Standard Test Method for Rubber Property—Durometer …

1 Designation: D2240 15 Standard Test Method forRubber Property Durometer Hardness1 This Standard is issued under the fixed designation D2240; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon ( ) indicates an editorial change since the last revision or Standard has been approved for use by agencies of the Department of This test Method covers twelve types of Rubber hardnessmeasurement devices known as durometers: Types A, B, C, D,DO, E, M, O, OO, OOO, OOO-S, and R. The procedure fordetermining indentation hardness of substances classified asthermoplastic elastomers, vulcanized (thermoset) Rubber , elas-tomeric materials, cellular materials, gel-like materials, andsome plastics is also This test Method is not equivalent to other indentationhardness methods and instrument types, specifically thosedescribed in Test This test Method is not applicable to the testing ofcoated All materials, instruments, or equipment used for thedetermination of mass, force, or dimension shall have trace-ability to the National Institute for Standards and Technology,or other internationally recognized organizations parallel The values stated in SI units are to be regarded asstandard.

2 The values given in parentheses are for informationonly. Many of the stated dimensions in SI are direct conver-sions from the U. S. Customary System to accommodate theinstrumentation, practices, and procedures that existed prior tothe Metric Conversion Act of Standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this Standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to Referenced Standards:2D374 Test Methods for Thickness of Solid Electrical Insu-lation(Withdrawn 2013)3D618 Practice for Conditioning Plastics for TestingD785 Test Method for Rockwell Hardness of Plastics andElectrical Insulating MaterialsD1349 Practice for Rubber Standard Conditions for Test-ingD1415 Test Method for Rubber Property InternationalHardnessD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesF1957 Test Method for Composite Foam Hardness-Durometer Standard :4 ISO/IEC 17025: 1999 General Requirements for the Com-petence of Testing and Calibration Laboratories3.

3 Summary of Test This test Method permits hardness measurements basedon either initial indentation or indentation after a specifiedperiod of time, or both. Durometers with maximum readingindicators used to determine maximum hardness values of amaterial may yield lower hardness when the maximum indi-cator is The procedures for Type M, or micro hardnessdurometers, 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 ofspecimens having a thickness or cross-sectional diameter mm ( in.) or greater, although specimens of lesserdimensions may be successfully accommodated under theconditions specified in Section6, and have a Type M durometerhardness range between 20 and 90. Those specimens whichhave a durometer hardness range other than specified shall useanother suitable procedure for determining durometer test Method is under the jurisdiction of ASTM CommitteeD11on Rubberand is the direct responsibility of Physical edition approved Aug.

4 1, 2015. Published January 2016. Originallyapproved in 1964. Last previous edition approved in 2010 as D2240 05 (2010).DOI: referenced ASTM standards, visit the ASTM website, , orcontact ASTM Customer Service at ForAnnual Book of ASTMS tandardsvolume information, refer to the Standard s Document Summary page onthe ASTM last approved version of this historical Standard is referenced from International Organization for Standardization (ISO), 1 rue deVaremb , Case postale 56, CH-1211, Geneva 20, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international Standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Copyright by ASTM Int'l (all rights reserved); Tue May 9 13:08:59 EDT 2017 Downloaded/printed byBill Bouchard (Plan Tech Inc) pursuant to License Agreement.

5 No further reproductions Significance and This test Method is based on the penetration of a specifictype of indentor when forced into the material under specifiedconditions. The indentation hardness is inversely related to thepenetration and is dependent on the elastic modulus andviscoelastic behavior of the geometry of theindentor and the applied force influence the measurementssuch that no simple relationship exists between the measure-ments obtained with one type of durometer and those obtainedwith another type of durometer or other instruments used formeasuring hardness. This test Method is an empirical testintended primarily for control purposes. No simple relationshipexists between indentation hardness determined by this testmethod and any fundamental property of the material specification purposes, it is recommended that Test MethodD785be used for materials other than those described Measuring Apparatus, or Durometer, and anOperating Stand, Type 1, Type 2, or Type 3 ( )consisting of the following Foot, the configuration and the total area ofa durometer presser foot may produce varying results whenthere are significant differences between them.

