What Are the Different Types of Ultrasonic Transducers?

As their name suggests, ultrasonic transducers are devices that produce or sense ultrasound energy. For nondestructive testing, ultrasonic transducers use high-frequency sound waves to measure certain parameters. In some instances, inspectors utilize them in a wide variety of industrial applications, including flaw detection, thickness gaging, and weld inspection.

They are available in a range of shapes and sizes, making it challenging to figure out what type of ultrasonic transducer you need for your operations. To determine what transducer you require, this blog will provide an overview of the five most common types, allowing you to better understand the role each transducer serves.

Dual Element Transducers

A dual element transducer has two crystal elements that are housed within the same case and are separated by an acoustic barrier. While one element produces sound waves, the other element acts as a receiver.

The two elements are angled toward one another to create a v-shaped sound path in the test material. Meanwhile, the transmit and receive beams cross under the examination surface, creating a pseudo-focus effect that enhances resolution in the area of focus. This effect is especially helpful when examining parts with rough back wall surfaces and measuring wall thickness for corrosion-prone applications.

Other popular uses for dual element transducers include:

  • Weld overlay and cladding bond/disbond inspection

  • Detection of porosity, inclusions, cracks, and laminations in castings and forgings

  • Crack detection in bolts and other cylindrical objects

  • High-temperature applications

Contact Transducers

A contact transducer is utilized for direct contact inspections. Serving as single element transducers, contact transducers have a wear-resistant surface optimized for contact with most metals, making them ideal for rugged industrial environments. This type of transducer is available in a wide range of styles and configurations, including in a fingertip style for compact, difficult-to-access areas.

Inspectors often use contact transducers for many applications, such as:

  • Straight beam flaw detection

  • Thickness gaging

  • Detecting and sizing delaminations

  • Inspecting plates, billets, bars, and other metallic and nonmetallic components

  • Velocity measurements

Angle Beam Transducers

Similar to contact transducers, angle beam transducers are also defined as single element transducers. Such devices are typically used with a removable wedge to introduce a refracted shear wave or longitudinal wave into a test piece as well as sound at an angle into the part. Inspectors typically implement angle beam transducers into their applications to test weld integrity as weld inspection requires that sound waves are aimed at an angle.

Other common uses for such transducers include flaw detection and crack sizing techniques. Keep in mind that wedges come in a variety of sizes to meet certain specifications. For example, some wedges provide a shorter approach distance while others are better-suited for high temperature applications. Additionally, wedges can be customized to create nonstandard refracted angles and contours.

Delay Line Transducers

This type of transducer is a single element transducer that finds use with a replaceable delay line. It works by introducing a time delay between the generation of the sound wave and the arrival of the reflected waves, improving the near-surface resolution in the process. It is important to note that higher transducer frequencies are ideal for inspecting and measuring thin materials as well as for locating small flaws when using the direct contact method.

With a replaceable delay line design, this transducer serves countless applications including:

  • Precision thickness gaging

  • Flaw detection of thin materials

  • Inspecting parts with limited contact areas

  • High-temperature applications

Immersion Transducers

Immersion transducers are the last single element variety with the exception that this type is designed to operate in water. Also, they do not make direct contact with a test piece. Instead, they utilize a column or bath of water to couple sound energy into a material.

This immersion technique creates uniform, fast coupling that enables inspectors to rapidly scan parts. Moreover, inspectors can select focused transducers to increase sensitivity and enhance performance in a specific section of a part. Often used for in-line or in-process tests on moving parts, automated scanning, and optimizing sound coupling into sharp radiuses, grooves, or channels in test pieces with complex geometry, immersion transducers serve a diverse set of operations.

Other applications include:

  • In-line thickness gaging

  • High-speed flaw detection

  • Time-of-flight and amplitude-based imaging

  • Material analysis and velocity measurements

  • Through-transmission testing


If you find yourself in need of transducers, transmitters, capacitors, PCBs, or other specialized devices, rely on Aviation Purchasing Platform. Aviation Purchasing Platform is a premier distributor of NSN products, aviation parts, civil aviation resources, and more. With over 2 billion parts on our database, customers can find exactly what they need with ease. Kickoff the purchasing process with a quote request, and let Aviation Purchasing Platform simplify part procurement for you.


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