D. Folding 1. Types of Folds Typically, there are only two basic types

D. Folding 1. Types of Folds Typically, there are only two basic types
D.
Folding
1. Types of Folds
Typically, there are only two basic types of folds: parallel and right-angle. Products
containing parallel folds consist of folds that run parallel to each other. Right-angle folds
are folds that run perpendicular to each of the preceding folds.
Common Parallel Folds
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4-Page Standard / Single / Half
6-Page Standard / C-Fold / Business Letter
6-Page Standard / Gate
6-Page Accordion / Z-Fold
8-Page Parallel Map
8-Page Reverse Map
8-Page Parallel / Roll
8-Page Accordion
8-Page Double / Double Parallel
10-Page Accordion
16-Page Parallel Booklet
Common Right Angle Folds
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8-Page Booklet with 2 Right Angle Folds (French Fold)
8-Page Right Angle - First Fold Short
12-Page Letter
12-Page Broadside - First Fold Short
16-Page Broadside
2. Types of Folding Equipment
A variety of different folds are now being accomplished on many different shapes and
sizes of printed materials. Paper and other substrate products can be folded either in-line
during the production of the printed piece or off-line on folding machines ranging from
free standing table-top folders to high speed production floor models.
In-line folding is generally best for large quantity products. Folding inline may result in
lower press speeds, however the reduced speeds are accepted for the economies gained. It
eliminates the additional cost of folding the product with an offline process. In-line
folding is limited to only a few types of products and a few types of folds. Off-line
folding or bindery folding provides the greatest number of different folds on high-speed
machines referred to as knife folders, buckle folders or combination folders.
A knife folder is used primarily for booklet work due to the accuracy that can be achieved
when producing right-angle folds, keeping the pages in close registration. A blunt steel
blade pushes the internal part of the paper at the desired location between two rollers to
create the fold in the material. The knife folder is a slower speed folder, but as stated,
more precise on the folds.
A buckle folder, the most common
type of folder, uses a set of guides
and plates with a "backstop" to
buckle the paper and create the
fold. The document enters through
a set of rollers and into a plate
where the paper strikes a backstop
as shown in the illustration at the
right.
When the paper strikes the
backstop, it buckles and is forced
downward and into a set of nip
rollers.
The nip rollers grab the sheet at
the buckle and pull it through,
compressing a fold into the sheet
as it passes through the rollers. If
several folds are desired, then the
material is sent into another plate
to repeat the process. The fold or
buckle location is adjustable by
altering the stop mechanism. This
allows for different folds to be
created depending upon the type of
fold required.
A combination folder, as the name implies, provides both close registration and a higher
speed for folding. The combination folder is used most often for large quantities and
more complex folding jobs.
3. Paper Grain
The paper grain direction has much to do with the quality of the fold. Paper that is folded
parallel with the grain of the paper will fold much more cleanly. A cleaner fold is
produced because the paper fibers (grain) are running in the same basic direction as the
fold. Only a few of the fibers provide any resistance to the folding action, which results in
a high quality fold.
When a fold is applied perpendicular to the grain of the paper, the resulting fold may
have a ragged appearance. A ragged fold is produced because all of the fibers are folded
at one time creating resistance to the folding action. The ragged appearance of the fold is
especially noticeable when folding heavy stocks.
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