1、Designation: G206 11G206 17Standard Guide forMeasuring the Wear Volumes of Piston Ring Segments Runagainst Flat Coupons in Reciprocating Wear Tests1This standard is issued under the fixed designation G206; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 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.1. Scope1.1 This guide covers and describes a profiling method for use accurately measuring the
3、 wear loss of compound-curved(crowned) piston ring specimens that run against flat counterfaces. It does not assume that the wear scars are ideally flat, as do somealternative measurement methods. Laboratory-scale wear tests have been used to evaluate the wear of materials, coatings, andsurface trea
4、tments that are candidates for piston rings and cylinder liners in diesel engines or spark ignition engines. Various loads,temperatures, speeds, lubricants, and durations are used for such tests, but some of them use a curved piston ring segment as onesliding partner and a flat or curved specimen (s
5、imulating the cylinder liner) as its counterface. The goal of this guide is to providemore accurate wear measurements than alternative approaches involving weight loss or simply measuring the length and width ofthe wear marks.1.2 This standard does not purport to address all of the safety concerns,
6、if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.3 This international standard was developed in accordance with internationally recognized
7、 principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2G40 Terminology Relating to
8、Wear and ErosionG181 Test Method for Conducting Friction Tests of Piston Ring and Cylinder Liner Materials Under Lubricated Conditions3. Terminology3.1 DefinitionsSee Terminology G40.3.2 Definitions of Terms Specific to This Standard:3.2.1 conformal contact, nin friction and wear testing, any macro-
9、geometric specimen configuration in which the curvatureof one contact surface matches that of the counterface.3.2.1.1 DiscussionExamples of conformal contact include a flat surface sliding on a flat surface and a ball rotating in a socket that conforms to theshape of the ball. A pair of surfaces may
10、 begin a wear or friction test in a non-conforming contact configuration, but develop aconformal contact as a result of wear.3.2.2 cylinder bore/cylinder liner, nin an internal combustion engine, the cylindrical cavity in which the piston moves.3.2.2.1 Discussion1 This guide is under the jurisdictio
11、n of ASTM Committee G02 on Wear and Erosion and is the direct responsibility of Subcommittee G02.40 on Non-Abrasive Wear.Current edition approved May 1, 2011June 1, 2017. Published May 2011June 2017. Originally approved in 2011. Last previous edition approved in 2011 as G206 11.DOI: 10.1520/G020611.
12、10.1520/G0206-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is
13、 intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit 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
14、current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1The terms cylinder bore and cylinder liner are used interchangeably in the description of th
15、is method. Cylinder liners are mostcommonly used in heavy-duty engines which are intended to be rebuilt. They are sleeves, generally of a cast iron, which aresurrounded on their outer surface by coolant for better heat transfer, and meant to be replaced when excessively worn. A cylinderbore is eithe
16、r machined directly into an engine block and is more commonly used in light-duty engines which are not meant forrebuilding. or is added as a sleeve (typically of iron) into a block of another material (typically aluminum). The material of thecylinder bore is, therefore, bore, therefore, may or may n
17、ot be the same material as the engine block, howeverblock and the insidesurface of the bore may or may not have additional surface treatment.4. Summary of Guide4.1 A reciprocating wear testing apparatus is used to simulate the back-and-forth motion of a piston ring within a cylinder borein the prese
18、nce of a heated lubricant. Depending on the duration and severity of the imposed test conditions, some degree of wearis generally produced on one or both members of the sliding pair. Mathematical models of the wear scar geometry on both thepiston ring and cylinder liner surfaces allow the degree of
19、wear to be quantified in terms of volume lost. The contact geometryfor such tests, in the context of ring-on-liner frictional behavior, is exemplified in Practice G181. That method uses pre-worn-insurfaces, and therefore it differs from the present case in which wear loss is based on measurements of
20、 initial and final profilesof the test specimens.5. Significance and Use5.1 The practical life of an internal combustion engine is most often determined by monitoring its oil consumption. Excessiveoil consumption is cause for engine repair or replacement and can be symptomatic of excessive wear of t
21、he piston ring or thecylinder bore or both. More wear-resistant materials of construction can extend engine life and reduce cost of operation. Althoughcomponents made from more wear-resistant materials can be tested in actual operating engines, such tests tend to be expensiveand time consuming, and
22、they often lead to variable results because of the difficulty in controlling the operating environment.Although bench-scale tests do not simulate every aspect of a fired engine, they are used for cost-effective initial screening ofcandidate materials and lubricants. The test parameters for those tes
23、ts are selected by the investigator, but the end result is a pairof worn specimens whose degree of wear needs to be accurately measured. The use of curved specimens, like segments of crownedpiston rings, presents challenges for precise wear measurement. Weight loss or linear measurements of lengths
24、and widths of wearscars may not provide sufficient accuracy to discriminate between small differences in wear. This guide is intended to address thatproblem.6. Reagents6.1 Cleaning SolventsSuitable solvents may be used to degrease and clean specimens prior to conducting wear tests andcleaning specim
