1、Designation: D 395 03 (Reapproved 2008)Standard 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
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 intende
3、dfor use in applications 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 Con
4、stant Force in Air 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 s
5、hall be used.1.3 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
6、 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1349 Practice for RubberStandard Temperatures forTestingD 3182 Practice for RubberMaterials, Equipment, andProcedures f
7、or Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsD 3183 Practice for RubberPreparation of Product Piecesfor Test Purposes from ProductsD 3767 Practice for RubberMeasurement of DimensionsD 4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Bl
8、ack ManufacturingIndustriesE 145 Specification for Gravity-Convection and Forced-Ventilation Ovens3. 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 r
9、esidual deformation of a test 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 spe
10、cified in the appropriate test 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
11、 the maintenance of a definite 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
12、closely by compression flexing 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 duplicat
13、e(Option 1) or triplicate (Option 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
14、 test specimen shall be a cylindrical diskcut from a laboratory prepared slab.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 May 1, 2008. Published June 2008. Originall
15、yapproved in 1934. Last previous edition approved in 2003 as D 395 03.2For 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
16、 website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2.1 The dimensions of the standard specimens shall be: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
17、 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 the required inside dimensions specified in 5.2.1 shallbe rotated in a drill press or similar device and lubricated bymeans o
18、f 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 aspossible to minimize cupping of the cut edges. The dies shallbe maintained carefully so that the cutting edges are sharp
19、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 specified in5.2.1.NOTE 1It should be recognized that an equal time and temperature, ifused for both the slab and molded sp
20、ecimen, 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 time of cure, must be taken into consideration if comparisons betweenthe specimens prepared by different methods are to be c
21、onsidered 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 compensated 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
22、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 0.012 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
23、 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 reduced first by cutting transversely with a sharp knifeand then followed by buffing to the required thickness inaccordance
24、 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 using the specimen sizesspecified in 5.2.1 and cutting as described in 5.2.2, or where adrill press is not available cutting th
25、e 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 uniformthickness, and shall not exceed seven in number for Type 1specimens and four in number for Type 2 specimens.5.5.2 Care shall be
26、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 results obtained on plied specimens may bedifferent from those obtained using solid specimens and theresults may be variable
27、, 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.5.6 For routine or product specification testing, it is some-times more convenient to prepare specimens of a different size
28、or 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 withstandard specimen. For such cases, the product specificationshould define the specimen as to the size and shape. If suitable
29、specimens 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 vulcanized test specimens or product samplesto be tested at least 24 h but not more than 60 days. When thedate of vulcanization is
30、 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 are cut for testing.6.3 Condition all specimens before testing for a minimum of3hat236 2C (73.4 6 3.6F). Specimens whose co
31、mpressionset 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 Bias37.1 These precision statements have been prepared in ac-cordance with Practice D 4483. Please refer to Practice D 4483
32、for 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 testedin duplicate each day on two separate testing days.Atest result,therefore, is the average of two test specimens, for both
33、 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 precision results are given in Table 1 andTable 2.3Supporting data have been filed at ASTM International Headquarters and maybe obt
34、ained by requesting Research Report RR: D111138.TABLE 1 Type 1 Precision Results, % Compression SetTestMethod AMaterialMeanLevelWithin LaboratoryABetween LaboratoryASrr (r) SRR (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.
35、r = repeatability (in measurement units).(r) = repeatability (in percent).SR= between laboratory standard deviation.R = reproducibility (in measurement units).(R) = reproducibility (in percent).D 395 03 (2008)27.5 BiasIn test method statistical terminology, bias is thedifference between an average t
36、est 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 test method. Bias, therefore, cannotbe determined.TEST METHOD ACOMPRESSION SET UNDERCONSTANT FORCE IN AIR8. Apparatus
37、8.1 Dial MicrometerA dial micrometer, for measuringspecimen thickness, in accordance with Practice 3767, MethodA1.8.2 Compression Device, consisting of a force applicationspring and two parallel compression plates assembled bymeans of a frame or threaded bolt in such a manner that thedevice shall be
38、 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 8.2.2.8.2.1 Calibrated Spring Force ApplicationThe requiredforce shall be applied by a screw mechanism for compressinga c
39、alibrated 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 suitablecompression device is shown in Fig. 1. The spring shallconform to the following requirements:8.2.1.1 The spring shall be
40、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 (0.01 in.). Thecurve obtained by plotting the forces against the correspondingdeflections shall have a slope of 70
41、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 The original dimensions of the spring shall notchange due to fatigue by more than 0.3 mm (0.01 in.) after ithas been
42、 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 dimensions shall show no greater changethan this over a period of 1 year.8.2.1.3 The minimum force required to close the
43、 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 is mounted in the apparatus.Either a calibrated compression machine or known masses maybe used for force applicati
44、on. 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 spring shall have essentially thesame characteristics as described in 8.2.1, but calibration is notrequired. A suita
45、ble 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 stresses without bending.8.3.1 The surfaces against which the specimen is held shallhave a chromium plated finish and
46、 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 chromium plated and polished.8.3.3 The chromium plating and subsequent polishing shallnot affect the final finish beyond
47、 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 manufacture or refurbishing as it is not a property that is easilydetermined in the course of routine use. The suitabilit
48、y 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 Results, % Compression SetTestMethod BMaterialMeanLevelWithin LaboratoryABetween LaboratoryASrr (r) SRR (R)1 13.7 (
49、%) 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).SR= 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 AD 395 03 (2008)38.4.1 Type IIB ovens specified in Specification E 145 aresatisfactory for use through 70 C. For higher TemperaturesType II A ovens are necessary.8.4.2
