1、Designation: D7685 11Standard 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 number immediately
2、 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.INTRODUCTIONIn-line wea
3、r 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 failure.Improved mach
4、ine 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, through-flow oil debris
5、 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 failure modes wit
6、h 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, phosphate esters, petro
7、leum 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 purport to addres
8、s 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 Specific to This Sta
9、ndard: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 and information so
10、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 and type of the meta
11、llic 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 allowingthe full flow
12、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 debris and eddy cur
13、rent effects for non-ferromagnetic debris.1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts and Lubricants and is the direct responsibility of Subcommittee D02.96.07on Integrated Testers, Instrumentation Techniques for In-Service Lubricants.Current edition approved
14、Jan. 1, 2011. Published March 2011. DOI: 10.1520/D768511.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.1.4.1 DiscussionA device that de
15、tects 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 time.2.1.5 machinery health, nqualitative expression of theoperational status of a machine sub-component, component or
16、entire machine, used to communicate maintenance and opera-tional recommendations or requirements in order to continueoperation, schedule maintenance or take immediate mainte-nance action.2.1.6 metallic wear debris, nin tribology, metallic par-ticles that have become detached in a wear or erosion pro
17、cess.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 operating time of measured parameters.3. Summary of Practice3.1 A full flow sensor is fitted in the oil line to detectmeta
18、llic 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 health relative to cumulative debris count, or esti-mated cumulative debris mass warning and alarm limits, or acombinatio
19、n 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-line,full-flow inductive wear debris sensors. According to (1),passing the entire lubrication oil flow for aircraft and a
20、ero-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 longbeen used as a means to determine overall machinery health(2). The implementation of smaller oil filter pore sizes
21、 formachinery operating at higher rotational speeds and energieshas reduced the effectiveness of sampled oil analysis fordetermining abnormal wear prior to severe damage. In addi-tion, sampled oil analysis for equipment that is remote orotherwise difficult to monitor or access is not practical. Fort
22、hese 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 have demon-strated the capability to detect and quantify both ferromagneticand non-ferromagnetic metallic wear debris.
23、 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 designedspecifically for the protection of rolling element bearings andgears in critical machine applications. Beari
24、ngs are key ele-ments in machines since their failure often leads to significantsecondary damage that can adversely affect safety, operationalavailability, or operational/maintenance costs, or a combinationthereof.4.4 The main advantage of the sensor is the ability to detectearly bearing damage and
25、to quantify the severity of damageand rate of progression of failure towards some predefinedbearing surface fatigue damage limiting wear scar. Sensorcapabilities are summarized as follows:4.4.1 In-line full flow non-intrusive inductive metal detectorwith no moving parts.4.4.2 Detects both ferromagne
26、tic 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.4.5 Fig. 1 presents a widely used diagram (2) to describe theprogress of metallic wear debris release from normal toca
27、tastrophic failure. It must be pointed out that this figuresummarizes metallic wear debris observations from all thedifferent wear modes that can range from polishing, rubbing,abrasion, adhesion, grinding, scoring, pitting, spalling, etc. Asmentioned in numerous references (1-11), the predominantfai
28、lure 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-face material. The propagation of existing subsurface cracksand creation of new subsurface cracks causes ongoing dete
29、rio-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 atypical size range from 100 to 1000 microns or greater. Thus,rotating machines, such as gas turbines and transmissio
30、ns,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-line wear debris monitoring provides a more reliableand timely indication of bearing distress for a number ofreasons:
31、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 samplingobservations.4.6.2 Secondly, since it is the larger wear metallic debristhat are being detected, there is a lower prob
32、ability of falseindication from the normal rubbing wear that will be associatedwith smaller particles.4.6.3 Thirdly, build or residual debris from manufacturingor maintenance actions can be differentiated from actualFIG. 1 Wear Debris CharacterizationD7685 112damage debris because the cumulative deb
33、ris 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 distribution is independent of bearing size. (2-5)and (11).5. Interferences5.1 Wear debris counts may be invalid due to excessiven
34、oise 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 system.The subsections in this section provide examples for a certaintype of inductive debris sensor system. The sensor has nom
35、oving components. As seen in Fig. 3, the sensor incorporatesa magnetic coil assembly and signal conditioning electronicsthat are capable of detecting and categorizing metallic weardebris by size and type. The magnetic coil assembly consists ofthree coils that surround a magnetically and electrically
36、 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 each other ata point inside the tube at the center sensor coil. Signalconditioning electronics process the raw signal from th
37、e sensorand extract information about the size and type of the metallicdebris detected. The sensor electronics perform several func-tions including: data processing, communication control, andBuilt-In-Test (BIT). Ferromagnetic and non-ferromagneticwear debris counts are binned according to size. Sig
38、nalconditioning 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 configured whichallow the tracking of the distribution of debris.6.2 Principle of OperationThe sensor operates by moni-toring the
39、 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 particlecouples with the magnetic field to varying degrees as ittraverses the sensing region, resulting in a characteristic outputsign
40、ature. 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 isferromagnetic or non-ferromagnetic. When a ferromagneticparticle passes by each field coil, it strengthens the magneticfield of
41、 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, resulting in acharacteristic signal being generated as the particle passesthrough the entire sensing region of the sensor. The signa
42、llooks 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 proportional to thespeed at which the particle passes through the sensor. For aferromagnetic particle, the size, shape, and orient
43、ation 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 coil, the principle issimilar except that the presence of the particle in the magneticfield weakens the field due to the edd
44、y currents generated in theparticle. This results in a difference in the signal phase allowingthe processing electronics to differentiate between ferromag-netic and non-ferromagnetic particles passing through thesensor. For a non-ferromagnetic particle, the surface area andorientation of the particl
45、e 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 ferromagnetic particle is considerably greater than thatcaused by a non-ferromagnetic particle resulting in the sensorbeing able
46、 to detect smaller ferromagnetic 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 the3The sole sour
47、ce 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, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting
48、of theresponsible technical committee,1which you may attend.FIG. 2 Typical Bearing SpallFIG. 3 Sensor Major Components (3)D7685 113same type from each other (for example, it cannot distinguishaluminum from copper). Although the sensor electronics havethe capability of processing metallic wear debris
49、 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 issueof concern.6.3 Particle CharacteristicsSeveral factors in addition tothe size of the metallic wear debris particle, affect the magn
