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This article will continue to provide suggestions on the reliability test sequence：
Factors to consider in the order of test projects：
Under normal circumstances, because the future use, transportation and storage of the product are very complex, it is often impossible to proceed in a predetermined order. It will often be in these three states repeatedly, which means that the order of the environments it will encounter in the future cannot be fixed. of. Therefore, in most cases it is impossible to arrange the reliability test items in the order of actual use. Instead, we must start from the purpose of the test and based on the principles mentioned above, further consider the characteristics of each test item and their possible mutual influence and other factors, to select the order of reliability test items. The following is a brief analysis of the characteristics and impacts of each reliability test item, and suggestions for sequence arrangement are made as much as possible.
1. Low pressure test →(Low pressure test chamber)
Under normal circumstances, low pressure tests should be conducted before other environmental tests, that is, environmental tests start with low pressure. The reason is that low air pressure is less damaging to the test sample, and if damage occurs, it usually occurs early in the life cycle. However, when other environmental tests on the test sample will have a great impact on the low-pressure test results, the low-pressure test should be performed after these tests. These tests and effects are: high and low temperature tests affect the sealing effect, dynamic tests affect the structural integrity of the test samples, and solar radiation tests cause non-metal parts to age and reduce their strength. If low-pressure testing is performed after these tests, the harmful effects will be further magnified.
2. Hot and cold shock test → (Hot and cold shock test chamber)
The impact of hot and cold shock tests on products is mainly manifested in material crushing, separation of components, bonding or slowing down of moving parts, electronic or mechanical failures caused by rapid condensation and frost, cracking of surface coatings, leakage of sealing parts, etc. . The upper and lower limits of the thermal shock test often use the upper and lower limits of the high and low temperature storage tests, so the temperature response characteristics of the test sample obtained in the high and low temperature storage tests can be used in the thermal shock test. Therefore, the thermal shock test is generally arranged after the high and low temperature storage tests.
3. Solar radiation test (light test) → (Xenon lamp aging test chamber)
Solar radiation tests are usually performed at any point in the test sequence. However, it should be noted that high temperature and photochemical effects may affect the strength and size of the material, thereby affecting the results of subsequent kinetic tests (such as vibration tests).
4. Waterproof test → (Rain test chamber)
Waterproofing tests are generally performed in any sequence, but if performed after kinetic testing this can be more effectively used to determine the structural integrity of the test sample enclosure. In order to prevent the dust and other debris on the product after the dust-proof test from affecting the circulating water filtration effect of the waterproof test chamber, the waterproof test should be done first and then the dust-proof test.
5. Dust proof test → (Sand and dust test chamber)
Because dust coating and severe abrasion will occur on the test samples after the dust proof test: on the other hand, the coexistence of dust and other environmental parameters such as temperature and humidity can cause corrosion and mold growth. Warm and moist environments can cause corrosion in the presence of chemically aggressive dust. This will affect the results of damp heat, mold and salt spray tests.
6. Salt spray test → (Salt spray test chamber)
If the same test sample is used for multiple climatic tests, in most cases the salt spray test should be performed after the other climatic tests. Because salt deposition can be potentially damaging and interfere with other tests. If the same test sample is required to be tested for dust resistance, the dust resistance test shall be carried out after the salt spray test.
Implementation recommendations
1) When using the same test sample to conduct two or more test items in sequence, different arrangements of the order of the test items will often result in different test results. This is because the stress exerted by the latter test item may accelerate the damage caused by the defects caused by the stress in the previous test, or the test medium inevitably remains on the surface or inside the test sample after the previous test item. Will aggravate or inhibit the destructive effect of the stress exerted by the latter test item. Jiayu Testing Network believes that different test project sequences will generally bring different test results. Therefore, attention should be paid to the reasonable arrangement and consistency of the sequence of test items to ensure the authenticity, representativeness and comparability of test results.
2) When the same test sample is used to conduct multiple test procedures for the same test item, the sequence of the test procedures should also be arranged reasonably. In principle, the test procedure with the least possibility of damage to the test sample is carried out first to ensure that the same test sample is used to complete multiple specified test procedures. For example, if the same test sample is used to perform the three test procedures of dust reduction, dust blowing and sand blowing in the dust proof test, the dust reduction test procedure should be performed first, then the dust blowing test procedure, and finally the sand blowing test procedure.
3) In order to ensure the consistency of the sequence of test items and test procedures, it is recommended that when stipulating test items and corresponding test conditions and test procedures in the finished product agreement or technical conditions, it should also be clear that the same test items should be used in the design finalization qualification test and batch production test. The product undergoes these test items and the order in which the test procedures are implemented. If it is not clear yet, it should be supplemented and confirmed by relevant experts and confirmation by relevant departments before conducting the test. The test schedule in the reliability development test can be determined by the developer himself.
4) The compliance inspection of environmental requirements has more specific and comprehensive requirements. Currently, many product design reviews only submit the results of various individual tests, which is not enough to fully demonstrate that the reliability of the developed product meets the technical requirements. With the in-depth development of product reliability requirements and reliability testing, a general report on compliance with reliability requirements should be prepared based on the implementation of reliability testing, test results, and the reliability requirements stipulated in technical conditions. The evaluation of compliance in the general report should be based on the detailed test report for each test item, the grouping of test samples, the reliability test items and procedures of each group of test samples, the status of the test equipment, the test unit and the test Comprehensive evaluation of personnel qualifications and levels.
5) The sensitivity of the product to the application of comprehensive conditions should be considered, for example, mixed testing of high temperature testing and vibration. Comprehensive testing can more realistically reproduce environmental effects than single testing. When the comprehensive conditions are acceptable in the operating environment, comprehensive environmental tests should be used as much as possible. By conducting a comprehensive test, failures may occur that do not exist under a single condition. The use of IEC60721-4 When appropriate, comprehensive testing can be considered when formulating test procedures.