1、BRITISH STANDARD BS3424-31: 1990 Testing coated fabrics Part31: Method34: Method for determination of resistance to scuffing and snagging IMPORTANT NOTE. It is recommended that this Part be read in conjunction with the information in Part0 “Foreword and general introduction”.BS3424-31:1990 This Brit
2、ish Standard, having been prepared under the directionof the Fibres, Yarns, Fabrics and Production StandardsPolicy Committee, waspublished under the authorityof the Board of BSI andcomes into effect on 31 October 1990 BSI 03-1999 The following BSI references relate to the work on this standard: Comm
3、ittee reference RUM/13 Draft for comment88/35826DC ISBN 0 580 18802 7 Foreword During use coated fabrics are commonly subjected to rapid glancing blows or direct impacts against hard objects and surfaces. If the object is sharp or pointed, a cut or snag of the material may be caused. If the object i
4、s blunt, then rather more extensive, but perhaps less severe, abrasion or scuffing damage will be produced. The present method simulates both types of damage, and it is envisaged that the method will prove relevant in the assessment of materials for such applications as shoe uppers, travel goods, pr
5、otective clothing, buoyancy aids and inflatables. 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 from legal obli
6、gations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to6, an inside back cover 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 th
7、e inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS3424-31:1990 BSI 03-1999 i Contents Page Foreword Inside front cover 1 Scope 1 2 Definitions 1 3 Principle 1 4 Apparatus 1 5 Selection of test specimens 2 6 Preparation of test assemblies 2 7 Preparation of ne
8、w granite chippings 2 8 Test procedure 2 9 Assessment of damage 4 10 Test report 5 Figure 1 Drum abrasion/snag tester 3 Figure 2 Plan view of drum abrasion/snag tester throughA-A 4 Figure 3 Damage sites counting template 6 Table 1 Snag/abrasion count reference table 5 Publications referred to Inside
9、 back coverii blankBS3424-31:1990 BSI 03-1999 1 1 Scope This Part of BS3424 describes a method for assessing the resistance of coated fabrics to damage by scuffing or snagging. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the
10、purposes of this Part of BS3424, the following definitions apply. 2.1 abrasion damage surface damage visible that is not composed of snag sites 2.2 snag site damage consisting of penetrative damage of a limited extent, such as a cut, puncture or partial delamination 2.3 snag/abrasion count the proba
11、ble number of snag/abrasion sites in the area of that part of the test piece being assessed. It is denoted as n (see9.2) 3 Principle The coated fabric to be tested is wrapped around and stuck to the curved surface of a short cylindrical steel bar. This test assembly is tumbled in a rotating drum con
12、taining granite chippings, causing an abrasive/scuffing action. The damage to the surface of the coated fabric is then assessed by comparison with a standard damage scale and by counting the sites of damage. 4 Apparatus 4.1 Drum abrasion/snag tester, consisting of a drum having an internal diameter
13、of254 1mm and an internal depth of95 1mm. The drum rotates on its axis at a speed of30 2r/min. The cylindrical wall of the drum is constructed of nylon and is not less than25mm thick. The front and back faces of the drum are of rubber6mm thick of hardness74 5IRHD 1) . The rubber faces are supported
14、on the outside by steel plates1.6mm thick. The front face of the drum is removable, to allow the drum to be loaded, and is held in place by three retaining bolts set at120 relative to each other. To the cylindrical wall of the drum are fixed nine equally spaced stainless steel rods95mm long 19mm dia
15、meter, with their axes parallel to the drum axis. The drum backplate is a push fit onto its driving shaft and is held in place with a grub screw, allowing easy removal of the drum for loading. Beneath the drum is a removable tray to collect any spillage. A timing device switches off the machine auto
