1、Designation: D 6125 97 (Reapproved 2002)An American National StandardStandard Test Method forBending Resistance of Paper and Paperboard (Gurley TypeTester)1This standard is issued under the fixed designation D 6125; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method determines the bending resistance ofpaper, paperboard,
3、and other flexible flat-sheet materials bymeasuring the force required to bend a specimen undercontrolled conditions. The instrument described allows for awide variation in specimen length, width and applied force.1.2 This test method is not recommended for soft, limp orcreped materials. Materials s
4、uch as tissue or toweling wouldnot normally be tested by this procedure and materials with apronounced degree of curl would give erroneous results.Products with a bending resistance below 1.39 Gurley Units (orproducts not able to give a deflection between 1 and 7 on thescale when using the lightest
5、weight) should not be tested bythis procedure.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regul
6、atory limitations prior to use.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:D 585 Practice for Sampling and Accepting a Single Lot ofPaper, Paperboard, Fiberboard, and Related Pr
7、oduct2D 685 Practice for Conditioning Paper and Paper Productsfor Testing22.2 TAPPI Standards:3T 543 Bending Resistance of PaperT 1200 Interlaboratory Evaluation of Test Methods to De-termine TAPPI Repeatability and Reproducibility3. Terminology3.1 Definitions:3.1.1 bending resistance, na material a
8、ttribute quantifiedby the magnitude of an applied force which produced deflec-tion of a specimen having specified dimensions.3.1.2 stiffness, of paper and paperboard, na synonym forbending resistance.3.1.3 machine direction bending resistance, nthe bendingresistance of a test specimen, clamped with
9、the machinedirection of the paper perpendicular to the specimen clamp.3.1.4 cross direction bending resistance, nthe bendingresistance of a test specimen, clamped with the cross directionof the paper perpendicular to the specimen clamp.3.2 Definitions of Terms Specific to This Standard:3.2.1 Gurley
10、stiffness, nstiffness or bending resistance ofpaper and paperboard determined using measurements madewith a specific instrument patented by Wthe test length and length ratio are used in evaluating Eq 1.8. Conditioning8.1 Condition and test the specimens in an atmosphere inaccordance with Practice D
11、685.9. Procedure9.1 Select an appropriate weight, mounting position andspecimen size to give a deflection between 1 and 7 on the scale.Level the base of the instrument so that the pendulum pointerwill indicate zero after attachment of the required weight. Notethat the pointer is on jeweled bearings.
12、 If the pointer losessensitivity, wipe it clean with a lint-free cloth. Do not oil thesebearings.9.2 Fasten the specimen strip in the specimen clamp in sucha manner that 6.4 6 0.2 mm (0.25 6 0.01 in.) will be held inthe jaws. Set the specimen clamp at a position so that the teststrip will overlap th
13、e top of the pendulum by exactly 6.4 6 0.2mm (0.25 6 0.01 in.). Note that the specimen should bebrought up close to the pendulum vane before applying force toavoid oscillation in the early stages of deflection.9.3 Press the reversing switch to cause the clamp arm tobring the specimen in contact with
14、 the top of the pendulum.Record the reading to the nearest 0.1 unit at the point where thespecimen clears the pendulum.9.4 Reverse the motor and load the test specimen against thependulum from the opposite side. Record the scale reading inthis direction. Average the results of the two readings.9.5 R
15、epeat the test with four more specimens.9.6 There are now digital machines that work as describedabove. The left and right readings are automatically capturedand stored. The average is also calculated and displayed as wellas the actual bending resistance value.10. Calculations and Theory10.1 Calcula
16、tion of Bending ResistanceBending resis-tance is calculated in three ways:10.1.1 Direct lookup via the table of conversion factorsprovided with each instrument (see Table 1).10.1.2 Computation via the equation upon which the lookuptable is based.S 5 1000RDMLR210 VWR(2)where:S = bending resistance or
17、 stiffness, Gurley units,R = scale reading,D = distance from weight to pivot, mm,V = distance from tip of vane to pivot = 127.0mm,M = weight, g,LR= length ratio = Ltest/Lstandard,Lstandard= 76.2 mm,WR= width ratio = Wtest/Wstandard, andWstandard= 25.4 mm.NOTE 1The size specimen used in Eq 2 was the
18、size specimen thatwas selected when the instrument was developed. It must not be confusedwith the preferred testing size given in 7.1.2.10.1.3 Automatic Digital ComputationNewer models ofthe Gurley tester incorporate optical encoders and micropro-cessors. The left and right scale readings are automa
19、ticallyaveraged and displayed. Conversion to Gurley bending resis-tance units are also automatically displayed.FIG. 2 Test SpecimenD 6125 97 (2002)310.2 Additional InformationIn Eq 2, the term R/10 isexactly the sine of the pointer angle at which the vane clearsthe specimen, and the term 1000 (R/10)
