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A Review of Sub-Scale Test Methods to Evaluate the Friction and Wear of Ring and Liner Materials for Spark- and Compression Ignition Engines

TL;DR: A review of past laboratory-scale test methods and to assess their validity for ranking materials and lubricants for use as piston and liner materials in compression-ignition (CI) and spark ignition (SI) engines is presented in this paper.
Abstract: A review was conducted of past laboratory-scale test methods and to assess their validity for ranking materials and lubricants for use as piston and liner materials in compression-ignition (CI) and spark-ignition (SI) engines. Most of the previous work was aimed at simulating SI engine environments. This report begins with a discussion of the numerous factors that can affect the validity of an approach to simulating engine conditions in a laboratory. These include not only mechanical, chemical and thermal factors, but also human factors as regards how the vehicle is operated and maintained. The next section provides an annotated review of open literature publications that address the issues of laboratory simulation of engine components. A comparison of these studies indicates a lack of sufficient standardization in procedures to enable a systematic comparison of one publication to another. There were just a few studies that compared several laboratory test methods to engine test results, and these indicated that some test methods correlate, at least qualitatively, better than others. The last section provides a series of recommendations for improving the accuracy and validity of laboratory-scale simulations of engine behavior. It became clear that much of the engine wear damage occurs during start-up whenmore » the engine is cold, and this calls into the question the usefulness of test methods that attempt to simulate steady-state running conditions. It is recommended that a new standard test method, perhaps developed with the help of the ASTM wear and erosion committee, be developed. It would use cold start-up conditions in the presence of degraded oil, or simulated degraded oil.« less

Summary (1 min read)

1.0 Introduction

  • That requirement poses a significant challenge for the test engineer because small changes in the way materials are exposed to the mechanical, chemical, and thermal aspects of their surroundings can affect their friction and wear behavior.
  • Therefore, the ultimate challenge becomes one of identifying and controlling the key factors needed to enable materials, lubricants, and coatings to be tested in the laboratory in such a way that directly correlates with their performance in the end application.
  • The degree of confidence by engineering decision-makers in laboratory test data must be based on laboratory-field correlations.

Development of a Bench Wear Test for the Evaluation of Engine Cylinder Components and the Correlation with Engine Test Results

  • Ring/cylinder bore Level E -ring segment and bore segment 80N (7 MPa) intended to represent typical pressure; scar width x ring width Reciprocating motion similar to piston and bore 600 rpm, 10 mm stroke, 5 hrs turn-around events per unit time similar to engine Thermally-spray modified aluminum alloy liners, cast iron , Cr and Mo plated rings.
  • There seemed to be a better more consistent ranking of wear for the bore segments, even thought results were not the same quantitatively between the two machines. [13].
  • The LS-9 data were said to produce scuffing effects due to dominant boundary regime lubrication, but the motored rig was said to produce not only boundary lubrication, but because of its longer stroke, mixed film as well.
  • Two laboratory tests were compared with engine results and lubricant volatility tests 1) 4-ball lubricant test -in accordance with ASTM D-4172 (for wear resistance of a lubricant) and ASTM D-2783 (load-carrying capacity of a lubricant).
  • Inadequate to distinguish between best and worst oils.

3.1 Conclusions

  • Lacking close similarity in bench-testing procedures and methods, it is practically impossible to conduct a meaningful quantitative comparison of friction and wear data throughout the tribology literature.
  • Among the most useful were studies that conducted several types of tests and compared their results.
  • The most meaningful comparisons were possible only in terms of relative rankings or observations that some materials and surface treatments perform relatively well in laboratory tests and engine tests.
  • Even then, the materials usually differed in preparation and surface condition.

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ORNL/TM-2001/184
A Review of Sub-Scale Test Methods to
Evaluate the Friction and Wear of Ring
and Liner Materials for Spark- and
Compression Ignition Engines
November 2001

ORNL/TM-2001/184
Metals and Ceramics Division
A Review of Sub-Scale Test Methods to Evaluate
the Friction and Wear of Ring and Liner Materials
for Spark- and Compression Ignition Engines
Peter J. Blau
November 2001
Prepared for
U.S. Department of Energy, Assistant Secretary
for Energy Efficiency and Renewable Energy,
Office of Transportation Technologies
Prepared by
OAK RIDGE NATIONAL LABORATORY
Oak Ridge, Tennessee 37831-6285
managed by
UT-BATTELLE, LLC
for the
U.S. DEPARTMENT OF ENERGY
Under contract DE-AC05-00OR22725

