Simulation of initial fibre retention by a forming fabric

Formation of the paper sheet on the forming section of the paper machine is a critical point in the papermaking process. Fibres interact with the form ing fabric such that the fabric design influences retention, formation and some other paper properties. A software application called CyberFab has been developed to simulate the s tructure of the forming fabric in 3D. Every design currently used can be si mulated from single layer to triple layer. Diameter and mesh count of each yarn are inputs used to `build' a fabric. Moreover fabric characteristics a re computed. Characterisation includes Fibre Support Index (FSI), void volu me profile, hole analysis and wear index. A new fabric can be simulated in order to quantify its advantages compared with existing designs. The model developed includes not only the characterisation of the forming f abric but also its interaction with the fibres. The mechanical retention of the first fibre has been studied depending on its position, orientation, a nd angle with the machine direction. A global value is compiled, based on t he conditions tested, which gives a global probability of retention for the first fibre.