ASTM D4812-05
(Test Method)Standard Test Method for Unnotched Cantilever Beam Impact Strength of Plastics
Standard Test Method for Unnotched Cantilever Beam Impact Strength of Plastics
SCOPE
1.1 This test method covers the determination of the resistance of plastics to breakage by flexural shock, as indicated by the energy extracted from standardized pendulum-type hammers, mounted in standardized machines, in breaking standard specimens with one pendulum swing. The result of this test method is reported as energy absorbed per unit of specimen width.Note 1
The pendulum-type test instruments have been standardized in that they must comply with certain requirements, including a fixed height of hammer fall that results in a substantially fixed velocity of the hammer at the moment of impact. Pendulums of different initial energies (produced by varying their effective weights) are recommended for use with specimens of different impact strengths. Moreover, manufacturers of the equipment are permitted to use different lengths and constructions of pendulums (with resulting possible differences in pendulum rigidities (see Section ), and other differences in machine design).
1.2 The values stated in SI units are to be regarded as standard. The values given in brackets are for information only.
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 2
This standard and ISO 180, Method 1U, are similar in content but are not technically equivalent.
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Designation:D4812–05
Standard Test Method for
1
Unnotched Cantilever Beam Impact Resistance of Plastics
This standard is issued under the fixed designation D4812; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope* Determine the Precision of a Test Method
1.1 This test method covers the determination of the resis-
3. Terminology
tance of plastics to breakage by flexural shock, as indicated by
3.1 Definitions—Definitions used in this test method are in
the energy extracted from standardized pendulum-type ham-
accordance with Terminology D883.
mers, mounted in standardized machines, in breaking standard
specimens with one pendulum swing. The result of this test
4. Summary of Test Method
method is reported as energy absorbed per unit of specimen
4.1 This test method differs from others of similar character
width.
in that unnotched test specimens are used (see Test Methods
NOTE 1—The pendulum-type test instruments have been standardized
D256 for procedures using notched test specimens). The lack
in that they must comply with certain requirements, including a fixed
of a notch makes this test method especially useful for
height of hammer fall that results in a substantially fixed velocity of the
reinforced materials where a notch may mask the effects of
hammer at the moment of impact. Pendulums of different initial energies
orientation. It may also be used with other filled or unrein-
(produced by varying their effective weights) are recommended for use
forced materials where a stress-concentrating notch is not
with specimens of different impact strengths. Moreover, manufacturers of
the equipment are permitted to use different lengths and constructions of desired. It is not valid for materials that twist when subjected
pendulums (with resulting possible differences in pendulum rigidities (see
to this test.
Section 5), and other differences in machine design).
5. Significance and Use
1.2 The values stated in SI units are to be regarded as
5.1 The pendulum-impact test indicates the energy to break
standard.Thevaluesgiveninbracketsareforinformationonly.
standard test specimens of specified size under stipulated
1.3 This standard does not purport to address all of the
conditions of specimen mounting and pendulum velocity at
safety concerns, if any, associated with its use. It is the
impact.
responsibility of the user of this standard to establish appro-
5.2 The energy lost by the pendulum during the breakage of
priate safety and health practices and determine the applica-
thespecimenisthesumoftheenergiesrequiredtoproducethe
bility of regulatory limitations prior to use.
following results:
NOTE 2—ThisstandardandISO180,Method1U,aresimilarincontent
5.2.1 To initiate fracture of the specimen,
but are not technically equivalent.
5.2.2 To propagate the fracture across the specimen,
5.2.3 To throw the free end (or pieces) of the broken
2. Referenced Documents
2
specimen (toss correction),
2.1 ASTM Standards:
5.2.4 To bend the specimen,
D256 Test Methods for Impact Resistance of Plastics and
5.2.5 To produce vibration in the pendulum arm,
Electrical Insulating Materials
5.2.6 To produce vibration or horizontal movement of the
D618 Practice for Conditioning Plastics for Testing
machine frame or base,
D883 Terminology Relating to Plastics
5.2.7 To overcome friction in the pendulum bearing and in
D5947 Test Methods for Physical Dimensions of Solid
the indicating mechanism, and to overcome windage (pendu-
Plastic Specimens
lum air drag),
E691 Practice for Conducting an Interlaboratory Study to
5.2.8 To indent or deform plastically the specimen at the
line of impact, and
5.2.9 To overcome the friction caused by the rubbing of the
1
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
striking nose (or other part of the pendulum) over the face of
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
the bent specimen.
Current edition approved Nov. 1, 2005. Published December 2005. Originally
approved in 1988. Last previous edition approved in 1999 as D4812-99.
5.3 For relatively brittle materials for which fracture propa-
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
gationenergyissmallincomparisonwiththefractureinitiation
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
energy, the indicated impact energy absorbed is, for all
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.
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