1、Designation: D395 14D395 15Standard 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 par
2、entheses 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.1. Scope1.1 These test methods cover the testing of rubber intended for us
3、e in applications in which the rubber will be subjected tocompressive stresses in air or liquid media. They are applicable particularly to the rubber used in machinery mountings, vibrationdampers, and seals. Two test methods are covered as follows:Test Method SectionACompression Set Under Constant F
4、orce in Air 710BCompression Set Under Constant Deflection in Air 11141.2 The choice of test method is optional, but consideration should be given to the nature of the service for which correlationof test results may be sought. Unless otherwise stated in a detailed specification, Test Method B shall
5、be used.1.3 Test Method B is not suitable for vulcanizates harder than 90 IRHD.1.4 The values stated in SI units are to be regarded as the standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this s
6、tandard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1349 Practice for RubberStandard Conditions for TestingD3182 Practice for RubberMaterials, Equipment, and Procedures for Mixi
7、ng Standard Compounds and Preparing StandardVulcanized SheetsD3183 Practice for RubberPreparation of Pieces for Test Purposes from ProductsD3767 Practice for RubberMeasurement of DimensionsD4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing
8、IndustriesE145 Specification for Gravity-Convection and Forced-Ventilation Ovens3. Summary of Test Methods3.1 A test specimen is compressed to either a deflection or by a specified force and maintained under this condition for aspecified time and at a specified temperature.3.2 The residual deformati
9、on of a test specimen is measured 30 min after removal from a suitable compression device in whichthe specimen had been subjected for a definite time to compressive deformation under specified conditions.3.3 After the measurement of the residual deformation, the compression set, as specified in the
10、appropriate test method, iscalculated according to Eq 1 and Eq 2.4. Significance and Use4.1 Compression set tests are intended to measure the ability of rubber compounds to retain elastic properties after prolongedaction of compressive stresses. The actual stressing service may involve the maintenan
11、ce of a definite deflection, the constant1 These test methods are under the jurisdiction of ASTM Committee D11 on Rubber and are the direct responsibility of Subcommittee D11.10 on Physical Testing.Current edition approved July 1, 2014Aug. 1, 2015. Published August 2014May 2016. Originally approved
12、in 1934. Last previous edition approved in 20082014 asD395 03 (2008).D395 14. DOI: 10.1520/D0395-14.10.1520/D0395-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to
13、the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes
14、accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United
15、 States1application of a known force, or the rapidly repeated deformation and recovery resulting from intermittent compressive forces.Though the latter dynamic stressing, like the others, produces compression set, its effects as a whole are simulated more closelyby compression flexing or hysteresis
16、tests. Therefore, compression set tests are considered to be mainly applicable to serviceconditions involving static stresses. Tests are frequently conducted at elevated temperatures.5. Test Specimens5.1 Specimens from each sample may be tested in duplicate (Option 1) or triplicate (Option 2). The c
17、ompression set of thesample in Option 1 shall be the average of the two specimens expressed as a percentage. The compression set of the sample inOption 2 shall be the median (middle most value) of the three specimens expressed as a percentage.5.2 The standard test specimen shall be a cylindrical dis
18、k cut from a laboratory prepared slab.5.2.1 The dimensions of the standard specimens shall be:Type 1A 2BThickness, mm (in.) 12.5 0.5(0.49 0.02)6.0 0.2(0.24 0.01)Diameter, mm (in.) 29.0 0.5(1.14 0.02)13.0 0.2(0.51 0.01)A Type 1 specimen is used in Test Methods A A, B, and B.C.B Type 2 specimen is use
19、d in Test Method B.B and C.5.2.2 When cutting the standard specimen, the circular die having the required inside dimensions specified in 5.2.1 shall berotated in a drill press or similar device and lubricated by means of a soap solution.Aminimum distance of 13 mm (0.51 in.) shallbe maintained betwee
