ASTM D7684-11(2016)
(Guide)Standard Guide for Microscopic Characterization of Particles from In-Service Lubricants
Standard Guide for Microscopic Characterization of Particles from In-Service Lubricants
SIGNIFICANCE AND USE
5.1 The objective of particle examination is to diagnose the operational condition of the machine sampled based on the quantity and type of particles observed in the oil. After break-in, normally running machines exhibit consistent particle concentration and particle types from sample to sample. An increase in particle concentration, accompanied by an increase in size and severity of particle types, is indicative of initiation of a fault. This guide describes commonly found particles in in-service lubricants, but does not address methodology for quantification of particle concentration.
5.2 This guide is provided to promote improved and expanded use of particulate debris analysis with in-service lubricant analysis. It helps overcome some perceived complexity and resulting intimidation that effectively limits particulate debris analysis to the hands of a specialized and very limited number of practitioners. Standardized terminology and common reporting formats provide consistent interpretation and general understanding.
5.3 Without particulate debris analysis, in-service lubricant analysis results often fall short of concluding likely root cause or potential severity from analytical results because of missing information about the possible identification or extent of damaging mechanisms.
5.4 Caution shall be exercised when drawing conclusions from the particles found in a particular sample, especially if the sample being examined is the first from that type of machine. Some machines, during normal operation, generate wear particles that would be considered highly abnormal in other machines. For example, many gear boxes generate severe wear particles throughout their expected service life, whereas just a few severe wear particles from an aircraft gas turbine oil sample may be highly abnormal. Sound diagnostics require that a baseline, or typical wear particle signature, be established for each machine type under surveillance.
SCOPE
1.1 This guide covers the classification and reporting of results from in-service lubricant particulate debris analysis obtained by microscopic inspection of wear and contaminant particles extracted from in-service lubricant and hydraulic oil samples. This guide suggests standardized terminology to promote consistent reporting, provides logical framework to document likely or possible root causes, and supports inference associated machinery health condition or severity based on available debris analysis information.
1.2 This guide shall be used in conjunction with an appropriate wear debris analysis sample preparation and inspection technique including, but not limited to, one of the following:
1.2.1 Ferrography using linear glass slides,
1.2.2 Ferrography using rotary glass slides,
1.2.3 Patch analysis using patch makers (filtration through membrane filters),
1.2.4 Filter debris analysis,
1.2.5 Magnetic plug inspection, or
1.2.6 Other means used to extract and inspect particulate debris from in-service lubricants.
1.3 This standard is not intended to evaluate or characterize the advantage or disadvantage of one or another of these particular particle extraction and inspection methods.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7684 − 11 (Reapproved 2016)
Standard Guide for
Microscopic Characterization of Particles from In-Service
Lubricants
This standard is issued under the fixed designation D7684; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This guide covers the classification and reporting of
D4130 Test Method for Sulfate Ion in Brackish Water,
results from in-service lubricant particulate debris analysis
Seawater, and Brines
obtained by microscopic inspection of wear and contaminant
D4175 Terminology Relating to Petroleum Products, Liquid
particles extracted from in-service lubricant and hydraulic oil
Fuels, and Lubricants
samples. This guide suggests standardized terminology to
D7416 Practice for Analysis of In-Service Lubricants Using
promote consistent reporting, provides logical framework to
a Particular Five-Part (Dielectric Permittivity, Time-
documentlikelyorpossiblerootcauses,andsupportsinference
Resolved Dielectric Permittivity with Switching Magnetic
associated machinery health condition or severity based on
Fields, Laser Particle Counter, Microscopic Debris
available debris analysis information.
