Wouldn't you like to see other Al. Alloys than 6061?

[tino_ale]

Hi all,

As far as I know, most of the aluminium machined flashlights are made from 6061 alloy... sometimes 6061-T6 which is heat treated.

While I totally understand this choice for low/middle priced flashlights, I am sometimes surprised that higher end models are not made from something more solid.

Expensive models and/or expensive custom torches are most of the time 6061 alloy too. You get 6061 T-6 if you're lucky. Don't get me wrong, 6061-T6 has good properties, but it's certainly not the best you can get. But when I see flashlights with to-be-released led bins, super-hyper-efficient drivers, 2mm thick (or more) AR coated sapphire glass, top notch o-rings, silver coated springs... in the middle of all these refinements well I feel that 6061 alloy, even T6, is kind of at the low end of the material choice. For example, I'm surprised to see that ARCmania $800 SF V, a zero-compromise high end and refined limited model, is machined from 6061-T6 only. Just an example.

You can go for titanium, but the offering is very limited, and prices are so much higher. Titanium has it's niche.

I would like to see something in between. It's perfectly doable with 7075-T6 alloy for example. It is something like 40% higher in tensile and yield strenght compared to 6061-T6. 300% and 700% higher if you compare to simple 6061. Upgrading from 6061-T6 to 7075-T6 would be a significant change in terms of dings/scratch/bend/breakage resistance.

I think the Tiablos are made from 7075 alloy, but I don't even know if there are flashlights out there that are made from 7075-T6. 7075 is actually a little less strong than 6061-T6.

So... I am the only one here?? I have that feeling that people are extremely picky about led bins (a P4 WC cree is kinda outdated as of today...), reflectors, glass and many other things but not the alloy used. Why? Manufacturer advertise over and over that alloy used is "aerospace aluminium"... that is 6061. Do people think when they read "aerospace" it's the very best you can get?

Thanks for your thoughts.
Cheers

 

[scott.cr]

When a manufacturer chooses the material, it's choosing the set of compromises that suits them best; let's go with your example of a 7000 series aluminum over a 6000. The 7000 will be at a disadvantage for a rough-use light because it cannot undergo as much deformation as a 6000. Once you pass the elastic limit of the metal, its strength quickly and severely diminishes. Then there's thread gall and wear, ability to take a finish (7000 is difficult to finish unless it's a plated or spray-on finish). And of course, it takes longer to machine and thread 6000/7000 aluminums over, say, 2000 aluminums.

Look at Surefire's infamous "bulletproof 6P" ad. I'm sure a speeding bullet would have exceeded the elastic limit of a 7000 series aluminum as used in a flashlight, and the police officer carrying it may not have gotten back up to resume the fight. The (what I think is) 2011 Surefire uses gains in toughness what the 6 and 7000s have in tensile strength.

Once you look at a flashlight as a system that will see non-textbook use, its design considerations become a lot more than "which material in my bluebook has the highest tensile strength?"

 

[Buck91]

6061 and its variants has to be fairly sturdy as Trek uses it a lot for bicycle parts/frames...

 

[Flash_Gordon]

I guess it somewhat depends on how much more you want your lights to cost with no real gain in quality, durability or utility.

Harder material requires more expensive and shorter lived machine tools. This cost will pass directly to the price of the light.

As scott.cr pointed out, there are added disadvantages. 7000 series aluminum is more brittle and might be more inclined to break rather than distort unless it is originally machined thicker and heavier.

Maybe more importantly to most of us, the harder aluminums to not take finish nearly as well. 6000 series aluminum are much easier to anodize and give us more choices in color.

7000 series aluminum is better suited for some applications but not necessarily for flashlights. It could just be over engineering without any gain.

Mark

 

[Marduke]

For those of you who would like to know:

6061-T6 specs
7075-T6 specs

6061-T6 is slightly more fracture resistant/less brittle, but 7075-T6 is superior is almost every other way. Cost is another matter altogether...

 

[tvodrd]

7075 T6/651 hard anodizes just fine, and the added strength helps reduce thread wear, especially with fine threads like my avatar.

Larry

 

[tino_ale]

The 7000 will be at a disadvantage for a rough-use light because it cannot undergo as much deformation as a 6000.

Unless some experts could confirm, I can't see how we could give a definite answer to the question : what is more important for "rough" use. Elasticity, tensile strentgh or yiels strength? As for dings, scratchs, thread wear, blemishes or other consequences of dropping a flashlight on concrete, I would intuitively say elasticity is not in play that much. I would like to do some tests about this but unfortunately I don't have the mean to do it.

6061 and its variants has to be fairly sturdy as Trek uses it a lot for bicycle parts/frames...

Which doesn't prove anything about the fact that 7075-T6 would or would not be superior for flashlight use. Bicycle frames are tubular structures, an entirely different subject. As I said 6061-T6 has good properties, the question is more can't mfgers/custom builders do better?

I guess it somewhat depends on how much more you want your lights to cost with no real gain in quality, durability or utility.

