Page 153 - Industrial Cutting of Textile Materials

140 Industrial Cutting of Textile Materials

9.4 Automated water-jet cutting systems

The first concept for a high-pressure water-jet cutting system was patented in 1968.
It was created by N. Franz who proposed to cut materials with water pressurized to
700 bar. In 1971, a more effective cutting system with a much higher water pressure
(4000 bar) was invented. Unfortunately, the low rate of material removal did not permit
the cutting of metals. This problem was solved in the early 1980s by adding particles
of solid material (cutting sand or garnet) to the jet of water. This so-called ‘abrasive’
process made it possible to cut and drill extremely hard materials. The water-jet cut-
ting process is used for cutting steel, stones, tiles, glass, plastics, wood, aluminium,
and paper. It can also perform drilling, ablation, and tapping operations.

9.4.1 Characteristics of the water-jet cutting process

The cutting operation is performed by a very thin jet (3) of pure water (1) or
water-abrasive mixture (6) that is forced at high speed through a tiny hole in an indus-
trial sapphire or diamond (2) (see Fig. 9.27A). Two types of water-jet cutting methods
are distinguished, pure water-jet cutting and abrasive water-jet cutting.
The widely used ‘abrasive’ water-jet process is started in the same way as with a
‘pure’ water jet. The difference lies in the manner in which the abrasives are added
to the water. An entrained system pressurizes water and pulls abrasive particles (5)
into the rapidly moving stream at its exit (see Fig. 9.27B). As the thin stream of wa-
ter leaves the jewel, abrasive is added to the stream. The jet of water accelerates the
abrasive particles, enabling them to cut through much harder materials (4). An abra-
sive slurry system mixes water and abrasive (6) before the water is pressurized (see
Fig. 9.27C). The abrasive jet stream works by particle erosion; therefore, it takes some

1 1 6

2 2 2

5

3 3 3
4 4 4
(A) (B) (C)
Fig. 9.27 Water-jet cutting process with a pure water system (A), an entrained abrasive system
(B), and an abrasive slurry system (C). See text for explanation of components.