Cut flatness: check the surface of aluminum alloy door and window profiles, there should be no depression or bulge. 

Surface gloss: avoid the purchase of aluminum storefront aluminum doors with open bubbles (white spots) and ash (black spots) on the surface, as well as cracks, burrs, peeling and other obvious defects.  

Profile oxidation degree: good aluminum alloy doors and windows oxide film thickness should reach 10 microns.  Aluminum alloy doors and windows can be selected on the surface of the profile to see whether the oxide film on the surface of the doors and windows can be erased.