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.
Reasons for the formation of surface rough defects of 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 line is called the base material or blank, white material.
Initial judgment of surface quality is generally when the mold is extruded to 2-3 rods after the machine, the first inspection sampling preliminarily judges whether the surface quality is qualified, and then inspects other items after the surface is qualified.
5 ways to quickly judge the surface quality defects of aluminum profile blanks
1. Feel touch: touch the surface of the substrate with your hands, or use the scratches that can be picked up with your fingernails, and you can feel the concave bones and convex bones to judge whether there is an obvious feel. It is suitable for judging various surface treatments.
2. Pencil scratches: In the process of extrusion of aluminum profiles, use pencils to scratch the surface of aluminum profiles, judge whether there are thick lines by the continuity of feel and pencil scratches, and the marking grooves are suitable for the surface judgment of oxide materials
3. Painting test: when sampling for the first inspection, spray the surface of the substrate with automatic spraying paint to simulate the spraying effect, wait for 1-2 minutes after the surface is dry, observe and judge whether there are defects such as marking, concave bones, convex bones, etc. 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 solution and the temperature of the bath, 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 grinding: During the first inspection and sampling, the 300mm sample section is used to polish the surface of the substrate horizontally with an industrial white cloth, and it is easier to observe the subtle defects on the surface of the substrate after grinding. It is used to judge surface defects such as fine scribing, concave bones (which are not easy to pick out nails), convex bones, and the above 4 methods. It is suitable for surface judgment of spray coatings, oxidizing materials and fluorocarbon materials.
