Delrin AF Rollers Squeaking

[GearsNsparks]

I have 1/4" OD x 0.1258 +0.0003/-0.0003" ID X 1.00" long rollers (material spec is Delrin AF) that are attached to a peristaltic pump head via 0.1250 +.0002/-0.0000".

Occasionally (1 out of 20) roller+dowel pin combinations will provide me with a periodic chirp/squeak as the pump head turns.

There is no lubricant applied to this process. Theoretically the 20% PTFE in the Delrin AF reduces friction enough during operation.

Is it expected that there will be occasional chirping/squeaking with this set up? Is there something I can do to minimize that effect?

 

[MikeHalloran]

The roller OD/ID ratio is too small. There may be enough friction between roller and hub that the friction between rollerOD and tube is not sufficient to overcome it, so the tube skids on the roller just a little, making a squeak.

Given that the pivot pins are fairly small, consider larger rollers.

With shorter rollers, you could get away with smaller pivot pins. Break open a tape cassette and see the corner rollers, of 6..8mm OD running on pivot pins ~<1mm dia.



Mike Halloran
Pembroke Pines, FL, USA

 

[GearsNsparks]

Thanks for the insight. I'll try some prototypes in the lab.