Analysis, and Orbital Viscometer) Integrated Tester
1.2 This guide shall be used in conjunction with an appro-
D7596 Test Method for Automatic Particle Counting and
priate wear debris analysis sample preparation and inspection
Particle Shape Classification of Oils Using a Direct
technique including, but not limited to, one of the following:
Imaging Integrated Tester
1.2.1 Ferrography using linear glass slides,
D7647 Test Method for Automatic Particle Counting of
1.2.2 Ferrography using rotary glass slides,
Lubricating and Hydraulic Fluids Using Dilution Tech-
1.2.3 Patch analysis using patch makers (filtration through
niques to Eliminate the Contribution of Water and Inter-
membrane filters),
fering Soft Particles by Light Extinction
1.2.4 Filter debris analysis,
D7690 Practice for Microscopic Characterization of Par-
ticles from In-Service Lubricants by Analytical Ferrogra-
1.2.5 Magnetic plug inspection, or
phy
1.2.6 Other means used to extract and inspect particulate
G40 Terminology Relating to Wear and Erosion
debris from in-service lubricants.
2.2 ISO Standard:
1.3 This standard is not intended to evaluate or characterize
ISO11171 Hydraulicfluidpower–Calibrationofautomatic
the advantage or disadvantage of one or another of these
particle counters for liquids
particular particle extraction and inspection methods.
3. Terminology
1.4 The values stated in SI units are to be regarded as
3.1 Definitions:
standard. No other units of measurement are included in this
3.1.1 abrasive wear, n—wear due to hard particles or hard
standard.
protuberances forced against and moving along a solid surface.
1.5 This standard does not purport to address all of the
G40
safety concerns, if any, associated with its use. It is the
3.1.2 abrasion, n—wear by displacement of material caused
responsibility of the user of this standard to establish appro-
by hard particles or hard protuberances. D4175
priate safety and health practices and determine the applica-
3.1.3 break-in, n—see run-in. G40
bility of regulatory limitations prior to use.
3.1.4 fatigue wear, n—wear of a solid surface caused by
fracture arising from material fatigue. G40
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
mittee D02.96.06 on Practices and Techniques for Prediction and Determination of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Microscopic Wear and Wear-related Properties. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 1, 2016. Published November 2016. Originally the ASTM website.
approved in 2011. Last previous edition approved in 2011 as D7684 – 11. DOI: Available from International Organization for Standardization (ISO), 1, ch. de
10.1520/D7684-11R16. la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, www.iso.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7684 − 11 (2016)
3.1.5 fretting, n—in tribology, small amplitude oscillatory abrasive particles present between wearing surfaces of unequal
motion, usually tangential, between two solid surfaces in hardness; sometimes called cutting wear particles or ribbons.
contact.
3.2.2 analytical ferrography, n—technique whereby par-
3.1.5.1 Discussion—Here the term fretting refers only to the
ticles from an oil sample deposited by a ferrograph are
nature of the motion without reference to the wear, corrosion,
identified to aid in establishing wear mode inside an oil-wetted
orotherdamagethatmayensue.Thetermfrettingisoftenused
path of a machine.
to denote fretting corrosion and other forms of fretting wear.
3.2.3 chunks, n—free metal particles >5 µm with a shape
Usage in this sense is discouraged due to the ambiguity that
factor (major dimension to thickness ratio) of <5:1.
may arise. G40
3.2.4 contaminant particles, n—particles introduced from
3.1.6 fretting wear, n—wear arising as a result of fretting
(see fretting). G40 an extraneous source into the lubricant of a machine or engine.
3.1.7 lubricant, n—any material interposed between two
3.2.5 corrosive wear debris, n—usually, extremely fine
surfaces that reduces the friction or wear between them. D4175
partially oxidized particles caused by corrosive attack. Par-
ticles can become quite large in cases of extreme corrosion.
