QC/T 709-2004 in English

Test method of compression set for automobile weatherstrips

1 Scope

This standard specifies the test method of compression set for automobile weatherstrips.

This standard is applicable to the test of compression set for automobile weatherstrips.

2 Normative references

The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this standard. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition applies.

GB/T 2941 Rubber - Standard temperatures, humidities and times for the conditioning environmental and testing of test pieces (eqv ISO 471: 1983)
GB/T 9868 Rubber - General directions for achieving elevated or subnormal temperatures for test purposes (idt ISO 3383: 1985)
GB/T 8170 Rules for rounding off of numerical values

3 Theory

Compress the weatherstrip test piece with a known height to a specified height according to the requirements for compression ratio, and hold it compressed at a specified temperature for a certain period of time, and then remove the compressive force at a standard temperature, and allow the test piece to recover gradually in a free state, then measure the height of it after recovery within the stated time. The ratio of the deformation that cannot be recovered after compression of the test piece to the maximum deformation when the test piece is compressed is taken as the result to indicate the deformation generated due to compression changes that prevent the material from recovering to its original state after the compression force is removed.

4 Apparatus and equipment
4.1 Drying oven

The drying oven shall meet relevant requirements of GB/T 9868, with the air as heat-transfer medium.
4.2 Height measuring instrument

The height measuring instrument shall have an accuracy of 0.02 mm.
4.3 Test device
4.3.1 The structure of the test device shall be designed according to the product structure. See Figure 1 for the schematic diagram of common structures.
4.3.2 The baseplate, the upper pressure plate and the limit sleeve shall be stainless steel plates or chrome-plated steel plates. The plate shall be large enough to ensure that the test piece does not contact the limit sleeve or exceed the upper pressure plate during the test.
4.3.3 Structure used to fix weatherstrips and the upper pressure plate shall be provided on the baseplate.
4.3.4 The surface roughness of the upper pressure plate shall be such that Ra is not more than 4 × 10-7 mm (0.4 μm), and the upper pressure plate shall have sufficient rigidity to ensure that the curvature of the pressure plate does not exceed 0.01 mm in case it is pressed.
4.3.5 The height tolerance between limit sleeves used for the same test piece shall be ±0.02mm, and the parallelism of the upper and lower end faces of each sleeve shall be less than 0.01mm.
4.3.6 The common fasteners are wing nuts.

Foreword i
1 Scope
2 Normative references
3 Theory
4 Apparatus and equipment
5 Test piece and conditioning
6 Test procedures
7 Representation of test results
8 Test report