Air tightness testerApplications of devices in the automotive electronics industry

Auto parts companies' process requirements for automotive connector sealing testing can be summarized as follows:

1. Sealing test: It is required to test the sealing of the connector under vacuum or positive pressure. Generally, it is required to use a clamp to seal the product under positive pressure or negative pressure of 10kpa to 50kpa and then conduct air tightness testing.The leakage rate of the tested product shall not exceed 1cc/min or, if higher requirements are required, not exceed 0.5cc/min.for qualified products

2. Pressure resistance test: Pressure resistance test is divided into negative pressure resistance test and positive pressure resistance test.The test requires selecting a precise proportional adjustment valve group to evacuate the product at a certain vacuum rate starting from the initial pressure value of 0. The vacuuming time and the proportion of vacuum obtained can be adjusted.For example, if the vacuum is set to -50kpa, the extraction rate is 10kpa/min.

The difficulty with this test is that it requiresAir tightness testerOr the leak detection instrument can set the starting pressure for extracting the negative pressure value, such as starting from 0. Of course, it can also be required to start from -10kpa, for example. The extraction rate must also be set and can be changed.As we all know, seal testers or air tightness detectors are equipped with manual or electronic pressure regulating valves, which can only adjust the pressure according to the set pressure. The starting pressure starts from 0. The vacuuming capacity is generated by the vacuum source (vacuum generator or vacuum pump). The vacuuming speed of the vacuum source after passing through the pressure regulating valve is fixed, that is, it can only extract from 0 pressure to the fixed pressure set by the pressure regulating valve instantaneously. It does not have the ability to control the extraction pressure and time at different ratios.The principle of the positive pressure withstand pressure test is similar to the principle of the negative pressure withstand pressure test, which is to set the positive pressure starting pressure to any pressure, such as 0 pressure or 10kpa, and the slope of the pressure rise, that is, the slope, can be set, such as 10kpa/min: the test requires that the pressure rise is proportional to time and can be adjusted.

3 Burst test (burst test): It is divided into negative pressure rupture test or positive pressure rupture test.The product is required to rupture instantly when vacuum is drawn or pressurized to a certain pressure range, and the rupture pressure needs to be recorded.

The difficulty of testing is:Air tightness testerThe extraction of negative pressure is required to meet the second test requirement, the pressure rate can be adjusted, and the pressure explosion must be completed within the set range and cannot exceed this range.That is to say, blasting below this range or above this range does not meet the product testing requirements, and the test pressure of this blasting point needs to be recorded.During the actual test, this measurement requires an explosion-proof device. The usual explosion-proof device places the test workpiece in a pressure-resistant stainless steel cylinder. The test workpiece needs to be sealed, and a high-pressure relief valve needs to be set on the stainless steel cylinder of the outer cover to ensure safety.When an explosion occurs, the fragments of the connector are scattered inside the pressure-resistant stainless steel cylinder and will not cause harm to personnel.

From the above analysis, we can see thatAir tightness testerGenerally, three different devices need to be designed to complete the test. The seal leakage test needs to be completed with a molded leak detector coupled with a fixture system.The pressure test requires adding a proportional adjustment valve group to accurately set the proportional relationship between pressure value and time.The burst test requires the product to burst within a certain range, and the burst value must also be recorded.If the three systems are combined, it will be a relatively complex system project.

Of course, the three tests often need to be completed comprehensively. The test requires that the starting pressure value can be set arbitrarily, and the rate of pressure increase or decrease can be adjusted. After the pressure increases or decreases to a certain value and reaches the explosion setting range, the product explodes, and the explosion pressure is recorded.If the pressure increases or decreases to a certain value and the product does not explode, conduct a seal leakage test and record the leakage rate of the seal test or the pressure change per unit time.After the test is completed, the test results need to be stored for quality traceability.It is required that all test data can be traced and stored and uploaded in the format required by the test to facilitate quality analysis and quality control.

For the seal leakage detection industry, these European and American automobile companies have specific requirements for leakage testing: before the test, the barcode of the workpiece needs to be scanned and recorded. After the test, the barcode must be matched with the specific date and time and other test results.

4 Products without air-filled holes, analysis by quantitative method of air tightness detector

For products without holes, a profiling cavity can be made on the outside of the product, and a quantitative air-tightness testing instrument can be used to detect leakage at the product end.Air tightness testerThe internal principle of the instrument is to first open the inflation valve and fill a fixed-pressure compressed air into a reference volume inside the instrument. After the instrument's own reference volume is filled with a certain amount of air, the inflation valve closes, the test valve group opens, and the pressure of the reference volume is released into the test chamber.If the product has a large leak, the air pressure of the reference volume that comes with the instrument will drop quickly and exceed the limit value we set, and an alarm will occur.If the product has a small leak, the air pressure in the reference chamber of the instrument will drop very slowly. After maintaining the pressure, the small leak of the product can be measured during the test, usually with an accuracy of 0.1cc/min (the instrument display resolution is 0.01cc/min).

This article comes from Hirays Automation Technology Co., Ltd. (www.hirays.com) which has been focusing on the R&D, production and sales of IP protection level testing equipment; waterproof testing equipment, air tightness testing equipment, and sealing testing equipment for ten years