1. The super extrusion ratio refers to the ratio between the cross-sectional area of the material before hot extrusion and the cross-sectional area after extrusion. Generally, it is 8-50 times, while the cross-sectional area of the microchannel aluminum flat tube is only about 4px2. The extrusion ratio should be more than 400 times, which is more than 8 times that of the aluminum extrusion process.
2. The dimensional accuracy of ultra-high dimensional precision microchannel aluminum flat tube is much higher than the domestic standard of hot extrusion tube for aluminum and aluminum alloy research. According to the domestic standards, the width deviation of typical varieties of 16mm is ± 0.3mm, while the width deviation of microchannel aluminum flat tube is ± 0.03mm, which needs to be increased to ± 0.01 - ± 0.02mm for high requirements.
3. Air tightness there are about 50-150 microchannel aluminum flat tube in a set of microchannel heat exchangers. As long as one of them has air tightness defects (such as pores and inclusions), the whole air conditioner will be scrapped. Therefore, the quality standard is calculated in ppm (1 million pieces), and the measurement standard is below 15ppm.
4. The small wall thickness of the high-quality rod microchannel aluminum flat tube is only 0.13MM. If the purity and hydrogen content of the cast rod material cannot meet the requirements, as long as there is a very fine pore or inclusion, the thin wall of the microchannel aluminum flat tube will leak. Therefore, high-purity refining rod must be used, with hydrogen content ≤ 0.09%.
5. Surface zinc spraying technology: since there is refrigerant medium inside the microchannel aluminum flat tube and atmospheric corrosion outside, it is easy to cause leakage due to pitting corrosion. A thin layer of zinc must be sprayed on the outer surface to protect the pipe wall from corrosion. Up to now, there is no manufacturer in China that can provide qualified zinc spraying equipment, and only a few manufacturers in China can provide it.
6. On line flaw detection and inspection technology due to the difficulty and difficulty of microchannel aluminum flat tube technology, how to use scientific and effective on-line flaw detection, surface quality and other inspection methods in the production process to detect (mark) defective products in time is extremely critical to the quality control of microchannel aluminum flat tube .
