Cartonboard machines

Cartonboard is a product with a wide range of basis weight of about 160 to more than 600 g m . Cartonboards have the highest share, about 80%, of the total paperboard production. Cartonboard is mainly used for production of carton boxes to 

In suction formers 3 to 11 cylinder formers in series with suction chambers produce webs of about 25 to 100 g m each which are couched on a transfer felt, thus building up the baseboard. The maximum speed is about 350 m min , the maximum width is about 5 m. Cylinder formers without vacuum appHcation are limited to a maximum speed of about 150 m min  

As the fourdrinier vtire sections have sufficient speed potential gap formers are seldom used in cartonboard production. Nevertheless gap former installations can be found for certain applications of specialty board like gypsum board. 

The dryer section consists of up to 100 drying cylinders in the pre-dryer section and about 15 in the after-dryer section. One or two single-tier groups are followed by double-tier drying groups. For good flatness of the finished product the top and the bottom cyhnder rows are heated separately to control curl tendency. 

Starch or size can be appKed in a film press or a pond size press to enhance surface strength and bending stiffness. In this case an after-dryer section is required for baseboard drying. 

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The cartonboard caliper, particularly the consistency, is more critical than for hand cartoning as it affects the pre-break of the carton and once a machine is set to open pre-break there is little tolerance for variation. The faster and more sophisticated machines need tight tolerances. 

Creasability of boards BS 4818 1993 described the method of determining the creasing quality of cartonboard within the range of 300-1000 4m. This is important to the packaging line, since if the creases are not correct and do not assist the carton erection, the cartoning machine will not function correctly. 

Virgin-fiber based cartonboard is mainly double coated on the top side and uncoated or single coated on the back side. White-Hned chipboard made of recycled fibers is mainly triplespecial tasks and coating formulations. Coating is done by roll appHcators or by free jet applicators for highest surface requirements and machine speeds. 

Final cartonboard post-calendering is mainly done with soft-nip calenders. The Pope reeler can be used for reeling up to 3.5 m diameter, reelers with center torque are applied for diameters of up to 4 m. A state-of-the-art board machine (Fig. 6.83) with on-Hne coating and final calendering has a length of up to 350 m. 

Artificial chromo hoard, triplex hoard, a gray core can also be used in this case. Other machine-made boards in the cartonboard group include ... 

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