Optimal design of a composite fibrous filter media through vertical integration of fibres in needle punched nonwoven

Present research work investigated the vertical integration of fibres by using newly proposed structural indices in needle punched nonwoven fabric. A new methodology was also proposed to measure the orientation of fibre in the Z direction of nonwoven fabric. The colour summarization technique was used to measure the percentage of fibre transfer from different layers and area covered by holes. The influence of punch density, needle penetration depth and stroke frequency on fabric structure and properties was studied and three-factor three-level Box-Behnken experimental design was used for sample preparation. The proposed structural indices provide useful information to explain the mechanism of vertical integration of fibres during punching operation. The bursting strength, mean flow pore size, filtration efficiency and pressure drop were highly influenced by considered punching parameters. A strong correlation was observed among measured properties and structural indices. Finally, punching parameters were optimised to achieve maximum filtration efficiency at minimum pressure drop.