Mechanical processing preparation method of plastic sample

日期:2019/11/26 9:12:36 / 阅读: / 来源:本站

Mechanical processing preparation method of plastic sample
In order to determine the performance of plastic plates, sheets, films, rods and other products, sample blocks are cut from these products and standard samples are prepared by mechanical processing.
There are many items for plastic performance testing, and many types of samples are used for testing. However, the preparation methods of each sample are different from each other. When comparing the different properties of the same material, the problem of the influence of the preparation conditions of the sample on the performance arises. For this reason, it should be prepared according to the standard of "GB / T 11997-2008 Plastic Multipurpose Sample". Multi-purpose samples prepared according to such standards can be used for a variety of performance tests directly or through simple machining. Its main advantage is that all the samples of various tests are prepared by the same molding conditions, which eliminates the effect of sample preparation conditions on the test results. The multi-purpose sample is suitable for measuring various mechanical properties and thermal properties. Sample size
This standard stipulates that both type A and type B samples are tensile samples, and other simple test samples can be obtained by simple machining. Because of its wide range of uses, this standard also refers to tensile samples as multipurpose samples.
The length of the parallel part of the narrow part of the A-type tensile specimen recommended for this standard for multi-purpose specimens is
(80 ± 2) mm, can be easily cut into samples suitable for other tests. Sample preparation
In order to ensure that the actual state of all the samples in a group of tests is the same, the sample preparation conditions should be strictly controlled. The surface of the test specimen shall be free of cracks, scratches and other defects.
When a multi-purpose sample is processed into a test sample, the sample is machined from a test piece molded by injection molding or compression molding according to ISO 2818-1994. The following points must be noted:
1. The middle surface of the specimen shall be kept in the original standard condition.
2. Specimens with a width of 10 mm shall be cut symmetrically from the middle parallel part of the multi-purpose specimen.
The surface of the middle parallel part of the sample should be kept in a molded state: the width of the machined part of the sample should not be less than the width of the middle parallel part of the sample, but it should not exceed the width of the latter by at most 0.2mm; Any damage to the molding surface of the middle part of the sample.
3. For specimens longer than 80mm, the wide end of A-type multipurpose specimens (or B-type specimens longer than 60mm) shall be machined to the width of the middle parallel portion.


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