Several common aluminum plate defects and their causes

I believe that the new aluminum plate enterprises do not know much about the common defects of aluminum plates. Let Xinyitong Aluminum briefly introduce several common aluminum plate defects for you, so as not to cause unnecessary trouble to the enterprise due to their own negligence!

1. Plate shape:

(1) Staggered layer: irregular staggered movement between the end surface layer and the layer of the strip, resulting in uneven end surface. Causes: uneven billet; improper control of rolling mill uncoiling and coiling tension; improper adjustment of flattening rolls, etc.

(2) Collapsed roll: The roll core is seriously deformed and the roll shape is not round. Cause: Improper tension during the crimping process; external force oppression.

(3) Lateral bending: It is manifested as the bending of the plate shape to one side. Cause: The pressure of the leveler is not enough.

(4) Wave: A general term for various uneven phenomena formed by uneven deformation of aluminum plates and aluminum strips. The waves generated by the plate and the edge are called edge waves, the waves generated in the middle are called middle waves, and the waves between the middle and the side are neither in the middle nor on both sides are called two-rib waves, which are smaller in size and usually Waves that are circular are called break waves. Causes: Unbalanced roll gap adjustment, unreasonable roll shape control; uneven lubrication and cooling, uneven deformation of the aluminum plate; unreasonable distribution of pass reductions, etc.

2. Dimensions:

(1) Thickness tolerance: allowable tolerance below 1.0 ± 1%, above 1.0 ± 5%, single out of tolerance * 2 times;

(2) Width tolerance: ±0.1MM below 3.2MM, ±0.2MM above 3.2MM;

(3) Length tolerance: +5-3MM. The reason for the thickness tolerance, the problem of the thickness gauge; the reason for the width tolerance, the improper adjustment of the disc shear; the reason for the length tolerance, the adjustment of the shearing machine is problematic.

3. Surface:

(1) Embossing: The irregular color difference on the roll surface is periodically printed on the surface of the strip during the rolling process due to the wrinkle and broken strip of the strip.

(2) Scratches: the appearance of scars distributed in bundles on the surface of the aluminum plate. Cause: mechanical or artificial dislocation between layers of aluminum plate.

(3) Edge warping: After rolling or shearing, the edge of the strip is warped.

(4) Corrosion: It is manifested as point-like or flaky white spots or black spots on the surface of the aluminum plate. Cause: Acid, alkali or water entered during production, packaging, transportation and storage.

(5) Oil stain on the surface: it is manifested as dirt on the surface. Cause: The cooling oil is dirty and the air blowing is not strong.

(6) Scratches: There are line-distributed scars on the surface of the aluminum plate. Causes: The guide plate is protruding or sticking to aluminum when it is rolled flat; scratches occur during the shearing process; improper manual inspection and lifting.

(7) Side bending: the longitudinal sides of the plate and belt are in a non-straight state that is bent to one side. Causes: The reduction amount at both ends of the rolling mill is different;

(8) Black spots on the surface: There are needle-shaped black spots on the surface of the aluminum plate. Cause: The furnace liquid is not clean.

4. Mechanical properties:

(1) The hardness is not enough. Reason, material/composition, heat treatment process.

(2) Stamping and cracking, hard or soft. Material or condition issues.

(3) Other defects: water ripples after oxidation, black and white lines; dark flowers on the surface; not bright on the surface, etc.