Controls for high paper quality in machine direction
OnQ GradeControl is a system for multi-variable control of basis weight, moisture, coat weight and ash content. It ensures the stability of the quality parameters in machine direction.
OnQ GradeControl can be used multi-functionally. In the case of a machine with several plies, it controls the individual material strands according to the requirements of the finished product. During the startup of an offline coater, the amount of broke in the paper produced can be kept as low as possible with OnQ GradeControl, since the coater can be accelerated to the minimum production speed as quickly as possible and then accelerated to the final production speed. OnQ GradeControl also reliably controls the parameters of basis weight, moisture, filler content, color and coat weight. With the controls' help the drying performance of the dryer section, and thus the moisture of the paper, is perfectly adjusted. Cylinder dryers, infrared dryers or air dryers of all machine types can be flexibly controlled. The basis weight is controlled by means of the thick stock flow rate into the “short cycle.” Reliable control of the dry weight is also possible during a web break or machine startup. The desired filler content in the paper is set via control of the filler addition into the “short circulation.” In the same way, the chromaticity coordinate of the finished paper is kept constant during production. With coated paper, the amount of coating color is controlled by the contact pressure of the doctor or the blade.
Multi-variable controls of the basis weight, moisture, coat weight and ash content in the paper by OnQ GradeControl can be used at various points along the paper machine and the manufacturing process.