1. Introduction
A “radial oilseal” or a “rotarylipseal” is commonlyusedto
preventleakageandreducefriction(Fig. 1). Thissealfamilykeeps
oil ontherotatingshaft,anddustparticlesoutside.Itconsistsofan
elastomeric lipbondedtoarigidcaseandagarterspringthat
compensates forchangesintherubberpropertiesduetoheatorto
chemical attacks.Typically,theinnerdiameterofthesealis
smaller thantheshaftouterdiametersothatwhenthesealis
installed, thelipcreatesastaticforceappliedtotheshaft.
A successfulrotarylipsealoperatesbyforminganoil film
between surfacesofthelipandtheshaft [1]. Indeed,thelip
asperities inducealoadsupportduetotherotatingshaftwhich
keeps thelipseparatedfromtheshaft.Inaddition,theseasperities
affect significantly thesealingmechanismand,namely,theleak-
age flowandfriction.
Accordingtotheliterature,theliproughnessproducesa
reversepumpingaction,whichtendstopumpaliquidfromthe
air-sideofthesealtowardtheliquid-side,opposedtotheleakage.
This flowisstronglydependingontheliproughness [2] or micro-
undulations [3,4] and thelipelasticity.Well-designedrotarylip