1. Reproducibility of environmental conditions
The material testing machine can completely and accurately reproduce the environmental conditions existing in nature in the laboratory. However, within a certain tolerance range, people can completely and accurately simulate the external environmental conditions experienced by engineering products during use, storage, and transportation. This paragraph is summarized in engineering language, that is, "The environmental conditions (including platform environment) created by the test equipment around the tested product should meet the environmental conditions and tolerance requirements specified in the product test specifications."
2. Repeatability of environmental conditions
An environmental test equipment may be used for multiple tests of the same type of product, and a tested engineering product may also be tested in different environmental test equipment, in order to ensure that the same product is in the environmental test specified by the same test specification The comparability of the test results obtained under the conditions inevitably requires the repeatability of the environmental conditions provided by the environmental test equipment. That is to say, the stress level (such as thermal stress, vibration stress, electrical stress, etc.) applied by the environmental test equipment to the tested product is consistent with the requirements of the same test specification. The repeatability of the environmental conditions provided by the environmental test equipment is guaranteed by the national metrological verification department in accordance with the verification procedures formulated by the national technical supervision agency. To this end, it must be required that the environmental test equipment can meet the requirements of various technical indicators and precision indicators in the verification regulations, and the use time should not exceed the time limit specified in the verification cycle. If the commonly used electric vibration table meets the technical indicators such as excitation force, frequency range, load capacity, etc., it must also meet the requirements of accuracy indexes such as lateral vibration ratio, table acceleration uniformity, harmonic distortion, etc. specified in the verification regulations And, the use period after each verification is two years, and more than two years must be re-verified before it can be put into use.
3. Measurability of environmental condition parameters
The environmental conditions provided by any environmental test equipment must be observable and controllable, not only to limit the environmental parameters to a certain tolerance range, but also to ensure the reproducibility and repeatability of the test conditions. Moreover, it is also necessary to proceed from the safety of product testing in order to prevent the uncontrolled environmental conditions from causing damage to the tested product and causing unnecessary losses. At present, various test specifications generally require that the accuracy of the parameter test should not be less than one-third of the error allowed by the test conditions.
4. Exclusiveness of environmental test conditions
Every time an environmental or reliability test is conducted, there are strict regulations on the types, values ​​and tolerances of environmental factors, and the non-tested environmental factors are excluded from penetration, so as to judge and analyze the product failure during or after the test It provides accurate basis for the failure mode, so it is required that the environmental test equipment should not add other environmental stress interference to the tested product in addition to the specified environmental conditions. The magnetic flux leakage of the table, the acceleration signal-to-noise ratio, and the ratio of the total rms value of the acceleration in and out of the band as defined in the electric vibration table verification regulations. Accuracy indicators such as random signal inspection and harmonic distortion are all verification items formulated to ensure the uniqueness of environmental test conditions.
5. Safety and reliability of test equipment
Environmental testing, especially reliability testing, has a long test period. The test object is sometimes a high-value military product. During the test, the test personnel often have to conduct patrols or test work around the site, so the environmental test equipment must be operational Safety, easy operation, reliable use, long working life and other characteristics to ensure the normal conduct of the test itself. The various protection, warning measures and safety interlocking devices of the test equipment should be perfect and reliable to ensure the safety and reliability of the test personnel, the tested product and the test equipment itself.
Vacuum Forming Machine is a simplified version of thermoforming, where a sheet of plastic is heated to a forming temperature, stretched onto a single-surface mold, and forced against the mold by a vacuum. This process can be used to form plastic into permanent objects such as turnpike signs and protective covers. Normally draft angles are present in the design of the mold (a recommended minimum of 3°) to ease removal of the formed plastic part from the mold.
Vacuum Forming Machine
Vacuum Forming Machine,Manual Vacuum Forming Machine,Thick Plastic Sheet Vacuum Forming Machine,Semi Automatic Blister Forming Machine
Hangzhou Xiaoshan Wanfeng Mechanical & Electrical Equipment Factory , https://www.wanfengmachinery.com