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: D2240 − 15
`
`Standard Test Method for
`Rubber Property—Durometer Hardness1
`
`This standard is issued under the fixed designation D2240; 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.
`
`This standard has been approved for use by agencies of the U.S. Department of Defense.
`
`1. Scope
`1.1 This test method covers twelve types of rubber hardness
`measurement devices known as durometers: Types A, B, C, D,
`DO, E, M, O, OO, OOO, OOO-S, and R. The procedure for
`determining indentation hardness of substances classified as
`thermoplastic elastomers, vulcanized (thermoset) rubber, elas-
`tomeric materials, cellular materials, gel-like materials, and
`some plastics is also described.
`1.2 This test method is not equivalent to other indentation
`hardness methods and instrument
`types, specifically those
`described in Test Method D1415.
`1.3 This test method is not applicable to the testing of
`coated fabrics.
`1.4 All materials, instruments, or equipment used for the
`determination of mass, force, or dimension shall have trace-
`ability to the National Institute for Standards and Technology,
`or other internationally recognized organizations parallel in
`nature.
`1.5 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 conver-
`sions from the U. S. Customary System to accommodate the
`instrumentation, practices, and procedures that existed prior to
`the Metric Conversion Act of 1975.
`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 appro-
`priate safety and health practices and determine the applica-
`bility of regulatory limitations prior to use.
`
`2. Referenced Documents
`2.1 ASTM Standards:2
`
`1 This test method is under the jurisdiction of ASTM Committee D11 on Rubber
`and is the direct responsibility of Subcommittee D11.10 on Physical Testing.
`Current edition approved Aug. 1, 2015. Published January 2016. Originally
`approved in 1964. Last previous edition approved in 2010 as D2240 – 05 (2010).
`DOI: 10.1520/D2240-15.
`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.
`
`D374 Test Methods for Thickness of Solid Electrical Insu-
`lation (Withdrawn 2013)3
`D618 Practice for Conditioning Plastics for Testing
`D785 Test Method for Rockwell Hardness of Plastics and
`Electrical Insulating Materials
`D1349 Practice for Rubber—Standard Conditions for Test-
`ing
`D1415 Test Method for Rubber Property—International
`Hardness
`D4483 Practice for Evaluating Precision for Test Method
`Standards in the Rubber and Carbon Black Manufacturing
`Industries
`F1957 Test Method for Composite Foam Hardness-
`Durometer Hardness
`2.2 ISO Standard:4
`ISO/IEC 17025: 1999 General Requirements for the Com-
`petence of Testing and Calibration Laboratories
`
`3. Summary of Test Method
`3.1 This test method permits hardness measurements based
`on either initial indentation or indentation after a specified
`period of time, or both. Durometers with maximum reading
`indicators used to determine maximum hardness values of a
`material may yield lower hardness when the maximum indi-
`cator is used.
`3.2 The procedures for Type M, or micro hardness
`durometers, accommodate specimens that are, by their dimen-
`sions or configuration, ordinarily unable to have their durom-
`eter hardness determined by the other durometer types de-
`scribed. Type M durometers are intended for the testing of
`specimens having a thickness or cross-sectional diameter of
`1.25 mm (0.050 in.) or greater, although specimens of lesser
`dimensions may be successfully accommodated under the
`conditions specified in Section 6, and have a Type M durometer
`hardness range between 20 and 90. Those specimens which
`have a durometer hardness range other than specified shall use
`another suitable procedure for determining durometer hard-
`ness.
`
`3 The last approved version of
`www.astm.org.
`4 Available from International Organization for Standardization (ISO), 1 rue de
`Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland.
`
`this historical standard is referenced on
`
`Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
`
`1
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`

`D2240 − 15
`
`FIG. 1 (a) Type A and C Indentor
`
`4. Significance and Use
`4.1 This test method is based on the penetration of a specific
`type of indentor when forced into the material under specified
`conditions. The indentation hardness is inversely related to the
`penetration and is dependent on the elastic modulus and
`viscoelastic behavior of the material. The geometry of the
`indentor and the applied force influence the measurements
`such that no simple relationship exists between the measure-
`ments obtained with one type of durometer and those obtained
`with another type of durometer or other instruments used for
`measuring hardness. This test method is an empirical test
`intended primarily for control purposes. No simple relationship
`exists between indentation hardness determined by this test
`method and any fundamental property of the material tested.
