What's the hardest aluminum availible?

G

GarageBoy

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May 23, 2003
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Just curious, as 6061 seems to be a pain to machine, while, this unmarked harder stuff just flies off.
 
GarageBoy said:
Just curious, as 6061 seems to be a pain to machine, while, this unmarked harder stuff just flies off.
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WHAT??!! :eek:

6061 is my mainstay. Its a decent compromise between machinability and toughness. The harder aluminums are also less gummy, meaning your chips will actually peel off a lot like steel. Softer aluminums will machine really well, but also tend to adhere, or weld onto whatever cutting tools you are using unless you use a coolant setup. :)
 
My Maxnc doesn't have a coolant system, but can I still use the cutting oil? 6061 sans cutting oil is melting onto the bit unless I use a VERY slow feed rate.
Also, how does duraluminum compare?
 
Yep...machining aluminum can be a love-hate relationship. I can't say that there are any secrets....you just get a "feel" for it and it machines very nicely. The bigest thing....is that the chips tend to pack up and jamb everything. You need a lub to keep the chips slippery. There are a few tricks that make a big difference...but not applicacble to manual machines. Climb milling with lots of spindle speed (6000-10,000 rpm) will eject the chips in a rooster tail behind the end mill. It's cool to watch a CNC mill out a profile.

6061 is on the softer side of the scale......but the most popular by far!!

2024 is much harder....and 7071...is the hardest that I've used. Both make a better chip. On the other hand....I picked up some ballistic/armour stuff that was very weird! It was light weight like aluminum....but as soon as a cutting tool touched it....it gummed up on the tool like sticky chewing gum ...then broke the tool. I couldn't saw it, mill it, or drill it. The scrap metal dealer warned me when I bought it...and giggled when I returned the next day to sell it back to him.

I keep a trigger style spray bottle on the drill/mill to spritz a stream of lub/coolant on the work. Keep it close by and use it often.
 
GarageBoy said:
My Maxnc doesn't have a coolant system, but can I still use the cutting oil?
Click to expand...

Huh. I figured I was the only one around with a MaxNC. Cool.

Yes, you can still use cutting oil. (A friend who used to work at an aerospace job shop says kerosene also makes a good aluminum cutting coolant.)

You also might look into coolant misting systems for the Max. They're relatively cheap, more appropriate to the task than flood coolant, and some of the MaxNC units actually come with a power circuit for running them (so you can use M08 and M09 to turn the mist on and off). MSC and McMaster-Carr sell them, among others.

-Allin
 
Thanks, right now I have been applying lube directly to the piece and praying that it stays.
Also, since this is my first CNC, is there a book I can make the most out of it. I have NO idea how to turn a drawing into G Code and CAD CAM programs are PRICEY
 
You mite wan't to try alcohol. as the lub, works well on alu. and doesn't contaminate for welding, and adhessives. Nasa use's it with good results. I find 7075 withe a T-6 heat treat is very hard. Used a lot in easton arrow shafts. cant cut it with a file when properly heattreated to T-6 or T-7, and hard annodized Very easy to treat. takes a killer polish. No clouding.
 
GarageBoy said:
Thanks, right now I have been applying lube directly to the piece and praying that it stays.
Also, since this is my first CNC, is there a book I can make the most out of it. I have NO idea how to turn a drawing into G Code and CAD CAM programs are PRICEY
Click to expand...

Yes, they are, though some are more affordable than others. The best place I've found for MaxNC help is the MaxNC-users group on Yahoo. Lots of helpful people in there doing work at home with MaxNC machinery.

As for an actual book, it can never hurt to have a recent edition of Machinery's Handbook on hand (though it, too, is expensive). I can't help you much more than that; I learnt G-code on the job at a company that doesn't use CAM. The best books I found at that time were the manuals for the CNC controls. The Matsuura/Yasnac machines had especially helpful manuals.

-Allin
 
If you want some incredibly strong stuff you should look for a source of scandium-aluminum alloy like S&W uses in their newer aluminum frames:
http://firearms.smith-wesson.com/co...ontent/00/01/32/32/75/userdirectory50.content

By the way 6061 is a weldable grade of aluminum. It comes in various hardnesses (a function of how it is rolled I believe). I've used a lot of 6061-T6 grade in the past (T6 is pretty hard for aluminum). I think that T3 grade is also common.
 
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