Surface Preparation for Radial Lip Seals

Type of Surface Preparation	Description / Comments
Plunge Grinding	The Grinding wheel is normal to the shaft axis at contact and does not traverse back and forth. The result is short to medium grinding marks that have little to no lead. This process can be relatively expensive but only needs to be performed in the seal contact region.Grade: A
Paper Polishing	his method is very affective if constant pressure is applied over the width of the emery cloth. Automatic equipment is more consistent than polishing by hand.Grade: B
Metal Peening	Small metal particles are impelled on the surface, imposing compressive stresses in the skin of the shaft. This is a secondary process that eliminates the potential of lead.Grade: B
Grit Blasting	Media such as sand is impelled onto the shaft as a secondary process. If correctly applied, machine lead can be eliminated.Grade: B
Tumbling	Method produces a uniform aggregate appearance and removes minor surface irregularities.Grade: C
Transverse Grinding	A centerless grinder is used as either the shaft or the wheel moves axially through the grind zone. This method can produce spiral grooves and can result in seal leakage.Grade: C
Roller Burnishing	This is a secondary process that uses rollers to compress the surface of the shaft. The shaft surface is only smoothed; lead and other defects remain.Grade: D
Honing	The resulting finish is a criss-crossing pattern that produces a pumping condition likely to cause seal leakage.Grade: F
Diamond Burnishing	In this process the media moves axially and does not remove machine lead, but instead makes it worse.Grade: F
Machine Turning	Machine turning will almost always generate lead and should be followed with a subsequent secondary operation.Grade: F