1、Designation: D395 161Standard Test Methods forRubber PropertyCompression Set1This standard is issued under the fixed designation D395; 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 parenthes
2、es 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 U.S. Department of Defense.1NOTEEditorially corrected 1.1 in March 2017.1. Scope1.1 These test methods cove
3、r the testing of rubber intendedfor 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. Three test methods are covered asfollows:Test Method
4、SectionACompression Set Under Constant Force in Air 811BCompression Set Under Constant Deflection in Air 1215CCompression Set Under Constant Deflection in AirConsidering Material Hardness16211.2 The choice of test method is optional, but considerationshould be given to the nature of the service for
5、whichcorrelation of test results may be sought. Unless otherwisestated in a detailed specification, Test Method B shall 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
6、 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 regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1349
7、Practice for RubberStandard Conditions for Test-ingD3182 Practice for RubberMaterials, Equipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD3767 Practice for RubberMeasurement of
8、DimensionsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesE145 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 f
9、orce and maintained under this condition for aspecified time and at a specified temperature.3.2 The residual 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 s
10、pecified conditions.3.3 After the measurement of the residual deformation, thecompression set, as specified 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 elasti
11、c properties after pro-longed action of compressive stresses. The actual stressingservice may involve 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 d
12、ynamic stressing, likethe others, produces compression set, its effects as a whole aresimulated more closely by compression flexing or hysteresistests. Therefore, compression set tests are considered to bemainly applicable to service conditions involving staticstresses. Tests are frequently conducte
13、d at elevated tempera-tures.1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and Rubber-like Materials and are the direct responsibility of SubcommitteeD11.10 on Physical Testing.Current edition approved April 15, 2016. Published May 2016. Originallyapproved in 1934. Las
14、t previous edition approved in 2015 as D395 15. DOI:10.1520/D0395-16E01.2For 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 AS
15、TM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopme
16、nt of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15. Test Specimens5.1 Specimens from each sample may be tested in duplicate(Option 1) or triplicate (Option 2). The compression set of thesample in Option 1 sh
17、all 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 cylindrical diskcut from a laboratory prepared slab.5.2.1 T
18、he dimensions of the standard specimens shall be:Type 1A2BThickness, mm (in.) 12.5 0.5(0.49 0.02)6.00.2(0.24 0.01)Diameter, mm (in.) 29.0 0.5(1.14 0.02)13.0 0.2(0.51 0.01)AType 1 specimen is used in Test Methods A, B, and C.BType 2 specimen is used in Test Method B and C.5.2.2 When cutting the stand
19、ard 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 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.
20、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 andfree of nicks.5.3 An optional method of preparing the standard specimenmay be the direct molding of a circular disk having thedimension
21、s 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 specimen, will not produce anequivalent state of cure in the two types of specimen. A higher degree ofcure will be obtained in the molded sp
22、ecimen. Adjustments, preferably inthe time 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 t
23、he 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 6 0.002 in.) in diameter, with overflow grooves, will provideType 1 specimens for Test Method A and Test Method B. A similar moldbut havin
24、g a cavity of 6.3 6 0.3 mm (0.25 6 0.012 in.) in thickness and13.3 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
25、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 with Practice D3183.5.5 An alternative method of preparing specimens is byplying up cylindrical disks cut from a standard sheet preparedi
26、n accordance with Practice D3182 using 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 s
27、hall 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 taken during handling and placing of theplied test specimen in the test fixture by keeping the circularfaces parallel and at right angles to
28、 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, particularly if air is trapped betweendisks.5.5.4 The results obtained on the specimens prepared by oneof the methods may be compared only
29、 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 sizeor shape, or both. When such specimens are used, the resultsshould be compared only with those obtained from specimensof similar size and sh
30、ape and not with those obtained withstandard 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
31、.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 not known, make tests within 60 daysafter delivery by the producer of the article represented by thespecimen.6.2 Allow buffed specimens to
32、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 compressionset properties are affected by atmospheric moisture shall beconditioned for a minimum of 24 h in an atmosphere controlledto a relat
33、ive humidity of 50 6 10 %RH (40 to 60 %RH).7. Precision and Bias37.1 These precision statements have been prepared in ac-cordance with Practice D4483. Please refer to Practice D4483for terminology and other testing and statistical concepts.7.2 Prepared test specimens of two rubbers for Test MethodsA
34、 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 TestMethods A and B.7.3 One laboratory did not run the Test Method A testing;therefore, the precision for Test Method
35、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 obtained by requesting Research Report RR:D11-1138.D395 16127.5 BiasIn test method statistical terminology, bias is thedif
36、ference 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 test method. Bias, therefore, cannotbe determined.TEST METHOD ACOMPRESSION SET UNDERCONST
37、ANT FORCE IN AIR8. Apparatus8.1 MicrometerA micrometer, analog or digital, for mea-suring specimen thickness, in accordance with Practice D3767,Method A1.8.2 Compression Device, consisting of a force applicationspring and two parallel compression plates assembled bymeans of a frame or threaded bolt
38、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 8.2.2.8.2.1 Calibrated Spring Force ApplicationThe requiredforce shall be applied
39、 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 suitablecompression device is shown in Fig. 1. The spring shallconform to the following r
40、equirements: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 (0.01 in.). Thecurve obtained by plotting the forces against the correspond
41、ingdeflections 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 The original dimensions of the spring shall notchange due to fatigue by more
42、 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 70 6 2C (158 6 3.6F). In ordinary use, a weeklycheck of the dimensions shall show no greater change than thisover a period of 1 year.8.2.1.3
43、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 is mounted in the apparatus.Either a calibrated compression machine or know
44、n 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 spring shall have essentially thesame characteristics as described in 8.2.1,
45、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 stresses without bending.8.3.1 The surfaces against which the specimen is held
46、 shallhave an industrial chrome (hard chrome) plated finish and shallbe cleaned thoroughly and wiped dry before each test.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
47、.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) = reproducibility (in percent).TABLE 2 Type 1 Precision Results
48、, % 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).SR= bet
49、ween laboratory standard deviation.R = reproducibility (in measurement units).(R) = reproducibility (in percent).FIG. 1 Device for Compression Set Test, Using Calibrated SpringLoading, Test Method AD395 16138.3.2 The steel surfaces contacting the rubber specimensshall be ground to a maximum roughness of 0.250 m (10in.), polished, and industrial chrome (hard chrome) plated.8.3.3 The polishing and subsequent industrial chrome (hardchrome) plating shall not affect the final finish beyond thetolerance stated in 8.3.2.NOTE 3The specific