`For specification purposes, it is recommended that Test Method
`D785 be used for materials other than those described in 1.1.
`
`5. Apparatus
`5.1 Hardness Measuring Apparatus, or Durometer, and an
`Operating Stand, Type 1, Type 2, or Type 3 (see 5.1.2)
`consisting of the following components:
`5.1.1 Durometer:
`5.1.1.1 Presser Foot, the configuration and the total area of
`a durometer presser foot may produce varying results when
`there are significant differences between them. It is recom-
`mended that when comparing durometer hardness determina-
`tions of the same type (see 4.1), that the comparisons be
`between durometers of similar presser foot configurations and
`total area, and that the presser foot configuration and size be
`noted in the Hardness Measurement Report (see 10.2.4 and
`5.1.1.3).
`5.1.1.2 Presser Foot, Types A, B, C, D, DO, E, O, OO,
`OOO, and OOO-S, with an orifice (to allow for the protrusion
`of the indentor) having a diameter as specified in Fig. 1 (a, b,
`c, d, e, f, and g), with the center a minimum of 6.0 mm (0.24
`in.) from any edge of the foot. When the presser foot is not of
`a flat circular design, the area shall not be less than 500
`mm2 (19.7 in.2).
`
`NOTE 1—The Type OOO and the Type OOO-S, designated herein,
`
`differ in their indentor configuration, spring force, and the results
`obtained. See Table 1 and Fig. 1 (e and g).
`5.1.1.3 Presser Foot—flat circular designs designated as
`Type xR, where x is the standard durometer designation and R
`indicates the flat circular press foot described herein, for
`example, Type aR, dR, and the like. The presser foot, having a
`centrally located orifice (to allow for the protrusion of the
`indentor) of a diameter as specified in Fig. 1 (a through g). The
`flat circular presser foot shall be 18 6 0.5 mm (0.71 6 0.02 in.)
`in diameter. These durometer types shall be used in an
`operating stand (see 5.1.2).
`(a) Durometers having a presser foot configuration other
`than that
`indicated in 5.1.1.3 shall not use the Type xR
`designation, and it is recommended that their presser foot
`configuration and size be stated in the Hardness Measurement
`Report (see 10.2.4).
`5.1.1.4 Presser Foot, Type M, with a centrally located
`orifice (to allow for the protrusion of the indentor), having a
`diameter as specified in Fig. 1 (d), with the center a minimum
`of 1.60 mm (0.063 in.) from any edge of the flat circular
`presser foot. The Type M durometer shall be used in a Type 3
`operating stand (see 5.1.2.4).
`5.1.1.5 Indentor, formed from steel rod and hardened to 500
`HV10 and shaped in accordance with Fig. 1 (a, b, c, d, e, or g),
`polished over the contact area so that no flaws are visible under
`20× magnification, with an indentor extension of 2.50 6 0.04
`mm (0.098 6 0.002 in.).
`5.1.1.6 Indentor, Type OOO-S, formed from steel rod and
`hardened to 500 HV10, shaped in accordance with Fig. 1 (f),
`polished over the contact area so that no flaws are visible under
`20× magnification, with an indentor extension of 5.00 6 0.04
`mm (0.198 6 0.002 in.).
`5.1.1.7 Indentor, Type M, formed from steel rod and hard-
`ened to 500 HV10 and shaped in accordance with Fig. 1 (d),
`polished over the contact area so that no flaws are visible under
`50× magnification, with an indentor extension of 1.25 6 0.02
`mm (0.049 6 0.001 in.).
`5.1.1.8 Indentor Extension Indicator, analog or digital
`electronic, having a display that is an inverse function of the
`indentor extension so that:
`
`2
`
`
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`

`D2240 − 15
`
`FIG. 1 (b) Type B and D Indentor (continued)
`
`FIG. 1 (c) Type O, DO, and OO Indentor (continued)
`
`FIG. 1 (d) Type M Indentor (continued)
`
`(1) The display shall indicate from 0 to 100 with no less
`than 100 equal divisions throughout the range at a rate of one
`hardness point for each 0.025 mm (0.001 in.) of indentor
`movement,
`(2) The display for Type OOO-S durometers shall indicate
`from 0 to 100 with no less than 100 equal divisions throughout
`the range at a rate of one hardness point for each 0.050 mm
`(0.002 in.) of indentor movement,
`(3) The display for Type M durometers shall indicate from
`0 to 100 with no less than 100 equal divisions at a rate of one
`hardness point for each 0.0125 mm (0.0005 in.) of indentor
`movement, and
`
`(4) In the case of analog dial indicators having a display of
`360°, the points indicating 0 and 100 may be at the same point
`on the dial and indicate 0, 100, or both.
