Due to the particularity of the production process of hot extrusion aluminum profiles, the surface defects of aluminum profiles directly or indirectly caused by the polishing quality of the mold or the process conditions during the hot extrusion process are as follows: rough texture, color separation, dark band, bright band, Scribing, bony (concave, convex), poor finish.
Reasons for the formation of rough surface defects of extruded aluminum profiles: In the extrusion production of aluminum profiles, common defects are relatively intuitive, such as bending, twisting, deformation, slag inclusion, itp.
The aluminum profiles coming down from the extrusion line are called substrates or blanks, white materials.
The initial judgment of the surface quality is generally when the mold is on the machine and extruded to 2-3 rods, the first inspection and sampling are used to preliminarily determine whether the surface quality is qualified, and then other items are inspected after the surface is qualified.
5 ways to quickly judge the surface quality defects of aluminum profile billets
1. Hand touch: touch the surface of the substrate with your hands, or scribe lines that can be picked with your fingernails, concave bones and convex bones that can be felt, and judge whether there is an obvious hand feel. It is suitable for the determination of various surface treatments.
2. Pencil scratches: During the extrusion process of aluminum profiles, use pencils to scratch the surface of aluminum profiles, and judge whether there are rough lines by the continuity of hand feel and pencil scratches, and scribe lines and grooves are suitable for the surface judgment of oxide materials.
3. Spray paint test: When sampling for the first inspection, use automatic spray paint to spray the surface of the substrate to simulate the spray effect. After the surface is dry for 1-2 minutes, observe and judge whether there are any defects such as scribe lines, concave bones, and convex bones. It is suitable for surface judgment of spray paint.
4. Alkaline washing test: When sampling for the first inspection, take a 300mm sample section from the third rod and soak it in the mold tank for 30-40 seconds. Properly prolong the soaking time, generally no more than 60 seconds.) After alkali cleaning, the surface of the substrate can be seen with or without color separation, scribing, mold welding lines and other defects. Suitable for oxides with high surface requirements.
In addition to the above four common methods, the following is another method for your reference.
5. Surface grinding: During the first inspection and sampling, take a 300mm sample section and use an industrial white cleaning cloth to grind the surface of the substrate horizontally. 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 thin lines, concave bones (not easy to be picked by nails), convex bones and the above 4 methods that are not easy to distinguish. It is suitable for surface judgment of spray paint, oxide material and fluorocarbon material.
The first inspection is the first step to quickly judge whether the surface quality is qualified. Even if the first piece is qualified, there will still be abnormal conditions during the extrusion process. Dlatego, in the actual production process, it is necessary to determine the different degrees of substrate defects and the type of surface. The processing method, combined with the quality requirements of the order and the customer, according to the requirements of the operation instructions, formulate a reasonable inspection frequency, and select the corresponding method to judge; make timely and accurate judgments, with the principle of not misjudging and not omitting judgments.–From Huawei Alu Metal Factory