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  1. #1
    Cheenist is offline Hot Rolled
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    Feb 2004
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    Alexandria Va. USA
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    I make some super precision aluminum hinges for an aerospace customer. He is asking for a better finish on a .251 ID. The parts are currently reamed. The ID tolerance is +-.0002. I have talked to several companies about roller burnishing. Anyone have any experience with roller burnishing aluminum? Cogsdill claim’s an incredible micro finish and is actually sending out a tool (worth $500.00) to try!
    Thanks,
    Carl

  2. #2
    toolmakerjim is offline Titanium
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    Jun 2004
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    titusville fl. usa
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    super finish and very tight tolerance once you get dialed in. have done this on f-16 oil pump housings and was able to hold microns...jim

  3. #3
    bspooh's Avatar
    bspooh is offline Cast Iron
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    Jun 2002
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    Salt Lake City, Utah USA
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    313

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    Yeah, i have a couple of roller burnishing tools..I have done hundreds and hundreds of hydraulic cylinders with the burnishing tool..It is a cogsdill..I was burnishing to a finish diameter of 1.125" in 1144 steel..works great, except after a 100 parts i had to send it back to get rebuilt..Maybe I wasn't using it efficiently, I don't know, but they are great..

    My only problem was that i was getting too fine of a finish for a cylinder, so I would have to hone it out a little to try and get it down to a 16 finish..I quit using it, and now I just bore the cylinders out...I bought this tool because my situation was boring 1.125" by 5.375" deep..this is quite the "overhang ratio", boring would chatter so I started burnishing..But now I have found a better way to bore the cylinder out so i don't have to use the burnishing tool anymore..

    brent

  4. #4
    JRIowa's Avatar
    JRIowa is offline Diamond
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    May 2003
    Location
    Marshalltown, Iowa, USA
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    I bet if I went out in the plant and found them all, we'd have 100 roller burnisher.

    If we have something besides Cogsdill, somebody would have to show it to me. We just bought 2 new machines to do shafting to a 4 finish in Nitronic 50.

    If you follow Codsdill's instructions, the burnishers will do what they say. Surface finish and diameter before burnishing have to be within a certain range. Aluminum should be easy.

    If you need help, Cogsdills got some really good regional people that know their stuff. Ours is Steve Evans.

    JR

  5. #5
    Ox's Avatar
    Ox
    Ox is online now Diamond
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    Aug 2002
    Location
    West Unity, Ohio
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    17,901

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    Cogsdill here.


    Think Snow Eh!
    Ox

  6. #6
    ObsoleteTom is offline Cast Iron
    Join Date
    Mar 2001
    Location
    Marlette, MI USA
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    441

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    I've used Cogsdill tools to burnish a shoulder with excellent results. Just make sure you don't let the tool sit and dwell-keep it moving at a good feed rate and get it back out quickly. The tool is cheap for what it does.
    Regards,
    Tom

  7. #7
    E-Stop is offline Cast Iron
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    May 2002
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    Ohio
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    Used to do alot of printing press frames and always roller burnished the bearing bores for the press rollers. These ranged anywhere from 3.50 inches to 7.00 inches in diameter and we held tolerences to +0 / -.0002 with a mirror finish with no problems.

    And, yes, they were Cogsdill Tools.

  8. #8
    toolsxp is offline Junior Member
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    Oct 2005
    Location
    coimbatore
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    6

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    I have found Burnishng tools very useful. You can save atleast 30% less cost by getting Burnishing Tools here. [img]smile.gif[/img]

  9. #9
    Maverickmachinist is offline Cast Iron
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    Mar 2005
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    traveling US
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    I have never tried it in Aluminum. But I used to do a high production burnishing job in 4140, 500-1200 pc. I found the trick to getting the best results was to tweak the boring bar so it was taking out exactly enough material at exactly the right feed. If there was to much stock in the bore the burnisher would get overloaded and chatter. Too little stock in the bore and burnisher couldn't eliminate the finish from the boring bar. The problem is that a machined surface is like a very fine saw blade, it has peaks and valleys. The burnisher forces the peaks down into the surface. But if there isn't enough stock removed from the bore the burnisher is left with to much stock to work with. The peaks are to big for it and it gets overloaded and leaves a bad finish. And if there is to much stock removed from the bore the burnisher doesn't have enough material to force down into the valleys. This leaves lines from the boring bar. I found that for a half inch hole the burnisher worked best only having to burnish .002-.003. Plus I found that your boring bar needed to have a very good edge on it and set at a very nuetral feed. The better the finish of the bore before you burnish it, the better the finish the burnisher can leave. Plus put plenty of coolant in the bore, this with help a lot with chatter and the wearing of the burnisher rollers. Hope this helps it worked for me.

  10. #10
    ObsoleteTom is offline Cast Iron
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    Mar 2001
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    Marlette, MI USA
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    I've used Cogsdill tools. They will design for your job. Works sweet and price is reasonable. The only issue I've heard of was with burnishing aluminum on screw machines where other operations were being done. The oil had to be changed periodically as aluminum particles would become suspended in it and degrade the quality of the burnished surface.
    Regards,
    Tom

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