In the production process of aluminum foil, there are multiple processes such as rolling, finishing, annealing, packaging, etc. The interlocking production process, any problem in any link may cause aluminum foil quality problems. The quality defects of the purchased aluminum foil products will not only affect the appearance, but also directly affect the quality of the products produced, and even more directly cause the aluminum foil to break and stop, which greatly affects the production efficiency. How to distinguish the quality of aluminum foil?
According to the experience of people in the aluminum industry, most of the quality of aluminum foil can be directly detected with your “intelligent eyes”. However, to distinguish the quality of aluminum foil, we should first understand the common quality defects of aluminum foil. Only when we have a good idea, and then check the common aluminum foil quality problems one by one, can we prevent the aluminum foil with quality defects from being stored in the warehouse.
1. Aluminum foil bruises
Aluminum foil bumps refer to the damage on the surface or end face of the foil after it collides with other objects during transportation or storage. Most of the bumps are caused by carelessness in aluminum foil packaging.
The surface of the aluminum foil is in contact with the surrounding medium, and after a chemical reaction or electrochemical reaction occurs, the defect produced on the surface of the aluminum foil, the surface of the corroded aluminum foil will lose its luster, and in severe cases, gray corrosion products will be produced. The corroded aluminum foil will have a great impact on the aesthetics of the products produced by the terminal.
3. Surface bubbles
The aluminum foil with surface bubble defects will have irregular round or strip-shaped cavities on the surface of the foil; the raised edges are smooth, the two sides are asymmetrical, and the distribution is irregular. The surface bubbles make the aluminum foil strip force on each point Unbalanced, it is likely to cause the pull-off shutdown.
4. Dark side stripes
Dark side stripes mostly appear on double products, and the dark side has obvious light and dark striped patterns along the rolling direction, which affects the appearance.
There are many situations that can 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, the surface of the sleeve or tube core is not clean or partially smooth and convex, or the surface of the foil during coiling There are foreign objects and so on. The surface of the foil with imprints generally has single or periodic depressions or protrusions, which are easy to distinguish.
Common grease stains on aluminum foil are formed after annealing, and are generally pale yellow, brown, and yellow-brown stains.
7. Degreasing is not clean
Check whether the degreasing is clean or not. Generally, after annealing, the degreasing level is tested by the water brushing method. If it does not reach the level specified in the water brushing test, there may be oil on the aluminum foil.
8. Cracked edges
The phenomenon that the longitudinal edges of the aluminum foil surface are cracked is called cracked edges. In severe cases, obvious gaps can be seen at the edges.
9. Poor board shape
Due to uneven deformation, local undulations on the surface of the foil are called poor plate shape. According to the location of the defect, it is divided into middle wave, side wave, two-rib wave and compound wave. The side waves are called side waves (as shown in the picture), and the middle waves are called middle waves. Both are called compound waves. Neither the middle nor the sides are called two-rib waves.
A single sheet of aluminum foil roll is not easy to open, and when multiple sheets are opened, it is in a hardened shape, and the free falling length of the product cannot meet the standard requirements. In severe cases, the single sheet cannot be opened, and the adhesion of aluminum foil will seriously affect the production of the product.
The surface of the foil is prone to holes.
12. Loose rolls
Because the winding is not tight during slitting, when the foil is held upright in the direction of the tube core, the foil will be misaligned between layers; when the foil is pressed with a finger, partial depression may occur.
After cutting, there are thorns of different sizes at the edge of the foil.
14. Split level
The end face layer of the aluminum foil roll is irregularly shifted between the layers, causing the end face to be uneven.
The dislocation between the aluminum foil end surface layer and the layer causes the tower-shaped offset, which is called the tower-shaped. The tower shape is a special case of split level, and the side looks like a spire.
16. Warped edge
The phenomenon that the two ends or one end of the aluminum foil roll up upward is called edge warping, which is characterized by the fact that the rolled edge of the aluminum foil rolls upward, which can be touched by hand, and there will be a noticeable unevenness.
Irregular small holes on the surface of the aluminum foil that are visible to the light. For the production of aluminum foil packaging materials, the pinhole problem will affect the tightness.
18.End surface pattern
The end of the aluminum foil is partially or completely rolled, and the tube core has a radial pattern along the wall thickness; after uncoiling, there is a slight wave at the edge of the aluminum foil.
19. White strips
The surface of the aluminum foil has white stripes that vary in the rolling direction, width or interval. Generally corresponding to the appearance of the lower surface of the cast-rolled strip, the stripes are mostly concentrated in the middle of the aluminum foil and the two ribs. With the rolling and thinning of the aluminum foil, the stripes show an obvious tendency to increase.
The surface of the aluminum foil presents small, longitudinally or obliquely partially convex, one or several smooth grooves.
Vertical or horizontal wrinkles that cannot be flattened on the surface of the aluminum foil roll.
When aluminum foil is double-rolled, the uneven bright spots on the dark surface of the aluminum foil are called bright spots.
23. Arrow (Bird’s Nest)
A certain number of layers on the end face of the aluminum foil roll are convex from the inside to the outside at the same place, and the degree of convexity is gradually weakened from the inside to the outside or from the outside to the inside.
24. Black line
The longitudinally continuous dark lines on the surface of the aluminum foil have obvious color differences between the generated parts and other parts.
25. Bright line
Similar to the dark lines, the bright lines are longitudinally continuous bright stripes on the surface of the aluminum foil, and the generated parts have obvious color differences from other parts.
The surface of the aluminum foil is protruding in strips longitudinally, with obvious convex and concave sensation when touched. Sometimes it disappears after removing the outer aluminum foil, and sometimes it penetrates the entire roll of aluminum foil.
27. Dark side chromatic aberration
28. Horizontal stripes
There are regular thin stripes on the surface of the aluminum foil, which are generally white and have no unevenness. Sometimes they are part of the coil, sometimes covering the entire surface, which also affects the appearance.
The regular herringbone pattern on the surface of the foil is generally white, with obvious chromatic aberration on the surface, but it is very smooth.
Due to the high hydrogen content in the melt, the aluminum foil is crushed in the rolling direction in the rolling process and has a certain width.
Bundles (or groups) of scars distributed on the surface of the foil caused by the relative sliding between the edges and the surface, or after the surface and the surface contact.
Intermittent or continuous groove-like scars on the surface of the foil. Generally, it occurs when a sharp object slides relative to the surface of the foil after contacting it.
33. Non-metallic press-in
Non-metallic inclusions are pressed into the surface of the foil, and the surface shows obvious dots or strips of yellow-black defects, which can be seen more clearly.
The phenomenon of natural cracking of aluminum foil along the longitudinal direction after rolling.
35. Rolling eyes
The small holes with rolling traces periodically appear on the surface of the aluminum foil, and some are mesh-shaped, and the size is generally larger than the pinhole.