White Fused Aluminum Oxide for Polishing Floating Oil Seals
Executive Summary
White fused aluminum oxide (WFA) is the industry-standard abrasive for achieving the mirror-finish sealing surfaces on floating oil seal rings. Its unique combination of hardness, purity, and fracture characteristics makes it indispensable for creating the atomically-flat, chemically-pure mating surfaces required for reliable sealing in extreme conditions.
1. Core Functions in the Polishing Process
| Function | Mechanism | Outcome |
|---|---|---|
| Micro-surgical Material Removal | Sharp, hard (Mohs 9) grains systematically shave micron-level peaks from the metal surface | Achieves nanometer-level flatness (<0.1μm deviation) essential for perfect contact |
| Mirror-Finish Generation | Sub-micron particles (W1.5) create “rolling burnishing” action rather than deep scratching | Produces Ra < 0.05μm surface finish with true specular reflection |
| Surface Purification | 99.5%+ Al₂O₃ purity eliminates iron/silicon contamination risks | Maintains chemically pristine metal-to-metal contact without embedded particles |
| Conformational Matching | During “lapping,” both rings wear into complementary curvature profiles | Creates uniquely matched sealing pairs with perfect geometric conformity |
2. Technical Specifications & Selection Guide
Critical Parameters:
Purity: >99.5% Al₂O₃ (lowest possible SiO₂, Fe₂O₃ content)
Grain Shape: Blocky, angular morphology for consistent cutting (not rounded)
Processing: Acid-washed and magnetically separated to remove impurities
Grit Size Selection Matrix:
| Application Stage | Recommended Grit | Particle Size (μm) | Purpose |
|---|---|---|---|
| Heavy Stock Removal | #600 / FEPA F | ~15 | Repairing deeply scored or pitted surfaces |
| Intermediate Finishing | W10-W14 | 7-10 | Establishing baseline flatness |
| Precision Polishing | W3.5-W5 | 3.5-5 | Achieving 90% of final finish |
| Mirror Finishing | W1.5-W0.5 | 0.5-1.5 | Final nanometer-level refinement |
3. Industry-Standard Application Protocol
Material Preparation:
Slurry Formulation (Most Common):
Base: WFAO powder (e.g., W1.5) + mineral oil/petroleum-based carrier
Concentration: 20-30% abrasive by weight
Optional additives: Stearic acid (1-2%) for anti-loading properties
Alternative Formats:
Pre-mixed commercial compounds (e.g., Loctite Clover, Hermes)
Water-based suspensions for washability
Grease-based pastes for manual applications
Step-by-Step Lapping Procedure:
Triple-Cleaning Protocol:
Ultrasonic clean in acetone (5 min)
Wipe with lint-free wipes soaked in isopropanol
Final inspection under bright light