`5.1.1.9 Timing Device (optional), capable of being set to a
`desired elapsed time, signaling the operator or holding the
`hardness reading when the desired elapsed time has been
`reached. The timer shall be automatically activated when the
`presser foot is in contact with the specimen being tested, for
`example, the initial indentor travel has ceased. Digital elec-
`tronic durometers may be equipped with electronic timing
`
`3
`
`
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`D2240 − 15
`
`FIG. 1 (e) Type OOO Indentor (continued)
`
`FIG. 1 (f) Type OOO-S Indentor (continued)
`
`devices that shall not affect the indicated reading or determi-
`nations attained by more than one-half of the calibration
`tolerance stated in Table 1.
`5.1.1.10 Maximum Indicators (optional), maximum indicat-
`ing 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 valued achieved until reset by the operator.
`5.1.1.11 Analog maximum indicating pointers have been
`shown to have a nominal effect on the values attained,
`however, this effect is greater on durometers of lesser total
`mainspring loads; for example,
`the effect of a maximum
`indicating pointer on Type D durometer determinations will be
`less than those determinations achieved using a Type A
`durometer. Analog style durometers may be equipped with
`maximum indicating pointers. The effect of a maximum
`indicating pointer shall be noted at the time of calibration in the
`calibration report (see 10.1.5), and when reporting hardness
`
`determinations (see 10.2.4). Analog Type M, OO, OOO, and
`Type OOO-S durometers shall not be equipped with maximum
`indicating pointers.
`5.1.1.12 Digital electronic durometers may be equipped
`with electronic maximum indicators that shall not affect the
`indicated reading or determinations attained by more than one
`half of the spring calibration tolerance stated in Table 1.
`for applying force to the
`5.1.1.13 Calibrated Spring,
`indentor, in accordance with Fig. 1 (a through g) and capable
`of applying the forces as specified in Table 1.
`5.1.2 Operating Stand (Fig. 2):
`5.1.2.1 Type 1, Type 2, and Type 3 shall be capable of
`supporting the durometer presser foot surface parallel to the
`specimen support table (Fig. 3) throughout the travel of each.
`The durometer presser foot to specimen support table parallel-
`ism shall be verified each time the test specimen support table
`is adjusted to accommodate specimens of varying dimensions.
`This may be accomplished by applying the durometer presser
`foot to the point of contact with the specimen support table and
`
`4
`
`
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`

`D2240 − 15
`
`FIG. 1 (g) Type E Indentor (continued)
`
`TABLE 1 Durometer Spring Force CalibrationA
`All Values are in N
`Type C, D, DO
`Type M
`0
`0.324
`4.445
`0.368
`8.89
`0.412
`13.335
`0.456
`17.78
`0.5
`22.225
`0.544
`26.67
`0.589
`31.115
`0.633
`35.56
`0.677
`40.005
`0.721
`44.45
`0.765
`0.4445
`0.0044
`± 0.4445 N
`± 0.0176 N
`
`Type A, B, E, O
`0.55
`1.3
`2.05
`2.8
`3.55
`4.3
`5.05
`5.8
`6.55
`7.3
`8.05
`0.075
`± 0.075 N
`
`Type OO, OOO
`0.203
`0.294
`0.385
`0.476
`0.566
`0.657
`0.748
`0.839
`0.93
`1.02
`1.111
`0.00908
`± 0.0182 N
`
`Type OOO-S
`0.167
`0.343
`0.520
`0.696
`0.873
`1.049
`1.226
`1.402
`1.579
`1.755
`1.932
`0.01765
`± 0.0353 N
`
`Indicated Value
`0
`10
`20
`30
`40
`50
`60
`70
`80
`90
`100
`N/durometer unit
`Spring Calibration
`Tolerance
`
`A Refer to 5.1.1.3 for the Type xR designation.
`
`making adjustments by way of the durometer mounting assem-
`bly or as specified by the manufacturer.
