1、Designation: D7685 11 (Reapproved 2016)Standard Practice forIn-Line, Full Flow, Inductive Sensor for Ferromagnetic andNon-ferromagnetic Wear Debris Determination andDiagnostics for Aero-Derivative and Aircraft Gas TurbineEngine Bearings1This standard is issued under the fixed designation D7685; the
2、number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRO
3、DUCTIONIn-line wear debris sensors have been in operation since the early 1990s. There are now thousandsof these devices operating in a wide variety of machinery applications accruing millions of operationalhours. Wear debris sensors provide early warning for the abnormal conditions that lead to fai
4、lure.Improved machine reliability is possible due to the enhanced sensor data granularity, which providesbetter diagnostics and prognostics of tribological problems from the initiating event through failure.1. Scope1.1 This practice covers the minimum requirements for anin-line, non-intrusive, throu
5、gh-flow oil debris monitoring sys-tem that monitors ferromagnetic and non-ferromagnetic metal-lic wear debris from both industrial aero-derivative and aircraftgas turbine engine bearings. Gas turbine engines are rotatingmachines fitted with high-speed ball and roller bearings thatcan be the cause of
6、 failure modes with high secondary damagepotential. (1)21.2 Metallic wear debris considered in this practice range insize from 120 m (micron) and greater. Metallic wear debrisover 1000 m are sized as over 1000 m.1.3 This practice is suitable for use with the followinglubricants: polyol esters, phosp
7、hate esters, petroleum industrialgear oils and petroleum crankcase oils.1.4 This practice is for metallic wear debris detection, notcleanliness.1.5 The values stated in SI units are to be regarded asstandard. The values given in parentheses are provided forinformation only.1.6 This standard does not
8、 purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions of Terms Sp
9、ecific to This Standard:2.1.1 condition monitoring, nfield of technical activity inwhich selected physical parameters associated with an operat-ing machine are periodically or continuously sensed, measuredand recorded for the interim purpose of reducing, analyzing,comparing and displaying the data a
10、nd information so obtainedand for the ultimate purpose of using interim result to supportdecisions related to the operation and maintenance of themachine. (2)2.1.2 control unit, nelectronic controller assembly, whichprocesses the raw signal from the sensor and extracts informa-tion about the size an
11、d type of the metallic debris detected.2.1.2.1 DiscussionA computer(s), accessories, and datalink equipment that an operator uses to control, communicateand receive data and information.2.1.3 full flow sensor, nmonitoring device that installsin-line with the lubrication system and is capable of allo
12、wingthe full flow of the lubrication fluid to travel through the sensor.Also referred to as a through-flow sensor.2.1.4 inductive debris sensor, ndevice that creates anelectromagnetic field as a medium to permit the detection andmeasurement of metallic wear debris via permeability forferromagnetic d
13、ebris and eddy current effects for non-ferromagnetic debris.1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-mittee D02.96.07 on Integrated Testers, Instrumentation Techniques for In-ServiceLu
14、bricants.Current edition approved Oct. 1, 2016. Published November 2016. Originallyapproved in 2011. Last previous edition approved in 2011 as D7685 11. DOI:10.1520/D7685-11R16.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.Copyright ASTM International,
15、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.1.4.1 DiscussionA device that detects metallic weardebris that cause fluctuations of the magnetic field. A devicethat generates a signal proportional to the size and presence ofmetallic wear debris with respect to
16、 time.2.1.5 machinery health, nqualitative expression of theoperational status of a machine sub-component, component orentire machine, used to communicate maintenance and opera-tional recommendations or requirements in order to continueoperation, schedule maintenance or take immediate mainte-nance a
17、ction.2.1.6 metallic wear debris, nin tribology, metallic par-ticles that have become detached in a wear or erosion process.2.1.7 sensor cable, nspecialized cable that connects thesensor output to the electronic control module.2.1.8 trend analysis, nmonitoring of the level and rate ofchange over ope
18、rating time of measured parameters.3. Summary of Practice3.1 A full flow sensor is fitted in the oil line to detectmetallic wear debris. The system counts wear debris, sizesdebris, and calculates debris mass estimates as a function oftime. This diagnostic information is then used to assessmachine he