16、matically after the completion of a preset test duration. A schematic illustration is shown in Figure 1 and Figure 2. 4.2 Cylindrical metal test bars, 50.8mm long 25.4mm diameter with each end of the cylinder plugged with a rubber disc of hardness97 IRHD,25.4mm diameter and approximately1mm thick, t
17、he exposed edge of the rubber disc being rounded to a radius of approximately0.55mm. The total mass of each bar, including the rubber end discs is2033g. NOTEDue to abrasive wear it is recommended that the rubber end discs are replaced when severely worn or damaged, this being necessary approximately
18、 every20h of testing. 4.3 Damage severity scales 4.3.1 Two “standard damage” scales, for assessing the general severity of damage. One scale is black and one white; both are prepared from the same polyurethane coated fabric, but with black and white pigmentation respectively. Each scale consists of
19、five test pieces of polyurethane coated fabric, graded from1, showing little or very minor damage, to5, showing severe damage. 1) International rubber hardness degrees.BS3424-31:1990 2 BSI 03-1999 4.3.2 Damage sites counting template, of translucent plastics material83mm 51mm covered with an opaque
20、film and having13 circular holes or cells each of area0.5cm 2randomly spaced within a central rectangle of area20cm 2 , i.e.approximately56mm 36mm (see Figure 3). 4.4 Granite chippings, of6mm to20mm pink granophyric monzonite. 4.5 Sieve, consisting of a perforated plate having19.0mm square holes, co
21、mplying with BS410. 4.6 Sieve, consisting of a perforated plate having6.7mm square holes, complying with BS410. 5 Selection of test specimens Cut two test specimens83mm 51mm from the longitudinal direction of the coated fabric and test two pieces83mm 51mm from the transverse direction of the coated
22、fabric. Ensure that the specimens are as widely dispersed as possible within the sample, and that, as far as possible, no two test specimens contain the same longitudinal or transverse threads and are not taken within50mm of any selvedge. 6 Preparation of test assemblies 6.1 Thin/flexible materials
23、Apply double sided adhesive tape to the reverse of the coated fabric test specimen, ensuring that the tape extends to all edges of the test specimen. Place the metal bar(4.2) carefully and centrally along a short edge of the test specimen and wrap the test specimen carefully around the metal bar, pr
24、essing it firmly all over, ensuring that no wrinkles or creases are introduced. Butt joint the two opposing edges of the test specimen. NOTEIf there is a gap of1mm to2mm this may be ignored, but any overlap should be carefully trimmed away to form a butt joint. 6.2 Thick/stiff materials Apply a suit
25、able adhesive 2)according to the manufacturers instructions that is compatible with the coated fabric under test. Bond the test specimen to the metal bar as described in6.1. 7 Preparation of new granite chippings Sieve at least1.5kg of unused chippings through the19.0mm sieve(4.5) and discard any ch
26、ippings retained on the sieve. Sieve the chippings passing through the19.0mm sieve through the6.7mm sieve(4.6) and retain the chippings retained by the6.7mm sieve. Discard the residue. Continue in this manner until1.5kg of chippings retained on the6.7mm sieve is obtained. Remove the abrasion drum fr
27、om the machine and tip in the1.5kg of sieved chippings. Replace the abrasion drum into the machine and re-attach the front plate to the drum and reassemble the drum carefully onto the motor shaft and secure in place. Run the machine for2h. Remove the drum and tip the chippings onto the6.7mm sieve. D
28、iscard all dust and small chippings that pass through this sieve when it is agitated. Wash the retained chippings and dry them for at least1h at100 C and allow to cool to room temperature. 8 Test procedure Remove the abrasion drum from the machine and brush out any dust present from a previous test.
