Extrusion defect. The quality of aluminum profile will be affected by the defects such as bubble, inclusion, layering, color difference and distortion in the extrusion process due to the complete extrusion equipment, mature extrusion technology and improper operation. Thin oxide film. National standards for the construction of aluminum oxide film thickness should not be less than 10um (Micron) . The thickness is not enough, the surface of aluminum profile is easy to rust and corrosion. Sampling inspection of some names, plant sites, production permits, certificates of compliance of the aluminum profile, its oxide film thickness is only 2 to 4um, and some even no oxide film. According to expert estimates for each reduction of 1um oxide film thickness, each ton of profiles can reduce power consumption costs of more than 150 yuan. The chemical composition is not up to standard. A large amount of mixed aluminum and waste aluminum can greatly reduce the cost, but it will lead to unqualified chemical composition of construction aluminum profiles, and seriously endanger the safety of construction projects. Reduce Section Wall thickness. 90 series push-pull window type, according to the national standard its aluminum profile wall thickness is not less than 1.4 mm, some products only 0.6 to 0.7 mm. 46 series ground bomb door type, national standard used aluminum profile wall thickness is not less than 1.62 mm, sampling inspection, some products only 0.97 to 1.18 mm. Low-quality aluminum profiles greatly reduce the sealing time, reduce the loss of chemical reagents, cost, but also greatly reduced the profile corrosion resistance.