Jumbo Roll Aluminium Foil Wholesale
In Aluminium Foil Jumbo Roll Suppliers, the editor talked about how to distinguish the quality of aluminum foil. Next, we will learn how to distinguish between good and bad aluminum foil
(1) Oil pollution. Oil stain refers to the excess oil on the surface of the aluminum foil after rolling, that is, the oil other than the rolling oil film. Oil stains on the surface of aluminum foil are more harmful than other rolled materials. First, most aluminum foil products are used as decoration or packaging materials and must have a clean surface; second, its thickness is thin, and it is easy to form bubbles during subsequent annealing. And because of the large amount of oil, too much residue is formed there, which affects the use. The number of grease defects is a very important indicator for evaluating the quality of aluminum foil.
(2) Water spots. Water spot refers to the white spot formed by water droplets on the foil surface before rolling, which will affect the surface condition of the foil surface when it is mild, and cause strip breakage in severe cases. Water spots are caused by water droplets in the oil or water droplets falling on the foil surface in the rolling mill. Controlling the moisture and water source in the oil is the only way to avoid water spots.
(3) Vibration marks. Vibration marks refer to the periodic transverse waves on the surface of the aluminum foil. There are two reasons for vibration marks: one is formed during roll grinding, with a period of about 10-20mm; the other is due to discontinuous oil film formation during rolling, which often occurs in a speed range with a period of 5 ~10mm.
(4) Tension line. When the thickness reaches 0.015mm or less, parallel stripes are formed in the longitudinal direction of the aluminum foil, commonly known as tension lines. The spacing between the tension lines is about 5-20 mm, the smaller the tension, the wider the tension lines, the more obvious the stripes. When the tension reaches a certain value, the tension line is very slight or even disappears. The smaller the thickness, the greater the possibility of tension lines, and the possibility of double-rolling is greater than that of single sheets. Increasing the tension and roll roughness is an effective measure to reduce and eliminate the tension line, and the large tension must be based on a good plate shape.
(5) Opening the seam. Seam is a peculiar defect of foil rolling, which splits straight along the longitudinal direction during rolling, often accompanied by metal wires. The root cause of the seam is the discount on the entrance side, which often occurs in the middle, mainly due to the loose middle of the incoming material or the bad roll. Severe slits cannot be rolled, while slight slits crack during subsequent slitting, which often results in a lot of waste.
(6) Airway. During the rolling time, strips of crushing occurred, the edges were in a droplet-shaped curve, with a certain width, the light airway was not crushed, and it was white strips with dense pinholes. Dense pinholes at the front and rear ends of crushed aluminum foil are the main indicators for judging airways and other defects. The air channel is derived from raw materials, and it is very important to choose a material with low air content as the aluminum blank.
(7) Coiling defects. Coiling defects mainly refer to loose coils or internal looseness and external tightness. It is ideal to obtain a tight inside and outside roll, and sufficient tension is the condition to form a certain tension gradient. The inner loose and outer tight coil will form a horizontal edge, while the loose coil will form an ellipse, which will affect later processing.
Although there are many types of aluminum foil rolling defects, the final main manifestations are: pinholes, roller holes, slits, and air passages characterized by holes; oil stains, uneven gloss, vibration marks, tension lines, and water characteristics characterized by surface conditions. Spots, bright spots, bright spots; plate shape, wrinkles, discounts, and poor coiling that affect the subsequent processing; thickness differences characterized by size. In fact, the unique defects of aluminum foil are only pinholes, and there are also several other defective plates, but the severity of the performance or the requirements are different.
