Machining Titianium in a lathe

[Joels]

Hello, I am trying to machine a 1 inch dia Ti bar in a Mori Seiki lathe, The issue is I have to use a boring bar to machine the center to .3385 dia, the OD is .3765 dia which leaves .019 a side wall thickness. the length is just over 2 inches. When i machine the part i get a big taper and the od comes out almost .02 oversize, the part is flexing, i have no center, no steady rest to work with just a spindle and a turret. I can up load the Mastercam file to the FTP server if you want as it has the geometry of what the part looks like.

 

I need help with this ASAp as i work nights and i am on the clock.

 

Thank you for your input.

 

Joel

[heavychevy2155]

WHO Quoted that!!!

[Brando]

WHO Quoted that!!!

the guy who didnt have to make it !!! LOL

[Brando]

but seriously imo thats a tall order for even a well seasoned machinist,

but i would do the bore first then fill the hole with a rod and glue it in or light press fit and do the od , that is the best practical solution i have , or if you have some of that low temp metal stuff that would probably work too anything to stiffen it up

 

a sharp insert would prob be best , stuff you would use in steel is not ideal

 

good luck

[YoDoug®]

How about machining the od to a very tight tolerance and the do the id in a second op chucked around a two piece sleeve around the od.

[JAMMAN]

Bore, part off, add a second op on an expandable arbor. Smallest tip radius possible, like a .008

[Joels]

Thanks for the ideas, they are very set in their ways here. I am going to try again tonight but they want this to run as a production job.

[Joels]

I tried everything I could think of tonight, we just don't have the proper equiptment to machine this part

[Mr. M]

Rough the OD down to .100" over, then rough and finish the ID, at that point take the .1 OD stock off in one pass. I've done parts like this with a flat bottom on it using similar methods

[Philcott]

I think you will have (as you seem to already know) nothing but trouble trying to do this in one opp. I would try roughing the OD, drill (use a 135 degree split point cobalt drill-peck drill but only retract .01 or so to break the chips), rough the ID to within .02 per side or so, finish the OD to size and part off.

 

2nd opp. Bore jaws so the part is holding almost all the way around the part (kind of like a collet with as much contact as possible). Finish bore to size. We have had great luck in Ti. with Seco TS2000 grade inserts. Bore the jaws to hold as much of the length of the part as you can and relief the bottom so the chips have a place to go.

 

It may not be production but at some point you'll just have to get the parts done.

[MrFish]

not easy to set up as far as tolerancing goes but if you can set up the od turning tool and boring bar to turn at the same time this can work quite well as it balances the cutting forces against each other

[Joels]

I have the part machined! Thank you for all your inputs!!!!

 

Joel

[K2csq7]

I have the part machined! Thank you for all your inputs!!!!

 

Joel

 

How did you end up getting through it?

[mkd]

a buddy does this stuff in inconel with thinner wall sections all day long.

i think they use mandrels on ID to finish OD,

then hone ID at final.

 

how did you get it done?

[CADCAM3D5AXIS]

+1000 ^^

[JAMMAN]

I have the part machined! Thank you for all your inputs!!!!

 

Joel

 

Oh Joel.... let us know......

[Newbeeee™]

Bore, part off, add a second op on an expandable arbor. Smallest tip radius possible, like a .008

Listen to the penguin - he talks sense.