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  • Aluminium suface finish

    Discussion in 'Surface finishes' started by valgamaa, Sep 20, 2011.

    1. valgamaa

      valgamaa Member

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      Hi,
      I have had a number of small aluminium panels cut for a music synthesiser I am making, and would like some advice on how to finish them. They are all 2mm thick aluminium, roughly 5 inches long and an inch wide with holes cut in them for potentiometers. They were cut by laser, and have some surface marks both from the cutting and specks of aluminium rubbing against them when they were in transit. I would like to have these panels anodised, but they need preparing before I can do this.
      So to my question: I have been hand-finishing each panel, but this very slow, and it has been suggested to me that they could be finished using a tumbler. Is this a practical option to both de-burr and remove the surface scratches, while giving a polished surface that would look good after anodising? If this is practical, can anyone suggest a company that could do this at reasonable cost, preferably in the Cambridge, UK area?

      Thanks in advance of any advice you may be able to give,

      Phil.
       
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    3. johntargell

      johntargell Member

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      Hi Valgamaa - the easiest way of getting a good even finish would be to fine grit blast the panels and then anodise them, but the parts would have a matt finish. If you really need a polished finish after anodising I would ask the anodiser to electropolish the grit-blasted parts before anodising them.

      Cheers John ( ex Cambridge!)
       
    4. mvalenti

      mvalenti Well-Known Member

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      Try....
      Enkay Aluminum Polishing Kit, Model 142
       
    5. valgamaa

      valgamaa Member

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      Thanks for the suggestions - grit blasting sounds like an option as I don't need a highly polished finish. My primary interest is to remove the scratches, while having a surface that will look good after anodising. I have added a picture of the panels with a Schroff one next to them. This is the sort of finish I want, but as you can see they need some work. I have 100 of each of these panels, so if there is an automated option that doesn't need much human intervention that would be my preferred choice.
      The interest in local companies is due to the weight of these panels.
      Edit: I'm unable to add a picture to this post, so will put it on my website and add a url tomorrow.
       
    6. mvalenti

      mvalenti Well-Known Member

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      scotchbrite pad will remove scratches. rub in a linear fashion rather than circular.
       
    7. stewlenox

      stewlenox Active Member

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      Mvalenti is right about Scotchbrite. I'd add that 3m sells both belts and wheels made of scotchbrite that fit standard shop machinery.
       
    8. mvalenti

      mvalenti Well-Known Member

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      heck I get the pads and lay em under my orbital sander or a block of wood. Pick em up at the doller store.
       
    9. adglew

      adglew New Member

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      You might consider a "brushed" aluminum finish, before anodizing. The brushing essentially involves putting scratches in the surface linearly, all in one direction. This tends to hide or remove current scratches and tooling marks, obscure future scratches, and hide finger prints. One often sees brushed aluminum on rack mount equipment. One can also buy pre-made rack panels, and then just drill them.

      One can buy brushed aluminum sheets, or brush it after the fact. The anodizing shop will generally be able to provide this service, or it can be performed with some simple fixtures and sand paper. The linear brushing should be performed before anodizing.


      Regards,

      Alexander D. Glew, Ph.D., P.E.
      Glew Engineering Consulting Inc.
      240 Pamela Dr.
      Mountain View, CA 94040-3204
      800 877 5892 main
      650 292 2210 fax
      adglew@glewengineering.com

      http://www.glew.com
      http://www.facebook.com/GlewEngineering
      http://twitter.com/glewengineering
       
    10. GarethW

      GarethW Chief Clicker Staff Member

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      I think this is also refered to as "graining". It's a nice, cheap, simple process that disguises minor surface defects effectively. definitely a good option.
       
    11. valgamaa

      valgamaa Member

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      Thanks all for your comments, as a non-mechanical engineer I know how to work with 1-off quantities by hand, but the quantity of panels (300 in total) is beyond that. As a result I want to find a way to get the panels processed commercially in a cost-effective way (this is for a hobby) and I didn't know the options or the terminology.
      I have put a picture of the panels, along with a Schroff blank that I have used in the past here http://www.liivatera.com/temporary/Panels.jpg. It's a little blurred, but the brushed finish looks like a good option to match the Schroff finish.
      I had started using Garryson Garryflex abrasive blocks, but it was taking about 30 mins to finish each panel - will Scotchbrite be faster than this? I should point-out that I don't have any workshop facilities, which is why I was looking for a company to do this. Unfortunately the company that does the anodising doesn't do any preparation other than degreasing etc due to space constraints.
      Thanks again for the suggestions, I certainly have several options to persue.
       

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