19、alth relative to cumulative debris count, or esti-mated cumulative debris mass warning and alarm limits, or acombination thereof. From this information, estimates ofremaining useful life of the machine can also be made.4. Significance and Use4.1 This practice is intended for the application of in-li
20、ne,full-flow inductive wear debris sensors. According to (1),passing the entire lubrication oil flow for aircraft and aero-derivative gas turbines through a debris-monitoring device is apreferred approach to ensure sufficient detection efficiency.4.2 Periodic sampling and analysis of lubricants have
21、 longbeen used as a means to determine overall machinery health(2). The implementation of smaller oil filter pore sizes formachinery operating at higher rotational speeds and energieshas reduced the effectiveness of sampled oil analysis fordetermining abnormal wear prior to severe damage. Inaddition
22、, sampled oil analysis for equipment that is remote orotherwise difficult to monitor or access is not practical. Forthese machinery systems, in-line wear debris sensors can bevery useful to provide real-time and near-real-time conditionmonitoring data.4.3 In-line full-flow inductive debris sensors h
23、ave demon-strated the capability to detect and quantify both ferromagneticand non-ferromagnetic metallic wear debris. These sensorsrecord metallic wear debris according to size, count, and type(ferromagnetic or non-ferromagnetic). Sensors are availablefor a variety of oil pipe sizes. The sensors are
24、 designedspecifically for the protection of rolling element bearings andgears in critical machine applications. Bearings are key ele-ments in machines since their failure often leads to significantsecondary damage that can adversely affect safety, operationalavailability, or operational/maintenance
25、costs, or a combinationthereof.4.4 The main advantage of the sensor is the ability to detectearly bearing damage and to quantify the severity of damageand rate of progression of failure towards some predefinedbearing surface fatigue damage limiting wear scar. Sensorcapabilities are summarized as fol
26、lows:4.4.1 In-line full flow non-intrusive inductive metal detectorwith no moving parts.4.4.2 Detects both ferromagnetic and non-ferromagneticmetallic wear debris.4.4.3 Detects 95 % or more of metallic wear debris abovesome minimum particle size threshold.4.4.4 Counts and sizes wear debris detected.
27、4.5 Fig. 1 presents a widely used diagram (2) to describe theprogress of metallic wear debris release from normal tocatastrophic failure. It must be pointed out that this figuresummarizes metallic wear debris observations from all thedifferent wear modes that can range from polishing, rubbing,abrasi
28、on, adhesion, grinding, scoring, pitting, spalling, etc. Asmentioned in numerous references (1-11), the predominantfailure mode of rolling element bearings is spalling or macropitting. When a bearing spalls, the contact stresses increase andcause more fatigue cracks to form within the bearing subsur
29、-face material. The propagation of existing subsurface cracksand creation of new subsurface cracks causes ongoing deterio-ration of the material that causes it to become a roughenedcontact surface as illustrated in Fig. 2. This deteriorationprocess produces large numbers of metallic wear debris with
30、 atypical size range from 100 to 1000 microns or greater. Thus,rotating machines, such as gas turbines and transmissions,which contain rolling element bearings and gears made fromhard steel tend to produce this kind of large metallic weardebris that eventually leads to failure of the machines.4.6 In
31、-line wear debris monitoring provides a more reliableand timely indication of bearing distress for a number ofreasons:4.6.1 Firstly, bearing failures on rotating machines tend tooccur as events often without sufficient warning and could bemissed by means of only periodic inspections or data sampling
32、observations.4.6.2 Secondly, since it is the larger wear metallic debristhat are being detected, there is a lower probability of falseFIG. 1 Wear Debris CharacterizationD7685 11 (2016)2indication from the normal rubbing wear that will be associatedwith smaller particles.4.6.3 Thirdly, build or resid
33、ual debris from manufacturingor maintenance actions can be differentiated from actualdamage debris because the cumulative debris counts recordeddue to the former tend to decrease while those due to the lattertend to increase.4.6.4 Fourthly, bearing failure tests have shown that weardebris size distr
34、ibution is independent of bearing size. (2-5)and (11).5. Interferences5.1 Wear debris counts may be invalid due to excessivenoise from environmental influences. See 7.4.6. Apparatus6.1 Sensor3Asensor system is identified that is a through-flow device that installs in-line with the lubrication oil sy
