Best Flashlight Material

[Art Vandelay]

It depends. Most of the time the answer would be aluminum.

For no reason in particular, I'd like one made of titanium.

 

[LukeA]

Swing and a miss.....

I disagree. The quoted post (with image completely irrelevant to the thread!) is informationally useless.

As for the OP, 6000 and 7000 series Aluminum alloys seem to me to be the best compromise among thermal, electrical and physical properties. I can't think of a better performing material than aluminum alloy at any price point.

That said, they all need a good coating to improve emissivity and environment resistance.

 

[Marduke]

I disagree. The quoted post (with image completely irrelevant to the thread!) is informationally useless.

The originally quoted post had no picture. It was also quite informative in the respect that it demonstrated the "best material" for ANY device does not, and cannot ever exist.

However, that underlying meaning in the statement, obvious to most, was clearly too cerebral for others, hence the later "swing and a miss" comment. I attempted to instead post an "over your head" comment, but I could not easily find an accompanying picture.

 

[Sgt. LED]

 

[popcornpicker]

So then we all agree on an aluminum alloy with a Ti coating, right?

 

[StarHalo]

I think the bigger question is if that much more thermal conductivity over what we already have will make that big a difference - we know if you put an MC-E in a 6P host, the aluminum won't be enough to sink away the heat, so if we had a hypothetical Super-6P made from Kestrel's BeCu alloy or Gunner's "Club Sandwich" multi-layers-of-everything design, would it then wick away heat so much better that the MC-E could be driven hard indefinitely?

It just seems to me that there's only so much you can do thermally with a limited amount of an inert material before you have to move to active cooling, and a lot of our current emitter/host combos have crossed that line..

 

[DM51]

Unnecessary bickering aside, this is an interesting thread about materials. Kestrel, you obviously know quite a bit about alloys, and it's intersting to hear it.

I'm moving the thread to MMM.

 

[KC2IXE]

There isn't one "Best" material (well, except for unobtainium - and folks, it is a standard line, usually from a more Sr designer to some Jr kid, who makes a design that needs it)

Engineering is the art of "the tradeoff" Silver will give you great thermal and electrical conductivity, but will scratch/tarnish, and is somewhat expensive. Gold won't tarnish, is an OK electrical/thermal conductor, but keeps conducting. Ti is light, but is thermally poor, and will scratch. Berylium - hahahaha - yeah, that'd keep you happy for the rest of your fairly short life (Machining Be is done in sealed hoods). BeCu has it's good points. Carbon fibre - nice, light strong, but doesn't conduct, and is brittle

If you wanted to go exotic - it might be something like:
Carbon fibre Battery tube, with 7075 (or even 6061 or Ti) inserts on the ends for threads, a BeCu strip on the inside to conduct the electrons. Gold plate on the contact points on the points where the strips connect on both ends, a Al or Ti tail cap, the head being a sandwich of say Al and CU, or even Ti and CU, with the Cu heatsink exposed out to the edge of the head - or maybe instead of copper, Nickle Silver (actually a Cu alloy that has the advantage of haning it's tarnish being electrically conductive) - or, how about, Cu, and have the outside Gold Plated (or maybe Rhodium) to prevent tarnish? Oh - I know - PVD Diamond coat (Diamond actually is a great thermal conductor)

Is Manufacturing this beast going to be EASY? NO. Cheap, Hahahahaha.

Asking what the "best" material to make a flashlight out of is like saying "what is the best material to make a car out of?" - different parts want to be made from different things

 

[Blindasabat]

It is not necessarily true than an Auminum MC-E/P7 6P will not work. Material is not everything - design can make a big impact. Often with adequate finning, AL can transfer the heat away via convection. I did some calculations on that in a thread a month or so ago when I compared AL to copper. Conductivity made very little difference as long as you could move the heat out to the body of the FL & allow it to dissipate via convection. In that case AL won by being lighter & lower cost than copper for only a degree or two difference at the LED. A properly designed 6P sized light with adequate finning or thermal path to the holder's hand would do better than a stock 6P made of the same AL alloy. The stock "drop-in" design of the 6P is the biggest problem. Make a finned head with the LED AA to the head itself and thermal dissipation will increase significantly.

...we know if you put an MC-E in a 6P host, the aluminum won't be enough to sink away the heat...

The stock "drop-in" design of the 6P is the biggest problem. Make a finned head with the LED AA to the head itself and thermal dissipation will increase significantly.
Even though this thread is about material, I just want people to know that proper thermal path design is more significant and will make a bigger difference than changing material alone. Turboferret put a MC-E Malkoff in a redesigned AL headlight designed for LED drop-ins and it runs 3.5-4 amps with no problem for long times. And that actually has less aluminum because it is missing a battery tube, but it has some (minimal) finning.

