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  1. #21
    Join Date
    Nov 2009
    Location
    Ontario/Burlington
    Posts
    21

    Default

    I'll take some pics and start a seperate thread on the purge chamber, I don't want to hi jack this one. An oxygen sensor is not necesessary, a strike test coupon to run a bead on to verify that it stays silver during welding is just as good, you just tend to wait longer then necessary at times waiting for the purge.
    Regards
    Jim

  2. #22
    Join Date
    Feb 2007
    Location
    Spruce Grove, Alberta,Canada
    Posts
    583

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    Quote Originally Posted by Burnt hands View Post
    Hi Dave reynolds,

    Thanks for the great tidbit of information in your post.
    I too have noticed that my wire would tend to "stick" to the weld pool on occasion when tigging titanium and I figured it was something I was doing wrong. I have not had the same problem with stainless so I thought it was me. Thanks for the help.

    And to everyone, if you look at my welds, they may be pretty with the "rainbow" effect but strictly speaking they would fail the AWS standards.

    I make titanium sculptures but would never attempt to do any aircraft quality welds as this is way beyond my expertise.

    I do not have a weld chamber so I made a poor substitute out of plexiglas. Looks like a glass bead box or the baby incubators for premature babies.

    I have learned the hard way that argon is a lot cheaper that titanium.

    The more I learn, the more I strive to make my welds better and I'm sure this is why everyone is here also.

    thanks,
    I held a Ti ticket a few years back and it's not extremely hard to weld but very easily contaminated. We used purging shoes with a guy under air in the pipe following me around with the trailing shoe. I had a big (#20 i think gas lense) with a trailing shield. Anything other than a mirror finish on the weld and a slight straw color in the heat affected zone were a failure. This line had wet chlorine gas running through it. If the moisture content went to low they said it would spontainiously combust and the only way to fight the fire would be to run out of one or the other. If you are planning on welding Ti make dam sure you store your filings and grinding dust in oil otherwise they will spontainiously combust and it burns white hot. DO YOUR REASEARCH before you do anything with Ti. Jef

  3. #23

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    Jim, thanks for the pics on the chamber, when you start your thread please post a link in mine.

  4. #24

    Default More info on Titanium

    Like many of the others have said, Titanium is not really hard to weld, but is embrittled by oxidation. If you get anything but a light straw color (yellow tint) on your welds you may have to check for gas leaks. Also keep in mind that with TIG welding sometimes lower gas flows work better, so you may need to work to get your shielding gas flow rates set just right. Want to use the largest gas cup that you can so keep as much of the material shielded as you weld.

    Also, if you are welding tubing, make sure that you purge the inside. A rule of thumb for purge time is 6 volume changes of gas before the start of welding. That means that if you look at a pipe that has a volume of 10 cubic feet, that at a flow rate of 10 cubic feet/ min that you would need to purge that pipe for at least 6 minutes before you start welding.

    Make sure that the flow rates for purging are kept relatively low and that there is no pressure buildup inside the pipes. If there is pressure buildup in side the pipes it can cause suck-back on the root of the weld and concavity on the inside of the pipe or tube.

    Since argon is heavier than air, it is a good idea to use a vent opening that is on the top of the pipe or tube. This way the argon will push out any other gases and keep the tube purged well.

    Purging doesnt need to be really exotic and can be as simple as taping a gas hose to one end of the pipe or tube, with the other end taped with a small vent hole. The vent hole doesnt need to be really large, just enough to allow some gas to escape to prevent pressure buildup.

    If you get into welding titanium you may find that the material is very fluid, especially compared to stainless steels. If your machine has the ability to pulse the current that may work well for welding titanium. Its very expensive, but is really a nice material to weld.

    Make sure that you clean all of your filler metal before welding. A good solvent wipe might be a good idea to get rid of any foreign material.

  5. #25

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    Quote Originally Posted by FullFusion View Post
    You have lots of good advice on welding titanium but I would like to offer a few suggestions from my own experience on building a purge chamber. Once you have it all sealed up I found the most important thing was a decent one way valve. Once you start moving your arms around inside the chamber the gloves work like bellows and if you don't have a good one way valve everytime you pull your arms out you're sucking air back into the chamber contaminating your environment.
    I found the best one way valve was to cut up a 3M half mask and use the port that is used for exhailing. I built a little enclosure and siliconed it in to seal it. I've attached a couple pics so that you may see how it was done.
    I've built a few chambers, this was the first one to work out any bugs, the next was a 60" diameter one to accomodate a large aerospace part that we weld. I use a cold wire feed system from Arc Zone to feed wire, I changed it to use a foot pedal to activate it and it is all sealed from the wire feeder to the chamber using a mig gun cable and liner.
    Regards
    Jim

    I have a question on the the chamber, did you use glass, pelxi-glass, lexan, other? Pleas give me more details (materials list) on the chamber you built, I think the best route would be building my own chamber rather than modify a sandblasting cabinet.

    Once you have the camber purged, do you still purge the chamber while welding, or does the purge hold using the check valve?




    Anyone now were I could get a trailing cup, or details on building one? I ask because there are case were I will need to tack it up or weld it in place.

  6. #26
    Join Date
    Dec 2008
    Location
    Arizona
    Posts
    812

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