ASTM F1957-99
(Test Method)Standard Test Method for Composite Foam Hardness-Durometer Hardness
Standard Test Method for Composite Foam Hardness-Durometer Hardness
SCOPE
1.1 This test method describes a type of composite foam hardness measurement device known as durometer: Type CF. The procedure for determining indentation hardness of substances comprised of two or more elastomeric materials, one of which is a foam or foam like material. These are classified as composite foam structures. The composite foam product may have an armature made of a material suitable for adding structural integrity including but not limited to metal, plastic, or wood. This construction is typical for lapbar restraints, seating, and other restraint devices, as well as some show elements.
1.2 This test method is not equivalent to other indentation hardness methods and instrument types, specifically those described in Test Methods D1415 and D2240.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. Many of the stated dimensions in SI are direct conversions from the U.S. customary system to accommodate the instrumentation, practices, and procedures that existed prior to the Metric Conversion Act of 1975.
1.4 All materials, instruments, or equipment used for the determination of mass or dimension shall have traceability to the National Institute for Standards and Technology (NIST) or other internationally recognized organizations.
1.5 This test method is not a safety standard as it pertains to ride legislation. The use of this test method is optional based upon an agreement between customers and suppliers of foam products.
1.6 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
Relations
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:F1957–99
Standard Test Method for
Composite Foam Hardness-Durometer Hardness
This standard is issued under the fixed designation F 1957; 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 (ϵ) indicates an editorial change since the last revision or reapproval.
1. Scope D 618 Practice for Conditioning Plastics and Electrical
Insulating Materials for Testing
1.1 This test method describes a type of composite foam
D 785 Test Method for Rockwell Hardness of Plastics and
hardness measurement device known as durometer: Type CF.
Electrical Insulating Materials
The procedure for determining indentation hardness of sub-
D 1349 Practice for Rubber—Standard Temperatures for
stances comprised of two or more elastomeric materials, one of
Testing
which is a foam or foam like material. These are classified as
D 1415 Test Method for Rubber Property—International
composite foam structures. The composite foam product may
Hardness
have an armature made of a material suitable for adding
D 2240 Test Method for Rubber Property—Durometer
structural integrity including but not limited to metal, plastic,
Hardness
or wood. This construction is typical for lapbar restraints,
D 4483 Practice for Determining Precision for Test Method
seating, and other restraint devices, as well as some show
Standards in the Rubber and Carbon Black Industries
elements.
1.2 This test method is not equivalent to other indentation
3. Summary of Test Method
hardness methods and instrument types, specifically those
3.1 This test method permits hardness measurements based
described in Test Methods D 1415D 1415 and D 2240D 2240.
on either initial indentation or indentation after a specified
1.3 The values stated in SI units are to be regarded as
period of time, or both.
standard. The values given in parentheses are for information
3.2 Those specimens, which have a durometer hardness
only. Many of the stated dimensions in SI are direct conver-
range other than specified, shall use another suitable procedure
sions from the U.S. customary system to accommodate the
for determining durometer hardness.
instrumentation, practices, and procedures that existed prior to
the Metric Conversion Act of 1975.
4. Significance and Use
1.4 All materials, instruments, or equipment used for the
4.1 This test method is based on the penetration by a
determination of mass or dimension shall have traceability to
specific type of indentor when forced into the material under
the National Institute for Standards and Technology (NIST) or
specified conditions. The indentation hardness is related in-
other internationally recognized organizations.
versely to the penetration and is dependent on the elastic
1.5 This test method is not a safety standard as it pertains to
modulus and viscoelastic behavior of the material. The geom-
ride legislation. The use of this test method is optional based
etry of the indentor and the applied force influence the
upon an agreement between customers and suppliers of foam
measurements, such that no simple relationship exists between
products.
the measurements obtained with one type of durometer and
1.6 This standard does not purport to address all of the
those obtained with another type of durometer or other
safety concerns, if any, associated with its use. It is the
instruments used for measuring hardness. This test method is
responsibility of the user of this standard to establish appro-
an empirical test intended primarily for control purposes. No
priate safety and health practices and determine the applica-
simple relationship exists between indentation hardness deter-
bility of regulatory limitations prior to use.
mined by this test method and any fundamental property of the
2. Referenced Documents material tested. For specification purposes it is recommended
that Test Method D 785D 785 be used for hard materials and
2.1 ASTM Standards:
Test Method D 2240D 2240 be used for solid elatomers.
D 374 Test Methods for Thickness of Solid Electrical Insu-
lation
5. Apparatus
5.1 Hardnessmeasurementapparatus,ordurometer,consist-
This test method is under the jurisdiction of ASTM Committee F-24 on
ing of the following components:
Amusement Rides and Devices and is the direct responsibility of F24.10 on Test
Methods.
