Milling Titanium

[DaveH]

Hi,
Has anyone done any milling of Titanium.

I’ve cut it on the lathe using HSS cutters (sharp) – not too problematic. (Apart from the occasional fire)

Milling it however, I just could not get it to cut properly. 

Small grooves only .003” deep using a 1mm dia mill. I even tried with some engraving cutters, still not successful.

Anyone done it, and would you like to share the secret.

 

DaveH

[John Stevenson]

Depends on grades,
I make some pump shafts out of Titanium as it's the only thing ferric chloride won't eat. I buy grade 2 as it's the best I have found for machining [ and the cheapest ] It machines a lot like stainless, milling and turning is OK but drilling and tapping can be a pain as it wants to grab and work harden.

Was given a bit of grade 9 for a job and it was harder than a witches tits.

John S.

[DaveH]

John S,

Seems like you and me are the only ones here.

 

Was given a bit of grade 9 for a job and it was harder than a witches tits.
John S.

WHOT! - sure you are alowed to say that?

DaveH

[doubleboost]

I have a friend who makes titanium exhausts for racing cars i have seen them milling manifold flanges .
It seems to machine like stainless . Iwill ask them what grade ect
Not machined any witches tits but i would think lots of cutting fluid would be needed 

[spuddevans]

I have milled titanium, what I've found works best is to use carbide cutters, or if using hss, don't let the cutter rub as the stuff I have work hardens in the blink of an eye. I use light cuts, but that may be down to my mill being a little more flexible than I'd like.

The smallest size of cutter I've used is a 2mm carbide, and I have also used a carbide V-point for engraving using extremely shallow cuts, with a little bath of thin cutting oil.

Tim

[DaveH]

John S,
Cuts fine on the lathe, never drilled or tapped it.
Milling - seems I am doing something wrong.

How should I mill it.
I should point out I don't use any coolant, sometimes use some cutting fluid to help.
However nothing seemed to help when milling it.

DaveH

[doubleboost]

It welds nice with tig 
I had some off cuts of pipe i used them on my diy gas turbine
Once welded it is hard 

[DaveH]

Tim,
I have tried cabide engraving cutters .003" depth of cut with cutting fluid, without cutting fluid still didn't come out right. All rough and raggity.

Could I have the spindle speed too high, do you think?

 

DaveH

[DaveH]

Doubleboost,

Hey, try to keep focused on the problem.     


(I'm just pulling your leg) 

 

Dave

[doubleboost]

You will have to pull harder than that 

[DaveH]

Doubleboost,

You will have to pull harder than that 

Wouldn't dream of it

A titanium exhaust - wow that's posh

 

DaveH

[doubleboost]

I will have a word with them they use titanium all the time
They also use inconell (talk about witches tits) that stuff is seriously tough
John

[DaveH]

John,

I can turn it seemingly with little difficultly - using HSS tool - I keep it sharp.

Now milling it just becomes a disaster. 

I want to mill it with a 1mm dia mill or an engraving cutter just .003" deep - seems carbide is the way to go. With some cutting fluid in a "puddle" around it.

I know it is quite small.
And maybe the spindle speed was too high, I'm not sure. Maybe it was too slow.
So should I use a slow spindle speed -say 200rpm?

Thanks

DaveH

[DaveH]

Tim,

I have also used a carbide V-point for engraving using extremely shallow cuts, with a little bath of thin cutting oil.
Tim

"extremely shallow cuts"  - .001" slightly deeper or shallower.

Any idea of the spindle speed for the engraving cutter.

Thanks

DaveH

[doubleboost]

Personally i would run it fast 1000 plus
I will ask my friend who machines it all the time 
John

[DaveH]

John,

Thank -you that's nice of you.

Ask your friend if he runs the spindle faster or slower than he does for steel.

 

DaveH

[doubleboost]

No problem
He made a con rod for a racing ic (glow plug ) engine on a big cnc machine out of titanium .
Just to get some time in with the machine .
It really was a work of art , i will try to get some pictures from him
As well as feed and speed rates
John

[spuddevans]

Tim,

I have also used a carbide V-point for engraving using extremely shallow cuts, with a little bath of thin cutting oil.
Tim

"extremely shallow cuts"  - .001" slightly deeper or shallower.

Any idea of the spindle speed for the engraving cutter.

Thanks


DaveH

I ran it at my mill's max (X2 with belt conversion) which I think is about 2500-3000rpm. DOC was 0.01mm-0.02mm for the engraving or I was breaking cutter tips (but I was using quite fragile and slender cutters). When I was actually milling (as opposed to engraving) I was using a 2mm end mill and ran it at about 2000rpm and 0.05mm DOC.

When engraving I found that the titanium would leave a very slight raised burr around the edge of the engraved portion, but a few wipes over with some wet and dry 800grit on a flat surface would take care of that.

  This is what I did





I broke a cutter after doing the "L", well actually several cutters, until I got the DOC's and feed's sorted.


Tim

[DaveH]

Tim,
Thank you Tim,

Looks a million times better than my feeble attemps.

