Today's automated production processes particularly require sheet metal to be of the ideal quality of smoothness. However, in reality, sheet metal usually has different degrees of deformation after processing. In this article, we will introduce some common sheet metal flatness defects and effective ways to eliminate them.
The most common defect that occurs after the material has been discharged from the rolling mill is coil warping. Although the coils are easy to transport in bulk, the resulting warpage can seriously interfere with subsequent processing – the poor flatness of the material makes it impossible to carry out subsequent precision machining.
Coil warping is common but must be treated
Coil warpage refers to the longitudinal bending of sheet metal material after winding. This defect is common on the coil, and sometimes other defects can occur as well, such as: the narrower coil will have lateral warping, i.e. bending perpendicular to the winding direction; Or twisting, i.e., twisting.
Wider rolls can also exhibit a number of other flatness defects, such as wavy (a waveform bend across the entire length of the web), edge corrugation, unilateral corrugation, and center wrinkle.
In addition to the inherent defects of the raw material, mechanical or thermal effects can also cause stress on the web. But usually these can happen to billets or sheet metal parts, and the cause of these problems is the cutting of sheet metal.
The cutting process can also lead to defects in the sheet metal
To make sheet metal into a product, it must be cut. However, the cutting process has a significant impact on the material. It is well known that common thermal processes such as laser cutting, plasma or flame cutting generate a large amount of heat when the cutting beam hits the material, which creates a large temperature gradient distribution in the material, resulting in stress and edge hardening. Machining such as cutting or punching can also stress the sheet metal.
Defects in sheet metal as well as internal stresses can affect the effectiveness of its machining. This is because during machining, defective sheet metal cannot produce a flatness that meets the required tolerances. Some experienced mechanics may be able to empirically keep material losses to a minimum, but this method is not suitable for automated production where processing is fast and prone to large amounts of scrap.
Leveling eliminates defects and residual stresses
Winding defects and residual stresses in sheet metal can be eliminated by leveling. The leveler levels the sheet metal with the help of leveling rollers, thus eliminating defects and stresses in the material. There are generally two types of leveling equipment: coil levelers are used to level coils, and part levelers are used to level individual parts or slabs. The coil leveler has a variety of processing capabilities, and its adjustable leveling roller can effectively eliminate the defects of the coil.
Leveling has a positive and far-reaching impact on the subsequent process: If residual stresses and defects in the sheet metal are effectively eliminated, the subsequent process, whether bending, milling, or welding assembly, can be carried out more precisely and efficiently, avoiding time-consuming and laborious rework.