1、Designation: D 2821 00 (Reapproved 2005)e1Standard Test Method forMeasuring the Relative Stiffness of Leather by Means of aTorsional Wire Apparatus1This standard is issued under the fixed designation D 2821; the number immediately following the designation indicates the year oforiginal adoption or,
2、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.This standard has been approved for use by agencies of the Department of Defense.e1NOTEAdjun
3、ct references were corrected editorially in April 2006.1. Scope1.1 This test method describes the use of a torsionalapparatus for measuring the relative stiffness of gloving leath-ers. This test method does not apply to wet blue.1.2 The values stated in SI units are to be regarded as thestandard. Th
4、e values shown in parentheses are provided forinformation only.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 applic
5、a-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1053 Test Method for Rubber Property-Stiffening at LowTemperatures: Flexible Polymers and Coated FabricsD 1610 Practice for Conditioning Leather and LeatherProducts for Testing2.2 ASTM Adjuncts:Standard tors
6、ion wire (2 pieces/set)3Torsion apparatus (1 drawing)43. Significance and Use3.1 This test method is designed to measure the apparenttorsional modulus of a leather specimen. Experience has shownthat the torsion modulus of leather is directly related to thecharacteristic known as stiffness when felt
7、in a glove.54. Apparatus4.1 Torsion Apparatus4The torsional apparatus, Fig. 1,shall consist of a torsion head, A, capable of being turnedthrough a complete circle in a plane normal to the torsion wire.The torsion head is equipped with an upper dial or protractor,K, graduated from 0 to 360 in increme
8、nts not greater than 5,and a fixed index pointer, L. The protractor is attached to thetorsion head by means of a friction bearing to permit move-ment for adjusting the zero point. The top of the torsion wire isattached to the torsion head at knob H by set screw B and1This test method is under the ju
9、risdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.04 on Apparel. This testmethod was developed in cooperation with the American Leather Chemists Assn.Current edition approved April 4, 2006. Published September 2005. Originallyapproved in 1969 as D 2821 6
10、9T. Last previous edition approved in 2000 asD 2821 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Lengt
11、hs of the standard wire can be obtained at nominal cost from ASTMInternational Headquarters. OrderAdjunctADJD282101. Original adjunct producedin 1975. A stainless steel rocket wire, Type NS-302, 0.010 6 0.0025 in. (0.025 60.06 mm) in diameter, bright finish, with chemical composition of 0.08 to 0.12
12、 %carbon, 8 to 10 % nickel, and 17 to 19 % chromium, available from NationalStandard Co., 1618-T Terminal Road, Niles, MI 49120; telephone: (616) 683-8100;fax: (616) 683-6249; has proved satisfactory. If other wire is used, it should becalibrated as described in Test Method D 1053 and have a constan
13、t of 0.0182gcm/deg.4The method is similar to Test Method D 1053. The original apparatus wasdescribed by Williamson, I., British Plastics, Vol 23, 1950, pp. 8790, 102; andtypical examples of the results of its use on leather were given in a paper byWitnauer, L. PA, and Palm, W. E., Journal, American
14、Leather Chemists Assn.,JALCA, Vol 59, 1964, pp. 246258. Working drawings for construction of theapparatus are available at nominal cost from ASTM International Headquarters.OrderAdjunctADJD282102. Original adjunct produced in 1985. There is no knownsource of supply of the equipment. The former produ
15、cer, Fulton County Machineand Supply Co., Inc. is no longer in business. If you are aware of alternativesuppliers, please provide this information to ASTM Headquarters. Your commentswill receive careful consideration at a meeting of the responsible technicalcommittee, which you may attend.5Gloves we
16、re made from the neck and butt areas of cattlehide work-gloveleather selected for 3 of softness varying from soft to firm. These were ranked fromsoftest to firmest by 20 individuals. Since there was some overlapping of rank asassigned by individual observers, the final rank was assigned according to
17、 highestnumber of selections. Specimens of leather cut from the sides in the area from whicheach glove was cut were tested for stiffness according to this test method. At 90 oftwist, the stiffness values gave a ranking similar to that obtained by feel. Specimenscut parallel to the backbone gave more
18、 consistant ranking than specimens cutperpendicular to the backbone. This undoubtedly reflects the fact that work glovesare cut from a side with the fingers parallel to the backbone. A report of theseexperiments and data used for calculation of precision and accuracy are on file atASTM Headquarters.
