Roll slitting

Roll slitting is a shearing operation that cuts a large roll of material into narrower rolls. There are two types of slitting: log slitting and rewind slitting. In log slitting, the roll of material is treated as a whole (the 'log') and one or more slices are taken from it without an unrolling/re-reeling process. In rewind slitting, the web is unwound and run through the machine, passing through knives or lasers, before being rewound on one or more shafts to form narrower rolls. The multiple narrower strips of material may be known as mults (short for multiple) or pancakes if their diameter is much more than their width. For log slitting, the machine used is called a paper roll saw, which typically uses a circular saw or band saw to cut rolls into narrower ones. For rewind slitting, the machine used is called a slitter rewinder, a slitter, or a slitting machine – these names are used interchangeably for the same machines. "Slitting" refers to the process of industrial cutting the material web in a lengthwise direction, while "cutting" refers to both lengthwise and crosswise cutting operations. The roll slitting machine is called a slitter or slitter-rewinder, rather than a cutter, due to this distinction. For particularly narrow and thin products, the pancakes become unstable, and then the rewind may be onto a bobbin-wound reel: the rewind bobbins are much wider than the slit width, and the web oscillates across the reel as it is rewound. Apart from the stability benefit, it is also possible to put very long lengths (frequently many tens of kilometres) onto one bobbin.