Replacing the 6P head with a KL3, will also be far more efficient as the KL3 was designed for an LED while the 6P was not. IIRC some people have even put MC-E & P7 into KL3 with no problem, and even smaller KL1/KX1 (smaller than a 6P head) with little problem if not driven too hard.

 

[precisionworks]

I noticed there was limited info on some of the metals discussed so far after trying to search them.

The best source for commercially available metals information (IMO) is Metals Handbook Desk Edition. If you have a fat wallet & need the newest information, buy the most recent 2nd Edition for $286 (ISBN 0871706547). Many users, self included, find the 1st Edition very useful, and a bargain for around $50 if you shop the online book sellers (Alibris, AbeBooks, etc.). Look for ISBN 087170188x.

Other than Machinery's Handbook, nothing else in the shop is used more often. The information from a Google search is so limited, compared to the information in this book.

What is the best flashlight material?

The larger volume makers, like SureFire, buy their material in near net shape extrusions, which lowers both materials cost & machining cycle times. It wouldn't surprise me to see them use a PM (powdered metal) aluminum alloy, as PM can be custom blended to achieve almost any desired physical, mechanical & electrical property ... within the limits of the alloy itself. Alcan 76 is the PM version of Type 7075, both having high strength & hardness.

 

[Blindasabat]

Even though brass does not have thermal conductivity as high as AL or Copper, Malkoff makes a good drop-in with it because of superior thermal design (patent pending he says on his site). A Malkoff might run two degrees cooler made from Copper, but would cost more... like KC2IXE said, engineering is an educated & reasoned balancing of tradeoffs.

 

[Anglepoise]

For me it is no contest. Ti is the perfect material ( forgetting that it is very hard on the tooling used to machine it.)

It is strong, tough, and a thin tube holds up well. It looks great with a gray sheen and does not corrode (Aluminum ) or tarnish (Brass ). If after extensive use, it can be made to look like new again with a few minutes spent with a 'Scotchbrite pad'. It does NOT need any type of coating.

It's electrical properties are good as its 'oxide' is conductive. And the lack of heat transmission as a problem has become a non issue for most of the builders. Weight ?. As flashlights are thin tubes, weight becomes less of an issue with Ti. Everyone at some stage in their CPF membership should own a Ti light with a single light weigh lithium rechargeable CR123a battery.
The ultimate EDC.

 

[precisionworks]

It (Ti) does NOT need any type of coating.

Threaded, moving connections, like a twist head or a twist tail cap, are the one area that can benefit from a coating. Ti on Ti galling is well documented ... one website says this:

When titanium slides against titanium it tends to gall or stick more so than any other metal combination. Similarly, titanium to titanium parts in threaded combination "cold weld" making disassembly impossible without destroying the parts. In order to prevent this, typically dry film lubricants are applied over suitably prepared titanium (i.e. either anodized or conversion coated).

http://www.finishing.com/Library/titanium.html

 

[Marduke]

The best source for commercially available metals information (IMO) is Metals Handbook Desk Edition. If you have a fat wallet & need the newest information, buy the most recent 2nd Edition for $286 (ISBN 0871706547). Many users, self included, find the 1st Edition very useful, and a bargain for around $50 if you shop the online book sellers (Alibris, AbeBooks, etc.). Look for ISBN 087170188x.

Other than Machinery's Handbook, nothing else in the shop is used more often. The information from a Google search is so limited, compared to the information in this book.

MIL-HDBK-5J is an excellent source for metals information. It has been superseded by MMPDS04, but 5J is now available for free.

For a quick search MatWeb is also a useful source, but you must take the numbers with a grain of salt since they are usually commercial "typical" values and not statistical design allowables.

 

[Kestrel]

Even though brass does not have thermal conductivity as high as AL or Copper, Malkoff makes a good drop-in with it because of superior thermal design (patent pending he says on his site). A Malkoff might run two degrees cooler made from Copper, but would cost more...

BTW I asked Gene about the possibility of using an aluminum heatsink / drop-in body, but he says that he can't get the soldering good enough to get a good thermal path.

 

[Mick]

Aluminum alloy 7068 is a good choice for high strength as it is about 30% stronger than 7075. It does not form well so would be tough to knurl.
Here is a nice aluminum properties chart for quick reference. Note you can get 7068 from McM-Carr. And check 6020 for free machining.
http://www.mcmaster.com/#about-aluminum/=1ddc25

 

[tino_ale]

I have yet to see any serious thermal study which conclusion is that Aluminium is not good enough in a flashlight, as a heatsink. Taking the heat from the flashlight to it's environment is much more of a limitation than taking the heat away from the LED to the rest of the body.

About Ti galling, I have never experienced or heard about it on flashlights as long as you keep the threads at least a little lubed.

I vote for Ti