Impact of cross-lapping angle and needling parameters on mechanical and functional properties of nonwoven air filter fabric

This research work investigated the influence of the cross-lapping angle in combination with punch density and stroke frequency on structural characteristics and properties of nonwoven fabric. An attempt has been made to change the cross-lapping angle by keeping the number of layers constant to maintain the same areal density of fabrics. The fibre orientation in the carded web was measured by using Lindsley and image analysis methods. Three variables, that is, cross-lapping angle, punch density and stroke frequency, were considered for the sampling plan to create a three-factor three-level Box–Behnken design. The properties such as mean flow pore size, bursting strength, filtration efficiency and pressure drop were evaluated and analysed in the light of fibre orientation in the carded web. It was concluded that the cross-lapping angle influenced the fibre orientation to a large extent; accordingly, the properties of nonwoven fabric were highly influenced by the fibre orientation.