6 It is recom-mended that when comparing durometer hardness determina-tions of the same type ( ), that the comparisons bebetween durometers of similar presser foot configurations andtotal area, and that the presser foot configuration and size benoted in the Hardness Measurement Report ( ). Foot, Types A, B, C, D, DO, E, O, OO,OOO, and OOO-S, with an orifice (to allow for the protrusionof the indentor) having a diameter as specified inFig. 1(a, b,c, d, e, f, and g), with the center a minimum of mm ( ) from any edge of the foot. When the presser foot is not ofa flat circular design, the area shall not be less than 500mm2( ).NOTE1 The Type OOO and the Type OOO-S, designated herein,differ in their indentor configuration, spring force, and the resultsobtained. SeeTable 1andFig. 1(e and g). Foot flat circular designs designated asTypexR, wherexis the Standard durometer designation andRindicates the flat circular press foot described herein, forexample, TypeaR,dR, and the like.

7 The presser foot, having acentrally located orifice (to allow for the protrusion of theindentor) of a diameter as specified inFig. 1(a through g). Theflat circular presser foot shall be mm ( in.)in diameter. These durometer types shall be used in anoperating stand ( ).(a)Durometers having a presser foot configuration otherthan that indicated not use the TypexRdesignation, and it is recommended that their presser footconfiguration and size be stated in the Hardness MeasurementReport ( ). Foot, Type M, with a centrally locatedorifice (to allow for the protrusion of the indentor), having adiameter as specified inFig. 1(d), with the center a minimumof mm ( in.) from any edge of the flat circularpresser foot. The Type M durometer shall be used in a Type 3operating stand ( ). , formed from steel rod and hardened to 500HV10 and shaped in accordance withFig. 1(a, b, c, d, e, or g),polished over the contact area so that no flaws are visible under20 magnification, with an indentor extension of ( in.)

8 , Type OOO-S, formed from steel rod andhardened to 500 HV10, shaped in accordance withFig. 1(f),polished over the contact area so that no flaws are visible under20 magnification, with an indentor extension of ( in.). , Type M, formed from steel rod and hard-ened to 500 HV10 and shaped in accordance withFig. 1(d),polished over the contact area so that no flaws are visible under50 magnification, with an indentor extension of ( in.). Extension Indicator, analog or digitalelectronic, having a display that is an inverse function of theindentor extension so that:FIG. 1 (a) Type A and C IndentorD2240 152 Copyright by ASTM Int'l (all rights reserved); Tue May 9 13:08:59 EDT 2017 Downloaded/printed byBill Bouchard (Plan Tech Inc) pursuant to License Agreement. No further reproductions authorized.(1)The display shall indicate from 0 to 100 with no lessthan 100 equal divisions throughout the range at a rate of onehardness point for each mm ( in.)

9 Of indentormovement,(2)The display for Type OOO-S durometers shall indicatefrom 0 to 100 with no less than 100 equal divisions throughoutthe range at a rate of one hardness point for each mm( in.) of indentor movement,(3)The display for Type M durometers shall indicate from0 to 100 with no less than 100 equal divisions at a rate of onehardness point for each mm ( in.) of indentormovement, and(4)In the case of analog dial indicators having a display of360 , the points indicating 0 and 100 may be at the same pointon the dial and indicate 0, 100, or Device (optional), capable of being set to adesired elapsed time, signaling the operator or holding thehardness reading when the desired elapsed time has beenreached. The timer shall be automatically activated when thepresser foot is in contact with the specimen being tested, forexample, the initial indentor travel has ceased. Digital elec-tronic durometers may be equipped with electronic timingFIG.

10 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)D2240 153 Copyright by ASTM Int'l (all rights reserved); Tue May 9 13:08:59 EDT 2017 Downloaded/printed byBill Bouchard (Plan Tech Inc) pursuant to License Agreement. No further reproductions that shall not affect the indicated reading or determi-nations attained by more than one-half of the calibrationtolerance stated inTable Indicators (optional), maximum indicat-ing pointers are auxiliary analog indicating hands designed toremain at the maximum hardness value attained until reset bythe operator. Electronic maximum indicators are digital dis-plays electronically indicating and maintaining the maximumvalue hardness valued achieved until reset by the Analog maximum indicating pointers have beenshown to have a nominal effect on the values attained,however, this effect is greater on durometers of lesser totalmainspring loads; for example, the effect of a maximumindicating pointer on Type D durometer determinations will beless than those determinations achieved using a Type Adurometer.