. Other important applications include measuring the thickness of molded bottles and similar containers, turbine blades and other precision instruments or castings, small-diameter medical tubular materials, rubber tires and conveyor belts, fiberglass hulls, and even contact lenses.
What types of defects can be found?
A wide range of cracks, pores, degumming, slag inclusions and similar problems that affect the integrity of the structure can all be located and measured by ultrasonic flaw detectors. The smallest defect size that can be detected in a given application depends on the type of material being tested and the type of defect under consideration.
Who uses ultrasonic flaw detectors?
Ultrasonic flaw detectors are widely used in strict safety-related and quality-related applications, including structural welding, steel beams, forgings, pipes and boxes, aircraft engine joint frames, cycling frames, railway tracks, power turbines and other heavy machinery , Castings and many other important applications.
What is an ultrasonic flaw detector?
Sound waves propagating through the material will be reflected back in a verbal manner when encountering defects such as cracks and pores. An ultrasonic flaw detector is an instrument that generates and processes ultrasonic signals and creates a waveform display. It can be used by a trained operator to find hidden defects in test pieces. The operator identifies characteristic reflection images from good parts and then looks for changes in the reflection images that may indicate defects.
What other types of instruments are available?
Ultrasonic imaging systems are used to produce high-resolution photos, similar to X-rays, which use sound waves to map the internal structure of components. The phased array technology originally developed for medical diagnostic imaging was used in industrial situations to produce representative pictures. The large-scale to seedling system is used by the aerospace industry and metal processing manufacturers to check for hidden defects in raw materials and final molded parts. Ultrasonic pulse generator / receiver and signal analysis are used in a variety of materials research applications.
What are the commonly used flaw detection methods?
Answer: China â€™s national standards currently stipulate five items: ultrasonic testing (UT), radiographic testing (RT), penetration testing (PT), magnetic particle testing (MT) and eddy current testing (ET). China â€™s national defense technology industrial system Recently, five new types of acoustic emission (AT or AE), computer tomography (CT), holographic interference and / or dislocation speckle interference detection, leak detection (LT) and visual detection (VT) have been added. method. In Europe and the United States, neutron radiographic testing (NRT) and strain testing in Japan have also been included in the non-destructive testing methods for the qualification and certification of non-destructive testing personnel.
Ultrasonic Testing (abbreviated UT) GB / T12604.1-2005 Non-destructive testing term ultrasonic testing;
Radiographic Testing (abbreviated RT) GB / T12604.2-2005 Non-destructive testing term radiographic testing;
Magnetic particle testing (abbreviated MT) GB / T12604.5-2005 Non-destructive testing term magnetic particle testing;
Penetrant Testing (abbreviated PT) GB / T12604.3-2005 Non-destructive testing term penetration testing;
Eddy current testing (abbreviated ET) GB / T12604.6-2005 Non-destructive testing term eddy current testing;
Unconventional non-destructive testing technologies are:
Acoustic Emission (abbreviation AE);
Leak Testing (abbreviated UT);
How to define the K value of an inclined probe?
Answer: The tangent value of the angle of refraction of the oblique probe is called the K value, which is equal to the ratio of the horizontal distance between the lamina to the reflection point of the oblique probe and the corresponding depth.
Foreign oblique probes are generally divided by refraction angles of 45, 60, and 70 degrees. They are marked by the angle of refraction of ultrasonic waves in steel. In China, the angle probe is marked by the tangent of the refraction angle Î². If K = 1, then Î² = 45.
What are the probe interfaces?
A) BNC interface, commonly known as Q9 interface in China
B) Lemo 00 interface
C) Lemo 01 interface
D) Microdot interface, used for micro and small probes
E) UHF interface, usually used for water immersion probe
What should I do if there is a problem with the portable flaw detector?
When there are some abnormal phenomena in the instrument, such as garbled characters, follow the steps below:
The first step is to turn on the system after it is turned off and let the system restart.
The second step, if the problem still exists, try to restore the instrument to factory settings.
Note: Use caution when using factory reset. Because this operation may cause all settings and data saved in the instrument to be lost.
The third step, when the problem can not be solved, please contact our company for maintenance.
Ultrasonic thickness gauge / flaw detector universal automatic calibration procedure, suitable for Panametrics-NDT brand?
Step 1: Prepare a thick and thin calibration block with the same material and the same surface condition as the tested material. The test block requires the upper and lower surfaces to be parallel and the thickness is known.
Step 2: Couple the probe to a thin test block and perform zero calibration.
2.1 When the thickness reading is stable, press [CALZERO] + ENTER or [CAL] + [ZERO] (select the corresponding operation according to the instrument)
2.2 Move the probe away from the test block, enter the known actual thickness and confirm the input
Step 3: Coupling the probe to the thick test block for sound velocity calibration
3.1 When the thickness reading is stable, press [CALVEL] or [VEL] (select the corresponding operation according to the instrument)
3.2 Move the probe away from the test block, enter the known actual thickness and confirm the input
Step 4: Press the MEAS key to complete the calibration.
