The Collaborative International Dictionary of English v.0.48:

slitting \slit"ting\ (sl[i^]t"t[i^]ng),
   a. & n. from slit.
   [1913 Webster]

   slitting file. See Illust.
   (i) of sile.

   slitting mill.
   (a) A mill where iron bars or plates are slit into narrow
       strips, as nail rods, and the like.
   (b) A machine used by lapidaries for slicing stones, usually
       by means of a revolving disk, called a slicer, supplied
       with diamond powder.

   slitting roller, one of a pair of rollers furnished with
      ribs entering between similar ribs in the other roller,
      and cutting like shears, -- used in slitting metals.
      [1913 Webster]