How are you so sure that there would not be any gain in real life? People want nothing else than HA-III now, there is a reason. They want durability against scratches and other blemishes. Don't you think 7075-T6 would be much better in that regard?

7000 series aluminum is better suited for some applications but not necessarily for flashlights. It could just be over engineering without any gain.

I think the idea that 6061-T6 aluminium is enough for a flashlight is totally acceptable. I do think "it's enough", after all a scratched/dinged/scratched/dinged flashlight can still fullfill it's purpose of illumination tool. But I don't think it is the best. But look at most of high-end/custom flashlights. Can you say they are not over engineered already? Most of them are advertised as "no-compromise", "ultimate", or "only the best for our customers" etc. In that regard, I'm surprised how we stick to 6061 that much.

The fact that the gain from 6061-T6 to 7075-T6 is not *needed* doesn't mean it's not there. High end flashlight often implement features which brings a gain that is not "needded", but because it's a no-compromise model, it's there.

I really wonder if the slick name "aerospace aluminium" given to a pretty soft alloy after all doesn't contribute to the fact that people think they get the best out there. I personnally find that my Al flashlights are too easily and too deeply damaged from a simple drop on the floor, even from a slight smack on a hard edge and so on. Things that happend often in everyday life.

Typically, I'd just like to see something between 6061-T6 and titanium in the flashlight offer. I'm surprised it looks like there is no demand for it, while anything that is not HA-III just won't sell (talking about high end models remember).

 

[Marduke]

I have yet to see a milled aluminum flashlight split in half from overstress. The 7075-T6 would not scratch or dent as easily, but that's what a good HA-III coating is for. Also, you would be less likely to strip the threads with 7075-T6. Either way, unless you are using the light as a hammer, the body with outlast both you and the electronics inside.

 

[Patriot]

Clearly the 7075 T-6 is superior in almost every area. My guess is that it's an issue of cost and availability. In the next few years we may see 7075 T-6 more frequently used in construction for our hobie. By then we will probably be asking why our lights aren't made from Weldalite 49-T8 or Kobe's new alloy. There is always a lag between what cutting edge industry is using and what is commonly available to the consumer.

 

[scott.cr]

My vote is for pure heat-treated unobtanium.

 

[elgarak]

Let's not forget that manufacturers have to machine it. A slight improvement in mechanical properties could result in huge increase in cost for the machining of large numbers of light, without much payoff for the end user (as already pointed out).

 

[Marduke]

My vote is for pure heat-treated unobtanium.

+1, or adamantium :twothumbs

 

[yellow]

glad to see there is always someone more crazed than oneself.
I'm a flashoholic, but I think I might possibly be cured
- You are lost
:nana:

 

[SCEMan]

I'd actually like to see flashlights with synthetic contact areas (non heat dissapating) to prevent marring, & scratching. It seems like my 6061-T6 flashlights are hard enough to damage about everything I accidently hit with them.

 

[DM51]

Very interesting thread, even for someone like me with little knowledge of metallurgy.

EDIT: Maybe it should be in the "Materials/Mechanical/Machining" section?

 

[tino_ale]

I've just noticed the Gotham is machined from 7075-T6 alloy, the front bezel ring being Grade 5 Ti.

http://www.lighthound.com/index.asp?PageAction=VIEWPROD&ProdID=2901

 

[sysadmn]

+1, or adamantium :twothumbs

I probably shouldn't mention this until the patents are filed, but I'm working on a few projects.

The first is a light made from an alloy of unobtanium and upsydaisium. I'm using it to make a light you can never buy, and never find if you do own one.

The second is a light made of heat-treated alloyed adamantium and upsydaisium. It flies around and kicks bad guys' butts!

 

[mudman cj]

Let's not forget that manufacturers have to machine it. A slight improvement in mechanical properties could result in huge increase in cost for the machining of large numbers of light, without much payoff for the end user (as already pointed out).

The data sheets on Matweb indicate a machinability index of 50% for 6061-T6 and 70% for 7075-T6. This seems to indicate that 7075-T6 is easier to machine than 6061-T6.

If 7075 is heat treated to temper T73 instead of T6, then the ductility is comparable to 6061-T6, which will of course improve impact resistance. Corrosion resistance is also improved while retaining increases in strength and hardness.

 

[tvodrd]

6061 T0 IMO, is a little "gummy" to machine- gives long continuous chips, which tend to wind-up on your workpiece. The T6 condition is a little better. 7075 T6 chips tend to break up and not clog things. I'll leave out things like cutter/chip breaker geometry, but at the end of the day, it's easier to machine!

Larry

 

[tino_ale]

For large manufacturers, even if "easier" to machine it may be more costy due to cutting tools requirements/wear. But for custom made or limited runs and offerings, it doesn't sound like an issue (some specialist could confirm).

A 7075-T6 D-cell mag with HA-III would be awesome. Unfortunately, nothing sound more unlikely than this considering Mag ability (or will or strategy) to evolve.