What kind of bearings would be best for salt water environment, specifically spherical bearings? I'm thinking stainless plain bearings. What do you think?
If you would provide more specific details about your bearing application it would be easier to give a better response. Information like loads, lifecycle, cost, etc would be very helpful. For example, a SiN spherical bearing with a PTFE liner would work quite well submerged in salt water, but its cost would be astronomical.
My question is vague though I am interested in vague answers. I have zero knowledge when it comes practices to selecting materials for this kind of thing.
To be more specific, in my application radial loads will be very minimal, axial thrust loads from 0-1000lb. RPM less than 100. Total cycles will be quite low and sporadic, but they will have to last for several weeks to months.
all too vague - if you want meaningful answers more application detail needed, if you want vague answers leave it as it is.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
Try looking at ORKOT bearings.
They used a lot for propeller and rudder shaft bearings in both fresh and salt water.
They very good PV ratings and can be custom made.
Erik3000:
It would seem that what you really want is a thrust bearing with some radial capacity, and that my not be a ball or spherical bearing. I would talk with one of the Reps. or the engineering depts. of several of the reputable U.S. bearing suppliers. I would not go to Harbor Freight or the like for these, because I think you need some knowledgeable engineering advice along with a part number and bearing type. There probably is also a lubricating system which keeps the bearing package full, that is, tends to exclude any seawater or other contaminants.
What kind of positional accuracy does this leadscrew need to provide?
I picture there is a bearing at each end of the lead screw and a nut that crawls back and forth in between.
Could you move the axially loaded bearing up above the water line?
Then some polymer bearing would probably work fine.
Is the screw and nut living in dirty water too?
Or, is the bearing down on the device being hauled up, or through the water? So the axial load must be applied therez?
Traditional leadscrew bearings are angular contact ball bearings stacked up to get the capacity needed.
Everything is submerged fully in the water. Accuracy is unimportant, it only has to stop at the ends. It will be on a stationary structure in the water but the nut on the screw will be pushing and pulling an externally supported load periodically, so the forces will be primarily axial on the screw. The bearings would be on either end of the screw, each one being pushed depending on which way the nut is moving the load.
