Titanium

[easilyled]

To put this into context the poorer thermal conductivity of Titanium relative to Aluminium would have probably made it a bad choice for higher powered flashlights when I first joined CPF in 2004.

In those days, the Luxeons of that time were far more inefficient than today's emitters and put out far more heat.
I would have said that the choice of Titanium would definitely have had an impact in a small light that was pushing out 100 lumens, like the Lummi raw CR2 for example which was made of Aluminium. I'm pretty sure that with Titanium, all that heat would have been kept inside for longer and would have jeopardized the luxeon at that time much more quickly than Aluminium. It was a direct-drive light and 100 lumens was shockingly bright in those days for such a small light and the heat it produced was enormous.

However in the times we live in now, I have much more confidence of using Ti in high-powered lights, especially beyond the tiniest of sizes like AAA or CR2 for example.

 

[js]

OK. So the Stefan-Boltzman law states that the power per unit area emitted by a blackbody is:

(5.67×10^−8 W * m^−2 * K^−4) * T^4

where T is the temperature of the blackbody in kelvin. However, NET power is emitted power - absorbed power. So you need to subtract the ambient air temperature from the temperature of the black body--in our case the head of the flashlight.

In the FLIR image above the hottest point of the head is 47.7 C and the air is 28.5 C, so the delta is 19.2 C = 19.2 K.

So, T^4 = 19.2K^4 = 135895 K^4 = 1.35895 * 10^5 K^4

Now, multiply this by 5.67×10^−8 W * m^−2 * K^−4 and then also by the area of the head (1 inch by 1.5 inch = .00095 m^2) and the units cancel except for W, and you get . . . drum roll please . . .

7.32 * 10^-6 Watts.

7.32 micro-watts.

Assuming that the head is a perfect blackbody and that it radiates from all of its area as it does from the hottest point in its area. The real head would be radiating even less heat to the environment.

In other words . . . NOTHING. Zip. Zero. Zilch. LOL!

So, even though titanium is about a quarter as good a radiator (grey-body) as black anodized aluminum, it really doesn't matter at these temperatures. Of course, since the power goes as the FOURTH power of the temperature, it doesn't take too much temperature increase above ambient to get to the point where some significant power is radiating. In our case, if the temperature delta were even just 15 C higher, that number would change from 7.32 micro-watts to .37 watts. Of course, that would mean that the head would literally be too hot to hold at about 150 F.

Anyway, point is that from everything I know, practically and theoretically, titanium doesn't present a thermal problem in flashlights--or not at our power dissipation levels, as easilyled and Don and others have pointed out. You don't want to make the heat-sink attached to the LED out of titanium, since there you have a lot of heat in small area needing to be transported out and dissipated, but no one in their right minds would do this and no one has proposed it. But by the time you are talking about the body of the light, titanium has plenty good enough thermal properties to handle the heat transfer.

 

[IsaacL]

To confirm the real-world implications of JS's expert post above...I have a titanium Torchlab light running an OR Triple XP-G2 drop-in at 4.65A. The head gets jet-engine hot after a few minutes on high but the thermal safety protection has yet to kick in (at 65C) let alone the overheating protection (at 120C). As has been said already, the titanium can dump the heat fast enough. Even if it couldn't, electronic safeties are in place to protect the light and the user.

 

[tino_ale]

I consider this great news for the most part but it could well be the end of my little niche.

Don, time will tell, but I doubt that. IMO your lights have always been a step above whatever was readily available on the market. Even if titanium lights become more commonly available, most -if not all- won't have an oversized sapphire glass. They won't have one -if not the best- clip on the market. Or the simplicity, repairability of your lights. They won't have that extra inch of engineering that make them pleasant to look at, pleasant to hold, functionnal, rugged all at the same time. Bottom line they won't be McGizmo and I believe your customer base appreciate and support those small, yet huge, differences.
Or, you could move to the next big thing in the flashlight industry, but what super-alloy would that be ?

 

[IsaacL]

I do appreciate you taking the time to make this thread, and you do have some good information. However, there one point you make that is just plain misleading.

