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Wednesday, 14 September 2016

CONTACT TRANSDUCER &IMMERSION TRANSDUCERS In ULTRASONIC TESTING.

Contact transducer :- are used for direct contact inspections,and are generally hand manipulated. They have elements protected in a rugged casing to withstand sliding contact with a variety of materials. These transducers have an ergonomic design so that they are easy to grip and move along a surface. They after have replaceable wear plates to lengthen their useful life. Coupling materials of water, grease, oils,or commercial materials are used  to remove the air gap between the transducer and the component being inspected.
Immersion transducer :-do not contact the component. These transducers are designed to operate in a liquid environment and all connections are watertight. Immersion transducers usually in a liquid environment and all connections are watertight. immersion transducers usually have an impedance matching layer that helps to get more sound energy into the water and, in turn, into the component being inspected. Immersion transducers can be purchased with a planer,cylindrically focused or spherically focused lens, A focused transducer can improve the sensitivity and axial resolution by concentrating the sound energy to a smaller area. Immersion transducers are typically used inside a water tank or as part of a squirter or bubbler system in scanning applications. Contact transducer are available in a variety of configuration to improve their usefulness for a variety of applications. The flat contact transducer shown above is used in normal beam inspection of relatively flat surfaces, and where near surface resolution is not critical. If the surface is curved, a shoe that matches the curvature of the part may need to be added to the face of the transducer. If near surface resolution is important or if an angle beam inspection is needed, one of the special contact transducer described below might be used.