generic aluminum material callout

[Tmoose]

We have some components to make that are extremely low stress in a clean environment and are hidden from view.

I'd like to specify a low cost, machinable, readily available alloy on the drawings.

For many sizes of bar Mcmaster Carr bargain offering is "Multipurpose Aluminum (Alloy 6061)"

Is this description really recognized by industry?
If not, is there a good generic aluminum callout?

thanks,

Dan T

 

[CoryPad]

Sure, alloy 6061 is recognized in industry. While chemical composition is important (which is the only thing 6061 gives you), so is the heat treatment (also known as temper).

I would include this on a drawing:

Material: 6061-XX according to ASTM B ###

Where XX is the appropriate temper (O, T6, whatever)

and ### is 209 (for sheet and plate) or 211 (for bar, rod, wire).

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Tmoose]

Sorry for the confusion.

In these mundane cases I want to use an "open" spec rather than limit a shop to a particular alloy and temper if it adds procurement time, material expense or fab time and difficulty.

For instance, I hate to default to 6061 (fair machinability) on the drawing when a shop may have 2007,2011, 6020 (excellent machinability) in stock.

Actually some of Master's pricing suggests there are uncertified grades of 6061 are the price leader, and that's a powerful incentive to use it.

I may see if I can create a table or insert a note that lists several acceptable alloys and tempers.

 

[CoryPad]

Not to be brusque, but you won't find 2007, 2011 or 6020 at the machine shops you are considering. How are you going to design your component without specifying the temper? The difference in strength is 3:1 between annealed and artifically aged.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[sreid]

As you describe your application, specify 6061-T6 and be done with it.

 

[Tmoose]

"extremely low stress" - Mounting capacitors and circuit boards in an electrical enclosure set up for DIN rails. Main requirements are Gotta be thick enough to tap, and wide enough to pick up the several different bolt patterns.

For this application I would not hesitate to use any aluminum alloy, at any temper (or pine strapping, if it was reasonably tappable) . When components enforce abominably small screws I spec larger tap drills and lean heavily away from materials with less than excellent machinability. And as I am a cheap bastitch, and usually trying to get a project back on schedule, creating an open material spec that gives a shop broad latitude in material selection (when appropriate) without delaying quote and procurement by burning up time with phone calls, discussions, and debate looks like an easy way to cut 3 days off delivery time.

My strong personal and professional preference is to take full advantage of what's "in stock." When the line is long I order from amongst the prefabbed burgers that MacDonalds has sitting in the warming rack, and would never pass by the closeout racks at Home Depot or Walmart without looking and poking around.

 

[Kwan]

just call out 2024-t3 per qq-a-250/4 or qq-a-250/5

permissible to use any temper of material

permissible to use the following alternates: 6061 per blah blah, 5052 per, 5056, 7075, etc

just cover the bases

 

[MikeHalloran]

Where corrosion resistance and appearance is not an issue,
I'd spec just the 2024, which cuts much better than 6061.




Mike Halloran
Pembroke Pines, FL, USA

 

[ewh]

In this situation, we may call out 6061-T6 and add a note to the drawing stating that material substitution is permisssable with engineering permission. That way the shop can ask if whatever they have on hand is sufficient or purchasing can ask to order something else if there would be substantial savings.