Positive effect on dry weight, moisture and ash content
Whereas CD quality measurements are usually made at the end of the paper manufacturing process, i.e. before winding, the properties of the paper – such as the dry weight, ash content and moisture – are influenced by machine direction mainly in the approach flow system.
The objective is to achieve an optimum stability of the pressures, stock flow rates, consistencies and ash content in the approach flow system of the machine. MD control has great significance particularly when the paper grade and speed of the machine is changed or after web breaks. The physical process model on which the control system is based is decisive. Our deep understanding of the processes is necessary to develop such a reliable model.