Possible surface defects caused by rolling of aluminium sheet and strip (6)

Possible surface defects caused by rolling of aluminium sheet and strip (6)

(20) small black strips (black spots)

Definition and characteristics: plate, strip surface distribution along the rolling direction of the black line or point defects.

The main causes: poor process lubrication; process lubricant is not clean; aluminum plate and strip surface scuffing; plate and strip through the guide path is not clean; casting and rolling strip surface segregation or hot rolling with casting block milling is not complete; metal inclusions; open billet rolling, produce a large number of aluminum oxide powder, and pressed into the metal, further rolling to produce black strip; brush roll process is not appropriate.

(21) bright and dark stripes

Definition and characteristics: the surface of the plate and strip because of uneven roughness in the surface of the plate and strip produced in the width of the bright marks.

Main causes: poor quality of roll grinding; poor process lubrication; rolling narrow material first and then wide material.

(22) Holes

Definition and characteristics: penetration of the aluminum sheet and strip holes or holes.

Main causes: billet rolling before the existence of sticky injury, pressure scratch, hole; pressed into the object after rolling off.