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  1. #11

    Default

    Thanks for the reply.

    Is the gauge thickness the same on Ti as it would be on Steel, as I know Aluminum is slightly different.

    Do you have any information on figuring out the pie cuts to build my on angles?

  2. #12

    Default

    It's the same for gauge.
    Try the fabricating forum at www.homemadeturbo.com - there is a sticky topic with info on pie cut bends there I think.

  3. #13

    Default

    The actual Welding of Titanium is pretty easy. The puddle is easy to see and is very fluid. All the headaches come from the prep work and adherence to procedures. The "criticality of application" is a really big factor.
    Some codes alloy only light straw discoloration while others allow blue and purple.

    Welding inside a chamber automatically increases difficulty and takes longer but sometimes is necessary.

    Whenever I have a choice , I use trailing shields, backup devices, and oversize cups to accomplish shielding. rather than opting for welding in a chamber.

    Here are the worst things you can do in order of importance.

    1. accidentally pick up the wrong rod....keep all other rods away from the work area unless you like hearing cracks form while you weld.

    2. not shielding the back side of the weld with argon...this makes for a brittle weld...not as bad as using the wrong rod, but still junk

    3. not cleaning the metal....porosity is usually the issue here.

  4. #14
    Join Date
    Feb 2007
    Posts
    11

    Default

    I ride a Litespeed bike. The folks there have a lot of Ti welding experience. Their Ti tubes and rods have similar sources.

    www.litespeed.com

    Another outfit that is at the top of the heap in Ti welds is Moots.

    www.moots.com
    Miller Pro 300
    Craftsman buzzbox

  5. #15
    Join Date
    Dec 2008
    Location
    North Central Utah
    Posts
    16

    Default Titanium

    I have welded Titanium ejectors *exaust pipes for the T-700 gas turbine engines on Helicopters*.
    Open air environment as they are way too big to fit inside of a purge chamber.
    A trailing cup is one thing I used *home made*
    However on these units there are places that a trailing cup is just too big and cumbersome to work.
    For those welds I found going slow and only welding about 3/8 to 1/2 inch at a time then letting the weld cool before continuing on worked out nicely.
    As stated Use a large cup *I myself like the # 10* gas lens if you have one.
    Use as low current as possible and still get adequate penetration. The welds on Titanium should never be allowed to turn ANY color, they should come out shiny almost like chrome. Too much gas flow can cause a real problem with Titanium if you draft air into the weld because of high gas flow the weld will be contaminated and become very brittle.
    Backup gas is a MUST DO! Pre and post purge is a MUST DO!
    I have even had to do some pretty long welds on these ejectors one spot at a time.*very time consuming* But then we are talking a very expensive Helo engine part and time is NOT of the essence.
    Others have posted good info on Titanium here These are just a few of my techniques
    Oh and dont forget .... cleanliness is next to Godliness and makes for good welds too.
    Hope this is some help
    P.S. one last thing, there are times when I have found a slight trailing angle of the torch is some help too, obviously not when using a trailing cup though. AND a trailing action on the torch has a tenancy to make it difficult to see what you are doing but a person must do what he must do to accomplish any given task.
    Last edited by RetWelder; 12-15-2008 at 04:09 PM. Reason: Speeeeeeeeeeeeling

  6. #16

    Default

    I know its been a awhile and I have not reread the full thread, but I have a few more questions regarding titanium.

    I am still looking to do build a Ti exhaust system, a few questions I have are in regards to the welding atmosphere and temperature/application.

    On the welding atmosphere, I was thinking of trying to use a sandblasting cabinet, add extra sealing and ad a port for vacuum or argon. The other option I was thinking of was to cap the ends and back purge the inside with argon, and sure a larger cup and/or build a trailing cup to shield the fresh weld. The welds are not going to see mechanical stress, but will see thermal, and need to seal (ie no leaks). Not sure what you guys would think on the couple options... Or if just welding it the same a stainless steel would suffice.

    Next question I have is on the propteries of Ti, from some research the melting temperture of Ti is 3200F while SS is 2500F, and the thermal expansion is of Ti is 8.5 while SS/steel is 17.4, if I were to use Ti in a high heat application, turbo downpipe, exhaust manifold, turbo manifold how do you think it would hold up to the heat cycling?

    In the case of building a Ti exhaust I know most exhausts systems (post cat) are .035, some full exhaust from a turbo downpipe or manifold are the same .035 wall thickness. If I were to build a turbo downpipe, turbo manifold, or N/A exhaust manifold what thickness would you suggest/recommend?

  7. #17
    Join Date
    Nov 2009
    Location
    Ontario/Burlington
    Posts
    21

    Default

    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
    Attached Images Attached Images

  8. #18
    Join Date
    Nov 2009
    Posts
    6

    Default Aircraft welding

    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'm just learning tig welding & on aircraft parts. I work in the aircraft industry and know the level of quality it must be done at. The cabinet you show looks great, could you tell me other than the argon supply, a connection for evacuating the cabinet, the tig torch connection what other connections to the cabinet do I need? Also after pulling a vacuum and introducing argon can I just vent the cabinet at the top based upon argon being heavier than normal air? thank you

  9. #19
    Join Date
    Nov 2009
    Location
    Ontario/Burlington
    Posts
    21

    Default

    I don't use any vacuum at all, as you mentioned I depend on the difference in weights between the gases, so the purge vent is located at the top of the cabinet. I use an oxygen sensor from Huntingdon Fusion to verify the environment prior to welding, for this chamber it takes approximately 20 minutes to reach .002% oxygen. This is with the flow meter set at 40cfh.
    I'll take more detailed pics if you're interested in making one yourself, it's not costly and works quite well. For the torch entry it's a simple rubber stopper (3" diameter I believe) with holes drilled for the 3 lines and cut and split to allow insertion and then sealed with silicon. The rubber stopper fits into a piece of 3"ss tube snugly that's welded to the cabinet. I have all the part numbers for pieces used, the only piece that requires machining is the connection for the mig gun cable to the cabinet if you are using a wire feed system.
    Regards
    Jim

  10. #20
    Join Date
    Nov 2009
    Posts
    6

    Default pictures

    Quote Originally Posted by FullFusion View Post
    I don't use any vacuum at all, as you mentioned I depend on the difference in weights between the gases, so the purge vent is located at the top of the cabinet. I use an oxygen sensor from Huntingdon Fusion to verify the environment prior to welding, for this chamber it takes approximately 20 minutes to reach .002% oxygen. This is with the flow meter set at 40cfh.
    I'll take more detailed pics if you're interested in making one yourself, it's not costly and works quite well. For the torch entry it's a simple rubber stopper (3" diameter I believe) with holes drilled for the 3 lines and cut and split to allow insertion and then sealed with silicon. The rubber stopper fits into a piece of 3"ss tube snugly that's welded to the cabinet. I have all the part numbers for pieces used, the only piece that requires machining is the connection for the mig gun cable to the cabinet if you are using a wire feed system.
    Regards
    Jim
    Yes if you don't mind more pictures. Also is the oxygen sensor mandatory or could I use a time factor (time at which the argon is allowed to flow into the cabinet)? thanks again

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