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  • Casting porosity

    Discussion in 'Metal casting & moulding' started by admin, Jul 30, 2009.

    1. admin

      admin Administrator Staff Member

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      Does anybody know anything about casting porosity? Is there a specification that can be put on engineering drawings?

      Thanks in advance.
       
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    3. joggies

      joggies Member

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      Hi

      only thing i have ever seen is ( as a note ) " Casting to be free from any defect/porosity " and ( as a specific section note ) " Critical area to be free from any defect/porosity "
       
    4. nj6za

      nj6za New Member

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      Hi Gary,

      There are no specifications for casting porosity in drawings usually-except as joggies mentioned. However if you do a casting simulation you can set limits for porosity levels usually around 5 % to see the location of the porosities (also depends on the components and application areas). You will also see that if you do x rays (or none destructive tests) of your real components you will see one often talk about level of defects which might be related to the percentage of porosity of your component.

      Hope it helps..
      cheers
      Navin
       
    5. mvalenti

      mvalenti Well-Known Member

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      Castings are pourous by nature due to the sand grain like structure. Typically you would call out something like voids and inclusions of "blah blah" size not permitted... There are secondary options to furthur densify the outer surfaces. You would look into someone who does Isostatic Pressing. Golf Club heads are often done this way as well as turbine blades. This would not remove any surface voids however. There is a company that will inject a casting, under vaccuum I believe with some ceramic powders that is suppose to fill the voids. I saw this pon a motorcycle show where the guys designed and built thier own engine, actually whole bike... The name escapes me though. Good Luck!


      -Mark
       
    6. When discussing porosity in sand castings,one needs first decide on which or what defect your talking about,there is a number of items that cause "porosity".Surface defects or internal is it non-metalic inclusions such as sand and or dross, or gas porosity like hydrogen or blow holes. Goes on for a while like this. But there is a chart ( 2 actually) for determining limits on hyrdrogen inside aluminum castings. One chart is used in X-rays exam,the other is used for vacum testing.
       

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