This is the biggest issue I have with your info. Titanium is in fact a lousy conductor (when compared to other common metals, like copper and aluminum). You acknowledged that copper is a superior conductor, but without numbers people might not understand the ENORMOUS difference. Taken from http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html. Copper has a thermal conductivity of 401 W/(m.K). Aluminum is 205 W/(m.K). Titanium is a mere 22 W/(m.K). In fact, aluminum is almost ten times as thermally conductive as titanium. And copper is close to twenty times more thermally conductive. Among metals, titanium is decidedly BELOW average in thermal conductivity.

The difference in electrical conductivity is similar. Aluminum is fifteen times as electrically conductive, and copper over 30 times as electrically conductive, compared to titanium.

There is no way you can say that titanium "conducts well" when you look at the numbers. And arguably even more important, you have to substantially reduce drive levels if you build a light body out of titanium, or it will overheat. It just isn't capable of spreading the thermal load like aluminum or copper.

I am in fact a huge fan of titanium...ever since I learned about the SR-71 Blackbird. A design like that would not have been possible without titanium. But I don't think we should pretend it is a miracle metal...like all others, it has advantages and disadvantages. And frankly, in my opinion, for flashlights, the advantages of copper or aluminum are more suited.

I'm not sure where Thedoc007 is coming from...a background in physics or if he is just trolling a well respected flashlight maker....regardless, some of the most powerful handhelds are being made out of 6Al4V Ti.

Like I mentioned before, my Torchlab Triple XP-G2's pump out 1680 lumens at 4.65A. I say this because Tom and Dan have done the thermal engineering to build a light that can run at those high levels.

There is more to thermodynamics than just charts on thermal conductivity. You have to take into account thermal transmittance and resistance to understand the process required for calculating the proper heat sink size. You also have to realize that the thermal conductivity of the heat sink is just one aspect of the thermal circuit. Thermal circuits are similar to electric circuits. You have the power dissipated by the device, the junction temp in the device, the temp at its case, the temp where the heat sink is attached, and the ambient air temp. You also need to know the the device's absolute thermal resistance from junction to case, the absolute thermal resistance from the case to the heat sink, and the absolute thermal resistance of the heat sink.

As Don has mentioned in the past, the junction between the heat sink and ambient air is a significant bottleneck.

thedoc007,
I have read some exciting news regarding new technologies and the potential of producing titanium powder at a much lower cost as well as the creation of parts from this powder at significant cost savings compared to current methods. I consider this great news for the most part but it could well be the end of my little niche. ... I don't venture out past the McGizmo forum but I am aware that there are others offering titanium lights and my days may be numbered anyway. I have seen pics of lights that people have mistaken as part of my offerings based on design elements and appearance. It's a real bummer to me but that's my problem and I understand this.

Don, I am sorry to hear that. Yes, there are other makers using titanium these days and yes, your designs have influenced many many lights. However, outside of this forum your lights are considered the embodiment of refined perfection, the gold standard by which other lights are judged. I have heard some makers say that if the customer wants a flawless light, to buy a McGizmo instead of the light they are making. That's a pretty high compliment.

This is not to say there aren't fancier, more expensive, and more luxurious lights out there. There are. But the name McGizmo has become synonymous with perfection in certain circles as well as within the custom knife community. Saying something is built like a McGizmo is like comparing it to a German car.

I've looked into Additive Manufacturing as well (AM is 3D printing with metal). It's pretty cool and the full possibilities are still untapped. Empire recently built a bicycle using AM titanium, for example. The surface finish on small components leaves something to be desired though and AM does not appear to match the precise tolerances of CNC stock removal. We may yet see lights being made using AM technology but I don't think they will directly compete with McGizmo or Cool Fall or the other high end titanium makers. I think AM will be used for much larger/complex components. Perhaps the best application of AM right now are SpaceX's Dragon 2 engine chambers, which are made from AM Inconel.

 

[thedoc007]

I'm not sure where Thedoc007 is coming from...a background in physics or if he is just trolling a well respected flashlight maker...

