1、BRITISH STANDARD BS EN ISO 8295:2004 Incorporating Amendment No. 1 to BS 2782-8: Method 824A:1996 (renumbers the BS as BS EN ISO 8295:2004) Plastics Film and sheeting Determination of the coefficients of friction The European Standard EN ISO 8295:2004 had the status of a British Standard ICS 83.140
2、BS EN ISO 8295:2004 This British Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 May 1996 BSI 27 September 2004 The following BSI references relate to the work on
3、this British Standard: Committee reference PRI/75 Draft for comment 94/304241 DC ISBN 0 580 25576 X Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PRI/75, Plastics and rubber film and sheets, upon which the following bod
4、ies were represented: British Plastics Federation Her Majestys Stationery Office Institute of Trading Standards Administration Ministry of Defence Packaging and Industrial Films Association PIRA International Amendments issued since publication Amd. No. Date Comments 15286 27 September 2004 Implemen
5、tation of the European StandardBS EN ISO 8295:2004 BSI 27 September 2004 i Contents Page Committees responsible Inside front cover National foreword ii 1S c o p e 1 2 Normative reference 1 3 Definitions 1 4 Principle 2 5A p p a r a t u s 2 6 Test specimens 3 7 Conditioning 4 8 Procedure 4 9 Expressi
6、on of results 4 10 Precision 5 11 Test report 5 Annex A (informative) Preliminary precision data 6 Figure 1 Example of moving-table apparatus for determination of coefficients of friction 2 Table A.1 Precision of dynamic coefficient of friction 6 Table A.2 Precision of static coefficient of friction
7、 6BS EN ISO 8295:2004 ii BSI 27 September 2004 National foreword This British Standard is the English language version of EN ISO 8295:2004. It is identical with ISO 8295:1995. It supersedes BS 2782-8:Method 824A:1984 which is withdrawn. Cross-references The Technical Committee has reviewed the provi
8、sions of ISO 291:1977, to which reference is made in the text, and which is related to BS 2782-0, Introduction, and has decided that they are acceptable for use in conjunction with this standard. The British Standards which implement international or European publications referred to in this documen
9、t may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Us
10、ers are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN ISO title page, the EN ISO foreword page, pages 1 to 8,
11、 an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 8295 July 2004 ICS 83.140.10 English version Plastics Film and sheeting Determination of the coefficients o
12、f friction (ISO 8295:1995) Plastiques Film et feuille Dtermination des coefficients de frottement (ISO 8295:1995) This European Standard was approved by CEN on 21 June 2004. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this Europ
13、ean Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English,
14、 French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech
15、Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de
16、Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 2004 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN members. Ref. No. EN ISO 8295:2004 EEN ISO 8295:2004 BSI 27 September 2004 Foreword The text of ISO 8295:1
17、995 has been prepared by Technical Committee ISO/TC 61 “Plastics” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 8295:2004 by Technical Committee CEN/TC 249 “Plastics”, the secretariat of which is held by IBN. This European Standard shall be given the s
18、tatus of a national standard, either by publication of an identical text or by endorsement, at the latest by January 2005, and conflicting national standards shall be withdrawn at the latest by January 2005. According to the CEN/CENELEC Internal Regulations, the national standards organizations of t
19、he following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain
20、, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 8295:1995 has been approved by CEN as EN ISO 8295:2004 without any modifications. NOTE Normative references to International Standards are listed in Annex ZA (normative).EN ISO 8295:2004 BSI 27 September 2004 1 1 Scope
21、1.1 This International Standard specifies a method for determining the coefficients of starting and sliding friction of plastic film and sheeting when sliding over itself or other substances. The method is intended to be used for non-sticky plastic film and sheeting (in the following text, referred
22、to simply as “film”) of up to approximately 0,5 mm thickness. 1.2 This test method serves primarily for quality control. It does not give a comprehensive assessment of the machinability on packaging or processing machines since other effects, e.g. electrostatic charges, air cushion, local rise of te
23、mperature and abrasion are, as a rule, involved. 1.3 The static frictional force increases as a rule, with the time the surfaces are in contact. Therefore, to get comparable results, this time span is specified. 1.4 Slip properties are sometimes generated by additives in the plastic material. The ad
24、ditives have varying degrees of compatibility with the film matrix. They may bloom or exude to the surface and change the slip properties. Since these effects are time-dependent, measurements on such films have to be related to the age of the film. 2 Normative reference The following standard contai
25、ns provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate
26、the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 291:1977, Plastics Standard atmospheres for conditioning and testing 3 Definitions For the purposes of this International Sta
27、ndard, the following definitions apply. 3.1 friction the resistance that two surfaces lying in contact with each other build up against sliding. A distinction is made between static friction and dynamic friction 3.1.1 static friction friction which has to be overcome as a “threshold value” at the on
28、set of sliding motion 3.1.2 dynamic friction friction which persists during a sliding motion at a given speed 3.2 frictional force the force necessary to overcome friction. A distinction is made between the static frictional force F Sand the dynamic frictional force F D 3.3 normal force, F p the for
29、ce acting perpendicular to the surfaces in contactEN ISO 8295:2004 2 BSI 27 September 2004 3.4 coefficient of friction the ratio of the frictional force to the normal force, acting perpendicular to the two surfaces in contact 3.4.1 static coefficient of friction 3.4.2 dynamic coefficient of friction
