New Trends in CD Weight Control For Multi-Ply Applications, 1998 Multi-Ply Forming Forum Proceedings

CD weight control on multi-ply board machines presents many challenges some of which are quite different to CD weight control on single-ply grades. Using conventional technology, there are issues relating to the selection of an actuator controlling, for example, the stiff throat cross section of a cylinder vat machine, or the more easily deformed slice of a Kobayashi type former. Deciding on the ply on which to apply the CD control and the means to obtain the narrowest CD weight resolution are other issues to consider. More recently, there are considerations relating to the new consistency profiling (CP) headbox technology and its application to multi-ply machines.

This paper will review the application of conventional and consistency profiling solutions to CD weight control on several types of multi-ply formers. Strategies to optimize CD weight control with a minimal number of actuators will be discussed. In addition, a new technology that allows the measurement of the individual CD weight profiles on a multi-Fourdrinier machine using a non-scanning measurement technology will be described. Typical improvement in CD weight from the application of selected technology will be reviewed.