3.1.8 lubricating oil, n—liquid lubricant, usually compris-
ing several ingredients, including a major portion of base oil
3.2.6 debris, n—in tribology, solid or semi-solid particulate
and minor portions of various additives. D4175
matter introduced to lubricant through contamination or de-
3.1.9 rolling, v—motion in a direction parallel to the plane tached from a surface due to a wear, corrosion, or erosion
of a revolute body (ball, cylinder, wheel, and so forth) on a
process.
surface without relative slip between the surfaces in all or part
3.2.7 ferrograph, n—apparatus that magnetically separates
of the contact area. G40
and deposits wear and contaminant particles onto a specially
3.1.10 rolling contact fatigue, n—damage process in a
prepared glass microscope slide.
triboelement subjected to repeated rolling contact loads, in-
3.2.8 fibers, n—long, thin, nonmetallic particles.
volving the initiation and propagation of fatigue cracks in or
under the contact surface, eventually culminating in surface
3.2.9 filter debris analysis, n—in tribology, a process for
pits or spalls. G40 extracting and inspecting debris accumulated on the filter
media taken from an in-line circulating lubrication system.
3.1.11 run-in, n—in tribology, an initial transition process
occurring in newly established wearing contacts, often accom-
3.2.10 filter patch analysis, n—in tribology, a process using
panied by transients in coefficient of friction or wear rate, or
a filter patch maker to extract solid or semi-solid matter from
both,thatareuncharacteristicofthegiventribologicalsystem’s
a liquid and subsequently analyzing the extracted solid or
behavior. Syn. break-in and wear-in. G40
semi-solid matter.
3.1.12 rust, n—of ferrous alloys, a corrosion product con-
3.2.11 filter patch maker, n—in tribology, apparatus to
sisting primarily of hydrated iron oxides. D4175
extract solid or semi-solid matter from liquid by drawing a
3.1.13 sliding wear, n—wear due to the relative motion in volume of solid-containing-liquid through a filter patch having
the tangential plane of contact between two solid bodies. G40
pores of prescribed dimension sufficient to retain the solid or
semi-solid matter while allowing the liquid to pass through.
3.1.14 sludge, n—precipitate or sediment from oxidized
mineral oil and water. D4130
3.2.12 normal, n—in a five level severity ranking, a one-of-
five relative severity rating commonly associated with undam-
3.1.15 spalling, n—in tribology, the separation of macro-
aged or as-new condition having reasonable wear or expected
scopic particles from a surface in the form of flakes or chips,
operational condition; see also low alert, high alert, low fault,
usuallyassociatedwithrollingelementbearingsandgearteeth,
and high fault severity conditions.
but also resulting from impact events. G40
3.1.16 three-body abrasive wear, n—form of abrasive wear
3.2.13 low alert, n—in a five level severity ranking,a
in which wear is produced by loose particles introduced or two-of-five level relative severity commonly associated with
generated between the contacting surfaces.
some deterioration from normal condition, however interven-
3.1.16.1 Discussion—In tribology, loose particles are con- tion is not yet recommended; see also normal, high alert, low
sidered to be a “third body.” G40
fault, and high fault severity ranking.
3.1.17 two-body abrasive wear, n—form of abrasive wear in
3.2.14 high alert, n—in a five level severity ranking,a
whichthehardparticlesorprotuberancesthatproducethewear
three-of-five level relative severity commonly associated with
of one body are fixed on the surface of the opposing body. G40
significant deterioration from normal condition closely ap-
proachingneedforintervention;seealso normal, low alert, low
3.1.18 wear, n—damagetoasolidsurface,usuallyinvolving
fault, and high fault severity ranking.
progressive loss or displacement of material, due to relative
motion between that surface and a contacting substance or
3.2.15 low fault, n—in a five level severity ranking,a
substances. D4175, G40
four-of-fiverelativeseveritycommonlyassociatedwithsignifi-
3.2 Definitions of Terms Specific to This Standard: cant deterioration from alert condition, and intervention is
3.2.1 abrasive wear particles, n—longwire-likeparticlesin recommended now; see also normal, low alert, high alert,
the form of loops or spirals that are generated due to hard, andhigh fault severity ranking.
