1、Designation: D 395 03Standard Test Methods forRubber PropertyCompression Set1This standard is issued under the fixed designation D 395; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthe
2、ses 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.1. Scope1.1 These test methods cover the testing of rubber intendedfor use in appli
3、cations in which the rubber will be subjected tocompressive stresses in air or liquid media. They are applicableparticularly to the rubber used in machinery mountings, vibra-tion dampers, and seals. Two test methods are covered asfollows:Test Method SectionACompression Set Under Constant Force in Ai
4、r 710BCompression Set Under Constant Deflection in Air 11141.2 The choice of test method is optional, but considerationshould be given to the nature of the service for whichcorrelation of test results may be sought. Unless otherwisestated in a detailed specification, Test Method B shall be used.1.3
5、Test Method B is not suitable for vulcanizates harderthan 90 IRHD.1.4 The values stated in SI units are to be regarded as thestandard.1.5 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 esta
6、blish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1349 Practice for RubberStandard Temperatures forTesting2D 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standar
7、d Compounds and Prepar-ing Standard Vulcanized Sheets2D 3183 Practice for RubberPreparation of Pieces for TestPurposes from Products2D 3767 Practice for RubberMeasurement of Dimensions2D 4483 Practice for Determining Precision for Test Meth-ods Standards in the Rubber and Carbon Black Industries2E 1
8、45 Specification for Gravity-Convection and Forced-Ventilation Ovens33. Summary of Test Methods3.1 A test specimen is compressed to either a deflection orby a specified force and maintained under this condition for aspecified time and at a specified temperature.3.2 The residual deformation of a test
9、 specimen is measured30 min after removal from a suitable compression device inwhich the specimen had been subjected for a definite time tocompressive deformation under specified conditions.3.3 After the measurement of the residual deformation, thecompression set, as specified in the appropriate tes
10、t method, iscalculated according to Eq 1 and Eq 2.4. Significance and Use4.1 Compression set tests are intended to measure the abilityof rubber compounds to retain elastic properties after pro-longed action of compressive stresses. The actual stressingservice may involve the maintenance of a definit
11、e deflection,the constant application of a known force, or the rapidlyrepeated deformation and recovery resulting from intermittentcompressive forces. Though the latter dynamic stressing, likethe others, produces compression set, its effects as a whole aresimulated more closely by compression flexin
12、g or hysteresistests. Therefore, compression set tests are considered to bemainly applicable to service conditions involving staticstresses. Tests are frequently conducted at elevated tempera-tures.5. Test Specimens5.1 Specimens from each sample may be tested in duplicate(Option 1) or triplicate (Op
13、tion 2). The compression set of thesample in Option 1 shall be the average of the two specimensexpressed as a percentage. The compression set of the samplein Option 2 shall be the median (middle most value) of thethree specimens expressed as a percentage.5.2 The standard test specimen shall be a cyl
14、indrical diskcut from a laboratory prepared slab.5.2.1 The dimensions of the standard specimens shall be:1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.10 on PhysicalTesting.Current edition approved Aug. 10, 2003. P
15、ublished September 2003. Originallyapproved in 1934. Last previous edition approved in 2002 as D 395 02.2Annual Book of ASTM Standards, Vol 09.01.3Annual Book of ASTM Standards, Vol 14.04.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Stat
16、es.Type 1A2BThickness, mm (in.) 12.5 6 0.5(0.49 6 0.02)6.0 6 0.2(0.24 6 0.01)Diameter, mm (in.) 29.0 6 0.5(1.14 6 0.02)13.0 6 0.2(0.51 6 0.01)AType 1 specimen is used in Test Methods A and B.BType 2 specimen is used in Test Method B.5.2.2 When cutting the standard specimen, the circular diehaving th
17、e required inside dimensions specified in 5.2.1 shallbe rotated in a drill press or similar device and lubricated bymeans of a soap solution. A minimum distance of 13 mm (0.51in.) shall be maintained between the cutting edge of the die andthe edge of the slab. The cutting pressure shall be as light
18、aspossible to minimize cupping of the cut edges. The dies shallbe maintained carefully so that the cutting edges are sharp andfree of nicks.5.3 An optional method of preparing the standard specimenmay be the direct molding of a circular disk having thedimensions required for the test method used and
