Type of aluminium to use for good machinability 2

[PatCouture]

Hi, I'm sorry for my lack of knowledge on the subject, but I would like to use a block of aluminium to build a little machine, I want aluminium that has good machinability properties and will be used in a corrosive environment (food processing). I don't know much about this material maybe I simply need the most common type of aluminium but I don't know what's the right number.

Thanks in advance

Patrick

 

[CoryPad]

For wrought alloys, try 3003, 3004, 5052, or 5182. For cast alloys, try 413 or 514. All of these alloys have good performance in food applications. They all should have adequate machining performance - you just need to work with your tooling supplier for appropriate parts and machine settings.

Regards,

Cory

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

 

[MintJulep]

Aluminum in a corrosive food processing environment seems like a bad idea, at least without a suitable protective coating.

Consider also the cleaning processes, not just the food.

 

[PatCouture]

The Aluminium won't be in direct contact with the food so even if it's not fully resistant to corrosion, at least it's better than Steel, easier to machine and a lightier than Stainless Steel that's why I want to use aluminium

MintJulep, you have a good point about the cleaning processes.

Thanks for the help

Patrick

 

[drawoh]

PatCouture,

The most popular machining grade aluminium is 6061-T6. 7075-T6 is used a lot in the aviation industry, but it is not as corrosion resistant. Either material can be delivered in large blocks suitable for CNC machining.

The 5XXX grades are more corrosion resistant, but these are usually punched out and welded. 5083 is sometimes called "shipping plate", so I assume it is very resistant to salts and such. The machine shop will think you are weird if you try to use this stuff. The material is harder to machine, and may not be available in thick blocks.

Anodizing provides good corrosion resistance, but not all grades are anodizable. 3XXX and utility grade aluminium cannot be anodized.

How corrosion resistant do you want to be, and what is going to corrode your machine?

JHG

 

[PatCouture]

Thanks guys

I need it to be corrosion resistant, because it will be washed every day, The machine will have to be approved by Agriculture Canada in order to be used in a food processing plant (pork processing) but the aluminium won't be in direct contact with the product so even if it's not absolutely corrosion resistant it's ok.

Patrick

 

[EdStainless]

The cleaning fluid will eat the Al up. Try to use a 5XXX alloy, it may be tough to work with but the corrosion resistance will be worth it. You might consider clear coating the part with a good urethane when you are done.
Using 316L SS would be a better choice in the long run.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[PatCouture]

Hi Ed, I absolutely agree with you on the fact that 316L SS would be better, but in this case even 304 SS is acceptable, so I'd rather have a material that is easily machinable and lightier

Patrick

 

[toolguy2000]

Hey I'm new to this forum but I've been doing this kind of thing for a while. I would suggest 6061-T6 for your part and follow it up with a hard anodize per MIL-A-8625, type 3, class I. I've used this in Sea water and in direct water contact. It is susepable to crevice corrosion if the anodize is scratched through to the base metal. I would not recomend, 2000 or 7000 series aluminums.