`5.1.2.2 Operating Stand, Type 1 (specimen to indentor
`type), shall be capable of applying the specimen to the indentor
`in a manner that minimizes shock.
`5.1.2.3 Operating Stand, Type 2 (indentor to specimen
`type), shall be capable of applying the indentor to the specimen
`in a manner that minimizes shock.
`5.1.2.4 Operating Stand, Type 3 (indentor to specimen
`type), hydraulic dampening, pneumatic dampening, or electro-
`mechanical (required for the operation of Type M durometers)
`shall be capable of controlling the rate of descent of the
`indentor to the specimen at a maximum of 3.2 mm/s (0.125
`in./s) and applying a force sufficient to overcome the calibrated
`spring force as shown in Table 1. Manual application, Type 1
`or Type 2 operating stands are not acceptable for Type M
`durometer operation.
`5.1.2.5 The entire instrument should be plumb and level,
`and resting on a surface that will minimize vibration. Operating
`the instrument under adverse conditions will negatively affect
`the determinations attained.
`5.1.2.6 Specimen Support Table, (Fig. 3) integral to the
`operating stand, and having a solid flat surface. The specimen
`
`support platform may have orifices designed to accept various
`inserts or support fixtures (Fig. 3) to provide for the support of
`irregularly configured specimens. When inserts are used to
`support test specimens, care must be taken to align the indentor
`to the center of the insert, or the point at which the indentor is
`to contact the specimen. Care should be exercised to assure that
`the indentor does not abruptly contact the specimen support
`table as damage to the indentor may result.
`
`6. Test Specimen
`6.1 The test specimen, herein referred to as “specimen” or
`“test specimen” interchangeably, shall be at least 6.0 mm (0.24
`in.) in thickness unless it is known that results equivalent to the
`6.0-mm (0.24-in.) values are obtained with a thinner specimen.
`6.1.1 A specimen may be composed of plied pieces to obtain
`the necessary thickness, but determinations made on such
`specimens may not agree with those made on solid specimens,
`as the surfaces of the plied specimens may not be in complete
`contact. The lateral dimensions of the specimen shall be
`sufficient to permit measurements at least 12.0 mm (0.48 in.)
`from any edge, unless it is known that identical results are
`obtained when measurements are made at a lesser distance
`from an edge.
`
`5
`
`
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`

`D2240 − 15
`
`FIG. 2 Durometer Operating Stand
`
`6.1.2 The surfaces of the specimen shall be flat and parallel
`over an area to permit the presser foot to contact the specimen
`
`over an area having a radius of at least 6.0 mm (0.24 in.) from
`the indentor point. The specimen shall be suitably supported to
`
`FIG. 3 Small Specimen Support Table
`
`6
`
`
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`D2240 − 15
`
`7.1.2 Indentor extension and shape shall be in accordance
`with 5.1.1.5, 5.1.1.6, or5.1.1.7, respective to durometer type.
`See Fig. 1 (a through g). Examination of the indentor under
`20× magnification, 50× for Type M indentors, is required to
`examine the indentor condition. Misshapen or damaged inden-
`tors shall be replaced.
`7.1.3 A combination of dimensional gage blocks shall be
`used to achieve a difference of 2.54 + 0.00/–0.0254 mm (0.100
`+ 0.00/–0.001 in.) between them. For Type OOO-S durometers,
`the gage block dimensions are 5.08 + 0.00/–0.0508 mm (0.200
`+ 0.00/–0.002 in.). For Type M durometers, the gage block
`dimensions are 1.27 + 0.0/–0.0127 mm (0.050 + 0.00/–0.0005
`in.) between them (Fig. 4).
`7.1.4 Carefully lower the durometer presser foot until it
`contacts the largest dimensional block(s),
`the indentor tip
`should just contact the smaller block, verifying full indentor
`extension.
`7.1.5 Adjust the indentor extension to 2.50 6 0.04 mm
`(0.098 6 0.002 in.). For Type OOO-S durometers, adjust the
`indentor extension to 5.0 6 0.04 mm (0.198 6 0.002 in.). For
`Type M durometers, adjust the indentor extension to 1.25 6
`0.02 mm (0.049 6 0.001 in.), following the manufacturer’s
`recommended procedure.