20、n the cutting edge of the die and the edge of the slab. The cutting pressure shall be as light as possible tominimize cupping of the cut edges. The dies shall be maintained carefully so that the cutting edges are sharp and free of nicks.5.3 An optional method of preparing the standard specimen may b
21、e the direct molding of a circular disk having the dimensionsrequired for the test method used and specified in 5.2.1.NOTE 1It should be recognized that an equal time and temperature, if used for both the slab and molded specimen, will not produce an equivalentstate of cure in the two types of speci
22、men. A higher degree of cure will be obtained in the molded specimen. Adjustments, preferably in the time of cure,must be taken into consideration if comparisons between the specimens prepared by different methods are to be considered valid.NOTE 2It is suggested, for the purpose of uniformity and cl
23、oser tolerances in the molded specimen, that the dimensions of the mold be specified andshrinkage compensated for therein.Atwo-plate mold with a cavity 13.0 6 0.1 mm (0.510 6 0.004 in.) in thickness and 29.20 6 0.05 mm (1.148 6 0.002in.) in diameter, with overflow grooves, will provide Type 1 specim
24、ens for Test Method A and Test Method B. A similar mold but having a cavity of 6.36 0.3 mm (0.25 6 0.012 in.) in thickness and 13.213.3 6 0.1 mm (0.52 6 0.004 in.) in diameter will provide Type 2 specimens for Test Method B.5.4 When the standard test specimen is to be replaced by a specimen taken fr
25、om a vulcanized rubber part of greater thicknessthan the one indicated in 5.2.1, the sample thickness shall be reduced first by cutting transversely with a sharp knife and thenfollowed by buffing to the required thickness in accordance with Practice D3183.5.5 An alternative method of preparing speci
26、mens is by plying up cylindrical disks cut from a standard sheet prepared inaccordance with Practice D3182 using the specimen sizes specified in 5.2.1 and cutting as described in 5.2.2, or where a drill pressis not available cutting the specimens with a single stroke from a cutting die.5.5.1 The dis
27、ks shall be plied, without cementing, to the thickness required. Such plies shall be smooth, flat, of uniformthickness, and shall not exceed seven in number for Type 1 specimens and four in number for Type 2 specimens.5.5.2 Care shall be taken during handling and placing of the plied test specimen i
28、n the test fixture by keeping the circular facesparallel and at right angles to the axis of the cylinder.5.5.3 The results obtained on plied specimens may be different from those obtained using solid specimens and the results maybe variable, particularly if air is trapped between disks.TABLE 1 Type
29、1 Precision Results, % Compression SetTestMethod AMaterial MeanLevel Within LaboratoryA Between LaboratoryASr r (r) SR R (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 25.7A Sr = within laboratory standard deviation.r = repeatability (in measurement units).(r) = repeata
30、bility (in percent).SR = between laboratory standard deviation.R = reproducibility (in measurement units).(R) = reproducibility (in percent).D395 1525.5.4 The results obtained on the specimens prepared by one of the methods may be compared only to those prepared by thesame method.5.6 For routine or
31、product specification testing, it is sometimes more convenient to prepare specimens of a different size orshape, or both. When such specimens are used, the results should be compared only with those obtained from specimens of similarsize and shape and not with those obtained with standard specimen.
32、For such cases, the product specification should define thespecimen as to the size and shape. If suitable specimens cannot be prepared from the product, the test method and allowable limitsmust be agreed upon between the producer and the purchaser.6. Conditioning6.1 Store all vulcanized test specime
33、ns or product samples to be tested at least 24 h but not more than 60 days. When the dateof vulcanization is not known, make tests within 60 days after delivery by the producer of the article represented by the specimen.6.2 Allow buffed specimens to rest at least 30 min before specimens are cut for
34、testing.6.3 Condition all specimens before testing for a minimum of 3 h at 23 6 2C (73.4 6 3.6F). Specimens whose compressionset properties are affected by atmospheric moisture shall be conditioned for a minimum of 24 h in an atmosphere controlled to arelative humidity of 50 6 10 %RH (40 to 60 %RH).
