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Automated cutting of textile materials 141

time to cut through the material. Abrasive water-jet cutting gives good tolerances and
surfaces but slightly conical cuts. The abrasive water jet is a well-established method
and a good alternative/complement to laser and plasma cutting. The advantages of
this type of system are the use of lower pressures, very high material removal rates,
and less expensive equipment. The slurry system is less precise and therefore is more
commonly used for rough cutting processes where a high rate of material removal and
cool cutting is important.
The main parameters of the cutting process are the water pressure (between 1300
and 6000 bar), the diameter of the water jet, the water speed, the distance between
the nozzle and the cut material, the minimum cutting kerf width, and the processing
accuracy.
The most important application of water-jet systems is for the cutting of ceram-
ics, stone, and metals of greater thickness. The main advantage of water-jet cutting
over other methods is the fact that it is a cold cutting technology (maximum tempera-
ture 50°C). In contrast to thermal cutting technologies by laser (see Chapter 10) and
plasma, water-jet cutting does not cause any thermal stress in the material. Therefore,
materials that are heat-sensitive or resistant to conduction and reflection have to be cut
by water jet. Unlike metal cutting devices, a water jet does not require sharpening and
cannot overheat. Water-jet cutting is an environmentally friendly and future-oriented
method to cut materials of almost all kinds. No chemical pollution forms during the
process. No hazardous fumes, splashes, or molten by-products are created, so there is
no need for additional investment in processes such as gas absorption, refining, and
filtration. As the jet is very thin, the cut contours are accurate and of high quality.
Water jet can cut fibre-reinforced materials, reflective materials, uneven surfaces, and
stacked layers of different materials. The cost of water-jet cutting systems is less than
that of laser cutting machines.
The disadvantages of water-jet cutting systems are as follows: limited thickness for
cut materials (processing is economical for materials between 10 and 50 mm thick),
time-consuming, and uneconomic cutting of hard materials; large quantities of cutting
waste occurring during an ‘abrasive’ water-jet process; high levels of noise during the
cutting process; and personal safety equipment of protective safety glasses, ear protec-
tion, and protection against contact with the high-pressure water jet that are necessary
when working with these systems.

9.4.2 The use of water-jet systems for cutting textiles
‘Pure’ water-jet cutters are used to cut soft materials such as paper, foam, plastic, rub-
ber, leather, composites, and textiles. Ordinary tap water is pressurized to ultra-high
levels (up to 6000 bar) and forced through a small orifice in an industrial jewel to form
an intense cutting stream. The jet stream moves at a speed of up to 2.5 times the speed
of sound.
A water-jet cutting device is fixed on the gantry of a cutting system. CAD/CAM
software combined with CNC controllers transfer drawings into a programmed path
for the cutting head. The control software then directs the cutting device in the work
area in a linear motion in vector mode. The machine can be equipped with one or more