D7684 − 11 (2016)
3.2.16 high fault, n—in a five level severity ranking,a a result of sliding and they frequently have straight edges.
five-of-five relative severity commonly associated with signifi- Their major dimension-to-thickness ratio is approximately
cant deterioration from alert condition, and intervention is both 10:1.
recommended and overdue; see also normal, low alert, high
3.2.29 severe wear particles, n—in tribology, free metal
alert, and low fault severity ranking.
particles >15 µm with major dimension-to-thickness ratios
3.2.17 magnetic plug inspection—process for inspecting between 5:1 and 30:1.
and, if necessary, extracting ferrous alloy debris from in-
3.2.30 spheres, n—in tribology, metal spheres may be the
service lubricants using a magnetic object placed in the oil
result of incipient rolling contact fatigue or they may be
compartment, typically associated with a drain plug.
contaminant particles from welding, grinding, coal burning,
and steel manufacturing. Spheres may also be caused by
3.2.18 nonmetallic particles, n—in tribology, particles com-
electro-pitting.
prised of compounds, organic material, sand, dirt, glasses, and
so forth, that often demonstrate some element of translucence
3.2.31 wear particles, n—particles generated from a wear-
under microscopic backlight.
ing surface of a machine.
3.2.19 platelets, n—flat metal particles with a length more-
4. Summary of Guide
or-less equal to their width, and a major dimension-to-
thickness ratio in the range of approximately 5:1 to 10:1 or
4.1 Periodic in-service lubricant samples are collected from
more (see rolling contact fatigue particles).
a machine as part of a routine condition monitoring program.
3.2.20 red oxide particles, n—rust particles present as poly- The sample is prepared to separate particles from the sample
crystalline agglomerates of Fe O appearing orange in re- fluid. The separated particles are subsequently examined using
2 3
flected white light. These are usually due to water in the an optical microscope to identify the types of particles present
lubricating system. to aid in identifying the wear mode occurring in the oil-wetted
path of the machine.
3.2.21 reworked particles, n—large, very thin, free metal
particles often in the range of 20 to 50 µm in major dimension 4.2 In usual practice of a routine condition monitoring
with the frequent occurrence of holes consistent with the
program, particle separation and examination is not done for
explanation that these are formed by the passage of a wear every sample taken, but may be done when routine tests such
particle through a rolling contact.
as spectrometric analysis, particle counting, or ferrous debris
monitoring indicate abnormal results.
3.2.22 ribbons, n—see abrasive wear particles.
4.3 This guide is to be used with a sample preparation
3.2.23 rolling contact fatigue particles, n—flat platelets,
method that extracts particulate debris from in-service lubri-
with a length more-or-less equal to their width, with smooth
cant systems for subsequent microscopic examination.
surfaces, random, jagged and irregularly shaped
circumferences, and a major dimension-to-thickness ratio in
4.4 The user of this guide should employ consistent termi-
the range of approximately 5:1 to 10:1 or more.
nology to achieve accepted and understandable interpretations
when communicating instructions and findings based on par-
3.2.24 rolling contact fatigue wear, n—in tribology, fatigue
ticle analysis.
wear caused by loaded rolling contact typically between roller
and race in bearings or between gear teeth in the vicinity of the
4.5 Aprocessissuggestedinstandardizedformattoidentify
pitch line, typically forming spall-type pitting and releasing
and further classify multiple distinct groups of particulate
rolling contact fatigue particles (see 3.2.23); also called rolling
debris extracted from an in-service machinery lubricating
fatigue wear or subsurface spalling.
sample.
