Page 175 - Industrial Cutting of Textile Materials

162 Industrial Cutting of Textile Materials

10.4.7 Distance between the cutting nozzle and cut material

The cutting quality depends on stand-off distance – the distance between the cutting
nozzle and the cut material surface. The smaller the distance, the more air pressure is
applied to the cutting gap, and more cutting emissions are blown out of the gap. If the
distance is increased, the air pressure applied to the cutting gap decreases, and less
flammable gases are blown out so that there is more build-up of smoke. However, for
some materials, increased distance between the cutting nozzle and the cut material
surface creates smoother cut edges. The optimal distance should be determined for any
certain material and desired cutting results – wide or thin kerf, big or small radius of
inner contours, smooth or rough cut edges, and others.

10.5 Gantry laser cutting systems

Large-format gantry laser cutting systems have similar design, work principles, and ap-
plication as automated knife cutting systems in processing textiles. They are used for
through cutting, engraving, and marking mostly wide materials and large work formats,
rarely for narrow textile materials (for laser cutting of narrow lace, see Chapter 17).
The gantry laser cutting systems are also good in applications where a large number of
small-size components are joined in a matrix to process them by the machine one by one
in rows or columns. The gantry laser cutting systems are not limited in size of a cutting
surface can ensure high precision, repeatability, automation capabilities, and flexibility.

10.5.1 The main work principles of a gantry laser cutting system
The main parts involved in the work process are a cutting head and a carriage in which
the cutting head is fixed, a gantry (crossbar, beam, and cutting bridge) that carries the
carriage across the cutting surface, a working surface, a control panel to control the
cutting process, and a nesting and cutter control software.
With the help of servomotors and belt-driven gantry, the cutting device can operate
in large work area. In performing through cutting, the laser beam in fixed power is
following the contours of cut components in vector mood. Cutting of the individual
components is carried out in a single work step. When performing work process on the
conveyor table, the software recognizes if some of the individual components do not
fit fully onto the processing table due to the arrangement of the cutting contours. These
components are not cut until they have been completely moved onto the processing
surface. This prevents any continuations of cutlines that could give bad cutting quality
at interruption places. Vector or raster mood and changing laser power are used to
engrave or mark the surface of textile material (see Section 10.2.2.3).
The work process is performed on static or conveyorized tables with grid kind of sur-
face (see Section 10.3.1.2). The textile material can be fed on the cutting table directly
from its roll by help of a special unwinding device that ensures tension- controlled fab-
ric tracking during its advances (see Section 9.3.3). The optical sensors ensure precise
material alignment with the edge of the table. For engraving and marking rolled mate-
rials, special device is used to roll up treated material immediately after its processing.