The Voith EdgeSaver trims off the edge of the paper web directly at the headbox. This innovative technology is especially attractive for multi-layer paper machines where the fibers in one of the layers are of a higher quality than those of the others. One of the first machines to use the technology was Smurfit Kappa's PM 3 in Diemelstadt in the German state of Hesse. The company produces kraft top liner, white top testliner, laminated liner and HP fluting on the two-layer paper machine. The EdgeSaver was installed on the PM 3 in April 2013. “One of our most important goals was to save pulp when producing white top testliner,” relates Project Engineer Frederic Jung from Smurfit Kappa.

EdgeSaver is attached to the headbox. It performs the edge cut directly at the headbox, i.e. at a point where the fibers are still single-grade (unmixed). In conventional systems the edge cut of the web is not done until after the individual layers have been couched. As a result, the separated edges consist of a mixture of different fiber qualities and can only be returned to the lower-quality fiber circuit. Through this process, a single paper machine will incur a fiber loss of around 1,000 euros every day. However, if the edge of the premium layer is trimmed by the Voith EdgeSaver directly at the headbox, a flow-optimized return duct conveys the high-quality fibers directly back into the system, thus making them available to the premium layer.

The edge cut can be done at the headbox because EdgeSaver features a specially developed cutting technology allowing turbulence-free cutting of the stock jet. The combination of this special cutting technology with a separate cleaning system also prevents fiber deposits. This is also the case at the PM 3 in Diemelstadt, where the edge trimmings are being returned to white water system 1 since the installation of the EdgeSaver. The new system has been operating smoothly since startup in April 2013.

ROI in less than a year. Variable adjustment of the edge width is a must for a modern edge-cutting system and allows the fiber savings to be calculated precisely, as Frederic Jung explains clearly below: “The EdgeSaver has a variable adjusting option of 0 – 120 mm on both sides of the headbox. The theoretical savings range amounts to around 2.5% of the headbox width. This value results from the outlet width of the headbox and the intake width of the dryer section. Currently we are returning about 1.3% of the headbox width to white water system 1 for the top layer in a process that is both stable and efficient. The 1.3% adds up to a lot of metric tons every month. Thanks to the savings in fiber volume alone, the investment has paid for itself at Smurfit Kappa in less than 12 months.

Better paper and fewer web breaks. A flexibly adjustable side plate provides for better paper quality in the edge area by preventing ridge formation at the web edges and helps produce a more uniform CD profile. In this area too, Smurfit Kappa is very pleased with the performance of the EdgeSaver. Its third significant benefit is the separate cleaning system that ensures efficient cleaning of all components and prevents deposits on the web that can cause web breaks.

The EdgeSaver is already successfully in operation at six different paper manufacturers, while another nine have been ordered and will shortly be commissioned. Voith EdgeSaver can be installed on all headbox models from Voith and other manufacturers. The system can be readily installed during a routine shutdown.//

Benefits of EdgeSaver at a glance

• Optimized use of fibers saves several metric tons of virgin fibers every day. As a result, consumption of additives, energy and water is also reduced.
• The investment pays for itself in just a few months.
• A teflon side shield prevents ridge formation on the paper edge and the CD profile is more uniform.
• A specially developed cleaning system prevents deposits on the components.
• The wire edges stay clean and as a result there is a substantial reduction in the number of breaks.