GUIDE TO PRELIMINARY SEAL SYSTEM
FAILURE MODE ANALYSIS

SYMPTOM

POSSIBLE CAUSE

CORRECTIVE ACTION

Early seal leakage

Nicks, tears or cuts on seal lip

Rough shaft

Scratched or nicked shaft

Machine lead on shaft

Shaft run out

Seal cocked in bore

Paint on seal or shaft

Inverted lip

Dislodged spring

Deformed case

Remove burrs or sharp edges from shaft. Use assembly bullet to protect seal from splines, keyways and shoulders.

Finish should be 10 to 20 Ra.

Protect shaft at assembly.

Plunge grind shaft.

Locate seal closer to bearing.

Design proper installation tool.

Mask assembly before painting.

Lead-in chamfer should be no greater than 30 degrees and 32 Ra.
Use tapered assembly bullet.
Protect against power wash.

Use tapered bullet and installation tool. Apply even installation force.

Use correct assembly tool, apply even force. Protect seals prior to assembly.

Mid-life seal leakage

Lip wear

Lip hardening or cracking

Lip softening

Offset lip wear

Grooved shaft

Correct shaft finish, vent system leakage pressure, grease lips to prevent dry start up. Add internal lube to compound.

Check for elevated temperature or lack of lubrication. Use higher temperature compound or add internal lubrication.

Check fluid/compound compatibility.

Correct shaft to bore misalignment. Prevent cocked seal.

Shaft hardness minimum 30 Rc. Reduce lip load. Add internal lubrication to compound. Check for contamination.

Outside diameter leakage

Damaged seal OD

Deformed seal case

Tool marks on bore

Oversize bore

Prevent scored or burred bore. Bore finish 125 Ra. Correct chamfer. Installation tool to prevent cocked seal.

Use proper assembly tools and apply even load. Possible damage during seal transit or storage.

Use proper machining techniques.

Make to diameter recommendations in bore section of this website.