Extrusion defects. In the extrusion process of aluminum profiles, the completeness of extrusion equipment, maturity of extrusion process and propriety of operation would generate the defects such as bubbles, inclusions, layering, color difference, distortion, etc., which affects the quality of the aluminum profile. 

Oxidation film is thin. The thickness of oxidation film of building aluminum profile shall be no less than 10um as specified. The thickness isn't enough, and the surface of aluminum profile is easy to rust and corrode. In the sampling, for some aluminum profiles without manufacturer name, factory site, production license and certificate of approval, the thickness of oxidation film only reaches 2- 4um, while some aluminum profiles even don't have the oxidation film. It is estimated that the power consumption cost of over RMB 150 can be saved in each ton of profiles when 1um oxidation film is reduced. 

Chemical composition is unqualified The cost could be reduced greatly by mixing lots of miscellaneous aluminum and scrap aluminum in aluminum profile, but which will lead to the unqualified chemical composition of the building aluminum profile and seriously endangers the construction project. 

The thickness of profile thickness is reduced. For the 90 series sliding window, its aluminum profile thickness is not less than 1.4mm as per the standard, some products are only 0.6-0.7mm in thickness. For the 46 series springdoor, the standard thickness of aluminum profile is not less than 1.62mm, and some products are only 0.97-1.18mm in thickness during sampling. 

Inferior aluminum profiles greatly reduce the closure time, the loss of chemical reagents and the cost, while its corrosion resistance is also greatly reduced.