WATER JET CONFERENCE - Waterjet Technology Association

hydraulic power required to cut through samples of plain furs and also those containing
some stitches (see Fiq. 8). It was also important to examine the quality of the cuts.
Before the tests could be run it was necessary to hold the fur in tension while
traversing under the jet. The required tension was applied by two rubber bands
incorporated into a clamping device shown in Figure. 7. Experimental data for plain furs
are summarized in table 1 and for furs containing stitches are depicted in Fig. 9. The cuts
made by the water jets (Figure. 8) were as good as those made by the mechanical knives (
Figure. 6) . As is clear from table 1 and Fig. 9, the magnitudes of pressure and power
required to cut through the material were dependent on the presence or absence of
stitches. Since the traverse speed was stated to be of minor importance, the requirements
would be much lower than those reported here. Fig. 9 shows that the pressure decreases
substantially as the nozzle diameter is increased from 0.076 to 0.203 mm. However,
minimum power levels are achieved for nozzle diameters in the range of 0.10 to 0.12
mm. Also, from the standpoint of the amount of water, quality and the spacing of the
cuts, nozzle diameters in this range would be well suited for this application.
Conclusions: The recommendation to the firm was that it is possible to use high pressure
water jets for fur cutting applications. For a typical fur sample containing stitches,
traversed under the jet at a speed of 30.5 cm/sec, the power required to cut through the
sample was approximately 0.6 kW (nozzle diameters 0.1 to 0.12 mm; pressure = 100 to
130 MPa).
3 . SEA FOOD PRODUCTS ( REF . 3 )
There appears to be a considerable interest in processing food products in general
with high pressure water jets ( Ref. . 4 ) . Work reported here had the objective of
determining if water jets had any distinct advantages over the band saws for processing
fresh cod fish, frozen ocean perch (redfish), lobster and frozen cod fish fillets, as limited
work conducted earlier in the laboratory (Ref. . 5) had indicated that it might be
worthwhile to pursue this investigation. Processing sea food products with conventional
methods is highly labor intensive. For example consider lobster . At present meat is re
novel from lobsters by a four-step process (Ref. 6). Lobsters are first boiled whole. This
serves to cook the meat and drive out some of the moisture contained in the meat, thereby
shrinking it. The lobster is then frozen so that the meat solidifies. This is done to make
the meat resistant to mechanical shock. The lobster is then exploded to remove the meat.
The exploding is accomplished by placing the lobster in a vacuum chamber where it
would explode due to the pressure differential between its interior and exterior. The meat
is then separated from the shell. Also, these manual and mechanical operations apparently
involve unavoidable wastage of edible meat. Therefore, the fishing industry is on the
lookout for new methods that would improve the production rates and minimize the
losses. Study of computerized prototype machines incorporating high-pressure water jets
for processing fish is already in progress in some countries (Ref. 7).
Tee requirements (type of cuts, etc) and the outcome of the tests are displayed in
Figs. 10 to 22. A limited number of experimental data pertaining to cutting of fresh cod
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