ASTM D256-05
(Test Method)Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
SCOPE
1.1 These test methods cover the determination of the resistance of plastics to "standardized" (see Note 0) pendulum-type hammers, mounted in "standardized" machines, in breaking standard specimens with one pendulum swing (see Note 0). The standard tests for these test methods require specimens made with a milled notch (see Note 0). In Test Methods A, C, and D, the notch produces a stress concentration that increases the probability of a brittle, rather than a ductile, fracture. In Test Method E, the impact resistance is obtained breakage by flexural shock as indicated by the energy extracted from by reversing the notched specimen 180 in the clamping vise. The results of all test methods are reported in terms of energy absorbed per unit of specimen width or per unit of cross-sectional area under the notch. (See Note 0.)Note 0
The machines with their pendulum-type hammers 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. However, hammers of different initial energies (produced by varying their effective weights) are recommended for use with specimens of different impact resistance. Moreover, manufacturers of the equipment are permitted to use different lengths and constructions of pendulums with possible differences in pendulum rigidities resulting. (See Section .) Be aware that other differences in machine design may exist. The specimens are "standardized" in that they are required to have one fixed length, one fixed depth, and one particular design of milled notch. The width of the specimens is permitted to vary between limits.Note 0
Results generated using pendulums that utilize a load cell to record the impact force and thus impact energy, may not be equivalent to results that are generated using manually or digitally encoded testers that measure the energy remaining in the pendulum after impact.Note 0
The notch in the Izod specimen serves to concentrate the stress, minimize plastic deformation, and direct the fracture to the part of the specimen behind the notch. Scatter in energy-to-break is thus reduced. However, because of differences in the elastic and viscoelastic properties of plastics, response to a given notch varies among materials. A measure of a plastic's "notch sensitivity" may be obtained with Test Method D by comparing the energies to break specimens having different radii at the base of the notch.Note 0
Caution must be exercised in interpreting the results of these standard test methods. The following testing parameters may affect test results significantly:Method of fabrication, including but not limited to processingtechnology, molding conditions, mold design, and thermaltreatments;Method of notching;Speed of notching tool;Design of notching apparatus;Quality of the notch;Time between notching and test;Test specimen thickness,Test specimen width under notch, andEnvironmental conditioning.
1.2 The values stated in SI units are to be regarded as the 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.
These test methods resemble ISO 180:1993 in regard to title only. The contents are significantly different.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
Designation:D256–05
Standard Test Methods for
Determining the Izod Pendulum Impact Resistance of
1
Plastics
This standard is issued under the fixed designation D256; 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 (ϵ) indicates an editorial change since the last revision or reapproval.
NOTE 4—Caution must be exercised in interpreting the results of these
1. Scope*
standard test methods. The following testing parameters may affect test
1.1 These test methods cover the determination of the
results significantly:
resistanceofplasticsto“standardized”(seeNote1)pendulum-
Method of fabrication, including but not limited to processing
type hammers, mounted in “standardized” machines, in break-
technology, molding conditions, mold design, and thermal
treatments;
ingstandardspecimenswithonependulumswing(seeNote2).
Method of notching;
The standard tests for these test methods require specimens
Speed of notching tool;
made with a milled notch (see Note 3). In Test MethodsA, C,
Design of notching apparatus;
Quality of the notch;
and D, the notch produces a stress concentration that increases
Time between notching and test;
the probability of a brittle, rather than a ductile, fracture. In
Test specimen thickness,
Test Method E, the impact resistance is obtained breakage by
Test specimen width under notch, and
Environmental conditioning.
flexural shock as indicated by the energy extracted from by
reversingthenotchedspecimen180°intheclampingvise.The
1.2 The values stated in SI units are to be regarded as the
results of all test methods are reported in terms of energy
standard.Thevaluesgiveninbracketsareforinformationonly.
absorbed per unit of specimen width or per unit of cross-
1.3 This standard does not purport to address all of the
sectional area under the notch. (See Note 4.)
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
NOTE 1—The machines with their pendulum-type hammers have been
priate safety and health practices and determine the applica-
“standardized” in that they must comply with certain requirements,
bility of regulatory limitations prior to use.
includingafixedheightofhammerfallthatresultsinasubstantiallyfixed
velocity of the hammer at the moment of impact. However, hammers of
NOTE 5—These test methods resemble ISO180:1993 in regard to title
different initial energies (produced by varying their effective weights) are
only. The contents are significantly different.
recommended for use with specimens of different impact resistance.
Moreover, manufacturers of the equipment are permitted to use different
2. Referenced Documents
lengths and constructions of pendulums with possible differences in
2
2.1 ASTM Standards:
pendulum rigidities resulting. (See Section 5.) Be aware that other
differences in machine design may exist. The specimens are “standard- D618 Practice for Conditioning Plastics for Testing
ized” in that they are required to have one fixed length, one fixed depth,
D883 Terminology Relating to Plastics
and one particular design of milled notch. The width of the specimens is
D3641 Practice for Injection Molding Test Specimens of
permitted to vary between limits.
Thermoplastics Molding Extrusion Materials
NOTE 2—Results generated using pendulums that utilize a load cell to
D4000 Classification System for Specifying Plastic Mate-
record the impact force and thus impact energy, may not be equivalent to
rials
results that are generated using manually or digitally encoded testers that
D4066 Classification System for Nylon Injection and Ex-
measure the energy remaining in the pendulum after impact.
NOTE 3—The notch in the Izod specimen serves to concentrate the
trusion Materials
stress, minimize plastic deformation, and direct the fracture to the part of
D4812 Test Methods for Unnotched Cantilever Beam Im-
thespecimenbehindthenotch.Scatterinenergy-to-breakisthusreduced.
pact Resistance of Plastics
However, because of differences in the elastic and viscoelastic properties
D5947 Test Methods for Physical Dimensions of Solid
of plastics, response to a given notch varies among materials.Ameasure
Plastic Specimens
of a plastic’s “notch sensitivity” may be obtained with Test Method D by
E691 Practice for Conducting an Interlaboratory Test Pro-
comparing the energies to break specimens having different radii at the
base of the notch. gram to Determine the Precision of Test Methods
2.2 ISO Standard:
1
These test methods are under the jurisdiction of ASTM Committee D20 on
2
Plastics and are the direct responsibility of Subcommittee D20.10 on Mechanical For referenced ASTM standards, visit the ASTM website, w
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