5 methods to quickly judge the surface quality defects of aluminum profile billets

Due to the particularity of the production process, the surface defects of the aluminum profile caused by the polishing quality of the mold or the process conditions directly or indirectly caused by the hot extrusion process are as follows: coarse grain, color separation, dark band, bright band, scribing, bone (concave bone, convex bone), poor finish.

Causes of surface roughness defects in extruded aluminum profiles: In the extrusion production of aluminum profiles, common defects are relatively intuitive, such as bending, twisting, deformation, slag inclusion, etc.

The aluminum profile coming down from the extrusion production line is called the substrate or blank or white material.

The initial judgment of surface quality is generally when the mold is squeezed to 2-3 rods after the machine is put on the machine, and the first inspection and sampling preliminarily judge whether the surface quality is qualified, and then inspect other items after the surface is qualified.

5 ways to quickly judge the surface quality defects of aluminum profile blanks

1. Touch the surface of the substrate with your hands, or use your fingernails to pick out the lines, concave bones, and convex bones that can be felt to judge whether there is an obvious feel. It is suitable for the determination of various surface treatments.

2. Pencil scratches: use a pencil to scratch the surface of the aluminum profile during the extrusion process of aluminum profiles, and judge whether there is a coarse texture by the feel and the continuity of pencil scratches

3. Painting test: when sampling for the first inspection, spray the surface of the substrate with automatic spraying paint to simulate the spraying effect, and wait for 1-2 minutes after the surface is dry, observe and judge whether there are defects such as marking, concave bones, and convex bones. It is suitable for surface judgment of spray coatings.

4. Alkali washing test: when sampling for the first time, take a 300mm sample section on the third rod and soak it in the mold groove for 30-40 seconds, (note: the concentration of alkali and the temperature of the tank, if the concentration and bath temperature are too low, the soaking time should be appropriately extended, generally not more than 60 seconds) through the surface of the substrate after alkali washing, you can see whether there are defects such as color separation, scribing, mold welding line, etc. Suitable for oxidizing materials with high surface requirements.

In addition to the above four common methods, there is another method for your reference.

5. Surface polishing: When the first inspection and sampling, take a 300mm sample section and use an industrial cleaning cloth to grind the surface of the substrate horizontally, and it is easier to observe the substrate surface after polishing. It is used to judge surface defects such as fine lines, concave bones (which are not easy to pick with nails), convex bones and the above four methods that are not easy to distinguish. It is suitable for surface judgment of spraying coatings, oxides, and fluorocarbons.

The first inspection is the first step to quickly judge whether the surface quality is qualified, even if the first piece is qualified, but there will be abnormal situations in the extrusion process, so in the actual production process, it is also necessary to determine the different degrees of substrate defects, and what kind of surface treatment method, combined with the quality requirements of the order and the customer, according to the requirements of the work instructions, formulate a reasonable inspection frequency, and choose the corresponding method to judge; Make timely and accurate judgments, and do not misjudge and do not miss judgments.