3.1 Fabric density

Fabric density increases with increase in depth of penetration, but punch density does not have any significant influence on the fabric density. A decrease in fabric thickness with increased depth of penetration is observed, due to Parameters Needled fabric Multilayered needled fabric the reorientation of fibres and the greater pressure exerted on fibres remaining in horizontal plane by the fibrous arcs between adjacent tufts as they are pulled further into the web. This causes compression of the web and increase in fabric density. Fabric density is highest for the multilayered needled fabric and lowest for the needled fabric, because more number of fine fibres at the surface are pulled deep into the structure leading to increased compactness. The fabric density increases significantly after calendaring for needled fabric samples, but fabric density decreases after calendaring for multilayered needled fabric samples, as shown in Figure 1(a).

3.2 Air permeability

Air permeability is not at all influenced by punch density but slightly increases with increase in depth of penetration. Multilayered needled fabric shows significantly lower air permeability as shown in Figure 1(b), because of increased compactness of the fabric. The air permeability decreases after calendaring for needled fabric, and increases after calendaring for multilayered needled fabric.

3.3 Breaking force

Breaking force increases initially and then decreases, as depth of penetration or punch density increase. Multilayered needled fabric shows lowest breaking force, however no clear cut effect of calendaring is observed on the breaking force of the fabric as shown in Figure 2 (a).

3.4 Breaking elongation

Breaking elongation decreases with increase in depth of penetration and punch density. Multilayered needled fabric shows significantly lower breaking elongation as shown in Figure 2 (b). Calendaring has a different effect on breaking elongation for needled and multilayered fabrics, breaking elongation decreases after calendaring for needled fabric and slightly increases for multilayered fabric.