Oil Marks and Watermarks? These Matters Cannot Be Ignored in the Aluminum Extrusion Process!

1. For stretching, the aluminum alloy profile must be cooled to below 50 degrees before it can be moved to the stretching frame for stretching work. The stretching will burn the operator and the top if the temperature is too high. And due to the internal stress of the aluminum alloy profile, there may be defects such as bending, twisting, and poor function before and after aging.

2. The control of the stretching amount is about 1%, and it should be noted that if the stretching amount is too high, there will be errors in the head, middle, and tail dimensions, water-like twists (fish scales) marks on the surface, low elongation, high hardness and the brittleness (low plasticity). Too low tensile strength will lower the compressive strength and hardness of the profile, and even aging (quenching) cannot increase the hardness, and the profile is easy to bend in an arc (commonly known as a big knife bend).

3. To control the amount of tensile deformation and better control the dimensional changes of the entire profile, it is necessary to choose special clamps and methods. Especially for open materials, arc materials, cantilever materials, and curved profiles, more attention should be paid to the reasonable use of stretch clamps.

4. Pay attention to the stress of small feet, thin teeth, long legs, arc surfaces, inclined surfaces, openings, angles, etc., to avoid partial or point-like scale deformation, twisting, spiral, and other profile defects.

5. Because wool tops have the effect of heat resistance, aluminum profiles with high decorative appearance requirements must be turned up and down to facilitate uniform heat dissipation and reduce horizontal bright spot defects caused by uneven heat dissipation and different crystallinity, especially large widths on the surface, more attention should be paid to the thicker aluminum profiles.

6. During the process of retrieving, moving and stretching, it is not allowed to rub, pull, stack, jam, or entangle with each other, and a certain distance should be reserved between each other. Aluminum alloy profiles that are easy to bend and have long and short discharge lengths should be disposed of promptly and properly protected from each other if necessary.

Oil stains on the surface of aluminum profiles

If the oil stains on aluminum profiles are not wiped clean before aging, watermarks will be produced on the surface of aluminum profiles after aging, and dark spots will appear after oxidation with a certain depth.

Causes of oil marks on the surface of aluminum profiles

1. The sawing oil stains on the finished product are left on both sides of the aluminum profile, and the gloves are not clean or even sticky with graphite dust when moving (lifting) the material;

2. When the aluminum profile is stretched, the gloves are dirty and the material is too long, and the sawing is not removed;

3. Gloves are dirty when handling materials in the middle, leaving "marks";

4. Extrusion equipment and tools leak oil stains (driving, hoisting belt).

Ways to eliminate oil marks on the surface of aluminum profiles

1. During the production process of aluminum materials, the gloves should be clean when handling materials, aluminum alloy profiles, and oil stains should be wiped off in time;

2. When stretching aluminum materials, the material should be appropriate;

3. Gloves and stretching materials when sorting and lifting materials, and gloves when adding rods should be separated;

4. Pay attention to oil leakage of equipment and tools, and clean the pads, straps, etc.

Watermark on the surface of the aluminum profile

Silver-gray wet spots appear on the surface of the aluminum profile, and the aluminum alloy profile fades or disappears with the increase in the intensity of oxidation and alkali washing.

Causes of watermarks on the surface of aluminum profiles

The surface of the aluminum profile is partially exposed to water and penetrates into the aluminum matrix through the tiny pores of the quenched oxide layer on the surface of the profile to form bayerite, which will become bright and light with the length of time the water stays. Corrosion spots will develop.

Watermark removal method on the surface of aluminum profile

The water-stained aluminum profiles should be wiped dry as soon as possible and must be wiped dry before aging. If conditions permit, the alkali cleaning time and oxide film thickness should be appropriately increased.

Summarize

As long as the oil and water stains are wiped clean before the aluminum profile is dust-free, there will be no oil marks and watermarks. The key is to cultivate good operating habits and quality awareness.

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