Mmmmm I think my spindle speed 200 - 1000rmp was too slow used the same DOC. For some reason I had it fixed in my head not to go above 1000rmp.

I think I'm going to give my brain cells a jolly good talking too

Thanks
 
DaveH

[spuddevans]

I forgot to say that the engraving on that ring took about 5-6 passes at 0.01-0.02mm DOC's.

Tim

[DaveH]

Tim,
Thank you - Later this week I'm going to give it another try.
 
DaveH

[jim]

i've machined a lot at work, slow and steady is the way. sharp tools and time work best

[DaveH]

Jim,

Thanks,
If I may - what tools do you use HSS /  Carbide

With respect to steel do you use a faster or slower spindle speed?

 
DaveH

[mgj]

I used to do some bits for racing cars - until I found how notch sensitive and gall sensitive it is. Horrible stuff and actually potentially very dangerous if one is not certain of what one is doing - in stressed or critical applications.

The trick I always found when taking small cuts is the feed rate. It does worrk harden easily, so whilst speeds were never an issure for me (a one off maker not a maufacturer) I found one had to stop it rubbing in any shape or form.  Been a while now, - thank heavens, but a relativley high feed was always a lot more imortant than speed - and if possible, don't take small fine cuts!

If it is a stressed application, its important (as in VITAL) to radius all corners, and if screw cutting to use a radiused tip.

[bp]

Totally agree with mgj.  Where I used to work they were looking into machining some high end Ti, the torque required was off the scale, with machine, cutter, and set up rigidity being absolutely vital.
cheers
bp

[doubleboost]

Dave
Had a word with the lads who machine the titanium.
They were using "grade 3 " a 5mill cutter running at 5000 rpm with coolant flood
They reckon if you let the job get hot it goes very hard , the finish they are getting is very good
John

[jim]

Jim,

Thanks,
If I may - what tools do you use HSS /  Carbide

With respect to steel do you use a faster or slower spindle speed?

 
DaveH

Either will work, but slow and steady, at least half the speed of steel and a slow feed to. as soon as the tool starts to wear, it'll need changing/regrinding.

HSS will cut very well (it will on most materials if its sharp), in fact, unless you've got the power to take a good size cut, throw away tipped cutters are a waste of time.
a bit like lowered suspension on little cars, done for form, not function!!!

[DaveH]

John, Jim,

Thanks very much for the info.

Haven’t tried anything yet but I have much better idea when I do.

Thanks
DaveH

[mgj]

I don't know what this is for but  basically there is no such thing as a bad finish on Ti. Because of its notch sensitivity and hence a very nasty habit of propagating cracks from any surface imperfections, the finish is either good, or it goes in the trash can. (Not if one is making a gear for a clock or something, of course, but where it is stressed to a useful load to take real advantage of its properties, like say suspension arms or con-rods)

Obviously there are many ways of machining Ti, all of which are succesful - probably the secret is simply a sharp tool. Still I'm surprised, with a work hardening material, that there is advice to keep feed rates down.

[jim]

i've been machining it for 16 years

[doubleboost]

Hi
Found the pictures of that titanium con rod
As usuall the pictures dont do it justice



John

[DaveH]

John,

My word that is good, especially because it is made from titanium, small as well.

I'm really going to get my butt in to gear and have another go.

Thanks for that

DaveH

[DaveH]

Jim,

i've been machining it for 16 years

So Jim when you coming to South Africa then?

 

DaveH

[Kinkajou]

I am a Vet and have to perform orthopedic surgery regularly.
Usually we can adapt implants made for people and use them on animals. But  we sometimes have to provide special solutions with patients and make impants made out of Stainless steel  or Titanium 6Al4V Eli.

This are some pictures of the first wrist replacement made for a dog.
Machining titanium has a lot of little problems as we found out. It will self ignite sometimes and that is scary.
Turning was best done at high speed and drilling as slow as posible. In both cases using a lot of cutting fluid.
We like to use carbide tools , very sharp. Steady, and progresive cuts, with little load.

This one was one of our favorite patients. Called Kissy, had arthritis that deformed very much the limbs. ( antebraquiocarpal joint affected seriously)


I started by evaluating the patient, then designed the implant using Vector Works in a Mac and finally machined the individual parts using a little lathe mill drill from grizzly ( I use this for my hobbies and a little for my work) . Implant looks like a fork / hinge.

There is a radial component and a metacarpal component. Carpal bones were almost all removed.


This is the Xrays showing the implant in place.


Titanium is a very interesting metal to work with. It is like aluminum sometimes, but it can harden in a snap and break the tools very easy.
It is a lot better than Stainless steel when used for implants, because it is very biocompatible.

[DaveH]

Kinkajou,

Wow that's impressive.

DaveH

[Henning]

Kinkajou,

Wow that's impressive.

DaveH

I will second that!

GREAT post and work!

[AdeV]

Kinkajou, let me get this straight, you made a TERMINATOR hand and implanted it in a dog?!?   



Even so, really good work, it looks amazing.