`7.1.5.1 When performing the procedures in 7.1, care should
`be used so as not to cause damage to the indentor tip. Fig. 4
`depicts a suitable arrangement for gaging indentor extension.
`to the
`7.1.6 Parallelism of the durometer presser foot
`support surface, and hence the dimensional gage blocks, at the
`time of instrument calibration, may be in accordance with Test
`Methods D374, Machinist’s Micrometers, or otherwise accom-
`plished in accordance with the procedures specified by the
`manufacturer.
`7.2 Indentor Display Adjustment:
`7.2.1 After adjusting the indentor extension as indicated in
`7.1, use a similar arrangement of dimensional gage blocks to
`verify the linear relationship between indentor travel and
`indicated display at two points: 0 and 100. Following the
`manufacturer’s recommendations, make adjustments so that:
`7.2.2 The indicator displays a value equal to the indentor
`travel measured to within:
`–0.0 +1.0 durometer units measured at 0;
`60.50 durometer units measured at 100;
`61 durometer units at all other points delineated in 7.4.
`7.2.3 Each durometer point indicated is equal to 0.025 mm
`(0.001 in.) of indentor travel, except for:
`7.2.3.1 Type M Durometers, each indicated point is equal to
`0.0125 mm (0.0005 in.) of indentor travel;
`7.2.3.2 Type OOO-S Durometers, each indicated point is
`equal to 0.050 mm (0.002 in.) of indentor travel.
`7.2.4 The indicator shall not display a value greater than 100
`or less than 0 at the time of calibration.
`7.2.5 Other means of determining indentor extension or
`indentor travel, such as optical or laser measurement methods,
`are acceptable. The instrumentation used shall have traceability
`as described in 1.4.
`7.2.6 The durometer shall be supported in a suitable fashion
`when performing the procedures described in 7.1 and 7.2.
`7.3 Calibration Device:
`
`FIG. 4 Detail of Indentor Extension and Display Adjustment
`
`provide for positioning and stability. A suitable hardness
`determination cannot be made on an uneven or rough point of
`contact with the indentor.
`6.2 Type OOO, OOO-S, and M test specimens should be at
`least 1.25 mm (0.05 in.) in thickness, unless it is known that
`results equivalent to the 1.25-mm (0.05-in.) values are obtained
`with a thinner specimen.
`6.2.1 A Type M specimen that is not of a configuration
`described in 6.2.2 may be composed of plied pieces to obtain
`the necessary thickness, but determinations made on such
`specimens may not agree with those made on solid specimens
`because the surfaces of the plied specimens may not be in
`complete contact. The lateral dimensions of the specimen
`should be sufficient to permit measurements at least 2.50 mm
`(0.10 in.) from any edge unless it is known that identical results
`are obtained when measurements are made at lesser distance
`from an edge. A suitable hardness determination cannot be
`made on an uneven or rough point of contact with the indentor.
`6.2.2 The Type M specimen, when configured as an o-ring,
`circular band, or other irregular shape shall be at least 1.25 mm
`(0.05 in.) in cross-sectional diameter, unless it is known that
`results equivalent to the 1.25-mm (0.05-in.) values are obtained
`with a thinner specimen. The specimen shall be suitably
`supported in a fixture (Fig. 3) to provide for positioning and
`stability.
`6.3 The minimum requirement for the thickness of the
`specimen is dependent on the extent of penetration of the
`indentor into the specimen; for example, thinner specimens
`may be used for materials having higher hardness values. The
`minimum distance from the edge at which measurements may
`be made likewise decreases as the hardness increases.
`
`7. Calibration
`7.1 Indentor Extension Adjustment Procedure:
`7.1.1 Place precision ground dimensional blocks (Grade B
`or better) on the support table and beneath the durometer
`presser foot and indentor. Arrange the blocks so that
`the
`durometer presser foot contacts the larger block(s) and the
`indentor tip just contacts the smaller block (Fig. 4). It is
`necessary to observe the arrangement of the blocks and the
`presser foot/indentor under a minimum of 20× magnification to
`assure proper alignment.
`
`7
`
`
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`D2240 − 15
`
`7.7 Spring Force Combinations:
`7.7.1 For Type A, B, E, and O durometers:
`Force, N = 0.55 + 0.075 HA
`Where HA = hardness reading on Type A, B, E, and O
`durometers.
