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  1. #1
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    Default Switch material from aluminum to magnesium alloy

    We need to reduce the mass of some small aluminum (6061) parts. We've already removed as much metal as possible, so the next step would be to machine them from a magnesium alloy. It seems as simple as just changing the material call-out on the prints, but nothing is simple. Our main vendor won't machine magnesium at all. I also don't see those materials being available in bar form, say 1" x 3". Is this something reasonable to do, or does everybody avoid it for some reason?

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    In your shoes I'd be very very careful, AFAIK (not much) some of the magnesium alloys structurally behave very differently to alu's, ………….also I'm not surprised your vendor doesn't want machine mag - the fire risk being just one of the problems.

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    my insurance company won't allow me to work with it. I also know of two shops that burned to the ground because of it.

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    Mag is not that bad, especially newer alloys that are more stable and corrosion resistant (relatively).

    I made a pair of Faraday Cups for a satellite from AZ31B ages ago, almost all the metal parts were nickel flashed, then gold plated. It was a bit of a pain, and yes, we had a fire, but not too big because we regularly cleared chips away from the machine.

    What's the purpose of the part, do you have engineers who can spec the right mag alloy? If you don't mind dealing with someone a bit distant from NY I'd be happy to look at drawings.

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    Fifty years ago out in the Connecticut woods we would put the chips in a 55 gallon barrel out back, get a little blaze going, then stand back and throw rocks at a gallon container of water until it got knocked over into the barrel. Instant joy - shooting flames about sixty feet in the air.

    You cannot imagine the violence of such until you have witnessed that. Tended to make us VERY aware when we were MAKING those chips

    Out in the country missile launch - only way faster

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    Quote Originally Posted by johnoder View Post
    Fifty years ago out in the Connecticut woods we would put the chips in a 55 gallon barrel out back, get a little blaze going, then stand back and throw rocks at a gallon container of water until it got knocked over into the barrel. Instant joy - shooting flames about sixty feet in the air.

    You cannot imagine the violence of such until you have witnessed that. Tended to make us VERY aware when we were MAKING those chips

    Out in the country missile launch - only way faster
    Back in my day - early 70's - the boss used to deliberately burn the chips so they weren't a hazard.

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    My experience is with AZ31, which is a cast plate. Not sure about other alloys, but this alloy is only available in plate as far as I remember... this was 8 years ago I think. I bought a type D fire extinguisher and had kiln dried sand in a 5 gallon bucket on hand to smother a fire, but never needed it. The stuff machines excellent, picture a less dense version of MIC6 or K100. I couldn't even set fire to the chips with a cigarette lighter, so in my experience the only way to get in real trouble is with a pretty major crash or a coolant pump failure. Sharp tools, good coolant coverage and keeping the machine cleaned out add extra insurance.

    It definitely fucks your coolant up in a hurry too. Blaser and Oemeta have special coolants or additives to deal with mag. Then you have to protect them post-machining like bare steel, this shit will corrode quickly. We just dipped our parts in WD-40 and never had issues with corrosion. I learned the hard way by leaving parts in a fixture overnight. That was a mess in the morning.

    If it's a big enough job and you have to outsource it, we have time to take a peak if you need.

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    Very low volume on this, probably 3 sets of part to start with, but we expect to pay accordingly. 3 "sets" still translates into a couple hundred of one of them. Should have some prints in a week or so. How porous is cast plate? I've had some nasty cast aluminum.

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    Quote Originally Posted by Conrad Hoffman View Post
    Very low volume on this, probably 3 sets of part to start with, but we expect to pay accordingly. 3 "sets" still translates into a couple hundred of one of them. Should have some prints in a week or so. How porous is cast plate? I've had some nasty cast aluminum.
    The worst part about small lots is the coolant. It's spendy getting the coolant ready with additives or even changing a sump out completely.

    We never had an issue with porosity, and all the mag parts we made were fluorescent penetrant tested to some mil-spec, and never had a failure out of maybe 1,000 parts or so. So that either says the plate we got was all good stuff and it's not an issue, or that the military requires penetrant testing because mag is an issue.

    cimg2337.jpg cimg2335.jpg

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    Quote Originally Posted by [email protected] View Post
    I bought a type D fire extinguisher and had kiln dried sand in a 5 gallon bucket on hand to smother a fire, but never needed it.
    Just in case anyone has never seen a class D fire extinguisher in action, they don't work. If you have any sort of significant metal fire going, nothing that comes in a can is going to put it out. Even smothering it is often not effective because the material retains so much heat that it will usually reignite the moment it gets fresh oxygen. Or begins liberating oxygen from the nearby environment (hint: don't use water). Our machines for titanium work had a pressurized fire suppression system built in that ran a plastic tube through the work area, if anything caught fire it would melt immediately and flood the machine with... something. Probably halon, I don't remember. They were more for teh insurance company, we never expected them to really do anything if we set a bar on fire.

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    Interesting. The American Bonanza Society recently announced a contest to design replacements for the magnesium ruddervators used on their classic design airplanes. The original magnesium had a lot of problems with corrosion, etc. I figure that some sort of carbon fiber material might be the solution. Anyway, there's money in it for whoever can solve this problem.

