1、BRITISH STANDARD BS5961:1980 IEC648:1979 Method for Determination of coefficients of friction of plastic film and sheeting for use as electrical insulation IEC title: Method of test for coefficients of friction of plastic film and sheeting for use as electrical insulation UDC 621.315.616.9:678.075:6
2、78.067-41:531.43.08BS5961:1980 This BritishStandard, having been prepared under the directionof the General Electrotechnical Engineering Standards Committee, was published under the authority ofthe Executive Board and comesinto effect on 31July1980 BSI 11-1999 The following BSI references relate to
3、the work on this standard: Committee referenceGEL/16 Draft for comment77/20116DC ISBN 0 580 11547X Cooperating organizations The General Electrotechnical Engineering Standards Committee, under whose direction this BritishStandard was prepared, consists of representatives from the following Governmen
4、t departments and scientific and industrial organizations: Associated Offices Technical Committee British Approvals Service for Electric Cables Ltd. British Electrical and Allied Manufacturers Association (BEAMA) British Radio Equipment Manufacturers Association British Steel Corporation Department
5、of Energy (Electricity) Electric Cable Makers Confederation Electrical Contractors Association Electrical Contractors Association of Scotland Electricity Supply Industry in England and Wales* Electronic Components Industry Federation* Electronic Engineering Association* Engineering Equipment Users A
6、ssociation Era Technology Ltd.* Health and Safety Executive Home Office Institution of Electrical Engineers Ministry of Defence* National Coal Board Oil Companies Materials Association Post Office* The organizations marked with an asterisk in the above list, together with the following, were directl
7、y represented on the committee entrusted with the preparation of this BritishStandard: Adhesive Tape Manufacturers Association British (AC) Capacitor Manufacturers Association British Industrial Ceramic Manufacturers Association British Paper and Board Industry Federation (PIF) British Plastics Fede
8、ration Department of Industry (British Calibration Service) Department of Industry (National Physical Laboratory) Electrical and Electronic Insulation Association (BEAMA) Electrical Installation Equipment Manufacturers Association (BEAMA) Packaging and Industrial Films Association Rotating Electrica
9、l Machines Association (BEAMA) Telecommunication Engineering and Manufacturing Association (TEMA) Transmission and Distribution Association (BEAMA) Amendments issued since publication Amd. No. Date of issue CommentsBS5961:1980 BSI 11-1999 i Contents Page Cooperating organizations Inside front cover
10、National foreword ii 1 Scope 1 2 Significance 1 3 Definitions 1 4 Test specimens 1 5 Conditions 2 6 Apparatus 2 7 Preparation of apparatus 3 8 Procedure 3 9 Calculations 4 10 Report 4 Figure 1 Five methods of assembly of apparatus for determination of coefficients of friction of plastic films 5BS596
11、1:1980 ii BSI 11-1999 National foreword This BritishStandard has been prepared under the direction of the General Electrotechnical Engineering Standards Committee. It is identical with IEC Publication648 “Method of test for coefficients of friction of plastic film and sheeting for use as electrical
12、insulation” published in1979 by the International Electrotechnical Commission (IEC). Terminology and conventions. The text of the International Standard has been approved as suitable for publication, without deviation, as a BritishStandard. Some terminology and certain conventions are not identical
13、with those used in BritishStandards. Additional information. This method is published by IEC as a Report and is taken directly from ASTM standard D1894. It has been issued to enable the test procedure in that standard to be available in IEC form so that the method may be used, wherever necessary, in
14、 specifications now being prepared for plastics films and sheeting for electrical insulation purposes. At a later date, when the ISO method for this property has been developed, it is understood that the IEC Publication will be withdrawn and the withdrawal of this standard will then be considered. A
15、 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 from legal obligations. Summary of pages This document comprises a
16、 front cover, an inside front cover, pagesi andii, pages1 to5 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS5961:1980 BSI 11-1999 1 1 Scope 1.1 This method cove
17、rs determination of the coefficients of starting and sliding friction of plastic film and sheeting when sliding over itself or other substances under specified test conditions. The procedure permits the use of a stationary sled with a moving plane, or a moving sled with a stationary plane. Both proc
