EMAtransducer is designed for transmitting and (or) reception of elastic waves in an electrically conductive medium as a result of the action of electromagnetic effects, based on the use of the effect of magnetic induction (Lorentz effect — the force acting from the electromagnetic field on a moving charged particle)
Use: for non-destructive testing of metal structures as a means of detecting defects in rolled products and structures such as tapes, strips, pipes, vessels, rails, etc.of ferrous and non-ferrous metals and alloys in a wide range of thicknesses with one-way contactless access.
Electromagnetic-acoustic method of excitation of ultrasound is a method of transformation of high-frequency electromagnetic wave of conductor (inductor) with flowing electrical current through it in elastic deformation (ultrasound) on the surface of the inspected object with a frequency equal to or multiple of the frequency of the electromagnetic wave.
Electromagnetic-acoustic reception of ultrasonic vibrations is based on the reverse EMA-excitation effect.
Advantages of EMA technology:
EMA-technology of excitation and reception of ultrasound has a number of advantages unattainable for others, including piezo-technology:
- ensuring reliable inspection of objects with contaminated surfaces;
- unlimited ability to inspect objects moving at high speeds;
- inspect extreme curvature objects;
- without limitation, the ability to control objects under conditions of low and extremely low temperature;
- ability to control high-temperature objects (up to 1200 degrees of Celsius)
Comparison of ultrasound excitation/receptionPiezo-and EMAtechnology:
|Contamination of the surface of an object||unacceptably||noeffect|
|Inspection of objects moving at high speeds||typically up to 1.5 m / s 1*||withoutrestrictions|
|Curvature of the inspected object||significantlyaffect||noeffect|
|Heated and highly heated objects|
(up to 1200 degrees of Celsius)
|typicallyupto 90 degrees 2*||Yes|
1* — practical limit is limited to 15 m / s subject to restrictions on the inspection conditions and special measures to ensure the stability of the acoustic contact;
2* — practical limit to 300 degrees of Celsius subject to the application of special measures for establishment of acoustic contact and the limitation on inspection (in practice, it does not have mass application)
Thickness of the electromagnetic-acoustic EMAT-100
Thickness measurement of products made of conductive materials with one-way access to them without the use of contact fluid, prior preparation of the control surface.
Measurement of the residual thickness of corroded materials, permissible surface roughness – Rz320.
The ability to measure through an air gap or insulating coating.
Thickness gauge is used to measure the thickness of sheets, walls of tanks, pipes, bends of pipes, pipelines, as well as bridge, hull, transport, ship and other structures and products, including coated surfaces, during and after their manufacture and operation.
The thickness gauge can be used on highly corroded surfaces.
The thickness gauge uses electromagnetic-acoustic (EMA) method of excitation and reception of ultrasonic shear vibrations, allowing to measure the thickness without contact liquid, cleaning the surface, through the air gap or non-conductive coating (paint, varnish, enamel, film).