High Efficiency Gapformer For Mini Mill Applications, 1995 Papermakers Conference Proceedings

Dr. Thomas W. Elenz Voith Sulzer Papiermaschinen GmbH Dipi.-Ing. Thomas Schaible Visy Paper PTY. LTD Gapformers are state of the art for the manufacture of printing papers and will also be the technology of the future for producing packaging grades because of their superiority over fourdriniers as described in the following. A second roll-blade gapformer with a two-layer hydrau-lic headbox was started up in August 1994 as part of an extensive rebuild of PM 6 at Visy Paper, Sydney/ Aus-tralia. The objectives were to produce testliner with two different furnishes for top and base layers at high speed whilst ensuring excellent paper properties as well as minimum production costs. These objectives have been fully reached. The rebuild also gave the chance to compare results of two different forming technologies: conventional four-driniers and gapformers. Paper properties such as burst, CMT and Scott plybond have improved by 5 to 10% despite a reduction in starch consumption at the size press of 50%. Paper profiles in machine and cross machine direction have improved dramatically and specific flow to the headbox has decreased by approx. 20%. In addition, the length of the gapformer is ten meters shorter than the old fourdrinier. Despite this, production capacity has increased by 30 %.