18、edures yield the same coefficients of friction values for a given sample. NOTEThe values stated in SI units are to be regarded as the standard. 2 Significance 2.1 Measurements of frictional properties may be made on a film or sheeting specimen when sliding over itself or over another substance. The
19、coefficients of friction are related to the slip properties of plastic films that are of wide interest in packaging applications. These methods yield empirical data for control purposes in film production. Correlation of test results with actual performance can usually be established. 2.2 Slip prope
20、rties are generated by additives in some plastic films, for example, polyethylene. These additives have varying degrees of compatibility with the film matrix. Some of them bloom, or exude to the surface, lubricating it and making it more slippery. Because this blooming action may not always be unifo
21、rm on all areas of the film surface, values from these tests may be limited in reproducibility. 2.3 The frictional properties of plastic film and sheeting may be dependent on the uniformity of the rate of motion between the two surfaces. Care should be exercised to ensure that the rate of motion of
22、the equipment is as carefully controlled as possible. 2.4 Data obtained by these procedures may be extremely sensitive to the age of the film or sheet and the condition of the surfaces. The blooming action of many slip additives is time-dependent. For this reason, it is sometimes meaningless to comp
23、are slip and friction properties of films or sheets produced at different times, unless it is desired to study this effect. 2.5 Frictional and slip properties of plastic film and sheeting are based on measurements of surface phenomena. Where products have been made by different processes, or even on
24、 different machines by the same process, their surfaces may be dependent on the equipment or its running conditions. Such factors must be weighed in evaluating data from these methods. 2.6 The measurement of the static coefficient of friction is highly dependent on the rate of loading and on the amo
25、unt of blocking occurring between the loaded sled and the platform due to variation in time before motion is initiated. 2.7 Care should be exercised to make certain that the speed of response of the recorder, either electronic or mechanical, is not exceeded. 3 Definitions 3.1 slip a term denoting lu
26、bricity of two surfaces sliding in contact with each other. In a sense, it is the antithesis of friction in that high coefficient of friction denotes low slip and low coefficient of friction high slip 3.2 friction the resisting force that arises when a surface of one substance slides, or tends to sl
27、ide, over an adjoining surface of itself or another substance. Between surfaces of solids in contact there may be two kinds of friction: 1) the resistance opposing the force required to start to move one surface over another, and 2) the resistance opposing the force required to move one surface over
28、 another at a variable, fixed, or predetermined speed. 3.3 coefficient of friction the ratio of the frictional force, defined in Sub-clause3.2, to the force, usually gravitational, acting perpendicular to the two surfaces in contact. This coefficient is a measure of the relative difficulty with whic
29、h the surface of one material will slide over an adjoining surface of itself, or of another material the static or starting coefficient of friction ( s ) is related to the force measured to begin movement of the surfaces relative to each other. The kinetic or sliding coefficient of friction ( k ) is
30、 related to the force measured in sustaining this movement 4 Test specimens 4.1 The test specimen that is to be attached to the plane shall be cut approximately250mm (10in) in the machine direction and130mm (5in) in the transverse direction when such extrusion directions exist and are identifiable.
31、4.2 A film specimen having a nominal thickness of not greater than0.254mm (0.01in) that is to be attached to the sled shall be cut approximately120mm (4“ in) square.BS5961:1980 2 BSI 11-1999 4.3 A plastic sheeting specimen (greaterthan0.254mm (0.01in) nominal thickness) or another substance that is
32、to be attached to the sled shall be cut63.5mm (2“ in) square. 4.4 Plastic sheeting specimens shall be flat and free of warpage. Edges of specimens shall be rounded smooth. 4.5 Five specimens shall be tested for each sample, unless otherwise specified. NOTE 1Plastic films and sheeting may exhibit dif
33、ferent frictional properties in their respective principal directions due to anisotropy or extrusion effects. Specimens may be tested with their long dimension in either the machine or transverse direction of the sample, but it is more common practice to test the specimen as described in Sub-clause4
34、.1, with its long dimension parallel to the machine direction. NOTE 2Caution: Extreme care must be taken in handling the specimens. The test surface must be kept free of all dust, lint, finger-prints, or any foreign matter that might change the surface characteristics of the specimens. 5 Conditions