iii
CONTENTS
Executive Summary ....................................................................................................... vii
1.0 Introduction........................................................................................................ 1
1.1 Factors Involved in Simulations ................................................................... 1
1.2 Levels of Testing Scale................................................................................. 4
2.0 Annotated Literature Review of Ring/Cylinder Bore Studies....................... 5
3.0 Conclusions and Recommendations ................................................................. 12
3.1 Conclusions................................................................................................... 12
3.2 Recommendations......................................................................................... 13
Appendix A - Factors Affecting Ring/Liner Tribology............................................... 16

v
Preface
Energy resources are of strategic interest to the United States, and the transportation sector is a
major consumer of energy. In 1998 the transportation sector accounted for about 27.7 % of the
total U.S. energy consumption.
The United States Department of Energy, Office of Energy
Efficiency and Renewable Energy, Office of Transportation Technologies, is sponsoring
programs to develop new scientific and technological strategies that will improve the efficiency
of vehicles and therefore reduce the consumption of vital U.S. energy resources.
Friction, lubrication, and wear (tribology) issues impact the energy efficiency of vehicles in
many ways, and therefore it is important to develop new design concepts, lubrication strategies,
and tribomaterials (materials whose functions involve friction or wear) for engine and drive-train
components. The current work supports that aim.
Testing is a significant component of materials development. Full-scale vehicle tests or
instrumented engine test cell programs can be very expensive, and industry seeks to reduce the
cost of obtaining engineering design and selection data for materials, lubricants, and coatings.
Any useful subscale test (simulative test) must rank materials in the same order of merit as they
would behave in the end-use applications, which in the present case are piston rings and cylinder
bores. This study was conducted to review past laboratory-scale test methods and to assess their
validity for ranking materials and lubricants for use in engines. It concludes with a summary
and recommendations for future research.
Peter J. Blau, Ph.D.
Senior Research Engineer
Metals and Ceramics Division
Oak Ridge National Laboratory
Transportation Energy Data Book , Edition 19, Oak Ridge National Laboratory report 6958 (1999), p. 2-4.

vii
Executive Summary
A review was conducted of past laboratory-scale test methods and to assess their validity for
ranking materials and lubricants for use as piston and liner materials in compression-ignition
(CI) and spark-ignition (SI) engines. Most of the previous work was aimed at simulating SI
engine environments. This report begins with a discussion of the numerous factors that can
affect the validity of an approach to simulating engine conditions in a laboratory. These include
not only mechanical, chemical and thermal factors, but also human factors as regards how the
vehicle is operated and maintained. The next section provides an annotated review of open
literature publications that address the issues of laboratory simulation of engine components. A
comparison of these studies indicates a lack of sufficient standardization in procedures to enable
a systematic comparison of one publication to another. There were just a few studies that
compared several laboratory test methods to engine test results, and these indicated that some
test methods correlate, at least qualitatively, better than others. The last section provides a series
of recommendations for improving the accuracy and validity of laboratory-scale simulations of
engine behavior. It became clear that much of the engine wear damage occurs during start-up
when the engine is cold, and this calls into the question the usefulness of test methods that
attempt to simulate steady-state running conditions. It is recommended that a new standard test
method, perhaps developed with the help of the ASTM wear and erosion committee, be
developed. It would use cold start-up conditions in the presence of degraded oil, or simulated
degraded oil.

Citations
More filters
Journal ArticleDOI
TL;DR: In this article, laboratory tests to evaluate piston ring and cylinder liner materials for their friction and wear behavior in realistic engine oils are described to support the development of new standard test methods.

121 citations


Cites background from "A Review of Sub-Scale Test Methods ..."

  • ...In many of the reported laboratory tests measuring piston ring and cylinder liner friction and wear, the lubricant employed is a fully formulated oil in the new condition [2]....

    [...]

Journal ArticleDOI
01 Jul 2005-Wear
TL;DR: In this paper, a test method has been developed to evaluate the friction and wear behavior of candidate piston ring and cylinder liner materials for heavy-duty diesel engine applications, using actual piston ring segments sliding on flat specimens of liner material to simplify alignment and to multiply the stress to the level normally seen in engine operation.

81 citations

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the tribochemical processes occurring in a fired engine test and a bench tribometer with the aim of identifying the challenges related to simulating fired engine oil additive/surface interactions in laboratory conditions.
Abstract: This study focuses on evaluating the tribochemical processes occurring in a fired engine test and a bench tribometer with the aim of identifying the challenges related to simulating fired engine oil additive/surface interactions in laboratory conditions. Tribofilms formed in cylinder liner and piston ring surfaces from a fired engine test and a bench tribometer are chemically characterised using the X-ray photoelectron spectroscopy (XPS). This study confirmed that the chemical nature of tribofilms formed in a fired engine and a reciprocating bench tribometer are different, not surprising considering the substantially different lubrication environments between the tests. The factors necessary to be considered to improve the simulation of fired engine tribochemistry processes in laboratory conditions are identified and discussed.

