Full definition
A radial lip seal installed in a bore that seals against a rotating shaft, retaining lubricant (oil or grease) inside and excluding external contaminants (dust, water, dirt). The seal consists of a metal case (stiffener, pressed into the bore), an elastomer body, and a precision-molded sealing lip that contacts the shaft with controlled interference pressure (typically 0.1-0.5 N/mm). A garter spring (coiled wire ring) behind the lip maintains contact force as the lip wears. Per ISO 6194, DIN 3760/3761 (dimensions and tolerances). Designation example: TC 40×62×8 = type TC (double lip — sealing + dust lip), 40 mm shaft diameter, 62 mm bore diameter, 8 mm width. Lip materials: NBR (standard, oil resistance to 100°C), FKM (high temperature to 200°C, aggressive chemicals), PTFE (highest speed, broadest chemical resistance, requires polished shaft). Shaft requirements: surface finish Ra 0.2-0.8 μm, hardness >45 HRC, no spiral machine marks (circumferential grinding only). Speed limit: 12-15 m/s for NBR, 20+ m/s for PTFE. Maximum pressure: 0.3-0.5 bar (standard lip seals are NOT pressure seals). Brands: NOK, Freudenberg (Simrit), SKF, Trelleborg, Parker. Per ISO 6194 and DIN 3760.