1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW14293 Determination of the Compressibility of a Cellular Elastomer Under a Specified Force Copyright 2012 General Motors Company All Rights Reserved May 2012 Originating Department: North American Engineering Standards Page 1 of 4 1 Scope Note: Noth
2、ing in this standard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. The object of this test procedure is the determination of the compressibility of a cellular elastomer, u
3、sed as a seal or shock absorber, under a specified force. The force used in the test is analogous to that exerted on the elastomer in service. The compressibility of a cellular elastomer under a given force acting in a specified direction shall be the relative or absolute distance by which the test
4、piece is deflected in that direction. 1.1.1 Summary of Test Procedure. The compressibility of a cellular elastomeric component at a given force shall be defined as the deflection obtained following compression at a uniform given velocity. 1.2 Foreword. Not applicable. 1.3 Applicability. Not applicab
5、le. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ISO 7500-1 ISO 9513 2.2 GM Standards/Specifications. GMW16676 3 Resources 3.1 Facilities. Not applicable. 3.2 Equipment. 3.2.1 Test Equipment. 3.2.1.1 Testing M
6、achine. The test machine shall fulfill the following requirements: The force measuring device of the test machine shall correspond to ISO 7500-1 Class 1; the he deflection measuring device shall correspond to ISO 9513 Class 0.2. The test machine shall be such that the test piece can be compressed be
7、tween its holder and a pressure foot in a vertical direction. Pieces shall be tested at a uniform rate of 0.5 mm/s (30 3 mm/minute). Other test velocities must have been agreed upon and stated on the respective drawing or math data file and test report. 3.2.1.2 Pressure Foot. Two (2) types of pressu
8、re foot are available, and shall be specified as: 3.2.1.2.1 Coding A. Circular with 60 1 mm diameter. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING
9、STANDARDS GMW14293 Copyright 2012 General Motors Company All Rights Reserved May 2012 Page 2 of 4 3.2.1.2.2 Coding B. Square, with 100 1 mm length. The pressure surface shall be plane and smooth in both types. Unless otherwise stated, the finish of the pressure foot shall be as follows: Ra = 0.03 m.
10、 Rz1max = 0.3 m. Surface finish shall be measured according to GMW16676. 3.2.1.3 Test Piece Support. The test piece support shall be horizontal and coplanar to the pressure foot and larger in dimensions than the respective pressure foot. The supporting table shall contain ventilation holes ( 6 mm in
11、 diameter) spaced in regular intervals ( 20 mm from hole center to hole center) so that air can escape rapidly during the test. Alternative test piece supports may be used if called upon the relevant part drawing or math data file. 3.3 Test Vehicle/Test Piece. 3.3.1 Test Material. 3.3.1.1 The test p
12、iece shall consist of a complete component, or a suitable part of it. The length of the test piece shall, if possible, be longer than the width of the pressure foot. Components of a length less than the width of the pressure foot shall be tested across their entire length. 3.3.1.2 For initial sample
13、 approval and arbitration purposes, at least five test pieces taken from at least two components shall be tested; for routine quality control purposes at least three test pieces, preferably taken from two components, shall be tested. 3.4 Test Time. Not applicable. 3.5 Test Required Information. Not
14、applicable. 3.6 Personnel/Skills. Not applicable. 4 Procedure 4.1 Preparation. 4.1.1 Test Sample Preparation. The minimum time period between vulcanization and testing of elastomers shall be 72 h. The test piece shall remain at a temperature of 23 C 5 C for at least 8 h before testing, and shall be
15、free from strain during this period. Humidity controls, if necessary, shall be specified on the relevant part drawing or math data file and on the test report. 4.2 Conditions. 4.2.1 Environmental Conditions. Not applicable. 4.2.2 Test Conditions. Deviations from the requirements of this standard sha
16、ll have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc. 4.3 Instructions. 4.3.1 Test Procedure. 4.3.1.1 The test shall be performed at a temperature of 23 C 5 C. Testing at other temperatures must have been agreed upon and stated on the
