Aluminum Material Callout on Drawing 1

[vc66]

This may be a very simple question, but I couldn't find anything on it. I am checking a drawing of a simple bracket made out of Aluminum 6061. The designer doesn't want a heat treatment, and as such, has listed them material as Al 6061. I don't think I've ever seen a drawing without a heat treatment callout for Aluminum, so I was wondering if this is correct, or if there is any specific way to put it on the drawing, that the aluminum doesn't require any treatment.

Any and all help is appreciated.

V

Mechanical Engineer
"When I am working on a problem, I do not think of beauty, but when I've finished, if the solution is not beautiful, I know it is wrong."

- R. Buckminster Fuller

 

[CheckerRon]

As a minimum, the alloy needs to state the temper by dash number. -T0 (0 temper) is the untempered state, but since -T6 is a common stock item, without need for subsequent tempering, I would consider that.

 

[KENAT]

Just listing 6061 would probably imply that any heat treat grade of 6061 was acceptable. As 6061-T6 is probably most common, that's what you'd likely end up with.

Is 6061-O what your designer actually intends?

Also, FYI I believe 6061 may naturally age to around T4 condition over time.

http://www.matsci.ucdavis.edu/MatSciLT/Other/Files/HT-Aluminum.pdf

http://www.matweb.com/search/DataSheet.aspx?bassnum=MA6010&n=1

KENAT, probably the least qualified checker you'll ever meet...

 

[ctopher]

If the call out is ALUM ALLOY 6061, the machinist is allowed to use any temper. But as CheckerRon pointed out, I would use ALUM 6061-T6, or whatever temper is req'd.

Chris
SolidWorks 08 0.0/PDMWorks 08
AutoCAD 06
ctopher's home (updated 10-07-07)
ctopher's blog

 

[ewh]

Pet Peeve time...
There is no such alloy as "ALUM ALLOY 6061". Alum is potassium aluminum sulfate KAl(SO4)2·12H2O or an ammonium aluminum sulfate NH4Al(SO4)2·12H2O used especially as an emetic and as an astringent and styptic. Way too soft for machining
I know that this is nit-picking, but it is a very simple matter to use the CORRECT abbreviation. A drawing should be able to be read literally without assumptions, and using ALUM as an abbreviation is an assumption that the reader will know to actually use aluminum, as remote as that possibility may be.

 

[KENAT]

Well for that matter isn't it Aluminium;-)

I thought I was the only one that got upset by incorrect abbreviations.

vc66, Is using 6061 without heat treat driven by function?

KENAT, probably the least qualified checker you'll ever meet...

 

[ctopher]

I agree ewh.
I don't have all abbrev memorized. For forum's sake, I use whatever is on top of my head or what the poster is using. It is up to the engineer questioning to find the proper abbrev, and I'm not going to look it up unless the question is asked.

Chris
SolidWorks 08 0.0/PDMWorks 08
AutoCAD 06
ctopher's home (updated 10-07-07)
ctopher's blog

 

[ewh]

I don't have to look that one up... I was pinged on it in my first detailing job (on the board) and it's stuck with me.

As to the other posts, I agree. If only AL 6061 is called out, that leaves the door open to use any temper of 6061.

 

[drawoh]

vc66,

Why not just call up ALUMINIUM, and forget the alloy?ALUMINIUM 6061-0 has a yield stress of 8000psi. It is not much stronger than ALUMINIUM 1000. A fabricator probably would prefer to machine heat treated 6061. If he is doing sheet metal, he will prefer 1000 or 5052.

I agree with the idea that we should not specify things that are not necessary, but let us take it to its logical conclusion.

JHG

 

[vc66]

The intent of the bracket isn't really load-bearing, just positional. Therefore, he doesn't care about strength. Seeing as though Al 6061-T6 is probably the most common, which I also believe we do stock, I'll tell him to use that, but thanks for all the replies.

Furthermore, I said Al (Elemental Name for Aluminum), so don't yell at me...





