Calibration Blocks for Bearing Rollers Testing

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Calibration Blocks for Welded Joints Testing

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Calibration Blocks for Surface Defects Detection (of a Flat Shape)

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Calibration Blocks for Surface Defects Detection (of Irregular Shape)

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Calibration Blocks for Subsurface Defects Detection

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Calibration Blocks for Holes Testing

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Calibration Blocks for Metric Thread Testing

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ECP for coating thickness evaluation (Single coil type)

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Conductivity probe (Reflection type)

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Right angle surface probe (Reflection type)

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Straight surface pencil probe (Reflection type)

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Dynamic Rotating Rigid Probe (with stainless steel housing) for bolt holes testing (coils are positioned at right angle to the probe shaft length, Differential Unshielded)

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Dynamic Rotating Bolt Hole Probe with Flexible Tip (coils are positioned at right angle to the probe shaft length; Differential Unshielded)

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Dynamic Rotating Bolt Hole Probe with Split Tip (coils are positioned at right angle to the probe shaft length; Differential Unshielded)

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Dynamic Rotating Countersink Probe (100˚ angle of chamfer, Differential Unshielded)

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Manual Bolt Hole Probes with Split Tip (coil is positioned at right angle to the probe shaft length; Single Unshielded / Shielded)

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Straight Surface Probe (Unshielded / Shielded, Bridge)

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Angle Shaft Surface Probe (45˚ tip, Unshielded / Shielded, Bridge type)

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Right Angle Surface Probe (90˚ tip, Unnhielded/Shielded, Bridge type)

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Straight Shaft Surface Probe (Unshielded / Shielded, Single coil)

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Angle Shaft Surface Probe (45˚ tip, Single / Single Shielded)

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Right Angle Surface Probe (90˚ tip, Single, Unshielded/Shielded)

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Right Angle Surface Probe (90˚ tip, handle angle 15°, Single / Single Shielded)

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Straight Weld Probe (Bridge type)

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Right Angle Weld Probe (90˚ tip, Transverse, Bridge type)

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Right Angle Weld Probe (90˚ tip, Inline, Bridge)

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Surface MDF-Type Probes (Multi-Differential)

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Straight Shaft Probe for sub-surface flaws detection in the second layer, through the first layer with up to 1.5 mm thickness (e.g., testing of load-bearing elements under aircraft skin) (Reflection type)

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Right angle Probe for sub-surface flaws detection in the second layer, through the first layer with up to 1.5 mm thickness (e.g., testing of load-bearing elements under aircraft skin) (Reflection type)

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Encircling probe for testing the cylindrical objects made of non-magnetic materials (Reflection type)

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Eddy current testing of aircraft

Eddy current non-destructive testing method is of paramount importance for technical diagnostics of aircraft parts.

The eddy current method has a number of advantages as compared to other methods, in terms of the costs of NDT equipment and consumables. This method is distinguished by high productivity, high reliability of testing and does not impose specific requirements on the quality or roughness of surface to be tested. Testing can be performed even without removing the coating or scaling.

The eddy current method is used for testing wings (fatigue cracks on the inside of wing boxes), bodies, wheel discs, engine parts (mainly - engine blades), rotors, axes, fasteners and holes (flaws in rivets, with the latter remaining in place), landing gears made of high-strength steel.

Eddy current testing is possible both at the stage of production of aircraft, helicopters or other aircraft equipment, and during on-site maintenance.

On-site maintenance of aircraft includes:

Detection of surface flaws

This task has been successfully solved thanks to high-frequency NDT technologies which are based on the use of relatively high operating frequencies (over 1 MHz). In aluminum alloy parts, cracks can be detected at a depth over 0.2 mm, with a minimum length of 2 mm and width of 0.1 mm. In titanium alloy, austenitic and ferritic steel parts, cracks can be detected at a depth over 0.5 mm, with a minimum length of 2 mm and width of 0.1 mm. Eddy current flaw detectors are provided with pencil-type or L-shaped probes, as well as with special-purpose probes for testing blades and hole edges.

Detection of hidden sub-surface flaws

An essential advantage of the eddy current non-destructive testing method is the possibility to detect flaws of fatigue and corrosion origin in the inner layers of multilayer structures, even without removing the fasteners and without disassembling the structures. This facilitates an effective use of the eddy current method not only during the repair of aircraft, when it is possible to remove the fasteners, but directly during tests or on-site maintenance.
Based on the new design of eddy current probes, fundamentally new technologies and means for recognizing the hidden flaws in integral multilayer aircraft structures have been created, particularly, for detecting the flaws under aircraft skin at low frequencies.
Test objects
Fasteners, integral multilayer structures, repair patch in the middle of aircraft wing, shock strut pistons, riveted joints, inside parts of wing boxes, skin-stringer interface.

