ASTM D7027-13

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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 14-Oct-2013
• ICS: 25.220.60 - Organic coatings
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.10 - Mechanical Properties

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7027 − 13
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 point of failure in a rising load scratch tests using contrast as
the failure criteria. The software determines failure if a
1.1 This test method describes a laboratory procedure using
continuous change in contrast between the scratch groove and
an instrumented scratch machine to produce and quantify
theundamagedmaterialsurfacereaches+3%,-3%,or 63%.
surface damage under controlled conditions. This test method
The continuity criterion is defined as a region of length equal
is able to characterize the scratch resistance of polymers by
to 2 diameters of the scratch stylus with 90 % or more of the
measuring many significant material parameters. The scratch-
region exceeding the contrast criterion. The lowest load point
inducing and data acquisition process is automated to avoid
on the scratch from which there is a continuous contrasting
user-influenced effects that may affect the results.
regionisconsideredthepointoffailure.Thisprogramisuseful
1.2 The values stated in SI units are to be regarded as
for visual analysis of the test and may be used for other
standard. The values in parentheses are for information only.
applications,suchaspass-failcriterionforscratchvisibility.An
1.3 This standard does not purport to address all of the example of the application of ASV is shown in Fig. 1.
safety concerns, if any, associated with its use. It is the
3.1.2 critical normal load, n—the normal load at which
responsibility of the user of this standard to establish appro-
failure(see3.1.4)ofthematerialwithinthescratchgroovefirst
priate safety and health practices and determine the applica-
occurs.
bility of regulatory limitations prior to use.
3.1.3 normal load, n—a load applied onto the scratch stylus
thatisimposedinaverticallydownwarddirection,perpendicu-
2. Referenced Documents
lar to the surface of the specimen. The normal load is also
2
2.1 ASTM Standards:
referred to as the “Z-direction load.”
D618Practice for Conditioning Plastics for Testing
3.1.4 point of failure, n—the point along a rising-load
D638Test Method for Tensile Properties of Plastics
scratch path at which the damage to the surface is first
D1894Test Method for Static and Kinetic Coefficients of
considered to be unacceptable.The point of failure for a given
Friction of Plastic Film and Sheeting
study shall be defined in a quantifiable manner. For aesthetic
E177Practice for Use of the Terms Precision and Bias in
studies the recommended criteria is a contrast of 63%
ASTM Test Methods
between the scratch groove and the undamaged material
G99Test Method for Wear Testing with a Pin-on-Disk
surface. For different studies other criteria for failure may be
Apparatus
used.Forexample,failuremayoccurwhenthescratchwidthor
G171Test Method for Scratch Hardness of Materials Using
depthexceedsapredeterminedvalue.Onsetofmicro-cracking,
a Diamond Stylus
crazing, fish-scale formation, plowing can also be used as
failurecriteria.Foracoatedspecimenthepointoffailuremight
3. Terminology
be defined as the point at which the coating is penetrated,
3.1 Definitions:
revealing the underlying substrate. An image of styrene acry-
3.1.1 ASV Software, n—Automatic Scratch Visualization,a
lonitrile (SAN) subjected to Test Mode A (4.1.1) under a
computer program which automates the identification of the
linearly increasing normal load range of 1-90 N is shown in
Fig. 1 to illustrate several possible points of failure that can
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
occur during the scratch process.
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
3.1.5 scratch coeffıcient of friction, n—the ratio of the
Current edition approved Oct. 15, 2013. Published October 2013. Originally
ε1
tangential force (3.1.10) to the normal load (3.1.3). This
approved in 2005. Last previous edition approved in 2005 as D7027–05 . DOI:
10.1520/D7027-13.
coefficient is a measure of the resistance of a material to
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
scratching motion. For tests conducted under constant load,
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
two distinct quantities may be characterized, the static and
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. kinetic coefficie
...

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.
´1
Designation: D7027 − 05 D7027 − 13
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
ε NOTE—Footnote 5 was editorially revised in April 2009.
1. 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 mar and 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 and health practices and determine the applicability of regulatory
limitations prior to use.
NOTE 1—FLTM BN 108-13, ISO 1518 and ISO 12137-2 are related to this test method; the contents are significantly different from this method.
2. Referenced Documents
2
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D638 Test Method for Tensile Properties of 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
F2215 Specification for Balls, Bearings, Ferrous and Nonferrous for Use in Bearings, Valves, and Bearing Applications
G99 Test Method for Wear Testing with a Pin-on-Disk Apparatus
G171 Test Method for Scratch Hardness of Materials Using a Diamond Stylus
3
2.2 ISO Standards:
ISO 1518 Methods of Test for Paints—Part E2: Scratch Test
ISO 12137-2 Methods of Test for Paints—Part E18: Determination of Mar Resistance using a Pointed Stylus
ISO 3290 Rolling Bearings: Balls—Dimensions and Tolerances
2.3 Other Standards:
4
FLTM BN 108-13 Resistance to Scratching
3. Terminology
3.1 Definitions:
3.1.1 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.
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 June 1, 2005Oct. 15, 2013. Published June 2005October 2013. Originally approved in 2005. Last previous edition approved in 2005 as
ε1
D7027–05 . DOI: 10.1520/D7027-05E01.10.1520/D7027-13.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7027 − 13
FIG. 1 Schematic of the Instrumented Scratch MachineImages of Polystyrene-Acrylonitrile (SAN) Subjected to Test Mode A Under a
Progressive Load of 1-90 N Showing Examples of Points 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.
3.1.2 critical normal load, n—the normal load at which whiteningfailure (see 3.1.103.1.4) of the material within the scratch
groove first occurs.
3.1.3 normal load, n—a load applied onto the scratch stylus that is imposed in a vertica
...