3.2.25 rubbing wear particles, n—particles generated as a
4.6 A grid format is suggested in which the user of this
result of sliding wear in a machine, sometimes called mild
guide can present findings and report possible root causes
adhesive wear. Rubbing wear particles are free metal platelets
along with an assessment of associated machinery health
with smooth surfaces, from appro
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7684 − 11 D7684 − 11 (Reapproved 2016)
Standard Guide for
Microscopic Characterization of Particles from In-Service
Lubricants
This standard is issued under the fixed designation D7684; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide covers the classification and reporting of results from in-service lubricant particulate debris analysis obtained by
microscopic inspection of wear and contaminant particles extracted from in-service lubricant and hydraulic oil samples. This guide
suggests standardized terminology to promote consistent reporting, provides logical framework to document likely or possible root
causes, and supports inference associated machinery health condition or severity based on available debris analysis information.
1.2 This guide shall be used in conjunction with an appropriate wear debris analysis sample preparation and inspection
technique including, but not limited to, one of the following:
1.2.1 Ferrography using linear glass slides,
1.2.2 Ferrography using rotary glass slides,
1.2.3 Patch analysis using patch makers (filtration through membrane filters),
1.2.4 Filter debris analysis,
1.2.5 Magnetic plug inspection, or
1.2.6 Other means used to extract and inspect particulate debris from in-service lubricants.
1.3 This standard is not intended to evaluate or characterize the advantage or disadvantage of one or another of these particular
particle extraction and inspection methods.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D4130 Test Method for Sulfate Ion in Brackish Water, Seawater, and Brines
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D7416 Practice for Analysis of In-Service Lubricants Using a Particular Five-Part (Dielectric Permittivity, Time-Resolved
Dielectric Permittivity with Switching Magnetic Fields, Laser Particle Counter, Microscopic Debris Analysis, and Orbital
Viscometer) Integrated Tester
D7596 Test Method for Automatic Particle Counting and Particle Shape Classification of Oils Using a Direct Imaging Integrated
Tester
D7647 Test Method for Automatic Particle Counting of Lubricating and Hydraulic Fluids Using Dilution Techniques to
Eliminate the Contribution of Water and Interfering Soft Particles by Light Extinction
D7690 Practice for Microscopic Characterization of Particles from In-Service Lubricants by Analytical Ferrography
G40 Terminology Relating to Wear and Erosion
2.2 ISO Standard:
ISO 11171 Hydraulic fluid power – Calibration of automatic particle counters for liquids
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.96.06 on Practices and Techniques for Prediction and Determination of Microscopic Wear and Wear-related Properties.
Current edition approved Jan. 1, 2011Oct. 1, 2016. Published March 2011November 2016. Originally approved in 2011. Last previous edition approved in 2011 as
D7684 – 11. DOI: 10.1520/D7684–11.10.1520/D7684-11R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, www.iso.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7684 − 11 (2016)
3. Terminology
3.1 Definitions:
3.1.1 abrasive wear, n—wear due to hard particles or hard protuberances forced against and moving along a solid surface. G40
3.1.2 abrasion, n—wear by displacement of material caused by hard particles or hard protuberances. D4175
3.1.3 break-in, n—see run-in. G40
3.1.4 fatigue wear, n—wear of a solid surface caused by fracture arising from material fatigue. G40
3.1.5 fretting, n—in tribology, small amplitude oscillatory motion, usually tangential, between two solid surfaces in contact.
3.1.5.1 Discussion—
Here the term fretting refers only to the nature of the motion without reference to the wear, corrosion, or other damage that may
ensue. The term fretting is often used to denote fretting corrosion and other forms of fretting wear. Usage in this sense is
discouraged due to the ambiguity that may arise. G40
3.1.6 fretting wear, n—wear arising as a result of fretting (see fretting). G40
3.1.7 lubricant, n—any material interposed between two surfaces that reduces the friction or wear between them. D4175
3.1.8 lubricating oil, n—liquid lubricant, usually comprising several ingredients, including a major portion of base oil and minor
portions of various additives. D4175
3.1.9 rolling, v—motion in a direction parallel to the plane of a revolute body (ball, cylinder, wheel, and so forth) on a surface
without relative slip between the surfaces in all or part of the contact area. G40
3.1.10 rolling contact fatigue, n—damage process in a triboelement subjected to repeated rolling contact loads, involving the
initiation and propagation of fatigue cracks in or under the contact surface, eventually culminating in surface pits or spalls. G40
3.1.11 run-in, n—in tribology, an initial transition process occurring in newly established wearing contacts, often accompanied
by transients in coefficient of friction or wear rate, or both, that are uncharacteristic of the given tribological system’s behavior.
