Machining 6061-O
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    Default Machining 6061-O

    Are there any recommendations on how to machine soft aluminum without lubricant, specifically 6061-O? What are the recommended methods?

    Found this post, but it's from 10 years ago, and maybe the cutting tool technology has changed since then: Cutting soft aluminum

    Would PCD tools be the way to go still?

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    Quote Originally Posted by ihopeitworks View Post
    Are there any recommendations on how to machine soft aluminum without lubricant, specifically 6061-O? What are the recommended methods?

    Found this post, but it's from 10 years ago, and maybe the cutting tool technology has changed since then: Cutting soft aluminum

    Would PCD tools be the way to go still?
    never used pcd, hss mills and drills it tends to stick to. getting ones made for aluminum helps, extra sharp and smoother polished flutes. got to watch drilling. anytime heat builds up and chips cant get out they can stick. needing a hammer and screwdriver to get chips stuck out of flutes is annoying obviously got to avoid heat buildup
    .
    some use high rpm and extremely light feed to let the air in and avoid heat build up. circular carbide tipped saws using extremely high sfpm and extremely low ipt feed work that way. still can cut extremely fast.
    .
    either way without coolant part can easily expand and contract with temp changes and tight tolerance going to be difficult

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    I guess why 0 condition and why no lube?
    I would want to find a way around either

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    Castings maybe, or a short-run custom extrusion?

    Anyway, it has been, IME, darn hard to get a consistently clean cut in 6061 without some lube, even a dab of WD40.

    Regards.

    Mike

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    Quote Originally Posted by DMF_TomB View Post
    never used pcd, hss mills and drills it tends to stick to. getting ones made for aluminum helps, extra sharp and smoother polished flutes. got to watch drilling. anytime heat builds up and chips cant get out they can stick. needing a hammer and screwdriver to get chips stuck out of flutes is annoying obviously got to avoid heat buildup
    .
    some use high rpm and extremely light feed to let the air in and avoid heat build up. circular carbide tipped saws using extremely high sfpm and extremely low ipt feed work that way. still can cut extremely fast.
    .
    either way without coolant part can easily expand and contract with temp changes and tight tolerance going to be difficult
    We won't need to do any drilling operations, just cutting with 1/8" - 1/4" end mills.

    Quote Originally Posted by gustafson View Post
    I guess why 0 condition and why no lube?
    I would want to find a way around either
    It's a special R&D application. So unfortunately these two constraints are stuck.

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    Can you get a coating on the endmill that the soft aluminum wont want to stick to as much? Not sure what coating that would be since I dont do to much of that.

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    Quote Originally Posted by Rob F. View Post
    Can you get a coating on the endmill that the soft aluminum wont want to stick to as much? Not sure what coating that would be since I dont do to much of that.
    You could try ZrN or TIB2, might help with dry cutting. If it is for a casting and you are worried about the porosity, there are ways to 'fix' that.

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    I used to have to machine condition zero aluminum (similar R&D process). I found it virtually impossible to not load up endmill without generous amounts of cutting oil. Even soluble flood coolant would load up on many operations. This was years ago. Today, I would use an air-blast and use high speed machining toolpaths that use a small radial depth of cut and a large axial depth of cut. If you try and plunge an endmill or do any sort of slotting, you'll probably load up the endmill. Just to give yourself a fighting chance, use a 2 flute endmill with the largest gullet possible. And talk to the engineer, he should be easy to intimidate since he just got out of school two weeks ago. There are many ways to clean or etch aluminum and it is easy to anneal back to a very soft condition.

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    High pressure air blast is gonna be your best bet.
    Unfortunately 0 condition aluminum is like cutting bubble gum. I don't envy you.

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    Quote Originally Posted by ihopeitworks View Post
    We won't need to do any drilling operations, just cutting with 1/8" - 1/4" end mills.



    It's a special R&D application. So unfortunately these two constraints are stuck.
    So, you don't know the answer?

    Seriously, I don't let anyone tell me how to machine anything without a really good reason, 'because I said so' is not a good reason.

    You cannot put water on it?

    Is it part of an assembly ?

    You will not get useful advise without lots of details

    Keep the spindle speed and feed down, less heat less melting,

    New sharp tools, low depth of cut, low stepover


    [shrug] there is no magic.

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    Alcohol mist spray (with care, need ventilation and fire extinguisher at hand), while it sounds iffy I did a lot of aerospace Al parts using this method. Never a fire, it's harder to ignite than you think.

