Nodularity Inspection of Ductile Cast Iron Automotive Components

As the use of nodular graphite iron material has expanded in recent years for automotive safety parts, ultrasonic velocity measurement is providing a reliable, industry accepted means of verifying material integrity.

Unacceptable degrees or variations in Nodularity, a type of graphite structure than can develop during the production process, can attenuate the velocity of sound waves passing through the material.

The Echomac® VM, measures this sound velocity, and using known limits, reports whether the part is acceptable.

About Nodular Cast Iron:

  • When graphite takes the form of spherical nodules, the result is nodular cast iron.
  • Nodular cast iron is softer and more malleable than gray cast iron.
  • The relative high strength and toughness of nodular cast iron provides advantages in many structural applications including automotive crankshafts, pistons and cylinder heads.
  • Microscopic examination and tensile strength tests are effective for checking nodularity, but they take time and are destructive.
  • The Echomac® VM is a simple, effective instrument that measures velocity to assess nodularity in ductile iron cast automotive components.


For Flaw Detection, Thickness & Dimensional Measurement
in Tube & Bar

  • Versatile Ultrasonic tester with superior performance and versatile, intuitive operation.
  • For full inspection of tubes, pipes and bars, plate and weld.
  • Operate on or off line
  • Upgrade and/or replace older ultrasonic testers
  • Use with rotary, spin-the-tube, squirter and bubbler installations.


High-speed Ultrasonic (UT) Systems enable a full volumetric examination of materials and are designed to detect surface, subsurface, internal and dimensional flaws.

This type of testing utilizes high-frequency sound waves that are transmitted throughout the material being tested in order to conduct a thorough inspection.

  • An ultrasonic wave is a mechanical vibration or pressure wave similar to audible sound, but with a much higher vibration frequency. For NDT purposes, the range is usually from 1MHz to 30MHz or higher.
  • Depending on the test requirements, these waves can be highly directional and focused on a small spot or thin line, or limited to a very short duration.
  • Two methods of UT are used for flaw detection – Shear and Compression Wave.