I am hoping someone can help me find a suitable sleeve bushing material for a product I am developing. I am having a heck of a time finding something that looks like it will wear well and be reliable.

I need a plain sleeve bushing that will be self lubricating and provide good life in a slow moving, intermittently oscillating application, where the bushing rocks back and forth very slowly and intermittently.

The bushing ID is 1/8" and the bushing OD is 3/16". I am using the bushing as a small cam-follower roller. The cam is rotated by hand via a small lever, so the motion is very slow and intermittent. However, the loads are fairly high for such a small bushing, and with the oscillating movement, and the fact that the bushing cannot be lubricated, I am worried about wear. I want the product to be maintenance free and provide years of service.

The maximum load on the bushing will be 7,168 PSI, plus I guess I should have some type of small safety factor. The average sweep angle will be about 9 degrees, at an average speed of about 1 to 3 Hz. I think the average surface speed would be 0.2 to a maximum of 0.4 FPM. The device will always be operated at room temperature, and be in a very clean household environment with no dust or dirt. There is also no chemical exposure. The bushing will rotate on a hardened dowel pin meeting ASME B18.8.2 standards, I can either use plain ground finish, or black oxide finish. I could also go with a 303 stainless shaft if needed. In this application as a cam-follower, the bushing oscillates on a stationary shaft. I could put a small amount of lube on the bushing at assembly, but never again after that point.

The motion will always last for only a few seconds and then stop. It may last 1-3 seconds on average, say two or three times per minute, and then the rest the time the device is at a standstill, with a static load on the bushing, of about 4,266 PSI, which could also be considered the “average” bushing load, but the maximum will be 7,168 PSI. The load changes as the cam is rotated. It might be used intermittently, for a "total" of about 36 minutes per day, ( i.e., the device is activated a few seconds at a time, a few times per minute, adding up to 36 minutes of total intermittent start / stop use, over the course of around 3 hours, each day).

I won’t need much running clearance, since the device always operates at room temperature, and since heat from friction will not be enough to cause any significant dimensional changes to the bushing, the speeds are too slow and intermittent. However, I would like to keep the maximum clearance between the bushing ID and the shaft at .004” or less. So, if I start out at a clearance of .003”, this only gives me .001” for wear. Maybe I could get away with .002” of wear for a maximum clearance of .005”, but I am not sure. Ideally, I need something that can provide years of service, with very low wear rates.

I tried some plastic bushings from www.igus.com, but found that they were so slippery, that there was sliding between the cam and the bushing OD. This caused the cam to wear a flat spot on the bushing OD. I then tried the "FB" series bushings from www.peerinc.com, but since they are a wrapped or spit bushing, it seems when the bushing seam lines up with the cam, the cam spreads the bushing apart at the seam. Plus the seam causes a little noice, and bumpiness.

I thought of pressing the above mentioned bushings into a steel tube, to solve the aforementioned problems, but then the bushing OD becomes about 1/4". I am working in such a confined space, that I cannot really make the cam any smaller at all, because the minimum radius of curvature becomes to small. Therefore, I really need to stay with a bushing that has a 3/16" OD.

I also thought of putting some “belt dressing” https://www.lpslabs.com/Products/Lubricants/Belt_Dressing.asp on the plastic bushing OD, to insure that the friction between the cam and roller OD is always greater than the friction between the roller ID & shaft, in order to eliminate sliding between the cam and bushing OD, but I just don’t know how long it would last, and I need the product to be maintenance free.

Since the plastic bushings seem to be to slippery on the OD, and I cannot press them into a metal tube to make the OD less slippery, since the OD will then be too big, I figure I must need some type of metal roller.

I have not been able to find a stock bushing that meets the requirements, so I am hoping someone can recommend a bushing material I can machine or fabricate the bushings from.

I am thinking of trying to use some 3/16" OD drill rod from www.mcmaster.com for this roller. It's held to close OD tolerance, and I can just cut to length and drill the center hole out. I could then lube it once, and put it in service.

Would drill rod provide both the needed load capacity and decent wear resistance ? Perhaps I can shoot for .001" or .002" running clearance, and then that will leave at least .002" for wear. Do you think I could get a decent service life ?

I will be using a standard 1/8" OD hardened dowel pin as the bushing shaft.

I can get the drill rod in A2, D2, M-2, 0-1, S-7,or W-1. Which grade would be best ? I am thinking of using W-1.

What type of lube would you recommend ? I can only lube once at assembly, and then never again. I guess the ideal lube would be a high pressure lube that is good for pivoting motion, and that will stay in place, and last. I also have to be careful not to get any on the bushing OD.

Would a dowel having a black oxide finish help at all, since black oxide has lubricating properties, and it could possibly help retain lube ?

Lastly, would this be just about as quiet as a standard bronze bushing ?

Please let me know what you guys think, I would appreciate any advice or comments from anyone. Perhaps someone at the forum has had experience with a steel bushing oscillating on a hardened shaft.

I would really appreciate any advice anyone might have.

Thanks for your help.