1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 27588:2012Rubber, vulcanized orthermoplastic Determinationof dead-load hardness usingthe very low rubber hardness(VLRH) scaleBS ISO 27588:2012 BRITISH STANDARDNational for
2、ewordThis British Standard is the UK implementation of ISO 27588:2012. Itsupersedes BS ISO 27588:2008 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/22, Physical testing of rubber.A list of organizations represented on this committee can beobtained
3、 on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2012. Published by BSI StandardsLimited 2012ISBN 978 0 580 78231 2ICS 83.060Compliance with a Briti
4、sh Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 August 2012.Amendments issued since publicationDate Text affectedBS ISO 27588:2012 ISO 2012Rubber, vulcanized or thermoplastic Determin
5、ation of dead-load hardness using the very low rubber hardness (VLRH) scaleCaoutchouc vulcanis ou thermoplastique Dtermination de la duret sous charge constante au moyen de lchelle de trs faible duret (VLRH)INTERNATIONAL STANDARDISO27588Second edition2012-06-15Reference numberISO 27588:2012(E)BS ISO
6、 27588:2012ISO 27588:2012(E)ii ISO 2012 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, with
7、out permission in writing from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 27588:2012ISO 27588:
8、2012(E) ISO 2012 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope 12 Normative references . 13 Principle . 14 Apparatus 15 Calibration . 26 Test pieces 27 Time interval between forming the test pieces and testing . 28 Conditioning . 29 Temperature of test . 210 Procedure 311 Test
9、 report . 3Annex A (normative) Relationship between indentation depth and hardness, and derivation of the VLRH scale 4Annex B (normative) Calibration schedule 7Bibliography . 9BS ISO 27588:2012ISO 27588:2012(E)ForewordISO (the International Organization for Standardization) is a worldwide federation
10、 of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee.
11、International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with
12、 the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval
13、 by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 27588 was prepared by Technical Committee IS
14、O/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis.This second edition cancels and replaces the first edition (ISO 27588:2008), which has been revised to include a calibration schedule for the apparatus used (see Annex B).iv ISO 2012 All rights reservedBS ISO 27588:2012ISO
15、27588:2012(E)IntroductionThe hardness test specified in this International Standard is intended as a more discriminating alternative to the international rubber hardness degrees scale (ISO 48) for rubbers below 35 IRHD. A durometer method for soft rubbers is described in ISO 7619-1 as the AO scale.
16、Examples of applications are low-modulus bearings, soft roller coverings and printing rubbers.Figure 1 shows a comparison of the ranges of the IRHD N and IRHD L methods in ISO 48 with the VLRH scale of this International Standard.The methods differ primarily in the diameter of the indenting ball and
17、 the magnitude of the indenting force, these being chosen to suit the particular application.Figure 1 Comparison of the ranges of hardness measurement methods for rubber ISO 2012 All rights reserved vBS ISO 27588:2012BS ISO 27588:2012Rubber, vulcanized or thermoplastic Determination of dead-load har
18、dness using the very low rubber hardness (VLRH) scaleWARNING Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to es
19、tablish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.1 ScopeThis International Standard specifies a dead-load method for the determination of the hardness of very soft vulcanized or thermoplastic rubbers using the very low rubber hardness (
20、VLRH) scale.The relation between the depth of penetration and the VLRH scale is linear.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of
21、the referenced document (including any amendments) applies.ISO 18898:2012, Rubber Calibration and verification of hardness testersISO 18899, Rubber Guide to the calibration of test equipmentISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test methods3 Pri
22、ncipleThe hardness test consists of measuring the difference between the depths of indentation of a ball into the rubber under a small contact force and a large total force. From this difference, the hardness in “very low rubber hardness degrees” (VLRH) is obtained using Table A.1 (see Annex A) or g
23、raphs based on this table or a scale, reading directly in very low rubber hardness degrees, calculated from the tables and fitted to the indentation-measuring instrument.4 ApparatusThe essential parts of the apparatus are as follows, the appropriate dimensions and forces being shown in Table 1. Deta
24、iled information can be found in References 1 and 2.4.1 Vertically guided plunger, having a ball or spherical surface on the lower end, and means for supporting the plunger so that the spherical tip is kept slightly above the surface of the annular foot prior to applying the contact force.4.2 Means
25、for applying a contact force and an additional indenting force to the plunger, making allowance for the mass of the plunger, including any fittings attached to it, and for the force of any spring acting on it, so that the forces actually transmitted through the spherical end of the plunger are as sp
26、ecified.4.3 Means for measuring the increase in depth of indentation of the plunger caused by the indenting force, either in millimetres with a maximum uncertainty of 0,001 mm, or reading directly in VLRH with a resolution such that a reading to at least 0,5 VLRH is possible.INTERNATIONAL STANDARD I
27、SO 27588:2012(E) ISO 2012 All rights reserved 1BS ISO 27588:2012ISO 27588:2012(E)4.4 Flat annular foot, normal to the axis of the plunger and having a central hole for the passage of the plunger. The foot rests on the test piece and shall be rigidly connected to the indentation measurement device so
28、 that a measurement is made of the movement of the plunger relative to the foot (i.e. the top surface of the test piece), not relative to the surface supporting the test piece.If it is required that measurements be made on test pieces with a curved surface, a calibration has to be carried out. Tests