V

Mechanical Engineer
"When I am working on a problem, I do not think of beauty, but when I've finished, if the solution is not beautiful, I know it is wrong."

- R. Buckminster Fuller

 

[KENAT]

Ah, so I was mislead by your OP.

You said "The designer doesn't want a heat treatment" when it sounds as if you meant "The designer doesn't require any specific heat treatment".

In this case there are 2 schools of thought.

1. Just put Aluminum Alloy (or an approved abbreviation there-of;-)) as drawoh suggests.

This assumes the vendor/machine shop will use the 'cheapest' grade available and hence give you the best cost (note it may not actually be the cheapest grade, it may be some overstock material they have and want to get rid of etc.) Some argue that you're not properly specifying the part but I'm not sure that ASME Y14 series says anything about this (please let me know if it does).

2. Always specify a grade as otherwise the machine shop can pick and may deliberately choose high grade material they have on hand and charge you accordingly.

I have only heard point 2 at my current employer, never before. I tend to think it's kind of dumb but, because we don't competatively tender or really estimate most jobs it could happen and I doubt the purchasing director at the time just made it up.

In government work of course you usually have to put not only the grade but also the controlling spec on the drawing, at least in the UK we did.

KENAT, probably the least qualified checker you'll ever meet...

 

[vc66]

You're absolutely right, KENAT. Sorry about that. He didn't specify because he didn't care. I don't really have that mindset. I feel that if it's a low strength situation, you choose a low strength alloy. He's switched to using 6061-T6, as it's what we have in stock.

V

Mechanical Engineer
"When I am working on a problem, I do not think of beauty, but when I've finished, if the solution is not beautiful, I know it is wrong."

- R. Buckminster Fuller

 

[KENAT]

If it's a low strength situation, as you phrase it, then I'd suggest you specify the lowest cost/most readily available alloy. This doesn't always correspond to a low strength alloy.

Rule of thumb at my current employer is that when the material properties aren't too significant then spec 6061-T6 as it's perceived to be most readily available/lowest cost.

I did some limited research on this a while back and there were aluminum grades that appeared to be cheaper in theory than 6061-T6. However unless you were using large enough quantities to buy direct from the mill then 6061-T6 seemed a better choice as it's more ready availability led to it being less expensive in practice.

I just realized I don’t know if annealed 6061 is –0 (number) or –O (letter) anyone know, or I guess I could ask over in materials.


KENAT, probably the least qualified checker you'll ever meet...

 

[MadMango]

It's "O" as in oyster.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[KENAT]

Thanks Mad, that was what I thought originally but then my google searches kept turning up zeros.

KENAT, probably the least qualified checker you'll ever meet...

 

[MadMango]

Machinery's Handbook (p558 25th ed)

Basic temper designations consist of letters. Subdivisions of the basic tempers, where required, are indicated by one or more digits following the letter.

In the case of the OP, "F" might have been valid as well, though I've never seen it on a drawing.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[looslib]

Slightly off topic, but has anyone considered using the UNS number system for materials and calling out the UNS number on the print. I think the different tempers of Aluminum 6061 each have their own UNS number.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[KENAT]

No one round here would understand it.

To us UNS is a special unified thread.

6061-T6 they know.

KENAT, probably the least qualified checker you'll ever meet...

 

[CheckerRon]

At my current job (out of commercial and back into aerospace)we use a lot of SAE AMS callouts in lieu of the old Mil specs, e.g. AMS QQ-A-250/11 for AL 6061-T651. It seems to me that UNS material numbers are only understood by M&P engineers and a few engineers and designers that are into exotic materials.

For looslib: Regarding your tag line about wildfires, do you perchance work in Pro/E Wildfire?

 

[fcsuper]

I believe that using a specification of a standard would be helpful, if the composition of the material is vital. However, for normal use where someone doesn't even care if the material is -T0 or -T6, I cannot imagine how it would be important and may even border on over specification.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
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