Deburring of small machined extrusions...HELP!!!
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  1. #1
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    We have an ongoing job that is machining of extrusions. THe qty. is normally 100-200 pcs. at a time, twice a year. The material is a small aluminum extrusion with LOTS of small cavities. "It" is a 1.3" cube. It has like 20 cavities. Simular to 80/20, or Item extruded products.

    My problem is deburring.
    I have tried tumbling, sandblasting, abrasive brushes, & so called vapor honing ect... The only way to make sure all of the burrs are gone is to do it by hand. That is too time consuming.

    This is the process:
    saw chop to ruff length
    use a 3/4 endmill to cut across the bottom and make it square ***
    insert the newly squared bottom side down and machine the top of the extrusion with a 1/2 endmill, a 1/8 endill, and a woodruff key mill to leave more pockets, and slots****


    *** indicates operations that creat burrs

    Then we deburr :mad:

    Then insert on the top side, and drill/tap 3ea. 3mm holes.

    The reason for the drill tap AFTER the deburr, is in case we have to bead blast. (you don't want beads in a fine pitch thread)

    I have tried everything I can think of to automate deburring.

    The problem with tumbling is the media.
    Even the smallest of media is TOO BIG to get into all the nooks and crannys. What is does do, is get stuck in the same nooks and crannys. Then we have to hand pick w/ needle nose pliers all of the media out.

    My bead blaster does not have the umph to do it. So I tried sending it out to a comercial sandblasting company. They used an automatic sandblasting thing...
    Well the product WAS better, but we still had to go back and remove lots of leftover burrs.

    Can anybody help with anymore ideas.
    I have heard of "flash deburring" but cannot locate anybody to try it.
    Thanks for ANY help you can give.
    Doug.

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    I think flash deburring involves subjecting the part to intense heat very quickly -- enough to burn off the burrs, but not hurt the parent metal. Never used it myself. How about a trial with a hand torch, locally applied?

    There's also that "Extrude Hone" process that forces an abrasive slurry through the parts. Fixturing for this could be pricey though.

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    Have you tried chemical deburring. It is kinda like chemical machining. North American Rockwell use to use this process Chem Machining to make wing skins for aircraft. Once, I had much the same problem with a aluminum part but our last process was to chemically iridite the part for painting. The first process in iriditing is to clean the part with a ammonia water solution, not your household cleaning variety stuff which is only a very low percentage of ammonia, but the industrial strength grade. You mix this with a given volume of water drop the parts in and watch for the fizz which is the chemical reaction of the aluminum to the ammonia. It removes any and all contaminants. By accident we found that if you left a part in long enough the once sharp edges are removed and the parts come out with a nice fillet on them. Care should be taken though because if you leave the part in long (hours) enough it will disappear. After this rinse throughly to remove the ammonia. Remember this is a trial and error process you may kill a few parts in the setup process. But with small thin flashing type burrs it works. Not to mention having some squeaky clean parts. And yes it is slow, but it is effective. [img]tongue.gif[/img]

    Scott

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    Ferrous, I looked at the extrude hone process. While I am sure it would work great, as you said the tooling is EXPENSIVE. They make an exact male replica to go up into the part. Not cheap!

    Do you really think I can try the flash deburring with an ox/aceteline rig?

    Scojen, I am curious about the process.
    Did you use a 20% ammonium hydroxide solution, or 50%?
    What hassles did you get for having a big tub of NASTY stuff in the shop,(or out of the shop)?
    How does one handle said chemical?
    What precautions would I need to know?
    Thanks, Doug.

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    Scojen,
    Oh wow...that is some bad stuff!!
    I just went and checked the MSDS sheet on it.
    Where did you al keep the stuff?

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    The flash deburring is also called "thermal" deburring. They put the parts in a chamber, flood with a combustible gas, then explode it. The heat will essentially vaporize any small burrs. This might be your best bet, if you can find somebody to do it, check the Thomas Register for places that might do something like this.

    I also used to do a lot of tube fabrication, small diameter hydraulic stuff for the aerospace industry. We used to cut the tubing, stainless steel and aluminum, to length and then used a double sided brush deburring machine to clean off the ends. The brushes were about 12" in diameter, made of stainless steel wire and stacked about a foot wide, the conveyor belt would feed the tubes past the brushes and no more burrs.