`7.7.2 For Type C, D, and DO durometers:
`Force, N = 0.4445 HD
`Where HD = hardness reading on Type C, D, and DO
`durometers.
`7.7.3 For Type M durometers:
`Force, N = 0.324 + 0.0044 HM
`Where HM = hardness reading on Type M durometers.
`7.7.4 For Type OO and OOO durometers:
`Force, N = 0.203 + 0.00908 HOO
`Where HOO = hardness reading on Type OO durometers.
`7.7.5 For Type OOO-S durometers:
`Force, N = 0.167 + 0.01765 HOOO-S
`Where HOOO-S = hardness reading on Type OOO-S
`durometers.
`
`7.8 The rubber reference block(s) provided for verifying
`durometer operation and state of calibration are not to be relied
`upon as calibration standards. The calibration procedures
`outlined in Section 7 are the only valid calibration procedures.
`7.8.1 The use of metal reference blocks is no longer
`recommended (see Note 2).
`
`7.9 Verifying the state of durometer calibration, during
`routine use, may be accomplished by:
`7.9.1 Verifying that the zero reading is no more than 1
`indicated point above zero, and not below zero (on durometers
`so equipped), when the durometer is positioned so that no
`external force is placed upon the indentor.
`7.9.2 Verifying that the 100 reading is no more than 100 and
`no less than 99 when the durometer is positioned on a flat
`surface of a non-metallic material so that the presser foot is in
`complete contact, causing the indentor to be fully retracted.
`7.9.2.1 It is important that when performing the verification
`of 100, as described in 7.9.2, that extreme care be taken so as
`to not cause damage to the indentor. Verification of the 100
`value is not recommended for durometers having a spring force
`greater than 10 N (Types C, D, and DO).
`7.9.2.2 When performing the verification of 100, as de-
`scribed in 7.9.2,
`the non-metallic material shall be of a
`hardness value greater than 100 of the type (scale) of the
`durometer being employed. Tempered glass of a thickness
`greater than 6.35 mm (0.25 in.) has been found satisfactory for
`this application.
`7.9.3 Verifying the displayed reading at any other point
`using commercially available rubber reference blocks which
`are certified to a stated value of the type (scale) of the
`durometer being employed. The displayed value of the durom-
`eter should be within 62 durometer points of the reference
`block’s stated value.
`7.9.4 Verification of the zero and 100 readings of a durom-
`eter provide reasonable assurance that the linear relationship
`between the indicated display and the durometer mechanism
`remain valid.
`
`FIG. 5 Example of Durometer Calibration Apparatus
`
`7.3.1 The durometer spring shall be calibrated by support-
`ing the durometer in a calibrating device, see Fig. 5, in a
`vertical position and applying a measurable force to the
`indentor tip. The force may be measured by means of a balance
`as depicted in Fig. 5, or an electronic force cell. The calibrating
`device shall be capable of measuring applied force to within
`0.5 % of the maximum spring force necessary to achieve 100
`durometer units.
`7.3.2 Care should be taken to ensure that the force is applied
`vertically to the indentor tip, as lateral force will cause errors
`in calibration. See 7.1.5.1 and 7.1.6.
`7.4 Spring Calibration—The durometer spring shall be
`calibrated at displayed readings of 10, 20, 30, 40, 50, 60, 70,
`80, and 90. The measured force (9.8× mass in kilograms) shall
`be within the spring calibration tolerance specified in Table 1.
`Table 1 identifies the measured force applied to the indentor for
`the entire range of the instrument, although it is necessary only
`to verify the spring calibration at points listed herein.
`7.5 Spring Calibration Procedure:
`7.5.1 Ensure that the indentor extension has been adjusted
`in accordance with 7.1, and the linear relationship between
`indentor travel and display is as specified in 7.2.
`7.5.2 Place the durometer in the calibration device as
`depicted in Fig. 5. Apply the forces indicated in Table 1 so that
`forces applied are aligned with the centerline of the indentor in
`a fashion that eliminates shock or vibration and adjust the
`durometer according to manufacturers’ recommendations so
`that:
`7.5.3 At the points enumerated in 7.4, the display shall
`indicate a value equal to 0.025 mm (0.001 in.) of indentor
`travel. For Type OOO-S durometers, the display shall indicate
`a value equal to 0.05 mm (0.002 in.) of indentor travel. For
`Type M durometers, the display shall indicate a value equal to
`0.0125 mm (0.0005 in.) of indentor travel within the spring
`calibration tolerances specified in 7.6.
