Flaw Detectors

Flaw detectors are non-destructive testing instruments that can detect or measure defects in raw materials or finished products.  Depending on the specific technique used, a wide variety of defects can be located such as surface cracks, subsurface flaws, pores / voids, internal corrosion, coating holidays, debonding, weld defects and packaging defects.  Three important parameters to consider when searching for flaw detectors include the instrument type or technology, operating specifications, and additional specifications and features.

Instrument type or technology choices for flaw detectors include acoustic emission, beta gauge, eddy current or electromagnetic, magnetic, magnetic particle system, optical or laser, Penetrant testing system, radiographic or x-ray, and ultrasonic.  Specific flaws or features within a mechanical system provide specific acoustic or vibrational responses.  In a Beta gauge, the absorption of Beta particles is used to measure the thickness of materials or coatings. Eddy current flaw detectors, penetrating radar and other electromagnetic techniques are used to detect or measure flaws, bond or weld integrity, thickness, electrical conductivity, detect the presence of rebar or metals. Several different magnetic techniques are used in nondestructive testing including Hall effect and induction. In a magnetic particle system current flow or an external magnet magnetizes the part. Optical based instruments using methods such as laser shearography, magneto-optical, holographic interferometry or other optical techniques to detect flaws, residual stress or measure thickness. In penetrant testing, Penetrant is applied to the part by spray or immersion. Radiographic or x-ray equipment uses penetrating X-rays or gamma rays to capture images of the internal structure or a part or finished product. Ultrasonic (UT) inspection techniques are used to detect surface and subsurface flaws or to measure thickness.  Choices for form factor include bench or rack or cabinet, computer board, portable or handheld or mobile, and monitoring system.

Important flaw detector specifications to consider include flaw detection or inspection area, measurement of nonconductive materials, and thickness measurements.  Choices for flaw detection or inspection area include aircraft or military inspection, coating flaw or holiday, debonding or bond integrity, general corrosion detection, inclusions, machining or grinding damage, metal detector or rebar absence, manufacturing of metals or webs, packaging defects or leaks, pore or void, pressure vessel flaws or cracks, rail inspection, subsurface crack detection, surface cracks or abrasion, tube or pipeline defects, weld or joint inspection, and wire rope or cable tester.  Some flaw detectors are capable of nondestructive testing components fabricated from nonconductive materials such as ceramics, composites, glasses or polymers.  Some NDT instruments can measure thickness in addition to the unit's primary function, flaw detection.

Other specifications or features to consider when searching for flaw detectors include thickness range,  number of channels or probes, sorting gates or alarm mode, English or metric selectable display, data logging capabilities, and operating temperature.

• Pipeline Defect Flaw Detectors
  Pipeline defect flaw detectors locate surface or sub-surface cracks, inclusions or pores in tubing, piping or pipelines. Pipelines are usually constructed of steel, so NDT techniques suitable for...
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• Vision Squad Files: Background Subtraction-Based Flaw Detection (.pdf)
  This document describes techniques on removing image backgrounds to detect flaws in images with the Matrox Imaging Library. One of the many challenges in computer vision is the detection of flaws such...
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• Ultrasonic Inspection Techniques
  Ultrasonic inspection techniques are used to detect surface and sub-surface flaws or to measure thickness. Beams of high frequency acoustic energy are introduced into the material and subsequently...
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