5 methods to quickly judge the surface quality defects of aluminum profiles billet

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

The reason for the formation of rough surface defects of extruded aluminum profiles: In the extrusion production of aluminum profiles, the common defects are relatively intuitive, such as bending, twisting, deformation, slag inclusion, etc.

The aluminum profiles that come down from the extrusion line are called substrates or billets and white materials.

The initial judgment of surface quality is generally in the mold after extrusion to 2-3 rods, the first inspection sampling to determine whether the surface quality is qualified, and then other items are inspected after the surface is qualified.

5 methods to quickly judge the surface quality defects of aluminum profiles billet

1. Feel touch: touch the surface of the substrate with your hand, or the lines that can be picked by your fingernails, the concave bones and convex bones that can be felt, and judge whether there is an obvious feel. Suitable for the determination of various surface treatments.

2. Pencil scratches: In the aluminum extrusion process, the pencil is scratched on the surface of the aluminum profile, and the continuity of the feel and pencil scratches is used to determine whether there is a rough line. The marking groove is suitable for the surface determination of the oxide

3. Spray painting test: During the first inspection and sampling, spray the surface of the substrate with automatic spray painting to simulate the spray effect, wait 1-2 minutes after the surface is dry, observe and judge whether there are defects such as lines, concave bones, convex bones. Suitable for surface determination of spray coatings.

4. Alkali washing test: During the first inspection and sampling, take 300mm sample section in the third rod and soak in the pot mold tank for 30-40 seconds (Note: lye concentration and tank temperature, if the concentration and tank temperature are too low, extend the soaking time appropriately, generally not more than 60 seconds) Through the base material surface after alkali washing, you can see whether there are defects such as color separation, marking, mold welding line. 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 grinding: During the first inspection and sampling, the 300mm sample section is horizontally polished with industrial white cloth on the surface of the substrate. After grinding, it is easier to observe relatively subtle defects on the surface of the substrate. It is used to judge surface defects such as fine lines, concave bones (nails are not easy to pick), convex bones and the above 4 methods are not easy to distinguish. Suitable for spray coating, oxidizing material, fluorocarbon material surface judgment.

The first inspection to quickly determine whether the surface quality is qualified is the first step, even if the first piece is qualified, but there will be abnormal conditions in the extrusion process, so in the actual production process, it is also necessary to formulate a reasonable inspection frequency according to the different degrees of substrate defects, and what kind of surface treatment method, combined with the quality requirements of orders and customers, according to the requirements of the work instructions. Select the corresponding method to judge; Make timely and accurate judgment, with no misjudgment and no missing judgment as the principle.