Fibre dynamics in the air-laid nonwoven process

Nonwoven manufacturing processes, generally speaking, aim to produce fabric more economically than can be achieved by traditional means of fabric formation namely weaving and knitting. Although all nonwovens are made by assembling fibres into some type of web, there are various ways of producing webs. The most common web forming methods are : carding ( parallel-laid and cross-laid ), meltblown, spunbonded, wet-laid and air-laid. This study focuses on the air-laid web process. The main objective of the reported work is to further develop the understanding of the dynamics of fibre flow in the air- laid web forming process by deriving a theoretical model which relates fibre properties (fineness, length, density) and process variables to fibre movement in the stripping zone of the process. Having read the literature and obtaining the necessary background about fibre dynamics in the air flow, a new theoretical model has been developed which describes the movement of fibres along the teeth of the opening roller and their passage along the channel. This model gives an insight into the general behaviour of fibres when the key process variables (such as air speed, cylinder speed, angle of teeth, length of the teeth,...) are altered. In an attempt to verify the theoretical model, high speed cine photography was used to visualise the flow of fibres through the system. Analysis of photographs gave good agreement with the main theoretical findings of the model in respect of the trajectory of fibres within the stripping zone of the air-laid web forming process