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Dissolving Aluminum

  1. Jan 23, 2015 #1
    I have a few spiral drills that are 3.3 mm diameter and have 2 tiny holes that are supposed to allow coolant to flow through the tool. Unfortunately they got clogged with chips of aluminum.
    I was wondering if there was a way to dissolve the aluminum out of the holes.
    I was told muriatic acid would work but over here we're machinists, not chemists, so I wouldn't know.
    Any help in saving these 200 dollar tools would be much appreciated.
     
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  3. Jan 23, 2015 #2

    mfb

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    What is the material of the spiral drills?
     
  4. Jan 23, 2015 #3

    Bystander

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    Boil them in a solution of baking or washing soda.
     
  5. Jan 23, 2015 #4
    They are made completely of carbide.
     
  6. Feb 2, 2015 #5

    NascentOxygen

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    That being tungsten carbide?

    Did you try the hot soda solution? I'm not confident it will work.
     
    Last edited: Feb 2, 2015
  7. Feb 3, 2015 #6

    Lok

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    I don't know about baking soda, could be slow or impractical.
    But NaOH will dissolve aluminum easily if you can get the solution to flow through your coolant ports.

    As with all DIY chemical stuff don't' boil your everyday corrosive agents on your stove. Pour some mildly hot water in a plastic vessel dunk your drills, ad a 1/4 teaspoon of sodium hydroxide (slowly) and leave overnight. Handle the drills with plastic instruments, rinse them nicely and finally kill your caustic soda solution with a shot of vinegar before disposal.
     
  8. Feb 3, 2015 #7
    Do you have a suggestion of a place to pick up some sodium hydroxide? Or a place to order any?
     
  9. Feb 3, 2015 #8
    I think it is tungsten carbide but I don't know for sure.
     
  10. Feb 3, 2015 #9

    Quantum Defect

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    Many granulated drain openers have this as the main ingredient. You can buy sodium hydroxide online, as well. People use it for making hand-made soap. It is probably cheaper to buy the drain opener.
     
  11. Feb 3, 2015 #10

    NascentOxygen

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    Caustic soda (NaOH crystals) is often sold in supermarkets, in the cleaners section. Also hardware stores. "Draino" is one source, but check ingredients list.

    I would try it in warm water, leave drill soaking for a day or two. Check at intervals to make sure it does not affect the drill coating.
     
  12. Feb 3, 2015 #11
    Thanks for the help, I'll definitely try this in the next couple of days.
     
  13. Feb 3, 2015 #12
    I seem to recall a product (likely recalled) that had NaOH (Lye) and bits of aluminum to create a self-heating reaction in a drain cleaner. I believe it puts off hydrogen during the process, so you probably want to keep it slow, or have ventilation (ignites with a 10% - 90% fuel-air mix)
    I've used dilute solutions on finished aluminum to etch it...
    Be careful with the stuff though. It's subtle and evil at getting to your skin and tiny drops seem to get everywhere when pouring. If it gets on you, you'll usually know because you have slippery skin (yep,that's you becoming soap), irritation, or outright burning. You have to wash like a maniac to get the slippery feeling to go away.
    Goggles are mandatory, long gloves a good idea. Neutralize it with dilute HCL (muratic acid) or vinegar before doing anything else with the left overs. If you see gooey slime, that's probably just aluminum hydroxide.
     
  14. Feb 4, 2015 #13

    Lok

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    True in that it does give of hydrogen. But just to ease Zach's mind. It is not a lot of aluminum in those drills (they are small) so not much hydrogen will be generated. And the port holes are small so the reaction will be retarded by the fact that the NaOH will have a hard time reaching the aluminum.
    The stuff is corrosive but, as I've seen above you will probably use the diluted version of some drain cleaner (the best choice :)), so it will be able to burn but not be that dangerous.The necessary quantity of drain cleaner is hard to estimate in this case.

    But safety first. Also you have the Al + NaOH reaction in the same section
    http://en.wikipedia.org/wiki/Sodium_hydroxide#Safety
     
  15. Feb 4, 2015 #14

    NascentOxygen

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    It goes without saying, but .....

    Probably best to remove any oil coating by first washing the drill bits in warm water with detergent. Rinse well before adding to the caustic soda solution.
     
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