Summary of common quality issues

In the production process of aluminum plates and strips, quality problems are prone to occur due to equipment or personnel operation errors. Here, Shanghai Lvmeng Aluminum Industry summarizes common quality problems as follows, hoping that the production department can pay attention to this issue.

Oil stains are a common quality issue: oil stains refer to excessive oil on the surface of aluminum tips after rolling, and excess oil other than the rolling oil film is added to the surface, which is visible to the naked eye during slitting production and finished product inspection. These oils are mainly caused by throwing, splashing, and dripping on the box surface at the roll neck or at the outlet of the rolling mill, as well as abnormalities in the rolling mill cleaning device and oil dripping from the thickness measuring head of the rolling mill, and are often dirty and complex in composition. This type of oil stain will cause significant harm to the surface of aluminum coils: firstly, as most aluminum coil products are used as decorative or packaging materials, they must have a clean surface; The second reason is that its thickness is thin, which can easily form bubbles during subsequent annealing, and due to the high amount of oil, it forms too much residue at this location, which affects its use. The number of oil stains is an important indicator for evaluating the quality of aluminum foil.

Solution: Strictly inspect the production equipment before production. If excessive oil stains are found in the equipment, clean it in a timely manner and identify the cause. At the same time, clean and process the production products on the board. If the products cannot be cleaned, dispose of them as scrap. Products with oil stains are prohibited from entering the warehouse or entering the market.

In the process of rolling various semi-finished and finished aluminum plates with billets, as well as in the production processes of coil finishing, annealing, transportation, packaging, etc., some defects are inevitable. The generation of these defects is partly due to the defects of the ingot and cast rolling strip itself. Sometimes they can be exposed in the ingot and cast rolling processes, sometimes they cannot be detected, and only in the subsequent further processing can they be exposed; The other part is generated during the production process of foil rolling, finishing, annealing, transportation, packaging, and other processes. Most of these defects are caused by equipment failures, violations of operating procedures, improper adjustment of process parameters, inadequate technical proficiency of operators, and various other reasons. In the production process of aluminum foil, there are many types of quality defects caused by aluminum plates, mainly a large number of pinholes, thickness exceeding the tolerance, poor flatness, and various reasons such as strip breakage. Reducing these defects is very meaningful for improving the quality of the foil material. Inclusions, air passages, metal and non-metallic pressure, scratches, scratches, and uneven thickness in the casting and hot rolling billets can all cause great difficulties in aluminum foil rolling, leading to strip breakage, pinholes, and thickness tolerances.

Scratches are common quality issues: scratches, abrasions, and bumps are intermittent or continuous, single groove like scars on the surface of aluminum plates. It is generally generated when sharp objects come into contact with the surface of the foil and slide relative to each other. The main cause of occurrence: there are pointed defects on the surface of the roller and guide roller, or hard debris is adhered; There are pointed defects or debris in the mechanical guide rollers and guides for cutting, winding, and slitting. Scratches: Bundles (or groups) of distributed scars on the surface of box materials caused by relative sliding or dislocation between edges or surfaces of objects. The main reason for scratches is that during the processing and production process of aluminum plates, relative friction occurs when they come into contact with guides and equipment, resulting in scratches; Loose roll, loose layer or bird's nest shaped end surface defect of the blank; Improper use of tension during rolling can result in interlayer misalignment and scratches during uncoiling. Collision: The scars on the surface or end face of the box roll caused by the collision of the aluminum roll with other objects. It manifests as a partial depression on the surface or end face. The main cause of collision: improper lifting or storage in various production processes; Collisions during transportation and handling; The aluminum foil rolls on the annealing rack or packaging platform are scratched by other protrusions.