Detection of the surface defects in the holes and countersinks

Another important task that can be successfully solved with the eddy current testing method is the detection of the surface defects in the holes and countersinks. These areas can be effectively and efficiently tested using rotary eddy current scanners equipped with special ECPs (reflection type) of different diameters.

Visual testing

This method combines a visual inspection and measurement of the geometrical parameters of welds to check their compliance with the required values. Before testing, the welds should be cleaned from scale, slag and metal splashes. After that, the surface should be treated with alcohol, or etched using a 10% solution of nitric acid. As a tool for this type of testing, a 5 or 10-power magnifier, as well as lighting devices and measuring instruments (ruler, calipers, templates) are normally used to verify both the weld and defect sizes. Despite its apparent simplicity, this type of testing is very effective and is prior to other methods. If the flaws are detected already at this stage, the weld is considered as rejected, and further testing is not performed. An obvious disadvantage of this method is the impossibility to detect the majority of hidden defects and the subjectivity of evaluation methods, which requires a lot of experience from NDT inspector.

Penetrant testing

This method is based on the ability of the liquid to penetrate into and fill the smallest capillary channels that are essentially made by weld defects. Such defects include pores and cracks that break the surface of the material. The rate and depth of penetration of the liquid depends on the radius of the capillary and the wettability of the liquid. Thus, the penetrant method is very effective for detecting surface flaws. To increase its efficiency, the so-called penetrants are used which can penetrate deep into the capillary due to their small surface tension. Their bright color makes them noticeable, which facilitates the detection of a defect. A penetrant testing kit normally includes a penetrant; cleanser for thorough cleaning of the surface before testing; developer for extracting the penetrant from the defect and creating an indicator pattern on a contrast background, using which it is possible to see the size and form of the defect. This method of testing is similar to the visual one, since it presupposes visual inspection of the weld, therefore, has the same disadvantages.

Ultrasonic testing

UT is one of the most common methods, because it ensures an accurate detection of hidden flaws located inside the weld. The method is based on the use of ultrasonic waves that propagate through a layer of metal and are reflected from its boundary and the boundaries of internal discontinuities. Based on the time difference between the sent and reflected signals, as well as the shape and amplitude of the reflected signals, it is possible to evaluate not only the metal thickness, but also the defects encountered on the sound path. An instrument that is used for ultrasonic testing is called ‘flaw detector’. The flaw detector utilizes special-purpose transducers (transmitters / receivers of ultrasonic signal), which allow implementing the echo pulse, pitch catch and through transmission techniques.

Pulse echo technique

With the pulse echo technique, the transducer sends a probing signal to a test object and receives echo signals reflected from defects, as well as from design features of the product. Based on the time of the signal arrival, it is possible to spot the location of the defects, and based on the signal amplitude - the size of the defects. The disadvantage of this technique is the need for the defect to have a reflecting surface perpendicular to the ultrasonic beam, or be located near the surface of the product. For example, the pulse echo technique does not allow detecting planar defects (cracks and lack of fusion) that are not located close to the surface of the product under test.

Pitch catch technique

The pulse echo technique does not allow detecting planar defects (cracks and lack of fusion) that are not located close to the surface of the product under test. The pitch catch techniques, Duet and Tandem, are used to recognize the above mentioned flaws. This is achieved with a pair of transducers installed so that the signal emitted by the first transducer is returned to the second transducer after reflection from the planar defect.

Through transmission technique

However, even the pitch catch mode does not guarantee the detection of all differently-directed flaws. For this purpose, the through transmission technique is used, with the transducers placed on both sides of the weld so that the signal reflected from the back surface comes to the receiver. Sufficiently large defects of almost any orientation crossing the ultrasonic beam shade the above signal, which evidences their detection. But, unfortunately, this technique does not provide exact information about the location (coordinates) of detected flaws. To obtain accurate readings from the ultrasonic flaw detector, it is necessary to make preliminary settings with the help of specialized reference blocks that are usually supplied together with the instrument. The reference blocks of various types can be also purchased separately, depending on a particular application or specific NDT task.

TOFD technique

In recent decades, the ultrasonictime-of-flight-diffraction (TOFD) technique for weld examination has become increasingly widespread. The TOFD technique is based on interaction of ultrasonic waves with the edges of discontinuities. This interaction leads to generating diffraction waves with a wide range of angles. The detection of diffraction waves enables to establish the presence of discontinuity. The transmission time of reported signals is a measure of estimating the discontinuity height, thereby allowing to measure the discontinuity size which is always determined by the diffraction signal transmission time. The signal amplitude is not used for size measurement. Both longitudinal and shear waves are generated and applied in this case. The main information characteristic is the arrival time of the signal. The TOFD technique has a number of benefits as compared to conventional manual ultrasonic testing: Several-times higher productivity; Low sensitivity to the orientation of defects; Possibility not to estimate but measure the actual sizes of planar defects; High degree of reportability of test results. To implement the TOFD technique, special equipment is used with one or several pairs of transducers that are placed on both sides of the weld and moved along it during inspection.