19、1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.passes through the center of a loosely fitting sleeve gripped bythe friction bearing. The torsion head support carries a splitbearing which can be activated by knob G, thus locking thes
20、leeve carrying the wire and permitting adjustment of the zeropoint of the protractor without disturbing the position of thetorsion wire. The bottom of the wire shall be fastened to the testspecimen clamp, C, by means of a set screw connector, D.Apointer, I, mounted above a fixed dial, J, shall be pr
21、ovided toindicate the twist applied to the specimen. Torsion is applied bymanually turning knob H or the remote control knob M.4.2 StandThe torsion apparatus shall be mounted on arigid supporting stand.4.3 Torsion Wires3Torsion wires shall be made of tem-pered spring wire 315 mm (12.5 in.) long, wit
22、h each end firmlyaffixed within a rod measuring 5 mm (316 in.) in diameter and12.5 mm (12 in.) long so as to give a free length between therods of 290 6 2.5 mm (11.5 6 0.1 in.).4.4 Specimen ClampsTwo clamps shall be provided forholding each test specimen. The top clamp, C, shall bemounted at the bot
23、tom of the torsion wire. The bottom clamp,E, shall be fashioned to move up and down without bindingwithin guides, F, mounted in the base. The weight of bottomclamp E shall be 15 6 0.01 g.5. Test Specimens5.1 Unless otherwise specified in the detailed specification,cut the specimen using a sharp die
24、measuring 12.70 6 0.03 mm(0.5006 0.001 in.) wide and 114 6 2 mm (4.5 6 0.1 in.) long.When known the direction to the backbone shall be indicated.It is good practice, however, to include a control specimen withknown twist characteristics.5.2 Condition the specimen as specified in Practice D 1610.6. P
25、reparation of Apparatus6.1 Clamp the specimen in the testing apparatus as de-scribed below so that 89 6 2 mm (3.5 6 0.1 in.) of thespecimen is free between the clamps. It is advisable to markthis distance on the specimen using a bench marker.6.2 Insert the specimen into the jaws of the bottom clamp,
26、E, until the edge of the clamp meets the bench mark, andtighten the two set screws using finger tip pressure. Be sure thespecimen is perpendicular to the jaws of the clamp.6.3 Insert the other end of the specimen into the jaws of theupper clamp, up to the bench mark and tighten the two setscrews usi
27、ng finger tip pressure. Be sure the specimen isperpendicular to clamp.6.4 Insert the bottom clamp into the clamp guide, F.6.5 Unlock the top dial by turning knob G counterclockwiseabout14 turn.6.6 Bring both clamps into parallel position by turning knobH, or knob M, either clockwise or counterclockw
28、ise so there isno twist to the specimen. When the clamps are parallel adjustthe top clamp indicator, I, so it is over the “0” mark on thelower dial, J, by holding the clamp parallel in one hand andturning the indicator. The indicator is attached to the upperclamp by a friction clasp.6.7 Lock the top
29、 dial, K, by turning knob G clockwise untiltight.6.8 Set the top dial by actually turning dial K to read 270(top dial is tension fitted).NOTE 1By setting the dial to 270, the 90 twist of the specimen willbe subtracted out automatically, and the readings obtained will be that ofthe wire to give the d
30、esired 90 twist of the specimen.NOTE 2When setting top dial care should be taken not to twist thewire, causing the top clamp indicator to move. Movement of the indicatormeans that knob G was not tightened sufficiently. If this happens repeatoperations 6.5-6.8 as may be necessary.NOTE 3Dial K is atta
31、ched to knob H through a friction bearing, thuspermitting dial K to be adjusted while the wire, which is attached to knobH, is in a locked position when knob G is tight. Loosening knob G permitsknob H and dial K to be turned freely as a unit.NOTE 4The procedure outlined here is for testing of specim
32、ens at 90twist. If in the detailed specification, other degrees of angular twist arespecified, then the preflexing cycles and the final measurement shall bemade at the specified degree of twist. The zero shall be adjusted to read360 minus the specified degrees of angular twist, and the torsion value