17、respective drawing or math data file and the test report. 4.3.1.2 Mount the pressure foot to the test machine and set the force to zero. The pressure foot shall be gently lowered so as to contact the test piece support under a force of 2 0.1 N and the device for measuring the deflection shall be set
18、 to zero. 4.3.1.3 Raise the pressure foot. The test piece shall then be placed on the test piece support with its midpoint centered to the pressure foot. It shall be placed upon the support such that the force is applied in the specified direction, as indicated on the relevant part drawing. In case
19、of components of axial symmetry, this indication is not necessary. 4.3.1.4 The pressure foot shall again be gently lowered to contact the test piece with a force of 2 0.1 N and the height of the test piece determined to the nearest 0.1 mm (h0). Record the initial height of the test piece. 4.3.1.5 Th
20、e force is then increased by 18 0.9 N (giving a total force of 20 1.0 N). Alternative loads may be used if specified on the relevant part drawing or math data file. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking p
21、ermitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14293 Copyright 2012 General Motors Company All Rights Reserved May 2012 Page 3 of 4 4.3.1.6 After obtaining the total force, the height of the test piece shall be determined immediately to the nearest 0.1 mm (h1). Record th
22、e final height of the test piece. 5 Data 5.1 Calculations. Not applicable. 5.2 Interpretation of Results. Not applicable. 5.3 Test Documentation. 5.3.1 Evaluation and Rating. There are two different procedures for evaluating the compressibility, and the pertinent procedure shall be indicated on the
23、relevant part drawing or math data file. 5.3.1.1 Evaluation Procedure 1. Determination of relative or percentage compression: C o m p r e s s io h hhr e ln Z in % 0 10 100 Where: h0 = initial height h1 = final height 5.3.1.2 Evaluation Procedure 2. Determination of absolute compression in millimeter
24、s (mm): C o m p r e s s io h habsn Z in m m 0 1 5.4 Report. Deviations from the requirements of this test standard (e.g., length of test piece, testing velocity, etc.) shall have been agreed upon. These requirements shall be specified on component drawings, and defined on test certificates, test rep
25、orts, etc. The compressibility of a cellular elastomer under a specified force shall be expressed as the range of values determined, with reference made to this test procedure. 5.4.1 Relative or percentage compression shall be rounded to the nearest whole number, and expressed as a percentage. Absol
26、ute compression shall be rounded to the nearest 0.1 mm, and expressed in millimeters (mm). Mean values for the sample set shall be reported. 5.4.2 The range of values determined shall be wholly within the tolerance range of values as specified on the relevant part drawing, and represent the producti
27、on variation found within the test pieces examined. 5.4.3 Report the following: specimen size, number of specimens tested, environmental conditions, location from which samples were taken (if cut from a part), pressure foot used, compressibility results, as well as any deviations to the test method.
28、 6 Safety This standard may involve hazardous materials, operations, and equipment. This standard does not propose to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the
29、applicability of regulatory limitations prior to use. 7 Notes 7.1 Glossary. Not applicable. 7.2 Acronyms, Abbreviations, and Symbols. Not applicable. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted withou
30、t license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14293 Copyright 2012 General Motors Company All Rights Reserved May 2012 Page 4 of 4 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Example: Compressibility to GMW14293 A1 - 15 to 25% Wher
31、e: Compressibility = Designation GMW14293 = Test Method A = Dimension of pressure foot to 3.2.1: circular with 60 mm diameter 1 = Evaluation Procedure 1 to paragraph 5.3.1.1: relative compression 15 to 25% = Requirement 9 Release and Revisions This standard was originated in September 2005. It was f
32、irst approved by the Global Elastomers Team in December 2006. It was first published in February 2007. Issue Publication Date Description (Organization) 1 FEB 2007 Initial publication. 2 MAY 2012 5 Year Refresh. (Elastomers Global Subsystem Leadership Team) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