25、ens afterward. No specific solvents are recommended here, except that they should not chemically attack the testedsurfaces, nor leave a residual film or stain after cleaning.7. Apparatus and Specimen Preparation7.1 Description of the Test ApparatusAny dimensional metrology instrument that is capable
26、 of measuring the length, width,and depths of the subject wear scars, and the curvatures of the regions that surround and contain them, may be used. These includestylus-type profiling instruments, optical or laser-based interferometric instruments, and the like. It is the responsibility of the usert
27、o ensure that the dimensional measurement apparatus used has been correctly calibrated.7.1.1 Specimen PreparationThe test specimens shall be solvent cleaned and free from debris or other measurement-complicating artifacts.7.1.2 Specimen FixturingA suitable fixture shall be used to clamp the specimen
28、s in the proper orientation for profiling anddimensional measurement without touching the area subjected or to be subjected to wear.8. Procedure8.1 The current procedure, examples of its use, and comparison with other methods for measuring wear, have been publishedelsewhere.3 Wear measurements for r
29、ing and liner specimens are separately described in the following paragraphs. It is the usersresponsibility to determine which of the following procedures best suits the wear scar geometry produced in the reciprocating testmethod that was used.8.2 Wear Volume of the Piston Ring SpecimenA hypothetica
30、l piston ring with compound curvatures can be considered as thecentral slice of an ellipsoid with initial ring radius ro as the minor semi-axis, as illustrated in Fig. 1. The worn surface on the ringusually will not be flat but also has compound curvatures. The wear scar can be considered as a patch
31、 of another ellipsoid whoseminor semi-axis is the final radius rw on the wear scar. The top view of the wear scar is in elliptical shape with scar length acrossthe crown (2b) and scar width in the conferential direction of the ring (2a), as shown in Fig. 2. Fig. 3 illustrates the side view of3 Qu, J
32、., and Truhan, J. J., “An Efficient Method for Accurately Determining Wear Volumes of Sliders with Non-flat Wear Scars and Compound Curvatures,” Wear, Vol261, 7-8, 2006, pp. 848-855.G206 172the worn surface, showing the curvature change after testing. By measuring the wear scar size (2a and 2b) and
33、ring curvatures (roand rw) before and after testing, the wear volume Vring and maximum wear depth hring can be obtained by the following formulae:Vring5pi a3b2ro3 22rw3 22ro21b2!=ro2 2b212rw21b2!=rw2 2b2# (1)hring5ro 2rw 2=ro2 2b21=rw2 2b2 (2)8.2.1 When the ring specimen has much lower wear resistan
34、ce compared to the flat specimen, the worn surface on ring will befairly flat and Eq 1 and Eq 2 can be simplified as follows:Vring5pi a3b2ro3 22ro21b2!=ro2 2b2# (3)hring5ro 2=ro2 2b2 (4)FIG. 1 Schematic Drawing of the RingFIG. 2 Schematic Top View of the Wear Scar on the Ring SpecimenG206 1738.2.2 P
35、lease note that when the crown curvature is zero or very small compared to the ring curvature, the wear scar length isrestricted by the ring thickness and the above formulae for wear volume calculations will no longer be valid. In this case, the ringsurface should be considered as cylindrical, as di
36、scussed in 8.2.3.2.8.2.3 Special Cases:8.2.3.1 Spherical Ring SurfaceWhen the two compound curvatures on a ring specimen are identical, the ring will be thecentral slice of a sphere with a round shape wear scar. The wear volumes and maximum wear depths can be calculated using Eq1-4 with a = b. Note
37、that the calculations in this case can be directly applied to commonly used ball sliders.8.2.3.2 Cylindrical Ring SurfaceWhen the crown curvature is zero or very small compared to the ring curvature, the ringsurface should be considered as cylindrical and the wear scar is rectangular with width 2b a
38、nd length equal to the ring thickness2a = t. The worn surface is also cylindrical with radius rw. Although Eq 2 and Eq 9 are still valid for maximum wear depths,different formulae have been derived for wear volumes. Namely:Vring5tSro2arcsinbro2rw2arcsin brw2b=ro2 2b21b=rw2 2b2 D (5)Vflat5LFrf2arcsin
39、S W2rfD 2brf22W24 G (6)When the ring specimen has far lower wear resistance than the flat specimen, the worn surface on ring will be relatively flat.In that case, the wear volume and maximum wear depth can be calculated by Eq 7 and Eq 4, respectively.Vring5tSro2arcsinbro2b=ro2 2b2D (7)8.3 Wear Volum
40、e of a Flat Counterface SpecimenA schematic drawing of the wear scar on the flat specimen is illustrated inFig. 4. Ls is the stroke length of the reciprocating test. The length and width of the wear scar on the flat are denoted as L and W,respectively. The wear scar on the flat is composed of three
41、segments, the cylindrical middle with radius of rf and the twocompound-curvature ends. The wear volume Vflat and maximum wear depth hflat can be calculated byVflat5LsFrf2arcsinS W2rfD 2W2rf22W24 G (8)1piL 2Ls!3W F2rf32S2rf21W24 Drf22W24 Ghflat5rf 2rf22W24 (9)9. Report9.1 Wear measurements, expressed
42、 as the volume of material lost, shall be reported in accordance with the test method that wasused to generate the wear.FIG. 3 Schematic Side View of the Wear Scar on the Ring SpecimenG206 1749.1.1 In addition to, or in place of the calculated wear volume, data may be normalized to express wear volu
43、me loss per unitsliding distance per unit applied normal force, or similar combined parameters, wear rates, or wear factors.10. Keywords10.1 cylinder liner; piston ring; wear measurementASTM International takes no position respecting the validity of any patent rights asserted in connection with any
44、item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical c
45、ommittee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a
46、 meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Dri
47、ve, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 4 Schematic Wear Scar on a Flat SpecimenG206 175
