Jun. 19, 2024
Due to its excellent properties, aluminum foil is widely used in food, beverages, cigarettes, medicines, photographic plates, household daily necessities, etc., and is usually used as its packaging material. Electrolytic capacitor materials; insulation materials for buildings, vehicles, ships, houses, etc. It can also be used as decorative gold and silver wires, wallpapers, and decorative trademarks for various stationery prints and light industrial products.
In recent years, with the characteristics of aluminum foil, more and more are used in industrial production: battery foil, air conditioning foil, medicine foil, etc., which puts more and more stringent requirements on aluminum foil manufacturers. However, various quality defects will occur during the production process. For this reason, the characteristics and causes of various quality defects are sorted out.
Aluminum foil bruises refer to the damage caused on the surface or end face of the foil after colliding with other objects during transportation or storage. The bruises are mostly caused by carelessness when packaging aluminum foil.
The surface of the aluminum foil contacts the surrounding medium, and after chemical or electrochemical reactions occur, defects are generated on the surface of the aluminum foil. The corroded surface of the aluminum foil will lose its luster, and gray corrosion products will be produced in severe cases. The corroded aluminum foil will have a great impact on the appearance of the terminal products.
Aluminum foil with surface bubble defects will have irregular circular or strip-shaped cavity protrusions on the foil surface; the protrusions have smooth edges, asymmetric two sides, and irregular distribution. The surface bubbles make the force of each point of the aluminum foil strip uneven, which is likely to cause the pull-off and shutdown.
Dark surface stripes mostly appear on double-combined products. The dark surface has obvious light and dark strip patterns along the rolling direction, which affects the appearance.
Causes
There are many situations that will cause imprints on the surface of the aluminum foil, such as defects on the surface of the roller or guide roller or dirt such as metal chips, unclean surface of the sleeve or tube core or smooth protrusions in some parts, or foreign matter on the surface of the foil when winding, etc. The surface of the foil with marks usually has single or periodic depressions or protrusions, which are easy to identify.
Common aluminum foil oil stains are formed after annealing, usually in light yellow, brown, or yellow-brown spots.
To check whether the oil removal is clean, it is usually done after annealing. The degreasing level is tested by brushing water. If the level does not reach the level specified in the brushing water test, the aluminum foil may have oil on it.
Causes
The phenomenon of the longitudinal edge of the aluminum foil surface being broken is called cracked edge. In severe cases, obvious gaps can be seen on the edge.
The phenomenon of uneven surface of the foil due to uneven deformation is called poor plate shape. According to the location of the defect, it is divided into middle wave, edge wave, two-rib wave and composite wave. The edge wave is called edge wave, the middle wave is called middle wave, the wave with both is called composite wave, and the wave neither in the middle nor on the edge is called two-rib wave.
It is not easy to open a single sheet of aluminum foil roll. When multiple sheets are opened, they are in a hardened state. The free falling length of the product cannot meet the standard requirements. In severe cases, a single sheet cannot be opened. The adhesion of aluminum foil will seriously affect product production.
The surface of the foil is prone to holes.
Causes
Due to loose winding during slitting, when the foil is held vertically along the tube core direction, the foil moves between layers. When the foil is pressed with fingers, local depression may occur.
Causes
After shearing, there are burrs of varying sizes on the edge of the foil.
Causes
Misalignment
The irregular displacement between the layers of the end surface of the aluminum foil roll causes the end surface to be uneven.
Causes
a) The incoming material shape is poor.
b) Improper adjustment of the winding tension.
c) Improper adjustment of the flattening roller.
d) Abnormal centering system during winding.
e) Too fast speed during rolling or slitting.
The displacement between the layers of the end surface of the aluminum foil causes a tower-shaped offset, which is called a tower shape. The tower shape is a special case of misalignment, and the side looks like a spire.
Causes
The phenomenon of the aluminum foil roll curling up at both ends or one end is called warping edge. Its characteristic is that the aluminum foil roll edge curls up. You can touch it with your hand and you will feel obvious bumps and depressions.
Causes
Irregular small holes visible on the surface of the aluminum foil facing the light. For the production of aluminum foil packaging materials, the pinhole problem will affect the sealing.
Causes
Looking at the end of the aluminum foil locally or on the whole roll, the tube core has a radial pattern along the wall thickness, and there is a slight wave on the edge of the aluminum foil after unwinding.
Causes
White stripes on the surface of the aluminum foil with different widths or intervals along the rolling direction. Generally, they appear on the lower surface of the corresponding cast-rolled strip. The stripes are mostly concentrated in the middle and two ribs of the aluminum foil. As the aluminum foil is rolled and thinned, the stripes tend to become more severe.
Causes
Small, longitudinal or oblique local protrusions, one or several smooth grooves on the surface of the aluminum foil.
Causes
Longitudinal or transverse wrinkles on the surface of the aluminum foil roll that cannot be flattened.
The uneven bright spots on the dark surface of the aluminum foil during double rolling are called bright spots.
Causes
A certain number of layers on the end surface of the aluminum foil roll are bulged from the inside to the outside at the same place, and the bulge gradually decreases from the inside to the outside or from the outside to the inside.
Causes
Dark lines that are continuous in the longitudinal direction on the surface of the aluminum foil, and the color difference between the location where the lines are produced and other locations is obvious.
Similar to dark lines, bright lines are continuous in the longitudinal direction on the surface of the aluminum foil, and the color difference between the location where the lines are produced and other locations is obvious.
Causes
The surface of the aluminum foil is vertically convex in strips, and there is a clear sense of convexity and concavity when touched by hand. Sometimes it disappears after removing the outer layer of aluminum foil, and sometimes it runs through the entire roll of aluminum foil.
Causes
The surface of the aluminum foil is vertically convex in strips, and there is a clear sense of convexity and concavity when touched by hand. Sometimes it disappears after removing the outer layer of aluminum foil, and sometimes it runs through the entire roll of aluminum foil.
The surface of aluminum foil has regular horizontal fine stripes, which are generally white and have no bumps. Sometimes they are local to the coil and sometimes they cover the entire surface, which also affects the appearance.
Causes
The regular herringbone pattern on the surface of the foil is generally white, with obvious color difference on the surface, but very smooth.
Causes
Due to the high hydrogen content of the melt, the aluminum foil is crushed in strips along the rolling direction during the rolling process, with a certain width.
The scars distributed in bundles (or groups) on the surface of the foil caused by the relative sliding between the edges and faces, or between faces after the contact between the materials.
The intermittent or continuous groove-like scars on the surface of the foil. Generally, they are caused when a sharp object contacts the surface of the foil and slides relative to it.
Non-metallic inclusions are pressed into the surface of the foil, and the surface shows obvious yellow-black defects in the form of dots or long strips, which can be seen more clearly.
The phenomenon of aluminum foil naturally cracking in the longitudinal direction after rolling.
Causes
Small holes with rolling marks appear periodically on the surface of aluminum foil. Some of them are in the form of a mesh and are generally larger than pinholes.
Causes
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