Current edition approved Feb. 10, 1999. Published May 1999. Annual Book of ASTM Standards, Vol 08.01.
2 4
Annual Book of ASTM Standards, Vol 10.01. Annual Book of ASTM Standards, Vol 09.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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.
F1957–99
5.1.1 Presser Foot, with an orifice (to allow for the protru-
sion of the indentor) having a diameter as specified in Fig. 1
with the center a minimum of 38.0 mm (1.5 in.) from any edge
of the flat circular presser foot.
5.1.2 Indentor, formed from steel rod, shaped in accordance
with Fig. 2, polished over the contact area so that no flaws are
visible under 203 magnification and with an indentor exten-
sion of 7.62 6 0.04 mm (.300 6 0.002 in.).
5.1.3 Indentor Extension Indicating Display, (analog or
digital electronic), having a display that is an inverse function
of the indentor extension.
5.1.3.1 Digital Electronic Indicating Displays shall indi-
cate from 0 to 100, with no less than 100 equal divisions
throughout the range, at a rate of one hardness point for each
0.50 mm (0.002 in.) of indentor movement.
5.1.3.2 Analog Indicating Displays shall indicate from 0 to
100, with no less 100 equal divisions throughout the range or
alternatively with no less than 90 equal divisions throughout a
FIG. 2 Indentor Detail
range from 10 to 100, at a rate of one hardness point for each
0.050 mm (0.002 in.) of indentor movement.
5.1.4 Maximum Indicators (optional), maximum indicating
pointers are auxiliary analog indicating hands designed to
remain at the maximum hardness value attained until reset by
the operator. Electronic maximum indicators are digital dis-
plays electronically indicating and maintaining the maximum
value hardness value achieved, until reset by the operator.
5.1.4.1 Analog maximum indicating pointers have been
shown to have a nominal influence on the values attained;
however, this influence is greater on durometers of lesser total
mainspring forces. The influence of a maximum indicating
FIG. 1 Presser Foot Detail pointer shall be noted at the time of calibration in the
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.
F1957–99
calibration report (see 10.1.4) and when reporting hardness or by an electronic force cell. The calibrating device shall be
determinations (see 10.2.4). capable of measuring applied force to within 50 % of the
5.1.4.2 Digital electronic durometers may be equipped with calibrationtolerancedescribedinTable1.Careshouldbetaken
electronic maximum indicators that shall not influence the to ensure that the force is applied vertically to the indentor tip,
indicated reading or determinations attained by more than one as lateral force will cause errors in calibration.
half of the calibration tolerance stated in Table 1.
7.2 Indentor Extension—Indentor extension and shape shall
5.1.5 Calibrated Spring, for applying force to the indentor
be in accordance with 5.1.2 and Fig. 2.
and capable of applying the forces as specified in Table 1.
7.3 Indentor Extension Adjustment Procedure:
7.3.1 Dimensional Gage Blocks:
6. Test Specimen
7.3.1.1 The presser foot must be attached to the durometer
6.1 The test specimen, herein referred to as “specimen” or
gage before adjustment. This allows a nominal indentor exten-
“test specimen” interchangeably, shall be at least 25.4 mm
sion of 7.62 mm (.300 in.).
(1.00 in.) thick, herein, unless it is known that results equiva-
7.3.1.2 Placeprecisiongrounddimensionalblocks(GradeB
lenttothe25.4mm(1.00in.)valuesareobtainedwithathinner
or better) on the test specimen support table and beneath the
test specimen. On specimens with solid armatures, it is
durometer presser foot and indentor.Arrange the blocks so that
suggested that readings not be taken in areas close to the
the durometer presser foot contacts the larger block and the
armature as this may affect the readings.
indentor tip is at the moment of contact with the smaller block
6.1.1 The lateral dimensions of the test specimen shall be
(Fig. 3).
sufficient to permit measurements at least 12.0 mm (0.48 in.)
7.3.1.3 A combination of dimensional gage blocks may be
from any edge unless it is known that identical results are
usedtoachieveadifferenceof7.62+0.00,–0.0254mm(0.300
obtained when measurements are made at a lesser distance
+0.00, –0.001 in.) between them:
from an edge.
7.3.2 Indentor Extension Adjustment:
6.1.2 The surfaces of the test specimen shall be flat and
7.3.2.1 Carefully lower the durometer presser foot until
parallel over a sufficient area to permit the presser foot to
contact with the largest dimensional block, the indentor tip
contact the specimen over an area having a radius of at least
should be at the point of contact with the smaller block,
30.0 mm (1.18 in.) from the indentor point if possible.
verifying full indentor extension.