    $200,000 in prizes offered to those who can help save the Bonanza fleet

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    Quote Originally Posted by Winterfalke View Post
    Just in case anyone has never seen a class D fire extinguisher in action, they don't work. If you have any sort of significant metal fire going, nothing that comes in a can is going to put it out. Even smothering it is often not effective because the material retains so much heat that it will usually reignite the moment it gets fresh oxygen. Or begins liberating oxygen from the nearby environment (hint: don't use water). Our machines for titanium work had a pressurized fire suppression system built in that ran a plastic tube through the work area, if anything caught fire it would melt immediately and flood the machine with... something. Probably halon, I don't remember. They were more for teh insurance company, we never expected them to really do anything if we set a bar on fire.
    Seen it work on a mag fire in a van...worked well till some asshat hit it directly with a straight stream lol...took a half hour and 2 hose lines to get it out. I ended up in there with a haligan moving shit off it...oooo bright sparklies


    Also...why not titanium?

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    Titanium is way heavier. Stronger, but there's no freedom to remove more material to lighten the parts.

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    Would Duocel 'aluminum foam' work? Might have to address the surface finish issue, as well as ultimate strength.

    Duocel(R) Aluminum Foam – ERG Aerospace

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    Quote Originally Posted by Milland View Post
    Mag is not that bad, especially newer alloys that are more stable and corrosion resistant (relatively).

    I made a pair of Faraday Cups for a satellite from AZ31B ages ago, almost all the metal parts were nickel flashed, then gold plated. It was a bit of a pain, and yes, we had a fire, but not too big because we regularly cleared chips away from the machine.

    What's the purpose of the part, do you have engineers who can spec the right mag alloy? If you don't mind dealing with someone a bit distant from NY I'd be happy to look at drawings.
    Just as a warning to anyone that might underestimate the fire hazard.

    Remember May 2,2018 when Ford 150 production was in jeporday from lack of dashboard production.

    YouTube

    This is-was the Eaton Rapids Meridian facility. Mainly a diecast and machining operation for a multitude of automotive parts. Mainly dash boards, engine cradles, and rear suspension cradles.

    At the time of the fire, majority of the manufactured stock and raw magnesium ingots were stored inside, the building was fully sprinkled and CO2 suppression systems were limited.Finished parts were also stored on racks for transportation and handling for customer use.

    The only method available and would work was to use ammonia sulphate which was normally used as a flux in the diecasting machines and bury the fire in it. Cleanup was a huge mess as the ammonia sulphate melts at a similar temperature as the magnesium.

    I think that they chief problem was in lack of a contingency plan in the event of a fire and how to proceed in extinguishing it. It should also be realized that many fire departments are not fully aware of all of the risks in their fire protection district. Water is usually the first line of defense in putting out most common fires and so that is the perspective that everyone has when they show up at the fire and hook up the hoses.

    I am not trying to scare anyone but if you are machining with combustible metals, the risks of a potential fire needs to be accounted for, the risks minimized, and an adequate fire and or disaster plan implemented and shared with your local fire protection district.

    Magnesium does not need to be feared but respected.

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    Yes, I posted about that event when it occurred. But as mentioned in my earlier post, when you keep the machine clean it's not that bad. I use active chip removal methods and grounded steel isolation canisters to help lower the risk. The one fire we had only involved ~50 grams or less of chips, so we just let it burn itself out.

    Here's some news video from that fire: YouTube

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    Quote Originally Posted by Milland View Post
    Yes, I posted about that event when it occurred. But as mentioned in my earlier post, when you keep the machine clean it's not that bad. I use active chip removal methods and grounded steel isolation canisters to help lower the risk. The one fire we had only involved ~50 grams or less of chips, so we just let it burn itself out.
    I didn't mean to post directly to your response. I just get amazed that so many large manufacturing facilities that have not done an adequate risk assessment regarding their raw materials and production.

    Yes, 50gm is a minimal hazard and or risk.

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    Quote Originally Posted by steve45 View Post
    Interesting. The American Bonanza Society recently announced a contest to design replacements for the magnesium ruddervators used on their classic design airplanes. The original magnesium had a lot of problems with corrosion, etc. I figure that some sort of carbon fiber material might be the solution. Anyway, there's money in it for whoever can solve this problem.

    $200,000 in prizes offered to those who can help save the Bonanza fleet
    Monash University in Australia came up with trace amounts of arsenic added to magnesium to give cathodic protection and very good corrosion resistance.

    'Poisoned' alloy the metal of the future › News in Science (ABC Science)

    Now.... where's my prize??.

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    Quote Originally Posted by SAG 180 View Post
    Monash University in Australia came up with trace amounts of arsenic added to magnesium to give cathodic protection and very good corrosion resistance.

    'Poisoned' alloy the metal of the future › News in Science (ABC Science)

    Now.... where's my prize??.
    Very interesting! Follow the link to claim your prize!

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    Long ago late 1970's I worked for a racing engine shop, we got cast mag GMC style blower cases that we machined. They were bored on an Okuma LS and faced on the same lathe. We machined them dry and used good house keeping, very small amounts of chips at any stage of production. We played with chips out in the yard, we never had a big fire, we had sand buckets near every station of production.

    Steve

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