Published on 05-Jun-2024

What are the Different Types of Ultrasonic Transducers?

What are the Different Types of Ultrasonic Transducers?

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Ultrasonic transducers play a pivotal role in Non-destructive Testing by utilizing high-frequency sound waves to assess critical parameters. These indispensable devices find applications across various industries, including flaw detection, thickness measurement, and weld inspection. Given the diversity of Ultrasonic Testing transducers available, selecting the right one for a specific application can be a daunting task. 

Understanding Various Types of Transducers

Ultrasonic transducers are categorised based on their operating frequency, size, and application. Common types include contact transducers, immersion transducers, and phased array transducers. Each type has specific advantages and limitations, depending on the inspection requirements. Let's delve into five common types of industrial ultrasonic transducers for industrial purposes.

1. Dual Element Transducers - Enhancing Precision with Dual Element Transducers


The dual-element transducer, as the name suggests, consists of two crystal elements enclosed within a single housing, with an acoustic barrier separating them. One of these elements generates sound waves, while the other acts as a receiver. The innovative design of dual-element transducers leads to a V-shaped sound path within the test material, as the two elements are angled towards each other. This arrangement results in a pseudo-focus effect, significantly enhancing resolution in the focal zone.

When examining components with rough back wall surfaces, the pseudo-focus effect's increased sensitivity proves to be particularly useful. As a result, these transducers have become the industry standard for measuring remaining wall thickness in Corrosion-related applications. However, their utility extends beyond this, encompassing:

  • Weld overlay and cladding bond/disband inspection
  • Detection of porosity, inclusions, cracks, and laminations in castings and forgings
  • Crack detection in bolts and other cylindrical objects
  • High-temperature applications

2. Contact Transducers -Direct Contact Inspections Made Easy with Contact Transducers


As the name suggests, contact transducers are tailored for direct-contact inspections. These single-element transducers boast a wear-resistant surface optimized for contact with most metals, rendering them robust and durable for use in rugged industrial environments. Contact transducers come in various styles and configurations, including fingertip variations designed for challenging-to-access areas.

These versatile devices find applications in:

  • Straight beam flaw detection
  • Thickness measurement
  • Detecting and sizing delaminations
  • Inspecting plates, billets, bars, and other metallic and non-metallic components
  • Velocity measurements

3. Angle Beam Transducers - Testing Weld Integrity with Angle Beam Transducers


Angle beam transducers are single-element types of transducers that work with a wedge to send either a refracted shear wave or a longitudinal wave into the test piece. The wedge, whether removable or integral, introduces sound at an angle into the part being inspected. Inspectors frequently employ angle beam transducers in Weld Integrity Testing, as this particular inspection requires directing sound waves at an angle. Wedges are available in a multitude of sizes to cater to specific requirements. Some offer shorter approach distances, while others are tailored for high-temperature applications. Select wedges can even be customized to create nonstandard refracted angles and contours.

Key Applications include: 

4. Delay Line Transducers - Enhancing Near-Surface Resolution with Delay Line Transducers