Eddy current weld inspection

Eddy current non-destructive testing is based on the analysis of interaction of an external electromagnetic field with the electromagnetic field of eddy currents induced in a test object by this field. The operating principle of ET detectors is based on the eddy current method, which consists in the distortion of eddy currents in the local test zone, followed by recording the changes in the electromagnetic field of the eddy currents that are caused by the defect and the electrophysical properties of the test object. This method is characterized by small test depths, as it is used to detect cracks and discontinuities in the material at a depth up to 2 mm. The design and setup procedure of eddy current testers resemble the design and setup procedure of their ultrasonic counterparts, using eddy current probes and eddy current reference blocks accordingly. Obviously, the ultrasonic and eddy current testing methods complement each other, ensuring a hundred-percent reliable examination of the weld over its entire depth and extent. OKOndt GROUP manufactures a series of eddy current flaw detectors for non-destructive testing of welds.

Magnetic particle testing

Magnetic particle inspection is a method of non-destructive testing based on the phenomenon of attraction of magnetic powder particles by magnetic scattering fluxes that arise over defects in magnetized control objects. The magnetic particle method is designed to detect surface and subsurface discontinuities such as hair, cracks of various origin, non-melting of welded joints, floken, sunsets, tears, etc. The Magnetic Particle Flaw Detector allows you to control various shapes, welds, internal surfaces of the holes by magnetizing individual controlled areas or the product as a whole with a circular or longitudinal field created by a set of magnetizing devices powered by pulsed or direct current or by using permanent magnets.

Radiographic testing

Radiography is described here only with the aim to provide a complete picture of NDT methods that are used for welds examination. Although this method is quite rigorous, its application is rather limited because it is associated with the use of gamma rays and X-rays with high permeation power, which allows them to pass through the metal, whilst the defects are recorded on the film. This increases danger to human health. In addition, instruments of this type are quite expensive. So, this is a very specific testing method that requires the use of appropriate personal protection equipment, as well as the creation of laboratory conditions for testing. Thus, we have considered the main methods of non-destructive testing of welds. It is obvious that the combined use of ultrasonic, eddy current and magnetic particle inspections ensures the most accurate test results and the safe test conditions.

UTG-8

For easy tasks not requiring structural data storage or corrosion mapping, a simple, reliable and easy to use ultrasonic corrosion gauge UTG-8 is used.

The device operation is maximum simplified. You have to connect the transducer, to calibrate the device on the in-built calibration block – and you may start measurements. The device also supports one-point and two-point calibrations.

When taking measurements there is also a so-called gauging accuracy indicator displayed on the screen – the more it is filled, the more accurate measurements are.

Sonocon B/BL

There is also a wide range of tasks, where it is required not only to measure the remaining thickness and search for corrosion damages, but also to analyze the whole measurements picture, their statistical analysis, measurements database and test reports formation. In order to solve these tasks, there are the Sonocon devices family made by OKOndt Group: Sonocon B and Sonocon BL. The devices have the same set of functions differing only by their form-factor. Sonocon B can be easily fit in your hand and weighs only 2 lb, though it is equipped with 800×480 pixels and 4.5 in display. Sonocon BL has 7.5 in diagonal screen with the same resolution, polyurethane-reinforced bumper case and extended keyboard. Meanwhile, its weight is only 3.5 lb.

Both devices have switchable software allowing to apply them as a universal flaw detectors («UT» version), and as the A-Scan ultrasonic corrosion gauges, and corrosion plotters («Thickness gauge +» version). With regards to the subject of the article, further we will speak about «Thickness gauge +» version functionality.

System of Non-destructive Work rolls Testing B-35

Work rolls is the main tool of the rolling manufacture, which ensures due quality of the finished rolled products. Uninterrupted operation of the powerful rolling mill and high-quality finished products depend a lot on the mill rolls surface condition and their quality

Eddy Current Testing System of Rails EDC RAIL 5065

Ultrasonic Immersion Inspection System for Railway Axles during Production AUTS Axle-4 OS-4

Nowadays, the railway transport is one of the major means for transportation of goods and passengers. To assure the safety of cargo traffic it is crucial to use high-quality elements of the railway car wheelsets which are highly succumbed to a dynamic loading in-service. That is why the quality control during production of one of the wheelset elements, namely axles, is critical.

Ultrasonic Immersion Testing. Application

Railway axles testing at their production release using automated means of non-destructive testing