1、BRITISH STANDARD BS 6563:1985 Method for Determination of the roughness of paper and board by the Parker Print-surf apparatus UDC 676.017.28:539.211BS6563:1985 This British Standard, having been prepared under the directionof the Paper StandardsCommittee, was published under the authority ofthe Boar
2、d of BSI and comes intoeffect on 28February1985 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference PAM/11 Draft for comment 83/39019 DC ISBN 0 580 14206 X Committees responsible for this British Standard The preparation of this British Standard was entr
3、usted by the Paper Standards Committee (PAM/-) to Technical Committee PAM/11 upon which the following bodies were represented: British Fibreboard Packaging Association British Paper and Board Industry Federation (PIF) British Printing Industries Federation British Wood Pulp Association Envelope Make
4、rs and Manufacturing Stationers Association Her Majestys Stationery Office Man-made Fibres Producers Committee Ministry of Defence Paper Sack Development Association Ltd. Pira (the Research Association for the Paper and Board, Printing and Packaging Industries) Post Office Society of British Printin
5、g Ink Manufacturers University of Manchester Institute of Science and Technology Amendments issued since publication Amd. No. Date of issue CommentsBS6563:1985 BSI 10-1999 i Contents Page Committees responsible Inside front cover Foreword ii 0 Introduction 1 1 Scope 1 2 Definition 1 3 Principle 1 4
6、Apparatus 1 5 Sampling 1 6 Conditioning 1 7 Preparation of test pieces 1 8 Procedure 2 9 Test report 2 Appendix A The calculation of roughness in absolute units 3 Appendix B Apparatus and its maintenance 3 Figure 1 Manual Print-surf types750and750/EPC 4 Figure 2 Manual Print-surf type PPS78 4 Figure
7、 3 The sensing head sectioned on two radii 5 Figure 4 Plan of the metering and guard lands of the sensing head 5 Publications referred to Inside back coverBS6563:1985 ii BSI 10-1999 Foreword This British Standard, which is one of a series relating to the testing of pulp, paper and board, has been pr
8、epared under the direction of the Paper Standards Committee. It is based on work done by the precursor of the Test Method Committee of the Technical Division of the British Paper and Board Industry Federation and was published as Proposed Procedure No59. The procedure described in this British Stand
9、ard is at present under consideration by the relevant technical committee of the International Organization for Standardization (ISO) and may eventually be adopted as an International Standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of Britis
10、h 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 front cover, an inside front cover, pages i and ii, pages1to6, an inside back cover and a back cover. Th
11、is 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.BS6563:1985 BSI 10-1999 1 0 Introduction There are several different methods for determining the roughness of paper and board. In recent
12、 years it has become apparent that, when testing paper and board intended for printing, conditions similar to those encountered in printing presses should be used. In particular, when paper is intended for letterpress printing, it is desirable to have a measure of the depth of the pits in the paper
13、surface when under the pressures encountered during printing, to indicate the ink film thickness required for a satisfactory result. Air-leak methods provide convenient means of testing paper roughness, but they are known to be subject to errors caused by the flow of air through the paper. This flow
14、 can become large in comparison with the flow across the paper surface, especially when the paper is highly permeable or two-sided and when the clamping pressure is so high that the surface flow is relatively small. The use of high clamping pressures with resilient backings also causes the paper to
15、become indented at the edges of the metering land which is pressed against the paper. Such distortion of the paper surface can affect roughness readings and should be avoided. These two sources of error can be minimized by an appropriate design of the sensing head, as in the instrument described in
16、this British Standard, which has been developed as a result of the above considerations. The derivation of a fundamental relationship between air-flow characteristics and roughness has made possible the direct calibration of the instrument in terms of the extent of departures from a reference plane.