As I have now repeatedly explained, I disagreed with js's original wording. I had heard on this forum that titanium was not nearly as good as conducting heat as aluminum, so I looked up the numbers, and it seemed to bear that out. Although I still maintain the original quote was a bit misleading, I have since learned that it isn't really a big deal in practice, and that my wording was if anything more problematic. I'm sorry I was mistaken, but that is how I learn...if I never put my take on it out there, I wouldn't have learned that I was mistaken. No trolling involved.

Thanks to js and Don for EDUCATING me, without being condescending.

Edit: I have also re-worded all my posts in this thread to be less argumentative and hopefully more in line with the facts.

 

[newbie66]

Does titanium get scratched easily?

 

[tino_ale]

Yes it does but at the same time it is easy to buff them out.

 

[easilyled]

Does titanium get scratched easily?

I should let js answer this really as he's the expert but in my experience, yes, Titanium can pick up very superficial scratches easily, although it takes some doing to gouge it sufficiently to feel the marks with a fingernail.

The beauty is that the superficial scratches are usually so shallow that they can be buffed out with the minimum of time and effort.

 

[nbp]

I think the scratches from daily use just add to its cool factor. I love worn Ti. One of the guys named it "pocketwashed" finish which describes it perfectly!

 

[kaichu dento]

Does titanium get scratched easily?

Yes it does, but it doesn't scratch deeply without some effort involved, and the shallow scratches and scuffs make a titanium light acquire a look that is more pleasant to my eye even than a brand new light with it's stock finish. My all time favorite finish is stonewash, which is nothing more than lot and lots of scuffs and scratches.

I think the scratches from daily use just add to its cool factor. I love worn Ti. One of the guys named it "pocketwashed" finish which describes it perfectly!

Yeah. :twothumbs

 

[js]

As I have now repeatedly explained, I disagreed with js's original wording. I had heard on this forum that titanium was not nearly as good as conducting heat as aluminum, so I looked up the numbers, and it seemed to bear that out. Although I still maintain the original quote was a bit misleading, I have since learned that it isn't really a big deal in practice, and that my wording was if anything more problematic. I'm sorry I was mistaken, but that is how I learn...if I never put my take on it out there, I wouldn't have learned that I was mistaken. No trolling involved.

Thanks to js and Don for EDUCATING me, without being condescending.

thedoc007,

I'm definitely going to change the wording to have more context and more details, so, I do agree that it should have been a little clearer. I guess I just (stupidly and unconsciously) assumed that people would be familiar with the calculations I did in my LunaSol 20 thread. Sorry about that! And, for the record, I never got the impression you were trolling. It certainly DOES look--from the numbers--like titanium is horrible for heat and electrical conductivity when compared to copper and aluminum. But, conductivity actually should be looked at on a log scale (powers of ten), like sound pressure levels or EM wavelength or sound frequency, etc. There are MANY powers of ten involved from an outright insulator to the best conductor, and everything is relative. Anyway . . . I will be updating the first post.

Everyone,

So, as mentioned above, I will be updating the first post of this thread to include all the good stuff that came up during the conversation so far, and also to clarify some of the points, etc. So, if there's anything else you think I should add or tweak or whatever, please chime in.

As for titanium scratching, yes, it definitely does scratch. It isn't that hard--which is why it's a horrible choice for a knife blade (except for a dive knife--salt water won't touch Ti)--but unlike some other metals or materials, when scuffed and scratched, titanium still looks good--like really good. It has a kind of "glow" or presence to it, both when in mint, perfect condition, and when in well-loved, long-carried condition. In the right light, you can see TONS of scratches in any titanium light that's been EDC'd for a time. So, in some B/S/T threads, if the seller is careless, he or she can make the light look like crap! But, in person, in most light, the flashlight will look great, even if its got tons of scratches. Finger oil and grime also don't really affect the look of a ti light--although I do think they detract from the feel of the light. (Stainless Steel on the other hand, looks bad with all sorts of finger marks on it. Or at least brushed stainless does.) And, as mentioned, it's pretty easy to polish or buff out those scratches in the titanium if you want. Any DEEP scratches would indeed detract from the light's appearance, I feel, and I personally would file / sand / brush / polish them out--whatever was appropriate.