35、5.1 Conditioning Condition the test specimens at23 2 C (73.4 3.6 F) and50 50% relative humidity for not less than40h prior to test, for those tests where conditioning is required. In cases of disagreement, the tolerances shall be 1 C ( 1.8 F) and2% relative humidity. 5.2 Test conditions Conduct test
36、s in the standard laboratory atmosphere of23 2 C (73.4 3.6 F) and505% relative humidity, unless otherwise specified in the test method or in this report. In cases of disagreement, the tolerances shall be 1 C ( 1.8 F) and2% relative humidity. In specific cases, such as control testing, where the cond
37、itioning requirements cannot be met and the data still may be of direct assistance to the operation, other conditioning procedures may be used and recorded in the test report. Frictional properties should be measured only after sufficient time has been allowed for the specimens to reach essential eq
38、uilibrium with the ambient atmosphere. 6 Apparatus 6.1 Sled A metal block63.5mm (2“ in) square by approximately6mm (0.25in) thick with a suitable eye screw fastened in one end. When flexible film (see Sub-clause4.2) is to be attached, the block shall be wrapped with3.2mm ( in) thick, medium density
39、foam rubber. The rubber shall be wrapped snugly around the sled end-to-end and fastened in position. When a plastic sheet (see Sub-clause4.3) is to be attached, double-faced tape shall be used to attach the specimen. The total mass of the wrapped) sled and specimen should be200 5g. 6.2 Plane A polis
40、hed plastic, wood or metal sheet, approximately150mm by300mm by1mm (6in by12in by0.040in). A smooth, flat piece of glass may cover the upper surface of the plane. This provides a smooth support for the specimen. 6.3 Scissors or cutter suitable for cutting specimens to the desired dimensions. 6.4 Adh
41、esive tape, cellophane or pressure-sensitive, single-faced. 6.5 Adhesive tape, double-faced. 6.6 Nylon monofilament, having a0.33 0.05mm (0.013 0.002in) diameter and capable of supporting a3.6kg (8lb) load. 6.7 Low friction pulleys A phenolic type pulley mounted in hardened steel cone bearings on a
42、metal fork. A ball-bearing type pulley may also be used. 6.8 Force-measuring device Capable of measuring the frictional force to 5% of its value. A spring gauge (see note) universal testing machine, or strain gauge may be used. NOTEThe capacity of the spring gauge (Figure 1a) and Figure 1b), page5)
43、needed will depend upon the range of values to be measured. For most plastics, a500g capacity gauge with10g or smaller subdivisions will be satisfactory. This spring will measure coefficients of friction up to and including2.5. 6.9 Supporting base A smooth wood or metal base approximately200mm by380
44、mm is necessary to support the plane. The supporting base may be a simple rectangular box. If a universal testing machine is used to pull a moving plane, a supporting base of sufficient structural strength and rigidity to maintain a firm position between the moving crosshead and the force-measuring
45、device will be necessary.BS5961:1980 BSI 11-1999 3 6.10 Driving or pulling device for sled or plane The plane may be pulled by a driven pair of rubber-coated rolls not less than200mm (8in) long, capable of maintaining a uniform surface speed150 30mm/min (0.5 0.1ft/min) Figure 1b), by the crosshead o
46、f a universal testing machine Figure 1d), page5, and note) or a worm drive driven with a synchronous motor Figure 1e), page5. A constant speed chain-drive system has also been found satisfactory Figure 1a). A power-operated source may be used for pulling the sled over the horizontally mounted specim
47、en at a uniform speed of150 30mm/min (0.5 0.1ft/min). A universal testing machine equipped with a load cell in its upper crosshead and a constant rate-of-motion lower crosshead has been found satisfactory seeFigure 1c), page5. NOTEWhere the moving crosshead of a universal testing machine is used to
48、pull the moving plane through a pulley system Figure 1d), the strain gauge load cell, or other load-sensing instrument in the testing machine, acts as the force-measuring device. 7 Preparation of apparatus 7.1 Figure 1, page5, shows five ways in which the apparatus may be assembled. The support base
49、s for all apparatus assemblies shall be level. 7.2 If the apparatus ofFigure 1a) orFigure 1b) is used, calibrate the scale of the spring gauge as follows: 7.2.1 Mount the low friction pulley in front of the spring gauge. 7.2.2 Fasten one end of the nylon filament to the spring gauge, bring the filament over the pulley and suspend a known weight on the lower end of the filament to act downward. NOTEThe reading on the scale shall correspond to the known mass within 5%. The weight used for this calibration shall be between5
