Hardness testing

Hardness Testing: Best Practices and Techniques

Ted Stroud
QA / QC United Kingdom, Joined Jul, 2

For reliable and efficient hardness testing, industry professionals often seek advice and shared experiences from peers. In a recent forum discussion, Ted Stroud initiated a conversation about implementing in-house raw material hardness testing using the Foundrax Model 134 Portable Brinell Hardness Tester. With specifications allowing an average raw bar diameter of around 8”-10” and lengths of approximately 12”-20”, Ted specified a procedural requirement of performing four test points at each end of the materials being tested.

As a newcomer to this field, Ted expressed a need for guidance on best practices for setting up the hardness testing process. Currently, he positions the hardness tester on its side, utilizing V blocks to support the testing material while rolling it into the tester's throat at floor level. He is seeking inspiration to enhance the safety and efficiency of this process. Suggestions from the community are welcome and greatly appreciated.

Nigel Armstrong responded to Ted's inquiry with valuable insights about alternative hardness testing equipment. Noting he has no experience with the Foundrax model, he suggested that machines such as the MicroDur, MIC 10, or Equotip might be more suitable for testing solid bars. These options use rebound dynamics and feature a cable-connected probe, allowing users to maneuver the probe easily while contributing to various hardness scales electronically. Nigel encouraged Ted to explore GE Instruments’ offerings for further insights.

Vicky, an NDT Inspector from India, strongly echoed Nigel’s recommendation, affirming that rebound-type hardness testers like Equotip are effective for achieving point measurements, making them ideally suited for Ted’s specific testing needs. However, Michael Lewis, an NDT Inspector and Quality Manager in the USA, raised a word of caution. He highlighted that many OEMs do not recognize rebound testers as valid for final inspection but will permit their use for sorting tests. He advised Ted to check if setting his hardness tester "on its side" complies with the applicable standards, as this configuration might not be permissible.

Noting that physical ergonomics is a critical factor in the testing process, Michael suggested using pipe racks combined with an adjustable office chair to alleviate physical strain and enhance testing ergonomics. This approach would allow the hardness tester to wheel around the testing setup rather than require manual rolling of the materials.

Even as new ideas emerged in the conversation, Nigel emphasized the importance of adhering to testing standards, particularly ASTM specification A-956. He urged Ted to ensure that if he correctly demonstrates compliance with the outlined specifications, it would diminish the risk of users rejecting the use of rebound testers for hard material applications.

In closing, the community consensus advocates for exploring various hardness testing solutions. Ted thanked everyone for their valuable feedback and confirmed that his facility currently utilizes an EQUOTIP device for comparisons of results achieved in the hardness-testing arena.

For additional guidance or to explore Ultrasonic Hardness Testers, please feel free to reach out for more information.