Syn. break-in and wear-in. G40
3.1.12 rust, n—of ferrous alloys, a corrosion product consisting primarily of hydrated iron oxides. D4175
3.1.13 sliding wear, n—wear due to the relative motion in the tangential plane of contact between two solid bodies. G40
3.1.14 sludge, n—precipitate or sediment from oxidized mineral oil and water. D4130
3.1.15 spalling, n—in tribology, the separation of macroscopic particles from a surface in the form of flakes or chips, usually
associated with rolling element bearings and gear teeth, but also resulting from impact events. G40
3.1.16 three-body abrasive wear, n—form of abrasive wear in which wear is produced by loose particles introduced or generated
between the contacting surfaces.
3.1.16.1 Discussion—
In tribology, loose particles are considered to be a “third body.” G40
3.1.17 two-body abrasive wear, n—form of abrasive wear in which the hard particles or protuberances that produce the wear
of one body are fixed on the surface of the opposing body. G40
3.1.18 wear, n—damage to a solid surface, usually involving progressive loss or displacement of material, due to relative motion
between that surface and a contacting substance or substances. D4175, G40
3.2 Definitions of Terms Specific to This Standard:
3.2.1 abrasive wear particles, n—long wire-like particles in the form of loops or spirals that are generated due to hard, abrasive
particles present between wearing surfaces of unequal hardness; sometimes called cutting wear particles or ribbons.
3.2.2 analytical ferrography, n—technique whereby particles from an oil sample deposited by a ferrograph are identified to aid
in establishing wear mode inside an oil-wetted path of a machine.
3.2.3 chunks, n—free metal particles >5 μm with a shape factor (major dimension to thickness ratio) of <5:1.
3.2.4 contaminant particles, n—particles introduced from an extraneous source into the lubricant of a machine or engine.
3.2.5 corrosive wear debris, n—usually, extremely fine partially oxidized particles caused by corrosive attack. Particles can
become quite large in cases of extreme corrosion.
3.2.6 debris, n—in tribology, solid or semi-solid particulate matter introduced to lubricant through contamination or detached
from a surface due to a wear, corrosion, or erosion process.
3.2.7 ferrograph, n—apparatus that magnetically separates and deposits wear and contaminant particles onto a specially
prepared glass microscope slide.
D7684 − 11 (2016)
3.2.8 fibers, n—long, thin, nonmetallic particles.
3.2.9 filter debris analysis, n—in tribology, a process for extracting and inspecting debris accumulated on the filter media taken
from an in-line circulating lubrication system.
3.2.10 filter patch analysis, n—in tribology, a process using a filter patch maker to extract solid or semi-solid matter from a
liquid and subsequently analyzing the extracted solid or semi-solid matter.
3.2.11 filter patch maker, n—in tribology, apparatus to extract solid or semi-solid matter from liquid by drawing a volume of
solid-containing-liquid through a filter patch having pores of prescribed dimension sufficient to retain the solid or semi-solid matter
while allowing the liquid to pass through.
3.2.12 normal, n—in a five level severity ranking, a one-of-five relative severity rating commonly associated with undamaged
or as-new condition having reasonable wear or expected operational condition; see also low alert,high alert,low fault, and high
fault severity conditions.
3.2.13 low alert, n—in a five level severity ranking, a two-of-five level relative severity commonly associated with some
deterioration from normal condition, however intervention is not yet recommended; see also normal,high alert,low fault, and high
fault severity ranking.
