Possible surface defects caused by rolling of aluminium sheets (3)

Possible surface defects caused by rolling of aluminium sheets (3)

(9) Metal indentation

Definition and characteristics: metal chips or metal fragments pressed into the surface of aluminium plates and strips. Pressed into the object scraped off the size of the depression, destroying the continuity of the surface of the plate, strip.

The main reasons: hot rolling with less roll edge, cracked edge of the metal chips or strips fall on the surface of the plate after being rolled into; after the rolls sticky aluminum, its sticky aluminum and rolled on the plate; hot rolling guide clamps too tight, with down the aluminum chips fall on the surface of the plate after being pressed into; disc shear edge quality is poor, resulting in burrs fall on the strip is rolled into.

(10) Non-metallic press-in

Definition and characteristics: non-metallic inclusions pressed into the surface of aluminium plates and strips. Non-metallic inclusions are dotted, long or irregularly shaped, and the colour varies with the inclusions.

The main causes: production equipment or environment is not clean; rolling process lubricant is not clean; the existence of non-metallic foreign matter in the blank; the surface of the slab has scratches, sludge and other non-metallic foreign matter residue in the depression; production process, non-metallic foreign matter fell on the surface of the plate, strip.

(11) Print marks (roll marks)

Definition and characteristics: The presence of single or periodic depressions or bumps on the surface of aluminium sheets and strips. The depressions or bumps are smooth.

Main causes: rolls, work rolls, packaging oiling rolls and the surface of the plate and strip are stuck with metal chips or dirt; other process equipment (e.g. calender, straightener, feed rolls, guide rolls) have defects or sticky dirt on the surface; the surface of the sleeve is not clean, uneven and there are smooth bumps; when coiling, aluminium plates and strips are stuck with foreign objects.