Page 110 - Industrial Cutting of Textile Materials

Manual cutting of textile materials 97

(A) (B) (C)
Fig. 7.18 Shape of cutting devices: a straight knife (A), a band knife (B), and a round
knife (C).

However, it should be noted that decreasing the width of a straight- or band-knife
blade causes the device to become blunt more quickly.

7.4.3 Movement of the cutting device

The maximum compression of a spread in the work zone of a cutting device has to be
ensured to reduce displacement of fabric plies during the cutting process. During the
manual cutting process, fabric plies are pressed together by a continuously downwards
moving cutting device and a presser foot acting directly in front of the knife.
The cutting device of a band-knife machine is a sharp metal band that creates a
moving circle during the work process. Its continuous downward movement and
the friction between the knife and fabric plies ensure compression of the plies (see
Fig. 7.19). This further enhances the superior precision of a band-knife machine over
other manual cutting machines.
A round-knife machine also ensures optimal movement of the cutting device.
A round blade is fixed on an axis and continually rotates towards the cut material. This
compresses the fabric plies in the work zone of the knife (see Fig. 7.20).

Band knife
Fabric plies

Fig. 7.19 Movement of a band knife during cutting.