3.2.14 high alert, n—in a five level severity ranking, a three-of-five level relative severity commonly associated with significant
deterioration from normal condition closely approaching need for intervention; see also normal,low alert,low fault, and high fault
severity ranking.
3.2.15 low fault, n—in a five level severity ranking, a four-of-five relative severity commonly associated with significant
deterioration from alert condition, and intervention is recommended now; see also normal,low alert,high alert, andhigh fault
severity ranking.
3.2.16 high fault, n—in a five level severity ranking, a five-of-five relative severity commonly associated with significant
deterioration from alert condition, and intervention is both recommended and overdue; see also normal,low alert,high alert, and
low fault severity ranking.
3.2.17 magnetic plug inspection—process for inspecting and, if necessary, extracting ferrous alloy debris from in-service
lubricants using a magnetic object placed in the oil compartment, typically associated with a drain plug.
3.2.18 nonmetallic particles, n—in tribology, particles comprised of compounds, organic material, sand, dirt, glasses, and so
forth, that often demonstrate some element of translucence under microscopic backlight.
3.2.19 platelets, n—flat metal particles with a length more-or-less equal to their width, and a major dimension-to-thickness ratio
in the range of approximately 5:1 to 10:1 or more (see rolling contact fatigue particles).
3.2.20 red oxide particles, n—rust particles present as polycrystalline agglomerates of Fe O appearing orange in reflected white
2 3
light. These are usually due to water in the lubricating system.
3.2.21 reworked particles, n—large, very thin, free metal particles often in the range of 20 to 50 μm in major dimension with
the frequent occurrence of holes consistent with the explanation that these are formed by the passage of a wear particle through
a rolling contact.
3.2.22 ribbons, n—see abrasive wear particles.
3.2.23 rolling contact fatigue particles, n—flat platelets, with a length more-or-less equal to their width, with smooth surfaces,
random, jagged and irregularly shaped circumferences, and a major dimension-to-thickness ratio in the range of approximately 5:1
to 10:1 or more.
3.2.24 rolling contact fatigue wear, n—in tribology, fatigue wear caused by loaded rolling contact typically between roller and
race in bearings or between gear teeth in the vicinity of the pitch line, typically forming spall-type pitting and releasing rolling
contact fatigue particles (see 3.2.23); also called rolling fatigue wear or subsurface spalling.
3.2.25 rubbing wear particles, n—particles generated as a result of sliding wear in a machine, sometimes called mild adhesive
wear. Rubbing wear particles are free metal platelets with smooth surfaces, from approximately 0.5 to 15 μm in major dimension
and with major dimension-to-thickness ratios from about 10:1 for larger particles to about 3:1 for smaller particles. Any free metal
particle <5 μm is classified as a rubbing wear particle regardless of shape factor unless it is a sphere.
3.2.26 scoring, n—in tribology, a consequence of severe sliding wear characterized by formation of extensive grooves and
scratches in the direction of sliding; also called striation.
3.2.27 severe sliding wear, n—in tribology, sliding wear that removes subsurface metal; also called abnormal sliding wear.
3.2.28 severe sliding wear particles, n—in tribology, severe sliding wear particles are >15 μm >15 μm and several times longer
than they are wide. Some of these particles have surface striations as a result of sliding and they frequently have straight edges.
Their major dimension-to-thickness ratio is approximately 10:1.
3.2.29 severe wear particles, n—in tribology, free metal particles >15 μm >15 μm with major dimension-to-thickness ratios
between 5:1 and 30:1.
D7684 − 11 (2016)
3.2.30 spheres, n—in tribology, metal spheres may be the result of incipient rolling contact fatigue or they may be contaminant
particles from welding, grinding, coal burning, and steel manufacturing. Spheres may also be caused by electro-pitting.
3.2.31 wear particles, n—particles generated from a wearing surface of a machine.
4. Summary of Guide
4.1 Periodic in-service lubricant samples are collected from a machine as part of a routine condition monitoring program. The
sample is prepared to separate particles from the sample flu
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.