TERM-FERROUS-WEAR-DEBRIS
Ferrous Wear Debris
Contamination Mechanisms
Also: iron wear debris · wear iron · ferrous particles · PQ index · magnetic plug deposits · iron debris
Abbrev: PQ
Canonical Definition
Iron-based metallic particles generated by abrasive or adhesive wear of ferrous components — cylinder liners, camshafts, crankshafts, gear teeth, and pump internals — suspended in engine oil, gear oil, or hydraulic fluid. Ferrous debris is detected and quantified by three methods: spectrometric oil analysis (ASTM D5185/ICP-OES, effective for particles <10 µm), analytical ferrography and patch microscopy (particles >10 µm, reveals morphology and composition), and the Particle Quantifier (PQ) Index — a magnetic induction measurement proportional to total ferrous mass concentration regardless of particle size, including large non-spectratable particles that indicate severe wear.
Engineering Context
Ferrous wear debris trending over time is the primary condition indicator for heavy-duty engine and drivetrain health. A gradually increasing PQ index trend indicates normal wear-in; a sudden spike indicates an acute wear event requiring immediate component inspection. Silicon spikes on the same oil sample indicate air filter bypass as the wear source — airborne silica entering the engine becomes the abrasive responsible for iron generation. Interpreting ferrous debris data without concurrent silicon data is incomplete for root-cause diagnosis.
Protection Systems
Knowledge Center Articles
KC-00 Governance Metadata
| Permanent ID | TERM-FERROUS-WEAR-DEBRIS |
| Category | Contamination Mechanisms |
| Status | Published |
| Version | 1.0 |
| Last Reviewed | 2026-07-05 |