GUIDE TO PRELIMINARY SEAL SYSTEM
FAILURE MODE ANALYSIS
Early seal leakage
Nicks, tears or cuts on seal lip
Scratched or nicked shaft
Machine lead on shaft
Shaft run out
Seal cocked in bore
Paint on seal or shaft
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 hardening or cracking
Offset lip wear
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
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.
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