Page 44 - Industrial Cutting of Textile Materials

Principles and methods of textile spreading 31

4.2.3 Safety fabric allowances

The laid material must be slightly longer than its marker. Safety allowances are added
at both ends of the spread. These eliminate a situation in which a prepared spread
becomes shorter than its marker. When a fabric ply is unwound from a roll, its tension
decreases, the fabric structure relaxes, and the ply may contract. In nonelastic fabrics,
the safety allowance is 1 cm, and for elastic material, it is 1.5–2.0 cm. As the first fabric
ply is spread on the underlay paper, the surface of which permits the fabric to shrink,
its safety allowance can be increased to 3 cm at both ends of the spread.

4.2.4 The fabric spreading process
The fabric is spread without tension and an operator smoothes the fabric surface as
each ply is laid (see Fig. 4.3). During the spreading process, one fabric edge is pre-
cisely aligned to the edge of the table, and previously spread fabric plies (see Fig. 4.4)
are aligned to the left edge of the spread. The permitted tolerance is ±0.5 cm. As the
fabric width in different rolls and even within one roll may differ (see Section 2.6.1),
the irregularities in the fabric width are left at the other side of the spread.
Knitted fabric must be unwound from a roll 24 h before spreading to eliminate ten-
sion that may have occurred during the winding process. The relaxation of knitted fab-
ric is necessary to avoid decrease in the size of components after their cutting. Fabrics
with a very high degree of elasticity must be left to relax for up to 48 h.

Fig. 4.3 Smoothening of a fabric surface during spreading process.

Aligned edge Layers of fabric
Spreading table
Fig. 4.4 Alignment of one spread edge.