ASTM D7027-20
(Test Method)Standard Test Method for Evaluation of Scratch Resistance of Polymeric Coatings and Plastics Using an Instrumented Scratch Machine
Standard Test Method for Evaluation of Scratch Resistance of Polymeric Coatings and Plastics Using an Instrumented Scratch Machine
SIGNIFICANCE AND USE
5.1 Scratch tests are performed on specimens:
(1) to evaluate the scratch resistance of a particular material,
(2) to rank the relative scratch resistance of different materials, or
(3) to determine the scratch coefficient of friction of materials.
5.2 Since polymers exhibit mechanical properties that are strongly dependent on temperature, the test standard prescribed herein is designed to yield reproducible results when users perform tests under the similar testing environment and on specimens of the same material and surface texture that are subjected to the same conditioning procedures.
5.3 Certain polymers are self-healing (recoverable) when subjected to scratches and other physical deformations because of their viscoelastic and relaxation properties. It is important to note the difference between the instantaneous (if readily measurable) and residual scratch damage and compare results appropriately to ensure reproducibility. It is recommended that 24 hours be allowed for viscoelastic recovery when considering residual scratch depth.
5.4 “Whitening” of the scratched surface is a key damage mechanism that has prompted much concern in automotive and other applications where surface aesthetics is important. This type of damage is undesirable because it is evident to the human eye. The critical normal load at which this phenomenon appears serves as a benchmark in ranking material performance, especially from an aesthetic point of view.
SCOPE
1.1 This test method describes a laboratory procedure using an instrumented scratch machine to produce and quantify surface damage under controlled conditions. This test method is able to characterize the scratch resistance of polymers by measuring many significant material parameters. The scratch-inducing and data acquisition process is automated to avoid user-influenced effects that may affect the results.
1.2 The values stated in SI units are to be regarded as standard. The values in parentheses are for information only.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: This standard is equivalent to ISO 19252.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7027 − 20
Standard Test Method for
Evaluation of Scratch Resistance of Polymeric Coatings and
1
Plastics Using an Instrumented Scratch Machine
This standard is issued under the fixed designation D7027; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* E177Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.1 This test method describes a laboratory procedure using
E456Terminology Relating to Quality and Statistics
an instrumented scratch machine to produce and quantify
G99Test Method for Wear Testing with a Pin-on-Disk
surface damage under controlled conditions. This test method
Apparatus
is able to characterize the scratch resistance of polymers by
G171Test Method for Scratch Hardness of Materials Using
measuring many significant material parameters. The scratch-
a Diamond Stylus
inducing and data acquisition process is automated to avoid
user-influenced effects that may affect the results.
3. Terminology
1.2 The values stated in SI units are to be regarded as
3.1 Terms used in this standard are defined in accordance
standard. The values in parentheses are for information only.
with Terminology D883, unless otherwise specified. For terms
1.3 This standard does not purport to address all of the
relating to precision and bias and associated issues, the terms
safety concerns, if any, associated with its use. It is the
used in this standard are defined in accordance with Terminol-
responsibility of the user of this standard to establish appro-
ogy E456.
priate safety, health, and environmental practices and deter-
3.2 Definitions:
mine the applicability of regulatory limitations prior to use.
3.2.1 ASV Software, n—Automatic Scratch Visualization,a
NOTE 1—This standard is equivalent to ISO 19252.
computer program which automates the identification of the
1.4 This international standard was developed in accor-
point of failure in a rising load scratch tests using contrast as
dance with internationally recognized principles on standard-
the failure criteria.
ization established in the Decision on Principles for the
3.2.1.1 Discussion—TheASVsoftwaredeterminesfailureif
Development of International Standards, Guides and Recom-
acontinuouschangeincontrastbetweenthescratchgrooveand
mendations issued by the World Trade Organization Technical
theundamagedmaterialsurfacereaches+3%,-3%,or 63%.
Barriers to Trade (TBT) Committee.
