Oil Analysis

Particle Characteristics

• Most important parameters of the wear debris are:
• Extent of wear
• Quantity
• Texture / Hardness
• Color
• How wear is occurring
• Size
• Shape
• Composition

• The shape of wear particles can be classified into any of the following categories:
• Platelets (P)
• Ribbons (R)
• Chunks (C)
• Spheres (S)
• Heat Related Fused Particles (T)
• Abrasive Debris (A)
• Fretting Wear (F)
• Needles (N)
• Corrosion (oxidant product) (O)

Particle Characteristics

• Color
• Severity of the wear (and hence temperature involved) is indicated by particle color.
• Colors range from light straw → brown → purple → blue as the temperature progressively rises (from 230 °C to 300 °C).
• Brass or bronze (copper based alloys) show a deep red or green discoloration from tempering.
• Dark discoloration on the particle surface may indicate surface oxidation (corrosion).

• Size
• Four descriptions for categories of size classification may be used:
• Fine: <10 microns
• Small: 10-25 microns
• Medium: 25-60 microns
• Large: >60 microns

References

• Schalcosky, D.C. and Byington, C.S. "Advances in Real Time Oil Analysis". Practicing Oil Analysis Magazine. November 2000.
• Barnes, M. "Fourier Transform Infrared Spectroscopy". Practicing Oil Analysis Magazine. March 2002