Challenge CMT 330, Installation And Operator'S Manual

Page: 64 / 68

APR 2018
CMT-330 Three Knife Trimmer 5-2 5. Book Quality
5.1 Burr Marks
Description
Burr marks are found on books cut with a knife
whose cutting edge has been burred. Figure 5-1
illustrates the appearance of burr marks.
Figure 5-1. Burr Marks
Possible Causes
1. Burrs on knives can occur from im-
proper knife handling.
2. Burrs may also occur from cutting hard,
irregular materials.
Solutions

If the any knife is burred, replace all
three knives and maintain as a set.
CAUTION
All three knives must be sharpened as a set.
Damage to the cut plates may result from using
knives sharpened separately.
5.2 Jagged Bottom Cover
Description
Books can appear as though the bottom few
sheets and cover were torn apart rather than
sharply cut. Tearing of the bottom sheets and
cover occur when deep score marks develop in
the cut stick or cut plates. The cover is pushed
into the score mark, folded over and torn.
Figure 5-2. Jagged Cover
Possible Causes
1. The knife may be dull.
2. The cut stick/cut plates may be worn.
Solutions

If the problem is on the face of the book,
the cut stick may need rotation or re-
placement. The knives may also require
replacement.

If the problem is on the top or bottom
faces of the book, the cut plates may
need rotation or replacement. The
knives may also require replacement.
5.3 Burr Marks/Jagged Cover
Description
A jagged bottom cover may also accompany
burr marks. A burred knife may not fully cut into
the cut stick or cut plate. As a result, it will leave
a jaggedly cut bottom cover.
Figure 5-3. Burr Marks/Jagged Cover
Possible Causes

The knife is burred, and the cut stick/cut
plates are worn.
Solutions

If the problem is on the face of the book,
replace the knives. Rotate or replace
the cut stick.

If the problem is on the top or bottom
faces of the book, replace the knives.
Rotate or replace the cut plates.