17、 It also permits the calculation of roughness from results obtained by a variety of techniques. Therefore, although a standard apparatus is described, the use of variants that meet certain basic requirements is not precluded. 1 Scope This British Standard describes a method for determining the rough
18、ness of paper and board under printing pressures, by use of the Parker Print-surf air-leak apparatus. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definition For the purposes of this British Standard the following definition applies. roughnes
19、s of a sheet material under pressure the extent of deviation of a sheet material from a reference plane against which it is pressed 3 Principle The test piece is firmly pressed at a fixed pressure by a deformable backing against a reference plane; this plane is interrupted by two narrow parallel slo
20、ts, separated by a narrow metal land. Air is supplied at constant pressure to one of these slots and the rate of flow between the test piece and the metal land into the other slot is observed. The roughness of the test piece is calculated as the cube root of the mean cube of the distance between the
21、 test piece and the reference plane and is expressed in absolute units using the following data: a) the dimension of the metering land; b) the rate of air flow and the pressure at which it is measured; c) the upstream and downstream air pressures. The width of the metering land is of the same order
22、of magnitude as that of a half-tone dot. The only departures from the plane to contribute to the results will be those that are wider than the metering land. The relationship used to calculate the roughness is given in Appendix A. 4 Apparatus 4.1 Sensing head, of circular form. 4.2 Hard and soft bac
23、king assemblies 4.3 Clamping mechanism, with fixed clamping pressures. 4.4 Measuring system, comprising either flowmeters or a fluidic impedance system. 4.5 Air supply, clean and water free at a pressure of300kPa to600kPa. NOTESee Appendix B for detailed descriptions of the apparatus. 5 Sampling Sel
24、ect samples in accordance with BS3430. 6 Conditioning Condition samples in accordance with BS3431. Carry out the tests in the same atmosphere as used for conditioning. 7 Preparation of test pieces For each side to be tested, cut at least ten test pieces not less than100mm 2from the selected specimen
25、s, avoiding any part of the sample that is less than15mm from the side of a sheet or reel. Also avoid the inclusion of any folds, creases, visible cracks or other defects in the test pieces. If watermarks are present, state this fact in the test report. Mark each test piece near the edge to identify
26、 the sides.BS6563:1985 2 BSI 10-1999 8 Procedure 8.1 Installation Set the instrument on a horizontal rigid surface, free from vibration. 8.2 Selection of backing assembly Select the appropriate backing assembly 1)and position it in the instrument. 8.3 Clamping pressure Ensure that the sensing head i
27、s in place and connect the air supply to the instrument. Select the clamping pressure as follows: 8.4 Flowmeter instruments (types 750 and 750/EPC) Adjust the sensing head to give a differential pressure of6.17kPa. Select the highest range flowmeter. Insert a spare test piece between the head and th
28、e backing. Clamp using the appropriate pressure. Select the correct flowmeter. NOTEIf the lowest range flowmeter is not sufficiently sensitive, increase the sensing head differential pressure to19.6kPa. Readings made at the higher differential pressure are corrected by dividing the flowmeter reading
29、 by a factor of1.5. Insert the first test piece. Read the roughness value in micrometres to the nearest0.054m3s to5s after the first application of the clamping pressure. Readings should be taken level with the top of the flowmeter float. Repeat with the remaining test pieces. NOTEThe instrument is
30、designed to measure compressibility also, so that, after the reading has been taken, it is possible to select a higher clamping pressure that permits a further reading to be taken without releasing the test piece. 8.5 Digital instruments (type PPS 78) Insert a test piece between the head and the bac
31、king. The action of the test piece obstructing a light beam automatically clamps the test piece against the sensing head. The indicator lamp marked “air” lights up and after about4s the roughness is shown on the digital display. At the same time the test piece is released. The reading is held until
32、the next test piece is inserted. NOTESmall samples may not actuate the automatic clamping process. When this occurs the sample may be clamped by operating the button marked “manual start”. NOTE to8.4 and8.5 The precision of the results obtained is affected not only by operator and instrument error b
33、ut also by the roughness of the paper or board surface and the variability of that roughness. Consequently it is difficult to give realistic values for precision. However, typical values obtained during the routine operation of calibration check services in the UK and USA are given below: 9 Test rep