The continuity criterion is defined as a region of length equal
to 2 diameters of the scratch stylus with 90 % or more of the
2. Referenced Documents
region exceeding the contrast criterion. The lowest load point
2
2.1 ASTM Standards:
on the scratch from which there is a continuous contrasting
A276/A276MSpecification for Stainless Steel Bars and
regionisconsideredthepointoffailure.Thisprogramisuseful
Shapes
for visual analysis of the test and may be used for other
D618Practice for Conditioning Plastics for Testing
applications,suchaspass-failcriterionforscratchvisibility.An
D638Test Method for Tensile Properties of Plastics
example of the application of ASV is shown in Fig. 1.
D883Terminology Relating to Plastics
3.2.2 critical normal load, n—the normal load at which
D1894Test Method for Static and Kinetic Coefficients of
failure(see3.2.4)ofthematerialwithinthescratchgroovefirst
Friction of Plastic Film and Sheeting
occurs.
3.2.3 normal load, n—a load applied onto the scratch stylus
1
thatisimposedinaverticallydownwarddirection,perpendicu-
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
lar to the surface of the specimen.
Current edition approved Sept. 1, 2020. Published October 2020. Originally
3.2.3.1 Discussion—The normal load is also referred to as
approved in 2005. Last previous edition approved in 2013 as D7027–13. DOI:
the “Z-direction load.”
10.1520/D7027-20.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.4 point of failure, n—the point along a rising-load
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
scratch path at which the damage to the surface is first
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. considered to be unacceptable.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it 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 current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7027 − 13 D7027 − 20
Standard Test Method for
Evaluation of Scratch Resistance of Polymeric Coatings and
1
Plastics Using an Instrumented Scratch Machine
This standard is issued under the fixed designation D7027; 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 Scope*
1.1 This test method describes a laboratory procedure using an instrumented scratch machine to produce and quantify surface
damage under controlled conditions. This test method is able to characterize the scratch resistance of polymers by measuring many
significant material parameters. The scratch-inducing and data acquisition process is automated to avoid user-influenced effects that
may affect the results.
1.2 The values stated in SI units are to be regarded as standard. The values in parentheses are for information only.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—This standard is equivalent to ISO 19252.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
A276/A276M Specification for Stainless Steel Bars and Shapes
D618 Practice for Conditioning Plastics for Testing
D638 Test Method for Tensile Properties of Plastics
D883 Terminology Relating to Plastics
D1894 Test Method for Static and Kinetic Coefficients of Friction of Plastic Film and Sheeting
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E456 Terminology Relating to Quality and Statistics
G99 Test Method for Wear Testing with a Pin-on-Disk Apparatus
G171 Test Method for Scratch Hardness of Materials Using a Diamond Stylus
1
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
Current edition approved Oct. 15, 2013Sept. 1, 2020. Published October 2013October 2020. Originally approved in 2005. Last previous edition approved in 20052013
ε1
as D7027–05–13. . DOI: 10.1520/D7027-13.10.1520/D7027-20.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D7027 − 20
FIG. 1 Images of Polystyrene-Acrylonitrile (SAN) Subjected to Test Mode A Under a Progressive Load of 1-90 N Showing Examples of
Points of Failure
3. Terminology
3.1 Terms used in this standard are defined in accordance with Terminology D883, unless otherwise specified. For terms relating
to precision and bias and associated issues, the terms used in this standard are defined in accordance with Terminology E456.
3.2 Definitions:
3.2.1 ASV Software, n—Automatic Scratch Visualization, a computer program which automates the identification of the point of
failure in a rising load scratch tests using contrast as the failure criteria. The software determines failure if a continuous change
in contrast between the scratch groove and the undamaged material surface reaches +3 %, -3 %, or 63 %. The continuity criterion
is defined as a region of length equal to 2 diameters of the scratch stylus with 90 % or more of the region exceeding the contrast
criterion. The lowest load point on the scratch from which there is a continuous contrasting region is considered the point of failure.
This program is useful for visual analysis of the test and may be used for other applications, such as pass-fail criterion for scratch
visibility. An example of the application of ASV is shown in Fig. 1.
3.2.1.1 Discussion—
The A
...
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