SLITTERS AND RE-WINDERS 315
A very common size cuts 40 inches and requires about 2* h.p. for 'handfuls'
of about 4 inches thickness. Smaller sizes are used by stationers, who get their
paper in bulk and cut it into writing and ledger sizes.
Webs, Slitting and Winding.—As more printing and other processes are
being made continuous, the demand for paper in webs or reels in place of sheets
is increasing and likely to increase. For this reason the production of paper
in reels is becoming of more importance in every paper-mill.
A good reel of paper should be evenly and cleanly slit, and run up to the
required size or length with no breaks, cracks on the edges, hard or soft places,
or unequal substance and finish. All these cannot be obtained if the paper is
poorly made and finished, and faults which would not be apparent in paper
cut into sheets become very obvious when it is wound into reels. In the first
place, the wire and clothing of the machine must be in very good order. Ridges
or dirty streaks on the wire, uneven spread of stuff at the slices, worn or scored
couch roll covers, dirty wet felts, badly-cambered rolls, dry felts that have
become worn and thin in the centres, unequal couching, pressing, drying,
damping or finishing are the most usual causes of bad reeling.
Variations in substance are difficult to check, since the machineman is
handicapped by the fact that he must not spoil a web by tearing out and weigh-
ing sheets, and has to keep correct substance by other means* An experienced
machineman will, however, come very near to being exact by keeping in close
touch with his machine. At the end of every reel a piece the whole width of
the machine should be taken and sheets marked and cut from the centre and
both sides, so as to cover all the width of the paper. Damping and drying
should be specially watched, since the success of the super-calender finish will
depend on this being regular all across the web. A slight extra damping at
any one place will produce a higher finish, which will show as a soft pkce
when reeled. This may be easily so serious as to cause the paper to be creased
on the slitter and winder.
Slitters and Winders.—These are of two kinds, friction and drum winders.
The friction winder has slitter discs, which are identical with the rotary cutter
discs and slit the paper in the same way. Each slit web is wound on a separate
spindle by a friction arrangement similar to that on the making machine. This
is not a very efficient machine, since the tightness of the web depends entirely
on the strain the paper will stand without breaking, so that the webs axe soft
and bulky. They are therefore very liable to damage in transit and become
lopsided on standing or being packed. This causes breaks on the printing
machine, as the result of the jerky motion of the unbalanced reel The drum
winder, as its name implies, winds the web by contact with one or two
cylinders by its own weight, and is regulated by levers at the spindle ends.