29、 need to be made on test pieces of the material with both flat and curved surfaces. The hardness difference (Hcurved Hflat) which is found for the flat and the curved test pieces is used with opposite sign as correction of the hardness values obtained on test pieces of a similar material with a curv
30、ed surface.4.5 Measuring table, as support for the test piece. The measuring table shall be flat and normal to the axis of the plunger.Table 1 Nominal values and tolerances of forces and diametersForce on ballForce on foot mNContact mNIndenting mNTotal mN8,3 0,5 91,7 0,5 100,0 1,0 235 30Diameter mmB
31、all Foot Hole2,50 0,01 6,0 0,5 3,0 0,15 CalibrationThe requirements for calibration of the test apparatus are given in Annex B.6 Test piecesThe test pieces shall be prepared in accordance with ISO 23529.The test pieces shall have their upper and lower surfaces flat, smooth and parallel to one anothe
32、r.The standard test piece shall be a minimum of 6 mm thick and shall be made up of one, two or three layers of rubber, the thinnest of which shall not be less than 2 mm. The lateral dimensions of the test piece shall be such that three or more measurements can be made at least 10 mm from each other
33、and at least 3 mm from the edges of the test piece.Test pieces of other dimensions or from finished products may be used but will usually produce results which differ from those obtained with standard test pieces.7 Time interval between forming the test pieces and testingThe time interval between fo
34、rming the test pieces and testing shall be in accordance with ISO 23529.8 ConditioningThe test pieces shall be maintained at a standard laboratory temperature (see ISO 23529) for a minimum of 3 h immediately before testing.9 Temperature of testThe test shall be carried out at the same standard labor
35、atory temperature as was used for the conditioning.2 ISO 2012 All rights reservedBS ISO 27588:2012ISO 27588:2012(E)10 ProcedurePlace a test piece on the horizontal measuring table. Bring the foot into contact with the surface of the test piece. Press the plunger and indenting ball onto the rubber fo
36、r 5 s, the force on the ball being the contact force.If the gauge is graduated in VLRH degrees, adjust it to read 100 at the end of the 5 s period. Then apply the additional indenting force and maintain it for 30 s, when a direct reading of hardness in VLRH degrees is obtained.If the gauge is gradua
37、ted in millimetres, note the differential indentation of the plunger caused by the additional indenting force, applied for 30 s. Convert this to VLRH degrees by using Table A.1 or a graph constructed therefrom.Repeat the test to obtain measurements at three different locations on the test piece, obs
38、erving the requirements for separation distances given in Clause 6. Take the median of the three results as the result of the test.11 Test reportThe test report shall include the following information:a) sample and test piece details:1) a full description of the sample and its origin,2) compound det
39、ails and cure details, where appropriate,3) the dimensions of the test piece,4) the number of layers in the test piece and the thickness of the thinnest layer,5) in the case of curved or irregularly shaped test pieces, a description of the test piece,6) the method of preparation of the test pieces f
40、rom the sample, e.g. by moulding or cutting;b) test method:1) a reference to the test method used, i.e. the number of this International Standard,2) for curved test pieces, the way in which the test piece was mounted and the way the test force was applied;c) test details:1) the time and temperature
41、of conditioning prior to the test,2) the temperature of test, and the relative humidity, if necessary,3) details of any procedures not specified in this International Standard;d) test result:1) the number of test pieces tested,2) the individual test results,3) the median result, e.g. 15 VLRH;e) the
42、date of the test. ISO 2012 All rights reserved 3BS ISO 27588:2012ISO 27588:2012(E)Annex A (normative) Relationship between indentation depth and hardness, and derivation of the VLRH scaleAs described in Clause 3, the hardness test measures the difference, D, between the depths of indentation of a ba
43、ll into the rubber under a small contact force and a large total force. From this difference, the hardness in very low rubber hardness degrees (VLRH) is obtained. Table A.1 shows the conversion of values of D to very low rubber hardness degrees (VLRH).4 ISO 2012 All rights reservedBS ISO 27588:2012I
44、SO 27588:2012(E)Table A.1 Conversion of values of D to very low rubber hardness degrees (VLRH)DmVLRHDmVLRHDmVLRH0 100 340 66 680 3210 99 350 65 690 3120 98 360 64 700 3030 97 370 63 710 2940 96 380 62 720 2850 95 390 61 730 2760 94 400 60 740 2670 93 410 59 750 2580 92 420 58 760 2490 91 430 57 770
45、23100 90 440 56 780 22110 89 450 55 790 21120 88 460 54 800 20130 87 470 53 810 19140 86 480 52 820 18150 85 490 51 830 17160 84 500 50 840 16170 83 510 49 850 15180 82 520 48 860 14190 81 530 47 870 13200 80 540 46 880 12210 79 550 45 890 11220 78 560 44 900 10230 77 570 43 910 9240 76 580 42 920 8
46、250 75 590 41 930 7260 74 600 40 940 6270 73 610 39 950 5280 72 620 38 960 4290 71 630 37 970 3300 70 640 36 980 2310 69 650 35 990 1320 68 660 34 1 000 0330 67 670 33 The general mathematical relationship between the depth of penetration, D, and VLRH is given by the equation:VLRH = 100 0,1D (1)Figu
47、re A.1 gives a graphical representation of this relationship. ISO 2012 All rights reserved 5BS ISO 27588:2012ISO 27588:2012(E)Figure A.1 Relationship between the depth of penetration, D, and VLRH6 ISO 2012 All rights reservedBS ISO 27588:2012ISO 27588:2012(E)Annex B (normative) Calibration scheduleB
48、.1 InspectionBefore any calibration is undertaken, the condition of the items to be calibrated shall be ascertained by inspection and recorded in any calibration report or certificate. It shall be reported whether calibration is made in the “as-received”condition or after rectification of any abnorm
49、ality or fault.It shall be ascertained that the apparatus is generally fit for the intended purpose, including any parameters specified as approximate and for which the apparatus does not therefore need to be formally calibrated. If such parameters are liable to change, then the need for periodic checks shall be written into the detailed calibration procedures.B.2 ScheduleVerification/calibration of the test apparatus is a normative part of this International Standard. However, the frequency of c