33、swill become corrected for the new value.7. Procedure7.1 Preflex the specimen by applying the same degree ofangular twist as specified for the test through a minimum oftwo cycles as detailed below.7.2 Loosen knob G and turn the top dial, K, using knob H orknob M, slowly in a counterclockwise directi
34、on until the upperclamp indicator, I, shows that the specimen has been twisted90 (see Note 4). (Try to keep a uniform rate that will takeabout 4 to 5 s/90. The use of the remote control knob M isrecommended as it permits a more uniform application oftwist.)7.3 Reverse rotation to the clockwise direc
35、tion and continuerotating slowly until the specimen clamp indicator I has passedthe original reference line indicated on the lower dial J byapproximately 45. Reverse the direction of rotation again andFIG. 1 Torsion ApparatusD 2821 00 (2005)e12slowly realign the specimen clamp indicator I with the o
36、riginalreference line indicated on lower dial J.7.4 If the upper dial does not read 270 (see Note 4), tightenknob G and bring the upper dial to 270 by actually turning dialK.7.5 Repeat steps 7.2-7.4 for one more cycle. This completesthe preflexing operation.7.6 Loosen knob G and again turn upper dia
37、l K using knobH or knob M, slowly and in a counterclockwise direction, untilthe specimen clamp indicator, I, shows a 90 twist (see Note 4).7.7 Read from the upper dial, K, the angle of torsion andrecord this value to the nearest 5.NOTE 5Torsion values can be obtained at several increments ofangular
38、twist on the same specimen without removing it from theapparatus. If torsion measurements are to be made at more than oneincrement of angular twist, it is advisable to make the first torsionmeasurement at the lowest degree of twist and proceed with the increasingincrements in consecutive order. When
39、 this is done it is essential that thespecimen be preflexed for two cycles at each increment of angular twist.NOTE 6Excessively high values may be due to either (a) overshootingthe end point from turning the dial too rapidly; ( b) the specimen is notperpendicular to clamp jaws and causes bottom clam
40、p to bind; or (c)neglecting to reset zero point between the second preflexing cycle and thefinal reading.NOTE 7Excessively low values, especially at higher degrees of twistmay be caused by inadvertently stopping the specimen at 90 instead ofgoing to the higher order.7.8 Release the specimen from the
41、 top clamp by looseningthe two set screws.7.9 Remove the bottom clamp from the guide and releasethe specimen by loosening the two set screws.8. Report8.1 The report shall include the following:8.1.1 Complete identification of the material tested includ-ing type, source, manufacturers code designatio
42、n, form, datemade, etc.8.1.2 Direction to backbone.8.1.3 Dimensions of test specimen, details of conditioningof specimens prior to test, and torsional constant of torsionwire used.8.2 Report torsion to the nearest 5, and indicate the angulartwist applied to the specimen.9. Precision and Bias9.1 The
43、precision of the test method is largely limited by thespecimen to specimen variation in such a complex material asleather.9.1.1 At the 95 % confidence level, repeat determinationson a single specimen made singly by the same operator ondifferent days should not differ by more than 13 % of thelowest v
44、alue.9.1.2 At the 95 % confidence level, single determinationsmade at different laboratories on the same specimen should notdiffer by more than 23 % of the lowest value.10. Keywords10.1 glove leather; stiffnessASTM International takes no position respecting the validity of any patent rights asserted
45、 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 riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the
46、 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 this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive c
47、areful 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 shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Internati
48、onal, 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 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).D 2821 00 (2005)e13