35、7. Precision and Bias37.1 These precision statements have been prepared in accordance with Practice D4483. Please refer to Practice D4483 forterminology and other testing and statistical concepts.7.2 Prepared test specimens of two rubbers for Test Methods A and B were supplied to five laboratories.
36、These were tested induplicate each day on two separate testing days.Atest result, therefore, is the average of two test specimens, for both Test MethodsA 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 Th
37、e Type 1 precision results are given in Table 1 and Table 2.7.5 BiasIn test method statistical terminology, bias is the difference between an average test value and the reference or truetest property value. Reference values do not exist for these test methods since the value or level of the test pro
38、perty is exclusivelydefined by the test method. Bias, therefore, cannot be determined.TEST METHOD ACOMPRESSION SET UNDERCONSTANT FORCE IN AIR8. Apparatus8.1 MicrometerA micrometer, analog or digital, for measuring specimen thickness, in accordance with Practice D3767,Method A1.8.2 Compression Device
39、, consisting of a force application spring and two parallel compression plates assembled by means ofa frame or threaded bolt in such a manner that the device shall be portable and self-contained after the force has been applied andthat the parallelism of the plates shall be maintained. The force may
40、 be applied in accordance with either 8.2.1 or 8.2.2.8.2.1 Calibrated Spring Force ApplicationThe required force shall be applied by a screw mechanism for compressing acalibrated spring the proper amount. The spring shall be of properly heat-treated spring steel with ends ground and perpendicularto
41、the longitudinal axis of the spring. A suitable compression device is shown in Fig. 1. The spring shall conform to the followingrequirements:3 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D11-1138.TABLE 2 Type 1 Precision Res
42、ults, % Compression SetTestMethod BMaterial MeanLevel Within LaboratoryA Between LaboratoryASr r (r) SR R (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 31.7A Sr = within laboratory standard deviation.r = repeatability (in measurement units).(r) = repeatability (in perce
43、nt).SR = between laboratory standard deviation.R = reproducibility (in measurement units).(R) = reproducibility (in percent).D395 1538.2.1.1 The spring shall be calibrated at room temperature 23 6 5C (73.4 6 9F) by applying successive increments of forcenot exceeding 250 N (50 lbf) and measuring the
44、 corresponding deflection to the nearest 0.2 mm (0.01 in.). The curve obtained byplotting the forces against the corresponding deflections shall have a slope of 70 6 3.5 kN/m (400 6 20 lbf/in.) at 1.8 kN (400lbf). The slope is obtained by dividing the two forces above and below 1.8 kN by the differe
45、nce between the correspondingdeflections.8.2.1.2 The original dimensions of the spring shall not change due to fatigue by more than 0.3 mm (0.01 in.) after it has beenmounted in the compression device, compressed under a force of 1.8 kN (400 lbf), and heated in the oven for one week at 70C6 2C (158
46、6 3.6F). In ordinary use, a weekly check of the dimensions shall show no greater change than this over a period of1 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 shall be applied to the compression pla
47、tes and spring by external meansafter the test specimen is mounted in the apparatus. Either a calibrated compression machine or known masses may be used forforce application. Provision shall be made by the use of bolts and nuts or other devices to prevent the specimen and spring fromlosing their ini
48、tial deflections when the external force is removed. The spring shall have essentially the same characteristics asdescribed in 8.2.1, but calibration is not required. A suitable compression device is shown in Fig. 2.8.3 PlatesThe plates between which the test specimen is compressed shall be made of
49、steel of sufficient thickness to withstandthe compressive stresses without bending.8.3.1 The surfaces against which the specimen is held shall have a chromium plated finish and shall be cleaned thoroughly andwiped dry before each test.8.3.2 The steel surfaces contacting the rubber specimens shall be ground to a maximum roughness of 0.250 m (10 in.),polished, and chromium plated.8.3.3 The polishing and subsequent chromium plating shall not affect the final finish beyond the tolerance stated in 8.3.2.NOTE 3The specifications regarding
