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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS ISO 7148-2:1999 ICS 21
2、.100.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Plain bearings Testing of the tribological behaviour of bearing materials Part 2: Testing of polymer-based bearing materials Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Cop
3、y, (c) BSI This British Standard, having been prepared under the direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 February 2000 BSI 02-2000 ISBN 0 580 34111 9 BS ISO 7148-2:1999 Amendments issued since publication
4、 Amd. No.DateComments National foreword This British Standard reproduces verbatim ISO 7148-2:1999 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee MCE/12, Plain bearings, which has the responsibility to: aid enquirers to unde
5、rstand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on
6、 this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled International Standards Correspondence Index, or by using
7、 the Find facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity fro
8、m legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 19 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Licensed Copy: sheffieldun sheffiel
9、dun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI A Reference number ISO 7148-2:1999(E) INTERNATIONAL STANDARD ISO 7148-2 First edition 1999-11-01 Plain bearings Testing of the tribological behaviour of bearing materials Part 2: Testing of polymer-based bearing materials Palier
10、s lisses Essai du comportement tribologique des matriaux antifriction Partie 2: Essai des matriaux pour paliers base de polymres Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 7148-2:1999(E) ii Contents Page 1 Scope1 2 Normative referen
11、ces1 3 Symbols and units.2 4 Special features for the tribological testing of polymer-based materials3 5 Test methods4 6 Test specimens6 7 Test methods and test equipment .11 8 Lubrication .12 9 Designation 13 10 Test conditions 13 11 Test procedure.16 12 Analysis17 Annex A (informative) Test report
12、 .18 Bibliography19 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 7148-2:1999(E) iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work
13、 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. International organizations, governmental and non-governmen
14、tal, 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 the rules given in the ISO/IEC Directives, Part 3. Draft
15、International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this part of
16、 ISO 7148 may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 7148-2 was prepared by Technical Committee ISO/TC 123, Plain bearings, Subcommittee SC 2, Materials and lubricants, their properties, characteris
17、tics, test methods and testing conditions. ISO 7148 consists of the following parts under the general title Plain bearings Testing of the tribological behaviour of bearing materials: Part 1: Testing of bearing metals Part 2: Testing of polymer-based bearing materials Annex A of this part of ISO 7148
18、 is for information only. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 7148-2:1999(E) iv Introduction A first step towards the specification of basic test conditions for friction and wear tests of polymer-based plain bearing materials
19、 was made with International Technical Reports ISO/TR 7147, ISO/TR 8285 and ISO/TR 9993. This initial step, lasting several years and which comprised the development of basic test equipment (pin-on-disc device) and its testing in parallel experiments in several institutes, is now concluded. It was s
20、ubsequently found that in the absence of any other uniform recommendations or standards, a reference for comparative testing was often needed especially in the case of new material development without detailed knowledge of specific applications. At the same time it was found necessary to limit the t
21、est variables or to accurately define them in order to obtain in addition, as wide a comparison as possible. It ought be possible to use different test combinations or to test for specific applications (i.e. tests which simulate service conditions). This part of ISO 7148 takes these requirements int
22、o account and specifies instructions for the preparation of test specimens, for test principles and test equipment as well as for the selection of test variables, test procedure and analysis. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI I
23、NTERNATIONAL STANDARD ISO 7148-2:1999(E) 1 Plain bearings Testing of the tribological behaviour of bearing materials Part 2: Testing of polymer-based bearing materials 1 Scope This part of ISO 7148 specifies tribological tests of polymer-based plain bearing materials under specified working conditio
24、ns, i.e. load, sliding velocity and temperature, with and without lubrication. From the test results, data are obtained which indicate the relative tribological behaviour of metal-polymer and polymer-polymer rubbing parts. The purpose of this part of ISO 7148 is to obtain, for polymer material combi
25、nations used in plain bearings, reproducible measured values for friction and wear under specified and exactly-defined test conditions without lubrication (dry surfaces) and with lubrication (boundary lubrication). The test results give useful information for practical application only if all parame
26、ters of influence are identical. The more the test conditions deviate from the actual application the greater will be the uncertainty of the applicability of the results. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute pro
27、visions of this part of ISO 7148. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 7148 are encouraged to investigate the possibility of applying the most recent editions of the normative
28、 documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 527-2, Plastics Determination of tensile properties Part 2: Test conditions for moulding and
29、 extrusion plastics. ISO 1184, Plastics Determination of tensile properties of films. ISO 2818, Plastics Preparation of test specimens by machining. ISO 4385, Plain bearings Compression testing of metallic bearing materials. ISO 6691, Thermoplastic polymers for plain bearings Classification and desi
