1. Non-metallic pressing
Definition: Non-metallic debris is pressed into the surface of the plate or belt. The surface showed obvious dot-shaped or strip-shaped yellow-black defects.
The main reasons: unclear equipment conditions in the rolling process; unclear lubricant in the rolling process; insufficient spray pressure of the process lubricant; scratches on the slab surface.
2. scratches
Definition: The flaws caused by the bunching (or group) distribution on the surface of the board or belt due to the relative sliding or misalignment between the edges and surfaces of the objects, or the relative sliding between the surfaces.
The main reason: when the plates and belts are in contact with the guides and equipment during the production process, they will cause relative friction and cause scratches; the end faces of the cold rolled coils are not straight, and they will be misaligned during the annealing and turning of the vertical furnace. Abrasion occurs during cold rolling; improper tension during cold rolling, and interlayer movement during unwinding to produce abrasions; improper finishing inspection or packaging operation results in abrasion due to sliding between plates.
3. Bruise
Definition: The scratches on the surface or end surface of the aluminum plate, aluminum coil and other objects after collision, and most of the metal is extruded at the edge of the depression.
The main reason: the board and roll collide with other objects during transportation or storage; the board and roll are caused by collision with other protrusions on the annealing rack or chassis.
4. warping
Definition: After rolling or shearing, the edge of the strip is raised.
Main reasons: excessive reduction during rolling; uneven distribution of lubricating oil during rolling; improper adjustment of cutting edge during shearing.
5. Folds
Definition: Deformation crease produced after bending of the sheet.
The main reason: the feeding of the multi-roller straightener is not correct; the force of the thin plate is unbalanced during turning or handling; the force is unbalanced when loading the stack.
6.collapsed volume
Definition: The core of the coil is severely deformed and the shape of the coil is not round.
Main reasons: improper tension during crimping; external force compression; low core strength; coiled material without core is produced by annealing.
7. Split Level
Definition: The irregular end-to-end misalignment between the end layers of the strip results in uneven end surfaces.
Main reasons: uneven billet; improper unwinding and winding tension control of rolling mill; uneven reduction, sleeve tandem; improper adjustment of flattening roller; abnormal centering system during winding; abnormal parallelism of roller system.
8. Tower shape
Definition: The coiled layer moves from side to side to form a tower-shaped offset.
Main reasons: bad incoming board shape, improper tension control; abnormal winding centering adjustment control system; unsatisfactory adhesion during winding.
9. loose roll
Definition: loosening between layers when coiling and uncoiling, and spreading the whole volume when serious.
The main reasons: uneven tension or too small during winding; the pressure of the pressing roller during unwinding is too small; the steel belt or clip is not firm, which occurs during lifting.
10. bird's nest
Definition: Local "V"-shaped defects occur on the end surface of the coil. This kind of defect occurs during the coiling process or after unwinding, and some will not occur until it is placed for a period of time.
The main reason: improper use of front and back tension during coiling; the expansion ring is not round or the bottom is not round when winding, which occurs after unwinding due to uneven stress distribution; the core quality is poor.