Milling Nonferrous Composites...

In the latest chapter of the question-a-thon which has been this latest design project, I am wondering about milling a part which is part 6061, part 6Al4V. I have a .1815 reamed hole which is going to have .07 of Ti in it. Am I going to have to plunge drill it with an endmill, and then will a carbide reamer work, or will it still want to wander? I'll try to get a picture up, so it's easier to tell what I'm talking about...

To a lesser extend I have to also make a bore which is a similar story, but I have been interpolating it with a .750 carbide endmill, and the amount of Ti is less, so I think i can get away just helixing it as usual, and slowing down for the part where it's eating the Ti...

I appreciate all the help I can get, as the only Ti I have worked with thus far has been pet projects, and not production parts...

Thanks!

-Parker



The black square is a Ti round, .25 dia, .325 long. The reamed hole is .625 deep, encountering the change in materials at approximately half the depth. In addition the circle below it is the hole I need to bore with the endmill, it's about .7525ish. (blue part is a hole which gets drilled in the Ti, and is of no consequence for this question)

Parkerbender
Not sure what's going on here !!
Would need a monitor about 4 feet wide
to see your Thread and picture !!

Davycrocket

Classic mix-up, I actually do have a reallly big monitor on my drafting computer, and had no idea it was so big. Terribly sorry about that, is this better?

-Parker

Anytime you split a drilled hole between mixed materials you're taking a chance on pushing the bore awry but, with what you have described and if you're using sharp tools and continually feed through the ti (it work hardens if you pause) I believe you should be ok. Depending on the tolerances you need to hold, If it had to be perfectly straight I would drill it and then ream it, a carbide reamer would be a good solution but I don't think I would use a carbide reamer. Titanium cuts good just move smoothly through it. I am assuming the titanium is almost a zero clearance fit with the aluminum.

The Ti is basically as tight as I can get it. I may go with a carbide reamer, as this is theoretically going into production (2000 holes/ month), and the customer is cool with paying tooling costs up front. If a guy has sharp cutters does a guy get away with drilling the pilot hole on the .181 part, or does a guy interpolate it with an 1/8 em, then ream?

tolerances are as close as manufacturably possible, in general a tight slip/loose press fit on a .180 pin after hard anodize. There is a set screw involved, so it just has to be pretty darn close, is all. but pretty darn.

Edit: is there a reason not to go with a carbide reamer?

Carbide is brittle, HSS is much more forgiving to interruptions in the cut and won't break. I know the carbide is stiffer but I would worry about breaking a carbide reamer in there. Try it, it might be just what the doctor ordered. Titanium is'nt anything to be afraid of, I really like cutting it, just don't let the tool dwell in one place, like I said keep the tool, whatever it is moving through the metal. I would just drill it and ream it. you'll be able to judge the viability of your method after one or two parts. I do not see any reason to use an end mill.. The reason I asked about the titanium being mated up solid with the Al is if the Ti is allowed to jiggle around in its location that would allow work hardening to occur.