30、gnation. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 7148-2:1999(E) 2 3 Symbols and units See Table 1. Table 1 Symbols and units Symbol Term Unit A, B, C, D Test method a Sliding distance km dr Dry f Coefficient of friction; ratio be
31、tween friction force and normal force, i.e: f F F = f n Ff Friction force N Fn Normal force N gr Grease Kw Coefficient of wear, volumetric wear rate related to the normal force, i.e.: K V Fa w F w w n v n = = mm3/(N.km) lw Linear wear as measured by change in distance mm Mf Friction moment Nm oi Oil
32、 pl Polymer-based material p Specific force per unit area (force/projected contact area) N/mm2 Rd,B Compression strengthN/mm2 Rd0,2 Compression limit 0,2 %N/mm2 so Solid lubricant T Specimens temperature near the sliding surface during testing under steady-state conditions C Tamb Ambient temperature
33、 C Tg Glass temperature C Tlim Maximum permissible temperature C tCh Test duration h U Sliding velocity m/s Vw Material removed by wear as measured by change in volume mm3 wl Linear wear rate, i.e: w l a l w = mm/km wv Volumetric wear rate, i.e: w V a v w = mm3/km h Lubricant viscosity mPa s License
34、d Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 7148-2:1999(E) 3 4 Special features for the tribological testing of polymer-based materials Polymers have a low thermal conductivity and a low melting temperature, so that heat resulting from cont
35、act friction may lead to partial melting and hence feign wear. Due to the high thermal expansion of polymers (up to ten times higher than that of steel) results obtained may be misleading because the test specimens have expanded under frictional heat. Hence allowance shall be made for the effects of
36、 thermal expansion (change of clearance) and thermal conductivity (melting) when assessing the results. Where possible the temperature of both test specimens should be controlled. Polymers have a glass transition temperature Tg which depends on their chemical structure. At this temperature their phy
37、sical properties and their tribological behaviour may change. Injection moulded polymer surfaces have different properties from machined surfaces. The test specimens shall be tested with the same surface conditions as they have in practical application. Reinforcements and fillers, i.e. fibres, may l
38、ead to very strong anisotropy of the material and influence its wear behaviour depending on fibre orientation. The test specimens should have the same fibre orientation as in practical application. In order to avoid stick-slip the test rig shall be very stiff and shall not be susceptible to vibratio
39、ns. The tribological behaviour of polymers depends very strongly on the material combination, which part moves and which part remains stationary. The test system shall be similar to practical application. Polymers show wear processes that are different from that of metals. There are not only abrasiv
40、e processes with powder-like wear debris but also adhesive processes with the creation of transfer layers which may be smooth or rough. Also ploughing wear and melting or plastic deformation is possible. Therefore wear cannot be gravimetrically measured in all cases and the wear status must be judge
41、d after the tests (whether the surfaces are fine- or coarse- grained, scored or plucked out, scaled, melted or plastically deformed). Some polymers may show poor repeatability of the results and require repeated testing (six or more repetitions). The preparation and preparatory treatment (e.g. condi
42、tioning, storage, cleaning) of the test specimens can have a high influence on performance. In some thermoplastics, e.g. polyamides, moisture absorption effects a gradual change in linear dimensions and modifies their mechanical properties. Environmental parameters should therefore be controlled in
43、the test array. Moisture absorption prohibits gravimetrical measurement of wear. The more the test conditions deviate from the actual application, the greater will be the uncertainty of the applicability of the results (see Figures 1 and 2). a) Plain bearing-on-shaft b) Linear guidance system Figure
44、 1 Simulation of real rubbing contacts Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 7148-2:1999(E) 4 a) Pin-on-disc b) Block-on-ring c) Sphere-on-prism Figure 2 Simulation under approximated practical testing conditions and model syst
45、ems for pre-selection of materials 5 Test methods 5.1 General Different test methods are provided for tests in accordance with this part of ISO 7148 so that the following contact geometries are available. The test methods should correspond to the practical application as closely as possible. 5.2 Tes
46、t method A: pin-on disc See Figure 3. Advantages: basic testing of simple test specimens; testing of tribological properties; no increase of sliding surface area due to wear; initial ranking of materials; simulation of linear guidance system see Figure 1b). Disadvantages: edge of the pin may wipe of
47、f lubricant; no injection moulding of the pin with fibre reinforced material; no injection moulding of the disc because of problems with shrinkage Figure 3 Test method A: pin-on-disc Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 06:27:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 7148-2
48、:1999(E) 5 5.3 Test method B: block (or pin)-on-ring See Figure 4. Advantages: basic testing of simple test specimens; testing of tribological properties; no increase of sliding surface area due to wear; initial ranking of materials; with and without lubrication. Disadvantages: no injection moulding
49、 of the block because of problems with shrinkage and fibre orientation; edge of the block may wipe off lubricant; no injection moulding of the disc because of problems with shrinkage Figure 4 Test method B: block (or pin)-on-ring 5.4 Test method C: plain bearing-on-shaft See Figure 5. Advantages: best simulation of all possible systems; testing of original or scaled bearings; prediction of practical behaviour; with and without lubrication. Disadvantages: long te