trying to make an extremely low torque shaft seal

[skoobiz]

I am trying to make an extremely low torque (.02-.08 inch ounces) hydraulic swivel. The device needs to be able to swivel both clockwise and counter clockwise at very low rpm’s. The shaft size is .125” and the ID of the housing is .250” the pressure we are working with is about 50psi.we can seal the device but can’t get the torque low enough. We have tried several ways but just can’t seem to get it . Anybody got any thoughts as to how we can achieve this

 

[flexibox]

Do you have a drawing of what you actually have? This is a very small diameter seal arrangement and it would be nice to see what this looks like. First thing that comes to mind is using PTFE

 

[skoobiz]

Thanks for your response. I am attaching a drawing of one of the designs we have tried. The device we are designing drives a micromanipulator. it must be able to swivel to avoid tangling of the line. It will be going down the center of a Commutator (electronic swivel) which will be attached to a mouse with electrodes fastened to it. Used for studying neurological activity for use in prosthetic devices. Hence the low torque requirement.

 

[flexibox]

Can you explain which components are doing the sealing. Is Item 2 static and item 8 swivel to seal. sounds like you just need material selections. Peek material may be suitable, are the parts lapped?

 

[sreid]

Ferro Fluid Seals.

http://www.ferrotec.com/

 

[iainuts]

Are you sure it's a seal issue? I'm sure a typical seal will create the resistance you're referring to, but before going down the road of reducing seal resistance, have you tried removing the seal and with no pressure in the device, verified it can meet the criteria you already have for torque?