At this time, the instrument will automatically calculate the sound velocity of the test block and the zero point of the probe.
Why must the test block be used in ultrasonic flaw detection and measurement?
The test blocks used in ultrasonic testing are divided into standard test blocks and comparative test blocks.
Standard test blocks have specified materials, surface conditions, geometric shapes and dimensions, and can be used to evaluate and calibrate ultrasonic testing equipment. The comparison test block is a test block used for detecting a specific test piece by a specific method.
The use of test blocks in flaw detection is to ensure the accuracy, repeatability and comparability of the test results.
The test block used in ultrasonic measurement is a test block of the same material and heat treatment process specially made for the workpiece to be tested. Its use is to calibrate the sound velocity and zero point of the instrument in order to get a more accurate thickness measurement.
Precautions for using ray machine (including source)
1. The user must hold the isotope work permit issued by the State Environmental Protection and the personal employment certificate
2. When using the ray equipment (including source), you must carry your personal ray alarm and on-site ray dosimeter
3. Only radiologists with strict, safe and standard training can be engaged in radiation work
4. If there is a sudden accident of radiation, please report it in time and contact us
1. Do not spray on the human body and tableware during use.
2. Do not expose to direct sunlight
3. Tinder should be avoided at the site of use.
4. Into the eyes and skin, rinse with water.
5. Use protective gloves whenever possible.
6. Do not let children play with it to avoid accidents.
7. Pay attention to the use of airtight containers.
Matters needing attention in magnetic particle inspection
1. When the instrument is in use, it should avoid no-load work to prevent unnecessary temperature rise or damage.
2. When using the probe, the end face should maintain good contact with the detected workpiece. Then press the magnetizing button switch on the handle, then the flaw detection effect is the best. The probe should avoid collision and fall, and keep clean.
3. In use, if the probe wire pack is found to be seriously hot, stop using it, check the cause of the failure, and then use it after maintenance, otherwise the probe will be damaged.
4. When the instrument is stopped, the power switch on the panel and the power distribution board should be cut off.
5. After the flaw detection is completed, debris should be removed and lubricated at the movable joint of the probe.
Common instrument maintenance
Common instrument maintenance and matters needing attention
a. The instrument should be kept and operated by a special person;
b. Since most of the instrument shells are engineering plastics, the instrument should be wiped in time after testing the oily parts to prevent aging
c. The buttons of the instrument can only be operated by hand, and cannot touch other hard or corner workpieces;
d. When plugging and unplugging the probe and probe cable, select the appropriate disassembly method according to the different probe interface types;
Maintenance of test block
Maintenance of test block:
a. It should be numbered and registered in an appropriate place to prevent confusion;
b. Pay attention to protection during use and handling to prevent collision, knocking and scratching;
c. Pay attention to rust prevention, usually use a fine oil cloth to polish. When not in use for a long time, it should be cleaned and dried, coated with oil, and the flat bottom hole should be sealed with nylon plug or adhesive;
d. Remove the oil and rust in the reflector body during use, so as not to affect the detection sensitivity;
e. Pay attention to proper storage, avoid heavy pressure and fire to prevent deformation.
Maintenance of lithium batteries of common instruments
Although lithium-ion batteries rarely have the memory effect of nickel-cadmium batteries, the principle of the memory effect is crystallization, and almost no such reaction occurs in lithium batteries. However, the capacity of lithium-ion batteries will still decline after being charged and discharged multiple times. Therefore, the use of lithium batteries still needs to pay attention to the following points:
a. Overcharge and overdischarge are prohibited, which will cause permanent damage to the positive and negative electrodes of the lithium ion battery;
b. Charging should be carried out at a suitable temperature;
c. No need to deliberately ensure that the battery is fully discharged and recharged each time
d. For a period of time, it can do a deep charge and discharge under the control of the protection circuit to correct the battery charge statistics;
e. A battery that has not been used for a long time should be charged with a certain amount of electricity and placed in a cool place to weaken the speed of its internal passivation reaction.
Special maintenance of 8500 high-precision Hall effect thickness gauge
a. Do not press the panel with sharp objects (such as screwdrivers, ballpoint pens, etc.) instead of fingers to avoid damage to the keyboard;
b. After a long period of use, if the instrument panel is dirty and needs to be cleaned, wipe the instrument panel with a soft damp cloth (dry water);
c. The instrument is splash-proof and dust-proof, but not immersed in water;
d. The probe should not be in contact with the ferromagnetic material on the large plane, so as not to affect the measurement accuracy or even damage the probe;
e. When calibrating, please put the target ball into the fixture (that is, the test block with red label and blue label), and then place the fixture on top of the probe. If you put the fixture on the probe first, then put the ball , The ball will knock out the test block for a long time, which will affect the measurement accuracy;
f. When plugging and unplugging the probe cable, power cord and computer connection cable, the metal spring sleeve at the cable interface should be put in force, and the cable should not be forcibly pulled;
g. The target ball is a steel ball, not a stainless steel ball, so the ball must not get wet when in use, so as not to cause the probe and the steel ball to rust and affect the measurement accuracy.
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