20、(D/V)M is thecorresponding force on the specimen. The term L2R/WRac-counts for the fact that, for a given scale reading R, longersamples are stiffer by the square of their length, and widersamples are less stiff, in proportion to their width.10.3 Taber EquivalencyGurley bending resistance (SG)can be
21、 converted to Taber stiffness (ST) by the equation:ST5 0.0146 SG1 0.053, where SG, 300 milligrams.ST5 0.01478 SG1 0.0588, where SG. 300 milligrams. (3)11. Report11.1 Report the following information:11.1.1 Bending resistance reading in Gurley units,11.1.2 Scale reading,11.1.3 Distance from weight to
22、 pivot in mm (in.),11.1.4 Weight used in grams, and11.1.5 Test length and test width as defined in Section 7.12. Precision12.1 PrecisionBased on data obtained from NationalBureau of Standards (NBS) - TAPPI Collaborative ReferenceProgram Number 25 through 51 (August 1973 through January1978). The ran
23、ge of test results of Gurley bending resistancecovered is 76 Gurley units to 870 Gurley units.12.2 Repeatability (between laboratory)The repeatabilityis 5.4 % of the test results. The range of all calculations ofrepeatability is 3.7 to 9.6 %. The range of the central 90 % ofthe calculations is 3.9 t
24、o 8.7 %.TABLE 1 Factors for Converting Scale Reading of Gurley Bending Resistance Tester(Reading to Milligrams with Gurley Bending Resistance Tester)NOTE 1Multiply Average Scale Reading by Conversion Factor Based on Instrument Settings:Size of Sample Width12 in.Actual length, in.: 1112 212 312 4125
25、Gram Weight:Distance from center, 1 in. 5.56 22.2 88.9 200 356Distance from center, 2 in. 11.1 44.4 178 400 711Distance from center, 4 in. 22.2 88.9 356 800 142225 Gram Weight:Distance from center, 1 in. 27.8 111 444 1000 1778Distance from center, 2 in. 55.6 222 889 2000 3556Distance from center, 4
26、in. 111 444 1778 4000 711150 Gram WeightDistance from center, 2 in. 111 444 1778 4000 7111Distance from center, 4 in. 222 889 3556 8000 14222200 Gram WeightDistance from center, 1 in. 444 1778 7111 16000 28444Distance from center, 2 in. 889 3556 14222 32000 55888Size of Sample Width 1 in.Actual leng
27、th, in.: 1112 212 312 4125 Gram Weight:Distance from center, 1 in. 2.78 11.1 44.4 100 178Distance from center, 2 in. 5.56 22.2 88.9 200 356Distance from center, 4 in. 11.1 44.4 178 400 71125 Gram Weight:Distance from center, 1 in. 13.9 55.6 222 500 889Distance from center, 2 in. 27.8 111 444 1000 17
28、78Distance from center, 4 in. 55.6 222 889 2000 355650 Gram Weight:Distance from center, 2 in. 55.6 222 889 2000 3556Distance from center, 4 in. 111 444 1778 4000 7111200 Gram Weight:Distance from center, 2 in. 222 889 3556 8000 14222Distance from center, 4 in. 444 1778 7111 16000 28444Size of Sampl
29、e Width 2 in.Actual length, in.: 1112 212 312 4125 Gram Weight:Distance from center, 1 in. 1.39 5.56 22.2 50 88.9Distance from center, 2 in. 2.78 11.1 44.4 100 178Distance from center, 4 in. 5.56 22.2 88.9 200 35625 Gram Weight:Distance from center, 1 in. 6.94 27.8 111 250 444Distance from center, 2
30、 in. 13.9 55.6 222 500 889Distance from center, 4 in. 27.8 111 444 1000 177850 Gram Weight:Distances from center, 2 in. 27.8 111 444 1000 1778Distance from center, 4 in. 55.6 222 889 2000 3556200 Gram WeightDistance from center, 2 in. 111 444 1778 4000 7111Distance from center, 4 in. 222 889 3556 80
31、00 14222D 6125 97 (2002)412.3 Reproducibility (between laboratory)The reproduc-ibility is 19.2 % of the test results. The range of all calculationsof reproducibility is 6.4 to 45.4 %. The range of the central90 % of the calculations is 12.2 to 25.5 %.13. Keywords13.1 Gurley stiffness; Gurley units;
32、stiffnessAPPENDIX(Nonmandatory Information)X1. ADDITIONAL TEST DATAX1.1 Data shown in Table X1.1 are taken from four reportsof Collaborative Testing Services (CTS) Analysis 336 (Gurleystiffness - standard Gurley units). These figures are based onten test determinations per sample and calculated as d
33、efined inTAPPI T 1200. The reader should be cautioned that thisanalysis is based on actual mill/laboratory bending resistancewith instruments or procedures that may not conform with thistest method. This information is given as a guide as to thepotential variation in Gurley bending resistance evalua
34、tion thatmay exist across the industry.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the
35、riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of
36、this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldma
37、ke your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained
38、by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE X1.1 Data Showing Estimates of PrecisionStatisticSample SH19A(Report 130S)Sample SH17B(Report 129S)Sample SH11C(Report 126S)Sample SH05D
39、(Report 123S)Grand mean 130.0 205.7 278.1 374.9Number of labs included 43 46 37 39Between - lab standard deviation 21.2 35.8 19.8 29.4Repeatability standard deviation 9.9 13.0 17.2 20.9Reproducibility standard deviation 23.3 38.1 26.1 35.5Repeatability limit 27.4 36.0 47.6 57.9Reproducibility limit 64.6 105.6 72.3 98.3Coefficient of variation, % 16.3 17.4 7.1 7.8A50 # Offset.B60 # Offset.C24 # Bond.D70 # Offset.D 6125 97 (2002)5
