Rough Casting

Discussion in 'Sand Casting' started by Greg, Sep 16, 2018.

  1. Greg

    Greg Copper

    I have made green sand moods
    The sand is sieved using a fine sieve and the kitty litter is also sieved and adding water.
    When casting Alliminum the item when removed from the sand the casting is rough.
    What can I do to make the casting smooth.
     
  2. Can you post some photos of the casting, what kind of aluminium alloy did you use?.
     
  3. crazybillybob

    crazybillybob Silver Banner Member

    Without pictures it's all guessing. But course sand, or too much moisture will give the casting a rough texture. Normally it will still be shiny in these cases. If it's cloudy you might be getting oxide in your casting.(too much air in the furnace).
     
  4. Greg

    Greg Copper

    I will post a photo as when I attempt my next casting.
     
  5. nel2lar

    nel2lar Lead

    Greg
    I have used graphite and alcohol. Put it in a spray bottle and spray your cope and drag when finished spraying use a torch to lite off the alcohol. The graphite will not hurt your sand and give you a nice finish.
    Nelson
     
  6. Greg

    Greg Copper

    Thank you.
    I will try that as that is my problem
     
  7. oldironfarmer

    oldironfarmer Silver Banner Member

    And if the aluminum is too hot you'll get a rough surface. It should not be red when you pour.
     
  8. Greg

    Greg Copper

    What is the desired temperature of the alloy for casting
     
  9. Khalid

    Khalid Copper

    Greg,
    Coating of green sand with graphite (acidic nature) is right approach, to have better surface finish.
    You can use fine zircon powder (acidic nature).
    Aluminium is acidic in nature. It reacts with coating material (if its basic), leads to rough surface finish.
     
  10. oldironfarmer

    oldironfarmer Silver Banner Member

    Most aluminums should be poured above 1,200F, but each alloy has an ideal temperature. If you have an unknown alloy start with 1,250F to 1,350F.
     
  11. Greg

    Greg Copper

    Thank you
     

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