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    Doug925,
    I’m not sure how you are making these parts, manual or on CNC machines, but I was hand deburring one part while the next was running…. I turned the job over to my 16 year old son and needless to say he just didn’t have the experience to do a professional looking(deburring) job. So I added deburring tools to the part cycle….nothing but a .125 dia. x 45 degree cutter. It races around the top edge of all the cavities, part edge and leaves a beautiful chamfer. The perimeter grooves are deburred with a 45 degree double angle cutter (think thread mill). This certainly adds to the cycle time and my son will never gain the experience but he’s got a CNC machine to deburr it for him!!
    Carl

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    And when you find a way to remove 100 percent of the media of bead blasting from threaded holes, patent it.

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    Doug,
    It was probably 20% solution. I do not remember what the mixture ratio was. The last time I did this was about 15 or more years ago. Try checking the recommended pretreatment for the irridite process. We use to use a plastic or fiberglass laundry sink for a tank and keep it covered with a lid. We had a stainless steel perferated basket and a assortment of hooks (welding wire) for dipping the parts with. The rinse station was the regular sink next to it once you dilute it with the rinse water it is no worse than the ammonia your missus may use to clean with. Rubber gloves are probably a good idea unless you want really clean finger nails and hands You must remember it will go inert after awhile seems like we had to freshen up the mix about once a month. Unless you splash it around and agitate it there are practically no fumes to deal with. Now the chem machining they did out at Rockwell in L.A. was probably with the 50% percent solution and if I remember if was nasty stuff, once they setup a skin for the process it was pretty much a automated process until after the rinse

    Scojen

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    Doug,
    I dont know the feasibility or practicality of a hand-torch, just offered it up as a trial alternative to the flash deburring. May be worth a try on a scrap part.

    How about a dunk in muriatic acid? Easy to obtain, but will it work on aluminum? Or maybe a strong solution of lye? I'm really guessing here...college chem class was a loooooong time ago.


    One thing that might help is to change your machining techniques to reduce the burrs, or at least the size of them:
    coldforming taps instead of cutting taps,
    climb milling onto an edge instead of off of it,
    slotting in 3 passes: one to rough, followed by a climbing pass on each wall to size the slot.

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    are the burrs from machining or tapping? machining burrs can be taken off with a vibratorty and the proper size media but tapping burrs will only go away if you have a good countersink

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    The company that provides my heatsink extrusions uses a abrasive brush first to take off big burrs. Then they send them to a anodizing shop for a heavy etch to smoothe them out. You don't want to use chemicals like that yourself.

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    There is a process called electro- polishing. Don't know much about it, but something you may be able to research.

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    Hey thanks guys.
    I wish I could deburr using a 45* tool. But I have no access to the digital file on the extrusion. Hence no way to draw it up. Some of the pockets are shaped like a cross, some are round, some are square, and some are a square with one corner rounded. TUFF JOB to program without the needed info.

    The brushes did not work for me, but how I tried!

    I like the idea of the chemical process. Even if I have to farm it out. I will have to check out the muratic acid, or lye.

    The burrs come from the machining process. Not the threads. I have tried to minimize with some programming changes, but lots still remain.

    Thanks again for the info.
    Doug.

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    Doug,
    You said "tumbling" in your original post. Did you use a rotary tumbler or a vibratory deburring machine? The terms are sometimes used interchangably, but in my experience there's a world of difference in what the two will do. I've found lots of things that will just ride around and beat the hell out of each other in my rotary, but with the vibe AND the right media, I've yet to find the part that it won't de-burr. A couple times I've gotten in touch with one of the media sellers and gotten their recommendation for something unusual and found that to be worthwhile. There's probably 50 or more different types and sizes of vibratory media available, and I'd be real surprised if there's not one that will work.

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    Metalmunchr,
    I used a vibratory deburring machine.
    I have gone to the media guys, and all they could reccommend was a small cylinder about 1/8" in dia. and 3/16 long with angular cuts on the ends. If I use any bigger, the media will not get into the little nooks/crannys. If I could come up with a smaller media, I think I would be golden.
    The small stuff gets stuck in the outside grooves, which are .125 wide, and deep. It is a nightmare to pick out the media which wedges itself nicley in those grooves.
    I will be going to talk with antoher media salesman tomorrow. Hopefully they will be able to get me something that works. If not, then I will try the chemical route.
    Doug.

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    big old thread dig but what did you come up with?

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    I just checked the date too. I guess this was before pictures were popular. Unless you were at the beach.If you're still out there Doug, please let us know.Texas is divided up into regions. I'd like to know where my fellows are located so I can be more helpful.I come across big heavy stuff quite often that I'd like to find a home for.

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    Quote Originally Posted by xa-mont View Post
    big old thread dig but what did you come up with?
    I think the burrs died of old age.

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