Voith Introduces EcoCal HiBulk – a New Approach to Bulk‑Saving Calendering for Board Producers

Voith has launched EcoCal HiBulk, a new calendering solution designed to help board producers reduce fiber consumption while maintaining surface quality and mechanical strength. The technology has been successfully tested under production conditions at a leading European papermaker and marks an important step forward in bulk-saving calendering.

In board production, surface smoothness and bulk traditionally stand in direct conflict. Improving printability through calendering often leads to higher sheet compression and a loss of bending stiffness. EcoCal HiBulk addresses this challenge through targeted condi-tioning of the paper web prior to the calender nip, allowing surface properties to be improved without excessive compaction of the sheet structure.

“The key is not to force smoothness through higher pressure, but to prepare the paper structure for calendering in a smarter way,” explains Dr. Katharina Blessing-Kehren, Product Manager Calendering at Voith Paper. “EcoCal HiBulk allows producers to enhance surface quality with minimal bulk losses.”

Conditioning the web instead of compressing the sheet

EcoCal HiBulk combines three proven Voith technologies into a single process concept. First, the paper web is cooled across its full thickness using an air-based cooling system (MCB Cooler). Immediately before calendering, the surface layer is selectively heated and humidified with steam (OnQ ModuleCal). The conditioned web then passes through a high-temperature hard-nip calender.

This sequence reduces the deformability of the sheet core while increasing the deformability of the surface. As a result, surface smoothness can be achieved at lower line loads, preserving bulk and stiffness while meeting printability requirements.

Validated under production conditions

The EcoCal HiBulk concept was validated during production trials on a papermachine of a leading European papermaker. The trials confirmed that, with steam application and reduced line load, surface roughness could be lowered while bulk and bending stiffness were maintained at a higher level compared to conventional calendering approaches.

Flexible application for new lines and rebuilds

EcoCal HiBulk is suitable for both new board lines and rebuild scenarios. In cases where cooling or high‑temperature calendering capabilities are already in place, the solution can be implemented with limited additional components, helping to reduce rebuild complexity. For board producers facing rising fiber costs and increasing sustainability pressure, the technology offers a practical way to improve material efficiency while keeping product performance stable.

A step forward in bulk‑saving technology

EcoCal HiBulk builds on more than a decade of development work in bulk‑saving calendering at Voith, including pilot studies and earlier concepts. By combining cooling, steam conditioning and high‑temperature calendering into a stable and reproducible process, the new solution translates long‑standing research into industrial application.

“With EcoCal HiBulk, we are not introducing a theoretical concept, but a solution that has been tested and validated in production,” says Dr. Blessing‑Kehren. “It gives our customers a new option to balance cost efficiency, quality and sustainability in board production.”