Features Research & Innovation
Two-Layer ValFormer Concept For Lightweight Containerboard

Metso has developed a new, cost-efficient two-layer ValFormer forming concept, which makes it possible to produce lightweight containerboard with only one hybrid forming unit. It tackles the boardmakers’ challenges of combining lower basis weights, faster speeds, and higher ash contents brought by the increased use of recycled fiber.

The benefits of the new forming concept include pure layer coverage, considerably lower residual variation in basis weight, as well as excellent formation with no streaks or tiger stripes. Sheet uniformity maximizes the use of the raw material strength potential, enabling the use of more cost-effective raw materials and less starch in surface sizing.

This patented forming concept combines a new ValFlo Pro two-layer headbox and a new VacuBalance vacuum-assisted forming board with the well-proven ValFormer shoe blade hybrid former.

The ValFlo Pro produces an excellent two-layer headbox slice jet quality, which generates a fully homogenized, disturbance-free flow onto the forming section. The VacuBalance vacuum-assisted forming board efficiently absorbs jet impact energy and eliminates stock jump on the forming board. The combination of these two units ensures that board layers will not mix together.

The proven ValFormer shoe and blade hybrid former, in turn, facilitates lower inlet consistencies combined with fast, non-pulsating drainage. The concept enables high speeds up to 1,400 m/min, which are impossible to reach with conventional Fourdrinier or hybrid forming solutions.

The new forming technology is especially suitable for rebuilds since it enables production of two-ply testliner with an existing Fourdrinier. One machine can produce both testliner and lightweight corrugating medium, making the concept a viable alternative to gap forming technology. Another application is a three-ply sheet concept with two existing Fourdriniers.

Metso Pulp & Paper 514-380-2418, www.metso.com