35、stem.The subsections in this section provide examples for a certaintype of inductive debris sensor system. The sensor has nomoving components. As seen in Fig. 3, the sensor incorporatesa magnetic coil assembly and signal conditioning electronicsthat are capable of detecting and categorizing metallic
36、 weardebris by size and type. The magnetic coil assembly consists ofthree coils that surround a magnetically and electrically inertsection of tubing. The two outside field coils are driven by ahigh frequency alternating current source such that theirrespective fields are nominally opposed or cancel
37、each other ata point inside the tube at the center sensor coil. Signalconditioning electronics process the raw signal from the sensorand extract information about the size and type of the metallicdebris detected. The sensor electronics perform several func-tions including: data processing, communica
38、tion control, andBuilt-In-Test (BIT). Ferromagnetic and non-ferromagneticwear debris counts are binned according to size. Signalconditioning using a threshold algorithm is used to categorizethe metallic wear debris that pass through the sensor on thebasis of size. Several size categories can be conf
39、igured whichallow the tracking of the distribution of debris.6.2 Principle of OperationThe sensor operates by moni-toring the disturbance to the alternating magnetic field causedby the passage of a metallic wear debris particle through themagnetic coil assembly as shown in Fig. 4 (12). The particlec
40、ouples with the magnetic field to varying degrees as ittraverses the sensing region, resulting in a characteristic outputsignature. The magnitude of the disturbance measured as avoltage defines the size of the metallic wear debris and thephase shift of the signal defines whether the wear debris isfe
41、rromagnetic or non-ferromagnetic. When a ferromagneticparticle passes by each field coil, it strengthens the magneticfield of that coil due to the high magnetic permeability of theparticle relative to the surrounding fluid (oil). This disrupts thebalance of the fields seen by the sense coil, resulti
42、ng in acharacteristic signal being generated as the particle passesthrough the entire sensing region of the sensor. The signallooks much like one period of a sine wave where the amplitudeof the signal is proportional to the apparent size of the particleand the period of the signal is inversely propo
43、rtional to thespeed at which the particle passes through the sensor. For aferromagnetic particle, the size, shape, and orientation of theparticle and the magnetic susceptibility of the material deter-mine the magnitude of the signal. When a non-ferromagnetic(conductive) particle passes by each field
44、 coil, the principle issimilar except that the presence of the particle in the magneticfield weakens the field due to the eddy currents generated in theparticle. This results in a difference in the signal phase allowingthe processing electronics to differentiate between ferromag-netic and non-ferrom
45、agnetic particles passing through thesensor. For a non-ferromagnetic particle, the surface area andorientation of the particle and the conductivity of the material,determine the magnitude of the signal. Also, for a given size ofparticle, the amount of disturbance caused to the magnetic fieldby a fer
46、romagnetic particle is considerably greater than thatcaused by a non-ferromagnetic particle resulting in the sensor3The sole source of supply of the apparatus known to the committee at this timeis GasTOPS, Ltd., Polytek St., Ottawa, Ontario K1J 9J3, Canada. If you are awareof alternative suppliers,
47、please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.FIG. 2 Typical Bearing SpallFIG. 3 Sensor Major Components (3)D7685 11 (2016)3being able to detect smaller ferr
48、omagnetic than non-ferromagnetic particles. Note that the detection capability ofthe sensor is limited to distinguishing ferromagnetic materialsfrom non-ferromagnetic (conductive) materials. It does nothave the capability to distinguish different materials of thesame type from each other (for exampl
49、e, it cannot distinguishaluminum from copper). Although the sensor electronics havethe capability of processing metallic wear debris rates of 60particles per second, this far exceeds the metallic wear debrisrates that have actually been observed from bearing failuretests under conditions of severe wear progression. Metallicwear debris rates have typically been observed in a range fromless than 1 to 5 particles per second for metallic wear debrisparticles that are 100 m or larger. Hence, dead time and thelikelihood of particles arriving at the same time is not an issu
