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The influence of forming surface on the vacuum pressure in hydroentangling process

Hydroentangling is a process that uses waterjet curtains issued from a series of parallel jet-heads (manifolds) for entangling and interloping fibres in a loose fibre web carried on a belt or perforated surface. The efficient removal of the stagnant water remaining from each waterjet curtain is crucial for the success of fibre entanglement when the web reaches the next jet-head. In this article, we discuss different methodologies that can be used to calculate the minimum vacuum pressure required for extracting the hydroentangling water from non-woven fabrics. A distinction has been made between hydroentangling on tightly and openly woven screens and different modelling strategies are recommended for each. In particular, it is demonstrated that a one-dimensional flow pattern coupled with available analytical permeability expressions can be used to predict the required vacuum pressure in the case of tightly woven screens. In the case of open woven screens where the flow pattern becomes three-dimensional, numerical simulation is needed for calculating the vacuum pressure required for complete removal of hydroentangling water. We also demonstrated that the vacuum pressure increases by decreasing the fibre diameter or increasing the fabrics' solid volume fractions.