Where to purchase laboratory samples?

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Discussion Overview

The discussion revolves around sourcing laboratory samples for mechanical testing, specifically Charpy impact test samples and standard tensile test samples. Participants explore recommendations for reliable suppliers and alternatives for creating their own specimens.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks recommendations for reliable sources to purchase laboratory samples for mechanical testing.
  • Another participant suggests a specific calibration source and mentions that operators should ideally make their own specimens for training purposes.
  • Some participants propose that low-cost tensile test specimens can be created using lengths of threaded rod with a turned down section, while Charpy specimens can be made from lengths of flat stock notched with a hack saw.
  • Concerns are raised about the challenges of obtaining good tensile specimens, emphasizing the importance of low surface stress machining and the need for machinists to understand material testing requirements.
  • Anecdotal evidence is shared about one participant's experience making better tensile specimens than those produced by a department machinist.

Areas of Agreement / Disagreement

Participants express differing views on whether to purchase samples or create them in-house, with some advocating for self-manufacturing while others suggest sourcing from suppliers. No consensus is reached on the best approach.

Contextual Notes

Participants highlight the importance of machining techniques and the background knowledge of machinists in producing quality specimens, indicating that there may be specific requirements that need to be addressed during the machining process.

mfig
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Hello,

I am looking to purchase laboratory samples for mechanical testing. For example, Charpy impact test samples and standard tensile test samples. Does anyone have a recommendation for a reliable source?

Thanks
 
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You need to make your own. If you only need low cost tensile test specimens to train operators, you can use lengths of threaded rod with a turned down section in the middle. Similarly, low cost Charpy specimens can be lengths of flat stock notched with a hack saw.

Getting good tensile specimens for material testing can be a challenge because few machinists understand the need for low surface stress machining of the necked region. If the specimens are made by a machinist that does not have a solid background in material testing, it's a very good idea to personally observe the machining process. If the specimens are made on a CNC lathe, discuss low surface stress, depth of cut, feed rate, and sharpness of tool with the machinist.

I once made some money as an undergrad when I showed that I could make better tensile specimens than the ME department machinist. On a manual lathe.
 
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