The trimming group (fig. B), which is the most important part of the trimmer, consists of:
a rotating trimming cylinder (figs. A and B, 8 and fig. 8, detail), called a male, which depending on
of its diameter, it can accommodate from 16 to 32 helical blades of tempered steel placed on it
it screws;
an adjustable blade, called a knife (fig. B, 9 and fig. 9, detail), as long as the cylinder and locked
on the appropriate support (fig. B, 10).
The helical blades of the trimming cylinder, in contact with the underlying fixed blade (knife) create
a contrasting hair cutting point. When the trimming cylinder has completed its rotation, the blade
with a propeller that is fixed to it, it cuts the hair from one selvedge to the other. The helical blades can be
wrapped around the cylinder from right to left or vice versa. On multi-cylinder trimmer machines the direction of the helices
It is alternated to avoid deviations of the patch and to stabilize it in the center.
The fluff produced by trimming is removed by a vacuum cleaner (fig. A, 12).
A pneumatic lift (fig. A, 11) intervenes when the end seam passes.
In addition to the velvet machine and the trimming groups, the following are present:
brushes covered with horsehair (fig. A, 13); the one placed before the group is particularly important
shear which, acting on the reverse, removes any threads or fibres from the surface of the fabric;
feelers, which activate the lifting of the cylinders when seams pass in the wide range;
a thick felt soaked in a special oil that rests on the trimming cylinder, which keeps the helical threads and the fixed blade efficient for longer;
a series of drive cylinders, which carry the cloths to the lapper.
The trimming machine configurations can include: 1) single machine; 2) multiple machines in line; 3)
machines arranged on a chain of different processes (for example, raising and shearing).