Common quality defects and causes of aluminum coil
Publish Time : 2022-03-18

1、 Non metallic press in

Definition: non metallic sundries are pressed into the plate and with appearance. The appearance shows obvious spot or strip yellow and black defects.

Main reasons: the equipment conditions of rolling process are not clean; Rolling process lubricant is not quiet; Lack of injection pressure of process lubricant; There are scratches on the surface of the slab.

2、 Scratch

Definition: a bunch (or group) of scars scattered on the surface of a board or belt due to relative sliding or dislocation between edges and surfaces between objects, or after touching surfaces.

Main reasons: when the plate and belt are touched with the guide and equipment in the process of processing and production, there is relative friction and scratch; The end face of cold rolled coil is not aligned, dislocation occurs during annealing turnover in vertical furnace, and scratch occurs between layers; Improper tension during cold rolling and scratch due to interlaminar dislocation during uncoiling; If the finishing inspection or packaging operation is improper, the sliding between plates will form scratch.

3、 Bruise

Definition: scratches on the surface or end face of aluminum plate and strip after aluminum plate and coil collide with other objects, and most of them have extruded metal on the edge of the depression.

Main reasons: the plate and roll collide with other objects during transfer or storage; The plate and coil collide with other outstanding objects on the annealing rack or chassis.

4、 Edge warping

Definition: after rolling or shearing, the edge of the strip is warped.

Main reasons: excessive reduction during rolling; Uneven distribution of lubricating oil during rolling; Improper adjustment of cutting edge during cutting.

5、 Fracture

Definition: deformation crease after plate bending.

Main reasons: incorrect feeding during feeding of multi roll straightener; The stress of the thin plate is unbalanced during turnover or transfer; When stacking the sheets, the force is unbalanced.

6、 Collapse roll

Definition: the roll core is severely deformed and the roll shape is not round.

Main reasons: improper tension during crimping; External force pressing; Low core strength; The coreless coil is annealed.

7、 Staggered layer

Definition: the irregular dislocation between the layers of the strip end face constitutes the uneven end face.

Main reasons: the blank is not flat; Improper control of uncoiling and coiling tension of rolling mill; The reduction is uneven and the sleeve moves in series; Improper adjustment of flattening roller; During coiling, the centering system is abnormal; The parallelism of roll system is not good.

8、 Tower shape

Definition: the belt roll moves to one side between layers to form a tower offset.

Main reasons: the shape of incoming materials is not good, and the tension control is improper; The coiling system is abnormal to the control system. The head is not firmly bonded during coiling.

9、 Loose roll

Definition: looseness occurs between layers during coiling and uncoiling, and it affects the whole roll when it is severe.

Main causes: uneven or too small tension during coiling; The pressure of the pressing roller is too small when uncoiling; When the clamp is not firm or the steel belt is not lifted.

10、 Bird's nest

Definition: local "V" defect occurs on the end face of the coil. This disadvantage occurs in the process of coiling or after unloading, and some occur after being placed for a period of time.

Main reasons: improper use of front and rear tension in the process of belt coiling; The expansion ring is not round or the backing is not round during coiling, which occurs due to uneven distribution of stress after coiling; Poor core quality.

Related News