Today I'd like to take you to understand some of the common quality defects and causes of aluminum sheet and coil:
First, non-metallic pressed into
Definition: non-metallic debris pressed into the plate, with the surface. The surface is obvious point or long yellow-black defects.
The main reason: rolling process equipment conditions are not clean; rolling process lubricant is not clean; process lubricant injection pressure is insufficient; slab surface has scratches.
Second, abrasion
Definition: due to the object between the prongs and surface, or surface and surface contact after the occurrence of relative sliding or wrong movement in the plate, strip surface caused by a bunch (or group) distribution of scars.
The main reason: plate, strip in the processing and production process with the guide road, equipment contact, resulting in relative friction and caused by abrasions; cold rolled volume end face is not flush, in the vertical furnace annealing flip produced by the wrong movement, layer and layer of abrasions; cold rolling tension is not appropriate, the uncoiling of the layer produced by the interlayer wrong and produced by the abrasion; finishing acceptance or packaging operations produced by the sliding between the plate and caused by the abrasion.
Third, bruises
Definition: Aluminum plate, aluminum coil and other objects collision in the plate, with the surface or end face of the scratch, and most of the depression in the margins of the presence of extruded metal.
The main reason: plate, volume in the handling or storage process and other objects collision; plate, volume in the annealing material frame or chassis with other protruding objects top collision and produce.
Four, warping
Definition: After rolling or shearing, the strip edge warping.
The main reason: rolling under the amount of pressure is too large; rolling lubricant distribution is not uniform; shear improperly adjusted shear edge.
Fifth, fracture
Definition: the deformation crease produced after bending the plate.
The main reason: multi-roller straightening machine feeding incorrectly; sheet in the flip or handling force imbalance; on the stack of sheet force imbalance.
Sixth, collapse of roll
Definition: the core of the roll is seriously deformed, the roll shape is not round.
The main reason: improper tension in the process of curling; external compression; low core strength; no core rolls produced by annealing.
Seven, wrong layer
Definition: irregular misalignment between the strip end layer and layer, resulting in end surface unevenness.
The main reasons: the blank is not flat; rolling mill uncoiling, winding tension control is not appropriate; the amount of uneven pressure down, sleeve crosstalk; flattening rollers are not properly adjusted; coiling process, the alignment system is abnormal; roll system parallelism is not good.
Eight, tower
Definition: the tape roll layer and layer to one side of the formation of tower offset.
The main reasons: the incoming board shape is not good, improper tension control; coiling centering adjustment control system is abnormal; coiling with the head of the bonding is not firm.
Nine, loose volume
Definition: loosening between layers when winding and unwinding, and in serious cases, the whole roll is affected.
Main reasons: uneven or too small tension in the process of coiling; too small pressure on the pressure roller when uncoiling; steel belt or card is not firm, when lifting.
Ten, bird's nest
Definition: the end face of the tape coil to produce a local "V" type defects. This defect is generated in the process of coiling or uncoiling, some to be placed for a period of time before they are generated.
The main reason: improper use of tension before and after the process of tape coiling; expansion ring is not round or rolled bottoming is not round, uncoiling due to uneven distribution of stress and produce; poor quality of the core.
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