34、ort The test report shall include the following: a) date and place of testing; b) the standard conditioning atmosphere used; c) the type of apparatus used; d) the mean and standard deviation of the readings for each side of the paper or board to the nearest0.054m; e) the type of backing used; f) the
35、 clamping pressure used; g) any departure from this method that may have affected the results. 1) The hard backing is recommended for papers that are to be printed on letterpress presses fitted with paper packings. The soft backing is recommended for all other papers and processes. a) with the hard
36、backing plate 1) 2000 kPa (20 kgf/cm 2 ); b) with the soft backing plate: newsprint 2000 kPa (20 kgf/cm 2 ); c) with the soft backing plate: offset papers 1000 kPa (10 kgf/cm 2 ); d) with the soft backing plate: gravure papers 500 kPa (5 kgf/cm 2 ). at 1 4m at 6 4m 4m 4m Repeatability 0.10 0.20 Repr
37、oducibility 0.20 0.40BS6563:1985 BSI 10-1999 3 Appendix A The calculation of roughness in absolute units Subject to certain limitations, the cube root mean cube gap G 3 between the metering land and test piece is given by the equation: where For differential pressures that are high compared with the
38、 absolute pressure, because air is compressible, the pressure drop P has to be replaced by the following equation: Equation (2) is derived on the assumption that the gap between the metering land and test piece is uniform across the breadth of land, but that it varies along its length w. Equation (2
39、) is subject to the restrictions that the flow is laminar, and that the kinetic energy changes per unit volume of gas are negligible compared with%P. The flow conditions are normally well within the laminar range, but the kinetic energy may be important when rough papers are measured, unless the dif
40、ferential pressure is restricted. The full equation for flow over the metering land, given below, may be used to estimate the extent of the error. where Appendix B Apparatus and its maintenance B.1 General The apparatus is composed of the following majorparts, interconnected as shown in Figure 1 orF
41、igure 2. B.2 Air supply A supply of clean air, free from water droplets, at a steady pressure of300kPa to600kPa, to maintain either of the following pressure differences across the sensing head: a) 6.17 0.2 kPa (631 15mmH 2 Oat23 C); or, b) 19.6 0.5kPa (2000 50mmH 2 Oat23 C). NOTEFor PPS 78type inst
42、ruments only item b) is applicable. B.3 Sensing head Three concentric annular steel lands with their working surfaces which are coplanar and polished and together form the reference surface. (See Figure 3 and Figure 4.) The metering land has a width of51.0 1.54m and an effective length of98.0 0.5mm.
43、 The guard lands are each at least5004m wide. The radial distance between them is152 104m. The metering land is centred between the guard lands to a tolerance of 104m. An airtight mounting for the three lands, constructed so that air may be passed into the gap between one guard land and the measurin
44、g land and may be collected from the other gap. The back surface of the mounting is flat and forms a ground mating surface with the flat surface of a manifold fitted with air inlet and outlet connections. B.4 Backing assemblies (see8.2) B.4.1 Holders Rigid metal discs, recessed to accommodate a defo
45、rmable backing at least10mm greater in diameter than the reference surface. B.4.2 Soft deformable backing A lithographic printing blanket composed of a layer of synthetic rubber600 604m thick, bonded to a fabric backing giving an overall thickness of2000 2004m, the apparent hardness of the complete
46、backing being836IRHD. The lithographic blanket should adhere to the holder. B.4.3 Hard deformable backing A cork backing covered by a polyester film125 54m thick, the apparent hardness of the complete backing being95 2IRHD. The polyester film should be attached only at the edges of the backing surfa
47、ce. (1) is the viscosity of air; b is the distance through which air flows across the metering land; Q is the volume of air flowing in unit time; w is the effective length of metering land; %P is the pressure drop across the metering land. (P u 2 P d 2 )/2P m (2) where P u is the absolute upstream p
48、ressure; P d is the absolute downstream pressure; P m is the pressure at which the flow Q is measured. (3) is the density of air; P m is the pressure at which is measured; C is the coefficient, found by experiment for a number of papers to be approximately2.5. G 3 12 bQ w%P - 0.33 = %P 12 bQ wG 3 3
49、- C Q 2 2w 2G 3 2 - + =BS 6563:1985 4 BSI 10-1999 Figure 1 Manual Print-surf types 750and 750/EPC Figure 2 Print-surf type PPS 78BS6563:1985 BSI 10-1999 5 Figure 3 The sensing head sectioned on two radii Figure 4 Plan of the metering and guard lands of the sensing headBS6563:1985 6 BSI 10-1999 B.5 Clamping mechanism A means of clamping the test piece between the sensing head and either of the deformable backings at any of the following pressures: 500 15 kPa (5 k