19、 specified in5.2.1.NOTE 1It should be recognized that an equal time and temperature, ifused for both the slab and molded specimen, will not produce anequivalent state of cure in the two types of specimen. A higher degree ofcure will be obtained in the molded specimen. Adjustments, preferably inthe t
20、ime of cure, must be taken into consideration if comparisons betweenthe specimens prepared by different methods are to be considered valid.NOTE 2It is suggested, for the purpose of uniformity and closertolerances in the molded specimen, that the dimensions of the mold bespecified and shrinkage compe
21、nsated for therein. A two-plate mold with acavity 13.0 6 0.1 mm (0.510 6 0.004 in.) in thickness and 29.20 6 0.05mm (1.148 6 0.002 in.) in diameter, with overflow grooves, will provideType 1 specimens for Test Method A and Test Method B. A similar moldbut having a cavity of 6.3 6 0.3 mm (0.25 6 0.01
22、2 in.) in thickness and13.2 6 0.1 mm (0.52 6 0.004 in.) in diameter will provide Type 2specimens for Test Method B.5.4 When the standard test specimen is to be replaced by aspecimen taken from a vulcanized rubber part of greaterthickness than the one indicated in 5.2.1, the sample thicknessshall be
23、reduced first by cutting transversely with a sharp knifeand then followed by buffing to the required thickness inaccordance with Practice D 3183.5.5 An alternative method of preparing specimens is byplying up cylindrical disks cut from a standard sheet preparedin accordance with Practice D 3182 usin
24、g the specimen sizesspecified in 5.2.1 and cutting as described in 5.2.2, or where adrill press is not available cutting the specimens with a singlestroke from a cutting die.5.5.1 The disks shall be plied, without cementing, to thethickness required. Such plies shall be smooth, flat, of uniformthick
25、ness, and shall not exceed seven in number for Type 1specimens and four in number for Type 2 specimens.5.5.2 Care shall be taken during handling and placing of theplied test specimen in the test fixture by keeping the circularfaces parallel and at right angles to the axis of the cylinder.5.5.3 The r
26、esults obtained on plied specimens may bedifferent from those obtained using solid specimens and theresults may be variable, particularly if air is trapped betweendisks.5.5.4 The results obtained on the specimens prepared by oneof the methods may be compared only to those prepared by thesame method.
27、5.6 For routine or product specification testing, it is some-times more convenient to prepare specimens of a different sizeor shape, or both. When such specimens are used, the resultsshould be compared only with those obtained from specimensof similar size and shape and not with those obtained withs
28、tandard specimen. For such cases, the product specificationshould define the specimen as to the size and shape. If suitablespecimens cannot be prepared from the product, the testmethod and allowable limits must be agreed upon between theproducer and the purchaser.6. Conditioning6.1 Store all vulcani
29、zed test specimens or product samplesto be tested at least 24 h but not more than 60 days. When thedate of vulcanization is not known, make tests within 60 daysafter delivery by the producer of the article represented by thespecimen.6.2 Allow buffed specimens to rest at least 30 min beforespecimens
30、are cut for testing.6.3 Condition all specimens before testing for a minimum of3hat236 2C (73.4 6 3.6F). Specimens whose compressionset properties are affected by atmospheric moisture shall beconditioned for a minimum of 24 h in an atmosphere controlledto 50 6 5 % relative humidity.7. Precision and
31、Bias47.1 These precision statements have been prepared in ac-cordance with Practice D 4483. Please refer to Practice D 4483for terminology and other testing and statistical concepts.7.2 Prepared test specimens of two rubbers for Test MethodsA and B were supplied to five laboratories. These were test
32、edin duplicate each day on two separate testing days.Atest result,therefore, is the average of two test specimens, for both TestMethods A and B.7.3 One laboratory did not run the Test Method A testing;therefore, the precision for Test Method A is derived from fourlaboratories.7.4 The Type 1 precisio
33、n results are given in Table 1 andTable 2.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D111138.TABLE 1 Type 1 Precision Results, % Compression SetTestMethod AMaterialMeanLevelWithin LaboratoryABetween LaboratoryASrr (r) SRR
34、(R)1 1.73 (%) 0.050 0.142 8.2 0.190 0.54 31.12 26.1 0.898 2.54 9.7 2.37 6.71 25.7ASr= within laboratory standard deviation.r = repeatability (in measurement units).(r) = repeatability (in percent).SR= between laboratory standard deviation.R = reproducibility (in measurement units).(R) = reproducibil