`7.6 Spring calibration tolerances are 61.0 durometer units
`for Types A, B, C, D, E, O, and DO, 62.0 durometer units for
`Types OO, OOO, and OOO-S, and 64.0 durometer units for
`Type M, while not indicating below 0 or above 100 at the time
`of calibration (see Table 1).
`
`8
`
`
`
`Copyright by ASTM Int'l (all rights reserved); Tue May 9 13:08:59 EDT 2017
`Downloaded/printed by
`Bill Bouchard (Plan Tech Inc) pursuant to License Agreement. No further reproductions authorized.
`
`ClearCorrect Exhibit 1059, Page 8 of 13
`
`

`

`D2240 − 15
`
`7.9.5 Verification of points between zero and 100 provide
`reasonable assurance that the curvilinear relationship between
`the indicated display and the durometer mechanism remain
`valid.
`7.9.6 This is not a calibration procedure, it is a means by
`which a user may routinely verify that the durometer may be
`functioning correctly. (See Note 2.)
`
`8. Laboratory Atmosphere and Test Specimen
`Conditioning
`8.1 Tests shall be conducted in the standard laboratory
`atmosphere, as defined in Practice D618, Section 4.2.
`8.2 The instrument shall be maintained in the standard
`laboratory atmosphere, as defined in Practice D618, Section
`4.1, for 12 h prior to performing a test.
`8.3 The specimen shall be conditioned in accordance with
`condition 40/23 exclusive of humidity control, as described in
`Practice D618, Section 8.1, Procedure A and tested under the
`same conditions, exclusive of humidity control.
`8.4 These procedures may be modified if agreed upon
`between laboratories or between supplier and user and are in
`accordance with alternative procedures identified in Practice
`D618.
`8.5 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 locally (see Practice D1349).
`
`9. Procedure
`9.1 Operating Stand Operation (Type 3 Operating Stand
`Required for Type M):
`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 affect test
`results.
`9.1.2 Adjust the presser foot to support table parallelism as
`described in 5.1.2.1. It is necessary to make this adjustment
`each time the support table is moved to accommodate speci-
`mens of varying dimensions.
`9.1.3 Prior to conducting a test, adjust the vertical distance
`from the presser foot to the contact surface of the test specimen
`to 25.4 6 2.5 mm (1.00 6 0.100 in.), unless it is known that
`identical results are obtained with presser foot at a greater or
`lesser vertical distance from the test specimen contact surface,
`or if otherwise stipulated by the manufacturer.
`9.1.4 Place the specimen on the specimen support table, in
`a manner that the contact point of the indentor is in accordance
`with Section 6, unless it is known that identical results are
`obtained when measurements are made with the indentor at a
`lesser distance from the edge of the test specimen.
`9.1.5 Actuate the release lever (Fig. 2) of the operating
`stand or activate the electromechanical device, allowing the
`durometer to descend at a controlled rate and apply the presser
`foot to the specimen in accordance with 5.1.2. In the case of
`“specimen to indentor” type operating stands, operate the lever
`or other mechanism to apply the specimen to the indentor in a
`
`manner that assures parallel contact of the specimen to the
`durometer presser foot without shock and with just sufficient
`force to overcome the calibrated spring force as shown in Table
`1.
`
`9.1.6 An operating stand that applies the mass at a con-
`trolled rate of descent, without shock is mandatory for Type M
`durometers. Hand-held application or the use of a Type 1 or
`Type 2 operating stand for the Type M durometer is not an
`acceptable practice, see 5.1.2.4.
`9.1.7 For any material covered in 1.1, once the presser foot
`is in contact with the specimen, for example, when the initial
`indentor travel has ceased, the maximum indicated reading
`shall be recorded. The time interval of 1 s, between initial
`indentor travel cessation and the recording of the indicated
`reading, shall be considered standard. Other time intervals,
`when agreed upon among laboratories or between supplier and
`user, may be used and reported accordingly. The indicated
`hardness reading may change with time.
`9.1.7.1 If the durometer is equipped with an electronic
`maximum indicator or timing device (refer to 5.1.1.9) the
`indicated reading shall be recorded within 1 6 0.3 s of the
`cessation of indentor travel and reported (refer to 10.2.9