30、 NOTE 1 The coefficient of friction of films usually ranges between 0,2 and 1. NOTE 2 Ideally, the coefficient of friction is a characteristic independent of the test equipment and the test conditions. Since films generally do not behave ideally, all test parameters are specified in this Internation
31、al Standard. 4 Principle The surfaces to be tested are placed together in plane contact and under uniform contact pressure. The force needed to displace the surfaces relative to each other is recorded. 5 Apparatus 5.1 The test device may be constructed in different ways. In general, it consists of a
32、 horizontal test table, a sled, and a driving mechanism to produce a relative motion between the sled and the test table, regardless of which is the moving part. Figure 1 shows an example of apparatus in which the table is moved horizontally. The vertical motion of a tensile tester may also be utili
33、zed; in this case, the test table is fixed to the crosshead of the machine and the force is deflected to the horizontal direction by a pulley. The force is recorded by a chart recorder or an equivalent electrical data-processing unit. Figure 1 Example of moving-table apparatus for determination of c
34、oefficients of friction m S F S F p - = m D F D F p - =EN ISO 8295:2004 BSI 27 September 2004 3 5.2 The test device shall comply with the following conditions. 5.2.1 The surface of the test table shall be flat and smooth, and made of a non-ferromagnetic metal. 5.2.2 The normal force shall be generat
35、ed by a sled with a square-shaped contact base of 40 cm 2(edge length 63 mm). To ensure uniform pressure distribution, the base of the sled shall be covered with an elastic material, for example felt. The structure of this covering material shall be fine enough to avoid embossing thin films. The tot
36、al mass of the sled shall be 200 g 2 g (exerting a normal force of 1,96 N 0,02 N). 5.2.3 The motion that induces the friction process shall be free of vibrations and shall normally have a speed of 100 mm/min 10 mm/min. In the case of specialist films or where difficulties are encountered, a speed of
37、 500 mm/min 10 mm/min may be used. This shall be reported in Clause 11, item f). 5.2.4 The force-measuring system, including the recording instrument, shall not exceed an error of 2 %. Its transition time t 99%shall not exceed 0,5 s. The pulling direction shall be in straight alignment with the fric
38、tional plane. If the force-measuring system of a tensile tester is used, the transition time t 99%shall be particularly checked, as the indicating systems of these machines are often rather inert. 5.2.5 For the measurement of the static friction, the friction drag of the force-measuring system shall
39、 be adjusted to 2 N/cm 1 N/cm. This may be accomplished by using a suitable spring. For the measurement of the dynamic friction in the case of slipstick behaviour, this spring shall be replaced by a rigid connection. NOTE The inertia of the mass of the sled induces an additional force at the start o
40、f the sled movement; thus the coefficient of friction differs from its true value by an amount given by where Under these conditions, the overshoot of the coefficient of friction is 0,005. In the worst case, this means that, at a low coefficient of friction of 0,2, the overshoot equals an error of 2
41、,5 %. 6 Test specimens For each measurement, two test specimens measuring about 80 mm 200 mm are needed. At least three such pairs of test specimens taken from points uniformly distributed over the width of the sample, or the circumference in the case of tubular film, shall be tested. Unless otherwi
42、se specified, the long axis, and thus the test direction, shall be parallel to the machine direction of the film. When different frictional properties are expected for the two surfaces, front (1) and back (2), the two surfaces shall be identified and tested 1/1, 2/2 and/or 1/2 as agreed between the
43、interested parties. Extreme care shall be taken in handling the samples and specimens. The test surfaces shall be kept free of dust, fingerprints or any foreign matter that might change the surface characteristics. NOTE 1 Testing of three pairs of test specimens represents a minimum for estimating t
44、he statistical tolerance interval. Depending on the intended precision and the homogeneity of the material under test, the number of specimens tested may have to be increased. ISO 2602:1980, Statistical interpretation of test results Estimation of the mean Confidence interval, gives guidance in this
45、 respect. NOTE 2 To avoid contamination of the surfaces, several test specimens may be cut simultaneously and separated immediately before testing. v is the speed of the sled relative to the table (= 100 mm/min); m is the mass of the sled (= 200 g); g is the acceleration due to gravity (= 9 810 mm/s
46、 2 ); D is the friction drag (2 N/cm = 2 10 5g/s 2 ). D v g - D m - =EN ISO 8295:2004 4 BSI 27 September 2004 7 Conditioning Unless otherwise specified, specimens shall be conditioned for at least 16 h in standard atmosphere 23/50 as defined in ISO 291 prior to testing. 8 Procedure The following dir
47、ections refer to an apparatus designed in accordance with Figure 1. If another equivalent apparatus is used, the appropriate procedure shall be followed. The testing shall be carried out in the same atmosphere as used for conditioning. 8.1 Measurement of film against film 8.1.1 Fix the right-hand en
48、d of the first test specimen on the test table with double-faced adhesive tape (or by a suitable clamp) so that the length axis of the test specimen coincides with that of the table. Reinforce the left-hand end of the second test specimen by attaching a small plate to it with double-faced adhesive t
49、ape. The mass of this plate shall not exceed 5 g. Connect this plate via a spring (see 5.2.5) to the load cell. Lay the second test specimen on the first and place the sled on top, gently and without shock, in the middle of the second test specimen (for films producing high blocking or other than frictional forces, the contact area, i.e. the size of the upper test specimen, shall be reduced as closely as possible to the area of the sled).