35、ity (in percent).D3950327.5 BiasIn test method statistical terminology, bias is thedifference between an average test value and the reference ortrue test property value. Reference values do not exist for thesetest methods since the value or level of the test property isexclusively defined by the tes
36、t method. Bias, therefore, cannotbe determined.TEST METHOD ACOMPRESSION SET UNDERCONSTANT FORCE IN AIR8. Apparatus8.1 Dial MicrometerA dial micrometer, for measuringspecimen thickness, in accordance with Practice 3767, MethodA1.8.2 Compression Device, consisting of a force applicationspring and two
37、parallel compression plates assembled bymeans of a frame or threaded bolt in such a manner that thedevice shall be portable and self-contained after the force hasbeen applied and that the parallelism of the plates shall bemaintained. The force may be applied in accordance with either8.2.1 or 8.2.2.8
38、.2.1 Calibrated Spring Force ApplicationThe requiredforce shall be applied by a screw mechanism for compressinga calibrated spring the proper amount. The spring shall be ofproperly heat-treated spring steel with ends ground and per-pendicular to the longitudinal axis of the spring. A suitablecompres
39、sion device is shown in Fig. 1. The spring shallconform to the following requirements:8.2.1.1 The spring shall be calibrated at room temperature23 6 5C (73.4 6 9F) by applying successive increments offorce not exceeding 250 N (50 lbf) and measuring thecorresponding deflection to the nearest 0.2 mm (
40、0.01 in.). Thecurve obtained by plotting the forces against the correspondingdeflections shall have a slope of 70 6 3.5 kN/m (400 6 20lbf/in.) at 1.8 kN (400 lbf). The slope is obtained by dividingthe two forces above and below 1.8 kN by the differencebetween the corresponding deflections.8.2.1.2 Th
41、e original dimensions of the spring shall notchange due to fatigue by more than 0.3 mm (0.01 in.) after ithas been mounted in the compression device, compressedunder a force of 1.8 kN (400 lbf), and heated in the oven forone week at 70C 6 2C (158 6 3.6F). In ordinary use, aweekly check of the dimens
42、ions shall show no greater changethan this over a period of 1 year.8.2.1.3 The minimum force required to close the spring(solid) shall be 2.4 kN (530 lbf).8.2.2 External Force ApplicationThe required force shallbe applied to the compression plates and spring by externalmeans after the test specimen
43、is mounted in the apparatus.Either a calibrated compression machine or known masses maybe used for force application. Provision shall be made by theuse of bolts and nuts or other devices to prevent the specimenand spring from losing their initial deflections when theexternal force is removed. The sp
44、ring shall have essentially thesame characteristics as described in 8.2.1, but calibration is notrequired. A suitable compression device is shown in Fig. 2.8.3 PlatesThe plates between which the test specimen iscompressed shall be made of steel of sufficient thickness towithstand the compressive str
45、esses without bending.8.3.1 The surfaces against which the specimen is held shallhave a chromium plated finish and shall be cleaned thoroughlyand wiped dry before each test.8.3.2 The steel surfaces contacting the rubber specimensshall be ground to a maximum roughness of 250 m (10 in.)and then chromi
46、um plated and polished.8.3.3 The chromium plating and subsequent polishing shallnot affect the final finish beyond the tolerance stated in 8.3.2.NOTE 3The specifications regarding the surface roughness (smooth-ness) of the contact surfaces of the plates is to be considered only at thetime of manufac
47、ture or refurbishing as it is not a property that is easilydetermined in the course of routine use. The suitability for the use of thedevice is to be determined by the user.8.4 Oven, conforming to the specification for a Type IIBlaboratory oven given in Specification E 145.TABLE 2 Type 1 Precision R
48、esults, % Compression SetTestMethod BMaterialMeanLevelWithin LaboratoryABetween LaboratoryASrr (r) SRR (R)1 13.7 (%) 0.591 1.67 12.2 1.54 4.36 31.82 52.8 0.567 1.60 3.0 5.92 16.8 31.7ASr= within laboratory standard deviation.r = repeatability (in measurement units).(r) = repeatability (in percent).S
49、R= between laboratory standard deviation.R = reproducibility (in measurement units).(R) = reproducibility (in percent).FIG. 1 Device for Compression Set Test, Using Calibrated SpringLoading, Test Method AD3950338.4.1 Type IIB ovens specified in Test Method E 145 aresatisfactory for use through 70 C. For higher TemperaturesType II A ovens are necessary.8.4.2 The interior size shall be as follows or of an equivalentvolume:Interior size of air oven:min. 300 bt 300 mm by 300 mm (12 by 12 by 12in.)max. 900 by 900 by 1200 mm (36 by 36 by 48 in.)8.4.3 Provision
