All Aluminum Everything

[Yianie123.]

I am struggling with that fact that my Stainless Steel rods are magnetic, but now I’m thinking will an all aluminum threaded rods, nuts and magnetic plate work?  It would be much lighter, corrosion free and dissipate the heat.  Will an all Ali Aluminum design work?  Right now, the main structure is aluminum withe the exception of the axial shaft.  Your comments are appreciated.

[JW]

Austenitic steels are non-magnetic stainless steels that contain high levels of chromium and nickel and low levels of carbon. Known for their formability and resistance to corrosion, austenitic steels are the most widely used grade of stainless steel.

use 316L and you shouldn't have any problems

[Adriaan Kragten]

If your stainless steel is magnetic, it doesn't contain enough nickel. It may contain only chromium. But the qualities AISI 303 and AISI 304 are non magnetic. AISI 316 and AISI 316L are also non magnetic but much more expensive as they contain other materials to make it sea water resistant. 

[Yianie123.]

Thank you for taking the time to reply.  What is your opinion on using aluminum?

[Adriaan Kragten]

The maximum allowable stress of most aluminium qualities is much lower than for stainless steel. Aluminium is also sensible for fatigue. So for a shaft in which you have fluctuating stresses I would never use aluminium except if you can make the diameter rather large.

[JW]

Fully Threaded Rod, 316 Stainless Steel, 4-40, 2 ft. Length Model: 44496
$2.75.$2.75Grainger Industrial Supply96% positive seller ratingCompare prices from 2 stores
Tensile Strength 70,000 psi, Rockwell Hardness Not Rated, Temp. Range Not Rated, Thread Class 2A, Yield Strength 30,000 psi
Other size options:  1 ft. Length · 3 ft. Length · More

this is what I go by for 316 stainless, Tensile Strength 70,000 psi  Yield Strength 30,000 psi, these are realistic numbers I use them with barlows formula

[Mary B]

That is typical 6061 T6 yield strength... aluminum will still have the same eddy current as stainless and I doubt you will see any cogging from the stainless. Even if it is magnetic it is not as magnetic as regular steel.

[richhagen]

If you have a conductor in a changing magnetic field, a current will be induced in the conductor.  Copper after all is not magnetic.  You are much better off with the stainless than aluminum.  Rich