What is camber?
In the language of steel, "camber" (or "saber effect" in Spanish) is known as the longitudinal deviation that a sheet, strip or steel strip presents when it is placed or unrolled and placed on a flat surface, showing a lateral curve of the sheet or strip with respect to a straight line, as shown in figure 1.
Origin
This defect originates during the hot rolling of slabs.
After its preheating, the slab is fed to the first section of the hot rolling mill (tandem mill), known as "roughing" where it undergoes a surface roughing through 4 or 5 reversible steps, to then be sent to the rolling section in which, through several reversible steps through rolling rollers, the thickness is gradually taken (rolled) to its final dimension and is rolled up at the end of the rolling mill into a master coil, which has the weight and the approximate width of the original slab (according to the capabilities of the equipment, slight adjustments can be made in the final width of the coil with respect to the initial width of the slab)
During the described processes, the tip and tail of the longitudinal strip "travel" loose, that is, there are no "jaws" or guides that lead the material during the reversible processes of hot rolling, which produces longitudinal tensions that are very difficult to correct and that originate this lateral bending known as "camber" or "saber effect".
Tolerance
The ASTM A480/A480M standard called "Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet and Strip" establishes the general requirements that stainless steel rolled products (plate, sheet and strip) must meet.
Table A2.29 (see figure 2) of this specification indicates the allowed variations in camber for cold rolled products and describes the method of how it should be measured
Measurement
By placing a sample (a sheet or a strip section) 8 feet long (2,438 mm) and placing a cord along one edge of the material; tension it from one end (0 mm) to the other (2,438 mm) of the sample. The camber is the measurement of the maximum space between the edge of the material and the tensioned cord, as shown in figure 3.
Source: ASTM International, American Society for Testing and Materials. “Table A2.29 Permitted Variations in Camber for Cold-Rolled Coil Processed Products in Coils and Cut Lengths”