The other thing to note, I think, is that titanium will stand up very well to drops. It's freaking tough stuff. That's why--IIRC--that there were titanium bezel rings offered before complete titanium lights. Hard Anodized Aluminum, OTO, doesn't fare nearly as well in a drop situation! To me, a hard used EDC HA Al light just starts to look a little aged and a little bad after a few years. But a titanium light will still look great, and if it doesn't, it can be made to look great again with a little elbow grease. That's a huge benefit over HA Al, I feel.

But, you know, it's all personal preference, and titanium certainly does make the light a LOT more expensive, and there are many really great aluminum lights out there. My purpose here was to try to explain why titanium might justify its high cost for some of us!

OK. Everyone please let me know if there's anything you'd like me to add / change / remove to the first post. I'll update it in the next week or so, if not sooner.

 

[js]

To confirm the real-world implications of JS's expert post above...I have a titanium Torchlab light running an OR Triple XP-G2 drop-in at 4.65A. The head gets jet-engine hot after a few minutes on high but the thermal safety protection has yet to kick in (at 65C) let alone the overheating protection (at 120C). As has been said already, the titanium can dump the heat fast enough. Even if it couldn't, electronic safeties are in place to protect the light and the user.

Great info! Thanks for posting this.

One other thing I thought I'd mention re: extreme situations, is that if you want a silver light, titanium is probably one of the best choices for radiative cooling. Even just bare, polished, machined, etc., it has an emittance of 0.2. Bare or silver anodized aluminum on the other hand is MUCH worse--what did I say above? 0.02 or something? Whatever, but much worse.

 

[scout24]

Bringing it down a few notches from the engineering discussion above, my main like for Ti is the lack of visible wear. When, on occasion, I drop my Haiku and find a ding big enough to bother me, a quick swipe or two with the file on my Leatherman makes all right with the world. The shiny spot oxidizes quickly, and you'd really have to look to find the offending spot.

 

[KITROBASKIN]

An 83 second video showing my love of titanium. The wedding ring has a very thin layer of industrial diamond coating (titaniumrings.com(?) out of Canada). After 4+ years of wear, it looks good. Had it buffed once, and it 'glowed' again but it is not necessary to appreciate.

 

[js]

OK everyone, I updated the first post in this thread to include all (or most) of the cool stuff we talked about in the ensuing discussion, and to fix a few errors and add a few references, and so on.

Please let me know if you think there is anything else that should be added or fixed or changed or whatever!

Thanks!

 

[Offgridled]

OK everyone, I updated the first post in this thread to include all (or most) of the cool stuff we talked about in the ensuing discussion, and to fix a few errors and add a few references, and so on.

Please let me know if you think there is anything else that should be added or fixed or changed or whatever!

Thanks!

That is one incredible write up. Very well thought out. Really appreciated reading this!!

 

[Policecar]

OK everyone, I updated the first post in this thread to include all (or most) of the cool stuff we talked about in the ensuing discussion, and to fix a few errors and add a few references, and so on.

Please let me know if you think there is anything else that should be added or fixed or changed or whatever!

Thanks!

The original post said "Only the so-called "superalloys" of steel have greater ultimate yield strength than the titanium alloys". This is confusing yield strength (the point where materials transition from elastic to plastic strain) and ultimate strength (the highest point on a stress-strain curve). Also, any ordinary high carbon steel can easily exceed the ultimate strength of titanium alloy which is about 1000MPa.

 

[js]

The original post said "Only the so-called "superalloys" of steel have greater ultimate yield strength than the titanium alloys". This is confusing yield strength (the point where materials transition from elastic to plastic strain) and ultimate strength (the highest point on a stress-strain curve). Also, any ordinary high carbon steel can easily exceed the ultimate strength of titanium alloy which is about 1000MPa.

Indeed. Good catch. I edited the first post.

 

[flashy bazook]

Indeed. Good catch. I edited the first post.

Thank you for the update, good info on titanium.

And I hope I am not out of turn, to say it's good to see you post here again! Always I admired your posts and the info you provided.