29、 Weigh1kg of prepared granite chippings (see clause 7) and add them to the drum together with four test assemblies (see clause 6). Close the drum and re-attach it to the machine. Set the timer on the machine for 2 h or such other period as required by the product specification. Switch on the machine
30、. When the machine is fully stopped and isolated remove the test assemblies from the machine. Carefully remove the coated fabric test specimens from the cylindrical metal test bars (4.2) and flatten out, without stretching, the coated fabric test specimens. Clean all granite dust off the surface of
31、the test specimens with a damp cloth and dry them gently with a lint free cloth. Clean any adhesive from the cylindrical metal bars using a suitable solvent, ensuring that the rubber end discs are not damaged by the solvent used. Tip the used granite chippings onto the 6.7 mm sieve (4.6) and agitate
32、 to remove dust and small particles. Wash and dry the chippings retained on the sieve as described in clause 7 and make up the mass to 1 kg using prepared chippings (seeclause7). Record the number of tests for which the batch of chippings has been used. Discard the batch of used chippings after four
33、 tests and select a new batch of 1 kg from chippings prepared in accordance with clause 7. 2) For a list of suitable adhesives, apply to Enquiry Section, BSI, Linford Wood, Milton Keynes, MK146LE, enclosing a stamped addressed envelope for reply.BS3424-31:1990 BSI 03-1999 3 Figure 1 Drum abrasion/sn
34、ag testerBS3424-31:1990 4 BSI 03-1999 9 Assessment of damage 9.1 Deterioration in appearance Using the black damage scale(4.3.1) for the assessment of dark shades and the white damage scale(4.3.1) for the assessment of light shades, compare the test specimens with the standard damage scale under the
35、 viewing conditions described in BS950-2 and record the number of the damage scale most closely resembling the appearance of the test specimen. If the damage is judged to lie midway between two standard damage scales, record a half point to the score, e.g.if the damage is judged to lie midway betwee
36、n3and4, report a score of3. If the damage is less than1 report a score of. If there is no damage report a score of0. If the damage is greater than5 report “greater than5”. 9.2 Snag count Place the opaque template(4.3.2) symmetrically on a test specimen with the film side down and, with the aid of a
37、10stereoscopic microscope or 10lens, count the number of cells or holes in which there is a snag A (see2.2). Do not count the number of snags; but count only the number of cells containing snags. The snag count n (see2.3) for the assessed area of the specimen (20cm 2 ), is then derived by reference
38、to Table 1. NOTEThis view is a cross section through the drum centre. Figure 2 Plan view of drum abrasion/snag tester through A-A (see Figure 1)BS3424-31:1990 BSI 03-1999 5 NOTETheoretically if every cell contains a snag site the total number of snags could be infinite, but for the sake of simplicit
39、y this is reported as “over200”. The mathematical basis of Table 1 is given below. where Table 1 Snag/abrasion count referencetable 9.3 Abrasion count Count the number of sites of abrasion damage (see2.1) in the manner described in9.2, discounting snag sites and convert the cell count to abrasion co
40、unt by reference to Table 1. 9.4 Loss of finish For coatings which show a very superficial and uniform change of appearance (which may be no more than a loss of gloss), but which cannot be assessed by an abrasion count, the severity of the type of damage is recorded by allocating a score A to D, fro
41、m the following scale: 10 Test report The test report shall include the following information: a) the description of the coated fabric; b) the duration of the test, if different than2h; c) the snag count (see 9.2); d) the abrasion count (see9.3); e) the deterioration in appearance in accordance with
42、 the relevant standard damage scale in9.1; f) where requested, the loss of finish (see9.4); g) reference to this method of test, i.e.method34of BS3424-31; h) details of any deviation from the standard test procedure. n is the snag count or abrasion count; C is the number of cells in template; A is t
43、he number of cells containing snags/abrasions. A n 1 3 2 7 3 10 4 15 5 19 6 25 7 31 8 38 9 47 10 59 11 75 12 103 13 over200 n C logCA () log 0.4343 -(area of specimen assessed)(area of single cell) - = A little or no change of finish appearance; B moderate change of finish appearance; C pronounced c
44、hange of finish appearance; D complete loss of finish.BS3424-31:1990 6 BSI 03-1999 Figure 3 Damage sites counting templateBS3424-31:1990 BSI 03-1999 Publications referred to BS410, Specification for test sieves. BS950, Specification for artificial daylight for the assessment of colour. BS950-2, View
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