Magnetic Coupling through 0.8" 316 SS

[JoelGuelph]

Is it possible to have a magnetic coupling of a motor to a shaft through 0.800" 316SS? What would the torque limitation be?

We mfg. a 316SS vessel to process water, with an acme screw inside the chamber that performs a cleaning function. We are experiencing seal problems and the idea of magnetic coupling came up. Is this possible? Are there off the shelf solutions? Where can I find more info?

Thanks in advance for any help,

Joel

 

[sreid]

The answer is no the way you describe it. 0.8 inches is a long way for a magnetic field plus there will be eddy current issues due to the SS being electricly conductive.

If, however, you could have a plastic housing inside or outside the tank, you could make a really good magnetic coupling.

 

[JoelGuelph]

Is there a max thickness or maybe a thickness v. torque curve where stainless would be an acceptable medium for the 'gap'?

Is coupling through stainless steel impractical? An external SS housing may be practical for us, but plastic would be a challenge.

 

[MagMike]

I wouldn't recommend exceeding 1/4" thick in stainless steel. Coupling through stainless steel is possible, it was just 0.8" was too much to hope for. Eddy currents, as sreid mentioned, may still be an issue.

I'm not aware of any thickness vs. torque curve, I would estimate you might get 1 ft-lb of torque. How much torque is involved now?

 

[sreid]

Re: using plastic. Is the problem strength, temperature or chemical resistance or?

 

[Warpspeed]

What sort of diameter is this vessel ?

While I agree 0.8" is a huge distance, if the vessel is very large in diameter, it may be possible to transmit "some" torque, but probably not enough to be useful.

Much better to put a motor inside the vessel(air, hydraulic, or electrical) if you can possibly do it.