# Titanium machining



## tino_ale (Feb 7, 2006)

Hi everyone!

I was just wondering how hard it was to machine titanium... Does this require special tools? Specific rpm?

The real question is : could a micro or mini-mill, for example, work on titanium? Would it be a realistic project to built a titanium flashlight or should I forget it fast? :naughty: 

Thanks for any info!


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## McGizmo (Feb 7, 2006)

sharp tools and you simply must keep the tool cool!!!! I won't pretend to have become proficient or even literate in speeds and feeds but with Ti you need to be firm but easy. When your tool is cuting and cool, go. When it isn't, don't. With your equipment, I would think shallow depth of cuts but with reasonably agressive feeds and did I mention coolant? :shrug:

There is one great advantage to cutting Ti. When you get back to Al and brass, you think you are hot stuff and enjoy the process all the more!!


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## Vee3 (Feb 8, 2006)

Depends on the type of Ti. One of the most common is 6-Al-4V, which machines similar to a semi-tough stainless steel (Which is kinda tough for most tools on a mini-mill). Another common grade is CP2 (Commercially Pure) which is very gummy and wants to stick to the tool. There are lots of other grades too.

Whatever you have in the way of Ti, a good Moly-based cutting fluid helps.


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## tino_ale (Feb 8, 2006)

Thank you for your expertise!

Cauz' you know, hearing (actually, reading) everywhere that "titanium is a hell to machine", "a ***** to work on"... It is very hard to make the difference between the truth and the myth. Titanium is definitly a symbol.

So, I understand that with some knowledge and causion, machining titanium is _possible_ even for an "amateur"...

I tell you, one day, I will machine as fine ti flashlight as Don one's.




It's good to dream...


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## Bravo25 (Feb 8, 2006)

IIRC machining titanium is a slow process. Shallow cuts, slow speed, and slow feed. Even then as others have mentioned, keep everything cool. The work piece, and the tools. TI tends to asorb the heat very well, and chatters very bad when you get aggressive with it.


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## scott.cr (Feb 9, 2006)

I had a piece of 6-4 titanium that was given to me from a friend who works at a bicycle frame shop. On my mini lathe a TiN coated cutter (yeah I know, Ti on Ti) would skid across the surface of the 6-4. It would cut with a wickedly high speed though, and the feed was so hard that the lathe and/or the work piece was flexing and causing the piece to have a larger OD "belly" in the middle.

I suppose a Ti personal project could be done on home tooling but it would be a lot of work for a neophyte.


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## TheOring (Feb 9, 2006)

How is the tensile strength of titanium though and how hard is it?

For example, if a tank ran you over, would the titanium flashlight survive so that you could bequeath it to your next of kin? (considering how much it costs....)

These are important questions that are worth thinking about.....

Has anybody done a "tank runover test" on a titanium flashlight? I mean, why get titanium if it's not gonna survive getting dropped from 10,000 feet up too?


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## wtraymond (Feb 9, 2006)

Onlinemetals.com recommends machining titanium at slow speeds with high feed rates and very high coolant flows.

As for strength, I've never done a "tank runover test" but no other lightweight material would be better suited. Titanium is harder (200 Brinell) and stronger (134 ksi yield strength) than most steel alloys. Standard 4130 construction steel is 197 Brinell and 60 ksi. High speed tool steel is 230-230 Brinell. Titanium has a melting boint about 500 degrees F higher than most steel alloys so taking your flashlight to Mercury might work okay. Titanium also has excellent corrosion and chemical resistance so taking your flashlight to Jupiter might work too.

Unfortunately, titanium is a poor conductor of heat and electricity so the body will not make a good common ground. This is okay if you've electrically isolated the flashlight body from the power source as is plastic lights.


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## Billson (Feb 10, 2006)

If only we could make titanium astronaut suits, they seem to be the perfect material. Nearly indestructible and great heat insulation.


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## tino_ale (Feb 10, 2006)

wtraymond, when you say that Titanium is a bad electricity conductor... How bad is it?

I do not have one (I wish...) but I *think* that McGizmo's T has the ti body as common ground.

Is this condictivity problem a real issue? I mean, how much power is lost overall?


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## MoonRise (Feb 10, 2006)

Regarding hardness, 'soft' titanium may be a bit harder than 'soft' (annealed) steel. But Ti, even hardened, is -much- softer than hardened tool or cutlery steel. In the ballpark of maybe 40 Rockwell-C for Ti, versus 60+ Rc for steel.

Yes titanium is strong and light, but it is not the strongest or the lightest. It's just pretty darn strong and light at the same time.


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## McGizmo (Feb 10, 2006)

Hi guys,
I am just an uncertified garage hack so I can provide opinion more than hard facts. Ti has an Alpha as well as Beta molecular strructure as I recall and one of them can provide respectable hardnesses. Alloys that are properly heat treated can provide some very respectable physical properties and numbers. The ability of Ti to retain its original state is one of its endearing features for me. Low maintenance I believe is the term; even subjected to unfriendly and corrosive environs.

Thermal and electrical contuctivity may be poor compared to other materials but this is a relative consideration and perhaps not as significant as one might think. A couple years ago this topic came up and I recall grabbing a 2' bar of AL and Ti and measuring the resistance from end to end. The Ti won as the Al required scratching the surface with the meters probe to get any continuity.

Aluminium and brass are good electrical conductors wheras the oxide of both is not. Ti is not so great but Ti oxide _is_ electrically conductive. Silver is the winner as I understand it because not only is silver a good electrical conductor but silver oxide is also good at allowing the passage of electrons. :shrug:

Now I would guess that some qualified aerospace engineers fluent in composite design could come up with a carbon fiber graphite matrix flashlight that would be a super conductor both electrically as well as thermally.  Such a light would have a distinct surface appearance and texture which could be replicated with clever decals and applied to cheap knock offs! :thumbsup: :nana:

Most of these comments would be better placed in another thread running on material selection for flashlights but I am lazy and need to get back tothe SHOT activities.


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## xochi (Feb 10, 2006)

McGizmo said:


> Hi guys,
> I am just an uncertified garage hack .....



Sorry Don, at this stage of the game I think you're at least a little beyond this bit of modesty. Do your Ti lights use the body as ground?


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## McGizmo (Feb 10, 2006)

xochi,
The McLuxIII-T does use the battery pack as a ground path betwen the silver plated battery contact spring and Kilroy (contact surface is an internal shoulder in the bore of the battery tube and internal to the environmental seal of the head/ body. In some other protos I have, ground path is either similar to this or via a Ti piston. With the constant current drivers used, any resistance will be manifest in a reduction in runtime but then I am not sure it would make sense to consider this a significant knock to the efficiency of the light or not. I would be more concerned if the light were an unregulated incan system with a lamp fine tuned to a specific voltage range. I have not bothered to measure the total risistance of the ground paths in various lights nor have i tried to determime how much the resistance might vary due to foreign contaminations or lubes used. Certainly we have seen cases where carbon or oxidation build up on contacts will interfere with the proper function of a light but I have yet to encounter this with a Ti light. :thinking:

It might be of interest to consider that in many types of anodizing and plating systems, the material used for the racks which carry the current to the parts are made of Ti. In the case of Al racks being used in Al anodizing, they have to be stripped of oxide (etched) after each cycle because the Al oxide resulting on the racks precludes proper electrical contact in the next cycle.

BTW, by most legitimate standards, I am a hack! On top of that, this is OT to the machining of Ti.


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