Label inspection: whether the aluminum profile and packaging are marked with the product standard code and production license number, etc.
Surface quality: The surface of the aluminum profile should be clean and free of defects such as cracks, peeling, corrosion and bubbles. It should also not have defects such as corrosion spots, electric burns, black spots, and oxide film shedding.
Oxide film thickness: The oxide film of aluminum profiles is formed during anodizing, which has protective and decorative effects and can be detected by an eddy current thickness gauge.
Sealing quality: There are many gaps on the surface of the aluminum profile after anodizing. If it is not sealed or sealed poorly, the corrosion resistance of the aluminum profile will be reduced.
Common methods for checking the quality of sealing include acid leaching, admittance method and phosphotyric acid method.
The acid leaching method is generally used in on-site inspections, that is, the surface of the aluminum profile is cleaned with acetone to remove oil and dust, 50% nitric acid by volume is dropped onto the surface and gently scrubbed, 1 minute later, the nitric acid is washed off with clean water, and then wiped dry, a drop of medical gentian violet is dropped onto the surface, 1 minute later, the gentian violet is wiped off and the surface is thoroughly cleaned, and the traces left are carefully observed. Aluminum profiles with poor sealing will leave obvious traces, and the heavier the traces, the worse the sealing quality.
Corrosion resistance: This index mainly affects the life of aluminum profiles. The corrosion resistance inspection includes copper accelerated acetate spray test and alkali drop test. Here we introduce the alkali drop test, that is, at 35℃±1℃, about 10mg, 100g/L NaOH solution is dropped onto the surface of the aluminum profile, and the droplets are visually observed until corrosion bubbles appear, and the time for the oxide film to be penetrated is calculated. This test is easy to make a rough judgment outdoors in summer. To ensure the accuracy of the test, it must be carried out under strict laboratory conditions.
