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Might have to mill some Titanium next week

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  • Might have to mill some Titanium next week

    Hi guys:

    One day I may help you guys, probably not with machining but maybe with electronics. Seems like mostly I'm asking questions.

    Here's the deal:
    I now work for a company who bought out my previous employer. My 3 month contract ends in 2 weeks. The work I've done for them thus far has not challenged me at all and I'm pretty sure they think they don't need me.
    They did not renew the contract of their Crackerjack tool&Die maker and quite frankly, in that department, I'm the best they've got left.

    They have a shop with pretty decent Chicom stuff in it. The cutters are crap but I'll be able to get a carbide one for this job if necessary. Minimally, I will buy a decent HSS bit.

    The problem:
    1/16" thick Titanium plate with 1/4" thick webs in it. I may be required to mill out a window about 4" x 6" for PCB access.
    I've searched here and googled and have gathered the following:

    Low speed is good(below 100 SFM)
    HSS works fine
    Don't be shy, work hardening happens fast.
    The chips may catch fire. - bad news (Good safety tip)
    Coolant not necessary unless you go too fast.

    I will find out what the alloy is before proceeding. At this point I have no clue. The part sure is pretty though and was expertly machined with a CNC mill.

    Any tips or tricks will be very much appreciated.
    Mike

    My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

  • #2
    If its CP Ti stay away from it, if its 6V4 or pretty heavily doped use caution. Make sure you have a fire extinguisher that can handle buring metals. More than likely it will not go out and you will also burn up the machine. Reactive metals should be left alone unless you have PLENTY OF REAL EXPERIENCE, not an internet education.

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    • #3
      .062" plate(sheet) with 1/4" web....? is that a typo ?

      Don't let it scare you off, I haven't worked with a whole lot of it, but what I have, has been of no big concern.

      You are correct about it can work harden , don't dwell.
      Mostly I have heard that the danger with fire is with a build up of fines...
      don't let the chips pile up if you are going to work that much of it.
      Keep sparks away from any fines that may be present.
      Heat doesn't seem to transfer very well, tools will get hot.

      Others will chime in.........

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      • #4
        Thanks Squirrel, not sure what CP means.

        Uncle O:
        Not a typo, I just didn't want to say "billet" because it seems to set people off. The part has been machined from solid 1/2" Titanium. Most of it is now 1/16" thick, the outside flange is 1/2" off the deck and there are interior webs in my way that are 1/4" thick. I can clamp the flange to the table with the 'tub' facing up, most of the cutting will be in 1/16" with 1/4" webs encountered at times.

        I have nothing to lose. If I demand the right cutter and fire extinguisher and impress these guys enough to call their Tool&die maker to confirm, I might still have a job. Then I can buy you guys beer!
        Mike

        My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

        Comment


        • #5
          I have very limited experience with some titanium, it turns well and will single point thread well, but drilling and taping can quickly become a nightmare. Use a very sharp drill if drilling.

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          • #6
            You seem to have the big picture. Yes work hardening may be your major problem. No fire problem unless you try to impress everyone by going too fast. Use SHARP high speed tooling, I recommend M42. Don't be afraid to change tools at the first sign of dulling.
            Don't let chips accumulate. Coolant is not necessary.
            CP means chemically pure and is not relevant here. It is only used in process items like plating racks. heat exchanger tubes, and reaction vessels.
            Don't ever call any thing "billet" unless you know what you are talking about. "Billet" is an intermediate step in metal production. NOTHING is machined from a billet because it is not a finished product. Billets go to the rolling stands in bar and rod mills. A special billet, called a slab, is rolled into plate. Billets do not have the grain established and are actually castings, with no regard for stress or cooling, because it is intended to be reheated and rolled into a finished product.

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            • #7
              decent hss isn't going to cut it. It has to be very good quality, and sharp. Keep a chip load on it. As for 100sfpm... well, that all depends on the type of Ti. Some of the stuff floating around has hard spots in it. Don't let chips build up. make sure everything you use is compatible with Ti. It is possible to get some pretty bad chemical reactions.

              Can't help beyond that, I just make sparks with the stuff

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              • #8
                If all you can do is make sparks, don't tell people how to machine it.

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                • #9
                  I once needed to machine a slot 1/16 inch wide and 1/2 inch deep into the edge of some plywood. I didn't have a cutter that I could make fit the router, but I remembered I had this piece of titanium. Cut out a square and drilled a center hole to fit a router bit shank. The four corners I hacksawed into tooth shapes, then sharpened it up.

                  It seemed that it never really came sharp, but it cut about fifty feet of groove on that job, and didn't seem to get any duller. Anybody who has milled into the edge of plywood much knows that it's hard on cutters, most especially non-carbide ones. I still have it- that is one SMOKIN cutter- literally- and stink! Nothing like the stench of burning plywood resin and end grain cuttings!

                  Anyway, I found that it's easy enough to cut with a hacksaw, so it shouldn't be too hard to cut with a jig saw using a suitable blade. One with a blade kicker feature would be best, like one of the Bosch ones.
                  I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                  • #10
                    The Ti I got to play with machined like stainless with a carbide bit and I got a decent finish.

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                    • #11
                      Check on what it takes to put out a Ti fire...I think it has to be smothered with sand so investigate that aspect.

                      Best regards, Jack

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                      • #12
                        I think the OP wanted to hear from people who have experience with machining Ti, not those who "think", "have heard", or have experience in plywood.

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                        • #13
                          tdmidget,

                          A little harsh, this is a public forum and the answers given benefit more than the original poster. Knowing that ti cuts easy enough with a hacksaw might be beneficial to someone...

                          Maybe practical machinist is the forum for you.

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                          • #14
                            Have a Class "D" fire extinguisher handy while machining. DO NOT USE WATER!

                            Good luck,

                            Rick

                            Please disregard, I was thinking of Magnesium. Sorry,

                            Rick
                            Last edited by boaterri; 06-12-2010, 11:49 AM.

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                            • #15
                              Originally posted by boaterri
                              Have a Class "D" fire extinguisher handy while machining. DO NOT USE WATER!

                              Good luck,

                              Rick
                              Pay attention to Rick's post. A Class D fire is nothing to play with. My fire fighting training from the US Navy sure came in handy when one of my student's set a crucible full of aluminum on fire.

                              Is this a "one off" or do you have several pieces to machine? If the latter, I seriously recommend looking into sending it out to someone with a water jet. Work hardening, fire, and any other associated issues are eliminated.

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