20 citations


Cites background from "A Review of Sub-Scale Test Methods ..."

  • ...Figure 1 lists the key factors that determine the tribological performance of engine systems and which need to be considered when developing bench tribometer test methodologies for simulating these systems.(2) A number of experimental tribometers have been developed so far and used for simulating the tribological conditions of valve train or piston ring/liner systems....

    [...]

Proceedings ArticleDOI
25 Oct 2016
TL;DR: In this article, the authors used the results obtained using tribotests with that performed using engines in dynamometers to understand the actuation mechanisms of additives on the friction and wear control of engine parts.
Abstract: The growing use of tribotest has been helping the researches to understand the actuation mechanisms of additives on the friction and wear control of engine parts. But, it is common to observe differences between the tribofilms formed in real situation from that obtained using tribotests. Furthermore, the automakers have difficulty to correlate the results obtained using tribotests with that performed using engines in dynamometers. For the piston ring/cylinder bore tribosystem is almost impossible to reproduce its real tribosystem using tribotests. Therefore simplifications are necessary and they affect the tribochemical behavior of the tribosystem. To understand how these simplifications and the test parameters affect the tribochemical behavior of the simplified tribosystem is critical to design a tribotest that correlate well with the real situation.

5 citations


Cites background from "A Review of Sub-Scale Test Methods ..."

  • ...Furthermore, Blau [6] concluded his review listing some details that deserve special attention such as: The contact stress and geometry should replicate the application....

    [...]

  • ...According to Blau [5] the ultimate challenge in developing reliable tribotests becomes of identifying and controlling the key factors needed to enable materials, lubricants, and coatings to be tested in the laboratory in such a way that directly correlates with their performance in the end application....

    [...]

Dissertation
01 Oct 2017
TL;DR: In this article, the tribological performance of vegetable oils (palm oil and soybean oil) as biolubricants and their blends with mineral oil and anti-wear additives was evaluated in order to assess their potential use in automotive engines.
Abstract: The concern about the pollution created by the use of mineral oil based lubricants and the depletion stock of petroleum has inspired research on alternative lubricants known as biolubricants. The tribological performance of vegetable oils (palm oil and soybean oil) as biolubricants and their blends with mineral oil and anti-wear additives was evaluated in order to assess their potential use in automotive engines. The tests were performed using a reciprocating ball-on-flat test-rig at severe contact conditions with grey cast iron specimens. The performance was compared with a commercial mineral engine oil for benchmarking purposes. At severe contact conditions, the friction and wear results of vegetable oil lubricants were found to be greatly influenced by the wide hardness range of the grey cast iron specimens. The measurement of hardness on the intended wear scar region prior to testing was used in order to provide more robust tribological data. In a pure oil state, the palm oil performance was found to be competitive in friction coefficient with mineral engine oil. However, the mineral oil is far superior in wear protection over vegetable oils due to the additive package it contains its superior oxidative stability. For a vegetable oil-mineral oil blend in equal ratio, the reduction of friction and wear was not significant. However, the addition of 2% zinc dialkyl dithiophosphate in vegetable oils gave significant improvement on the friction and wear. The friction coefficient of palm oil with this additive was very close to the commercial mineral engine oil. The zinc dialkyl dithiophospate in vegetable oil was found to perform three functions; as an anti-wear agent, anti-oxidant and friction modifier. The blend of vegetable oils with boron nitride, however, did not give better results. This could be mainly due to the selection of particles size which was not suitable with the surface roughness. When putting all the results together, the downside of pure vegetable oils is found to be greater in terms of wear resistance and oxidative stability compared to friction. This effect was prominent when they were blended with mineral oils where their tribological performance dominated. However, with the commercial anti-wear additive, specifically the zinc dialkyl dithiophosphate, the vegetable oils showed positive signs as a potential candidate to be used as an alternative lubricant in automotive engine systems even though there is still much room for improvement.

5 citations

References
More filters
Book
01 Jan 2000
TL;DR: In this paper, the authors describe the application of simulation and statistical analyses to the improvement of a shipping and distribution system supporting a component-fabrication plant and two automotive assembly plants interconnected by truck lines and railroads.
Abstract: We describe the application of simulation and statistical analyses to the improvement of a shipping and distribution system supporting a component-fabrication plant and two automotive assembly plants interconnected by truck lines and railroads. These analyses enabled managers to determine the number and location of loading docks required, optimize the inventory level and distribution of racks (containers) circulating throughout this shipping system, determine the sizes of turnaround areas for truck and rail cargo at each plant, and predict annual truck and rail shipping volumes and costs.

29 citations