ASTM G206-11
(Guide)Standard Guide for Measuring the Wear Volumes of Piston Ring Segments Run against Flat Coupons in Reciprocating Wear Tests
Standard Guide for Measuring the Wear Volumes of Piston Ring Segments Run against Flat Coupons in Reciprocating Wear Tests
SIGNIFICANCE AND USE
The practical life of an internal combustion engine is most often determined by monitoring its oil consumption. Excessive oil consumption is cause for engine repair or replacement and can be symptomatic of excessive wear of the piston ring or the cylinder bore or both. More wear-resistant materials of construction can extend engine life and reduce cost of operation. Although components made from more wear-resistant materials can be tested in actual operating engines, such tests tend to be expensive and time consuming, and 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 of candidate materials and lubricants. The test parameters for those tests are selected by the investigator, but the end result is a pair of worn specimens whose degree of wear needs to be accurately measured. The use of curved specimens, like segments of crowned piston rings, presents challenges for precise wear measurement. Weight loss or linear measurements of lengths and widths of wear scars may not provide sufficient accuracy to discriminate between small differences in wear. This guide is intended to address that problem.
SCOPE
1.1 This guide covers and describes a profiling method for use accurately measuring the 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 some alternative measurement methods. Laboratory-scale wear tests have been used to evaluate the wear of materials, coatings, and surface treatments 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 one sliding partner and a flat or curved specimen (simulating the cylinder liner) as its counterface. The goal of this guide is to provide more accurate wear measurements than alternative approaches involving weight loss or simply measuring the length and width of the wear marks.
1.2 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
Standards Content (Sample)
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Designation: G206 − 11
Standard Guide for
Measuring the Wear Volumes of Piston Ring Segments Run
against Flat Coupons in Reciprocating Wear Tests
This standard is issued under the fixed designation G206; 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 3.2.1 conformal contact, n—in friction and wear testing,
any macro-geometric specimen configuration in which the
1.1 This guide covers and describes a profiling method for
curvature of one contact surface matches that of the counter-
use accurately measuring the wear loss of compound-curved
face.
(crowned) piston ring specimens that run against flat counter-
3.2.1.1 Discussion—Examples of conformal contact include
faces. It does not assume that the wear scars are ideally flat, as
a flat surface sliding on a flat surface and a ball rotating in a
do some alternative measurement methods. Laboratory-scale
socket that conforms to the shape of the ball.Apair of surfaces
wear tests have been used to evaluate the wear of materials,
may begin a wear or friction test in a non-conforming contact
coatings, and surface treatments that are candidates for piston
configuration, but develop a conformal contact as a result of
rings and cylinder liners in diesel engines or spark ignition
wear.
engines. Various loads, temperatures, speeds, lubricants, and
3.2.2 cylinder bore/cylinder liner, n—in an internal combus-
durationsareusedforsuchtests,butsomeofthemuseacurved
tion engine, the cylindrical cavity in which the piston moves.
piston ring segment as one sliding partner and a flat or curved
3.2.2.1 Discussion—The terms cylinder bore and cylinder
specimen (simulating the cylinder liner) as its counterface.The
liner are used interchangeably in the description of this
goal of this guide is to provide more accurate wear measure-
method. Cylinder liners are most commonly used in heavy-
ments than alternative approaches involving weight loss or
dutyengineswhichareintendedtoberebuilt.Theyaresleeves,
simply measuring the length and width of the wear marks.
generally of a cast iron, which are surrounded on their outer
1.2 This standard does not purport to address all of the
surface by coolant for better heat transfer, and meant to be
safety concerns, if any, associated with its use. It is the
replaced when excessively worn. A cylinder bore is machined
responsibility of the user of this standard to establish appro-
directly into an engine block and is more commonly used in
priate safety and health practices and determine the applica-
light-duty engines which are not meant for rebuilding. The
bility of regulatory limitations prior to use.
material of the cylinder bore is, therefore, the same material as
theengineblock,howevertheinsidesurfaceoftheboremayor
2. Referenced Documents
may not have additional surface treatment.
2.1 ASTM Standards:
4. Summary of Guide
G40 Terminology Relating to Wear and Erosion
G181 Test Method for Conducting Friction Tests of Piston
4.1 A reciprocating wear testing apparatus is used to simu-
Ring and Cylinder Liner Materials Under Lubricated
late the back-and-forth motion of a piston ring within a
Conditions
cylinder bore in the presence of a heated lubricant. Depending
on the duration and severity of the imposed test conditions,
3. Terminology
some degree of wear is generally produced on one or both
members of the sliding pair. Mathematical models of the wear
3.1 Definitions—See Terminology G40.
scar geometry on both the piston ring and cylinder liner
3.2 Definitions of Terms Specific to This Standard:
surfaces allow the degree of wear to be quantified in terms of
volume lost.The contact geometry for such tests, in the context
of ring-on-liner frictional behavior, is exemplified in Practice
This guide is under the jurisdiction of ASTM Committee G02 on Wear and
G181. That method uses pre-worn-in surfaces, and therefore it
Erosion and is the direct responsibility of Subcommittee G02.40 on Non-Abrasive
differs from the present case in which wear loss is based on
Wear.
Current edition approved May 1, 2011. Published May 2011. DOI: 10.1520/
measurements of initial and final profiles of the test specimens.
G0206–11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5. Significance and Use
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.1 The practical life of an internal combustion engine is
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. most often determined by monitoring its oil consumption.
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G206 − 11
FIG. 1 Schematic Drawing of the Ring
Excessive oil consumption is cause for engine repair or laser-based interferometric instruments, and the like. It is the
replacement and can be symptomatic of excessive wear of the responsibility of the user to ensure that the dimensional
piston ring or the cylinder bore or both. More wear-resistant measurement apparatus used has been correctly calibrated.
materialsofconstructioncanextendenginelifeandreducecost 7.1.1 Specimen Preparation—The test specimens shall be
of operation. Although components made from more wear- solvent cleaned and free from debris or other measurement-
resistant materials can be tested in actual operating engines, complicating artifacts.
such tests tend to be expensive and time consuming, and they 7.1.2 Specimen Fixturing—Asuitableshallbeusedtoclamp
often lead to variable results because of the difficulty in the specimens in the proper orientation for profiling and
controlling the operating environment. Although bench-scale dimensional measurement without touching the area subjected
tests do not simulate every aspect of a fired engine, they are or to be subjected to wear.
used for cost-effective initial screening of candidate materials
8. Procedure
and lubricants. The test parameters for those tests are selected
by the investigator, but the end result is a pair of worn
8.1 The current procedure, examples of its use, and com-
specimens whose degree of wear needs to be accurately
parison with other methods for measuring wear, have been
measured. The use of curved specimens, like segments of
published elsewhere. Wear measurements for ring and liner
crowned piston rings, presents challenges for precise wear
specimens are separately described in the following para-
measurement. Weight loss or linear measurements of lengths
graphs. It is the user’s responsibility to determine which of the
a
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