    You can also look into cold air generators, Co2 sprays, and single flute (router style) endmills, which are much less likely to load up. They're also more fragile, so you have to adjust feeds to suit.

    And keep in mind that many milling spindles spit out a little lubricating oil during use, so you may have to clean the parts carefully afterwards anyway. If so, just factor in a proper cleaning process after using a real coolant.

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    Quote Originally Posted by gustafson View Post
    So, you don't know the answer?

    Seriously, I don't let anyone tell me how to machine anything without a really good reason, 'because I said so' is not a good reason.

    You cannot put water on it?

    Is it part of an assembly ?

    You will not get useful advise without lots of details

    Keep the spindle speed and feed down, less heat less melting,

    New sharp tools, low depth of cut, low stepover


    [shrug] there is no magic.
    I apologize for the lack of info. The application has IP so I'm unable to provide more information. The environment that this will be in does not allow for any fluids to be used.

    I think the best form may be using high pressure air.

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    Dip it in liquid nitrogen for a bit then machine it leaving 15k or so...let it warm back up and do a finish pass. Just a thought lol

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    Quote Originally Posted by ihopeitworks View Post
    ......The environment that this will be in does not allow for any fluids to be used........
    I think what is really being said is that the designer doesn't know what cleaning process will get any residual oils off the part so is specifying no fluid as a requirement.

    Once the parts are done, a dip in agitated caustic followed by a couple rinses in RO water and heated air dryer. That will give you a water-break free clean surface. Nothing there but aluminum. If there are really tight tolerance details you may have to allow for the slight amount of aluminum that will be removed in the caustic.

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    Quote Originally Posted by Vancbiker View Post
    I think what is really being said is that the designer doesn't know what cleaning process will get any residual oils off the part so is specifying no fluid as a requirement.

    Once the parts are done, a dip in agitated caustic followed by a couple rinses in RO water and heated air dryer. That will give you a water-break free clean surface. Nothing there but aluminum. If there are really tight tolerance details you may have to allow for the slight amount of aluminum that will be removed in the caustic.
    It's rather, the environment where this is being machined does not allow for any sort of lubricants to be used. The environment is not a typical machine shop. The finished part will not receive any post processing and will be used as is straight from the machine.

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    Quote Originally Posted by ihopeitworks View Post
    It's rather, the environment where this is being machined does not allow for any sort of lubricants to be used. The environment is not a typical machine shop. The finished part will not receive any post processing and will be used as is straight from the machine.
    So you have a CNC machine tool that does not use a variety of lubricants for its own operation in this lube free envirionment?

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    If this is the case (been there done that, but it involved leaded glass and much heavier materials), then you will need to think outside the box. First, why condition zero material. Is this a requirement or is it a function of the part being annealed during the process. Go to T6 and most of these issues go away.

    This is actually an interesting application for using supercritical CO2 as a cutting fluid. It would be a liquid free cutting application that will keep the part and cutter very cold and provide a modicum of lubrication at the cutting edge. This is a reasonably esoteric process, but it involves using very high pressure CO2 in a through coolant like mode. It will put a jet of supercritical fluid onto the actual cutting edge and cool it with Joule Thompson cooling. In addition, even the neat fluid will have some lubrication properties. The SCCO2 will actually clean the part as you machine and then sublimate into the atmosphere.

    Back when I was young and idealistic, I did my graduate degree in supercritical fluids. Fascinating stuff, but I was more interesting in making parts that sitting in a lab... followed the blue collar dream

    Supercritical Carbon Dioxide | Fusion Coolant Systems

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    Quote Originally Posted by ihopeitworks View Post
    It's rather, the environment where this is being machined does not allow for any sort of lubricants to be used. The environment is not a typical machine shop. The finished part will not receive any post processing and will be used as is straight from the machine.
    Pure speculation, but he might be in an "environment" that has completely asinine restrictions trying to maintain some stupid ridiculous EHS 'specs'. I worked at a place like that, the cnc machines with flood coolant were required to be mounted on/in a giant (2x tank capacity) pan in case any coolant leaked it would not go down a drain or anything.


    Quote Originally Posted by Vancbiker View Post
    So you have a CNC machine tool that does not use a variety of lubricants for its own operation in this lube free envirionment?
    Good point! No waylube, no grease packs...

    Ok, back to OP question. You could try a cold air gun too, but it might condense and spray a bit of water vapor...?


    https://www.mscdirect.com/product/details/77314375


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