Variations are acceptable as agreed upon between laboratories
or between customer and supplier. The test specimen shall be 7.3.2.2 Adjust the indentor extension to 7.620 6 0.04 mm
supported suitably to provide for positioning and stability. A (0.300 6 0.002 in.), following the manufacturer’s recom-
suitablehardnessdeterminationmaybedifficulttoobtainonan mended procedure.
uneven or rough point of contact with the indentor.
7.3.2.3 When performing the procedures in 7.3, care should
be used as not to cause damage to the indentor tip.
7. Calibration
7.3.2.4 Parallelism of the durometer presser foot to the test
7.1 Calibration Device—The durometer spring shall be
specimen support surface (table), and hence the dimensional
calibrated by supporting the durometer in a calibrating device
gage blocks, at the time of instrument calibration shall be in
in a vertical position and applying a measurable force to the
accordance with Test Methods D 374D 374, machinist’s mi-
indentor tip.The force may be measured by means of a balance
crometers.
7.4 Indicator Display Adjustment (Analog and Digital):
TABLE 1 Durometer Spring Force Calibration
7.4.1 After adjusting the indentor extension as indicated in
Indicated Value Force, N Force, lbf 7.3,useanidenticalarrangementofdimensionalgageblocksto
verify the linear relationship between indentor travel and
0 1.099 0.247
indicated display at two points: 0 and 100. Following the
10 9.928 2.232
manufacturer’s recommendations, make adjustments so that
the indicator displays a value equal to the indentor travel
20 18.757 4.217
measured to within:
30 27.586 6.202
6 ⁄2 durometer units measured at 0;
6 ⁄2 durometer units measured at 100, and
40 36.415 8.186
6 1 ⁄2 durometer units at all points enumerated in 7.5.
50 45.244 10.171
7.4.2 Each durometer point indicated is equal to 0.050 mm
(0.002 in.) of indentor travel.
60 54.073 12.156
7.5 Spring Calibration—The durometer spring shall be
70 62.902 14.141
calibrated at displayed readings 20, 30, 40, 50, 60, 70, 80, and
80 71.731 16.126
90. The measured force (9.8 3 mass in kilograms) shall be
within the calibration tolerance specified in Table 1, which
90 80.560 18.111
identifies the measured force applied to the indentor for the
100 89.389 20.095
entire range of the instrument, although it is necessary only to
verify the spring calibration at points listed herein.
Calibration Tolerance 60.893 60.200
7.6 Spring Calibration Procedure:
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.
F1957–99
7.9 Spring Force Combinations:
7.9.1 For Type CF Durometers:
force, N5 1.09871 0.8829 H (1)
CF
where:
H = one durometer unit on Type CF durometers.
CF
8. Instrument and Test Specimen Conditioning
8.1 Tests or instrument calibrations shall be conducted at
23.0 6 2.0° C (73.4 6 3.6° F).
8.2 The instrument and specimen(s) to be tested shall be
maintained at 23.06 2.0° C (73.46 3.6° F) for a minimum of
12 h prior to performing a test or calibration.
8.3 For materials whose hardness depends on relative hu-
midity, the test specimens shall be conditioned in accordance
with ProcedureAof Practice D 618D 618 and tested under the
same conditions.
8.3.1 Accordingly, the relative humidity at the time of a test
shall be reported in 10.2.2.
8.3.2 The relative humidity may be reported in 10.2.2 when
the influence of relative humidity on the hardness of the test
specimen is not known.
8.3.3 The relative humidity at the time of instrument cali-
bration shall be reported in 10.1.6.
8.4 No conclusive evaluation has been made on durometers
at temperatures other than 23.0 6 2.0 °C (73.4 6 3.6 °F).
Conditioning at temperatures other than the above may show
changes in calibration. Durometer use at temperatures other
than the above should be decided between customer and
supplier (see Practice D 1349D 1349).
8.5 These procedures may be modified if agreed upon
between laboratories or between customer and supplier.
9. Procedure
9.1 Manual (Hand-Held) Durometer Testing:
9.1.1 Care shall be exercised to minimize the exposure of
the instrument to environmental conditions that are adverse to
the performance of the instrument or adversely influence test
results.
9.1.2 Place the test specimen on a flat, hard, horizontal
surface. Hold the durometer in a vertical position with the
indentor tip at a distance from any edge of the test specimen as
FIG. 3 Indentor Extension Calibration Setup
described in Section 6, unless it is known that identical results
are obtained when measurements are made with the indentor at
7.6.1 Assure that the indentor extension has been adjusted a lesser distance.
in accordance with 7.3 and the linear relationship between 9.1.3 Apply the indentor to the test specimen, maintaining
indentor travel and indicated display is as specified in 7.4. the durometer in a vertical position keeping the presser foot
7.6.2 Place the durometer in the calibration device (see 7.1). parallel to the test specimen, with a firm smooth downward
Apply t
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.