A textbook plant

As part of the replacement and expansion investment, a new EWD saw line was put into operation in 2023 at the largest sawmill in the French-speaking part of Switzerland. Sägewerk Zahnd, a family business, has a total annual cutting volume of 180,000 m³, which it wants to increase to 200,000 m³ a year by 2025. As was the case with EWD, Zahnd also relied on a trusted long-time partner for the wood waste disposal system. Bruks Klöckner and Zahnd have worked very well together for many years, and the Swiss sawmill company is convinced of the machine technology of its German partner. The new plant is designed in a way that it can accommodate future capacity increases.

All sawmill by-products which accumulate in the Zahnd sawmill, i.e. around 250,000 m³ of bark, wood chips and sawdust a year, are transported to the neighboring Enerbois biomass power plant and pellet mill where they are either processed into ENplus-certified pellets or used to generate electricity. In 2023, the pellet production output was 20,000 tonnes.

Same model, new features

The heart of the Bruks line, both of the existing and the new plant, is a DH400 (550) drum chipper with an infeed width of 1,000 mm. The horizontal drum chipper is equipped with a 315-kW motor which makes it possible to process more than 50 stere of sawmill by-products. “As part of the capacity increase, the entire waste disposal system was modernized and is now state-of-the-art,” Josef Keßler, Bruks project manager for the project at the Zahnd sawmill, explains. In addition to the drum chipper, Bruks Klöckner also supplied scraper chain conveyors, conveyor belts, vibrating conveyors, hanging screens and two Tubulators, which are positioned next to each other. The entire shredding technology is manufactured in Germany, while the transport and screening technology is produced in Sweden, at another branch of the Bruks Siwertell Group.

The two 61-meter-long Tubulators transport wood chips and sawdust from the sawmill hall to the containers and silos. In the old existing plant, this task was done by a scraper chain conveyor. “Thanks to the air-cushion technology and a belt speed of up to 130 m/min, the new Tubulators achieve an extremely high conveying capacity with low drive power even in the smallest of spaces, which reduces the overall energy consumption of the plant. Compared to high-maintenance, mechanical conveyor technology, the lack of abrasion in the conveyor channel saves the customer a lot of time for repairs,” Martin Felber, sales manager at Bruks Klöckner, emphasizes. “The plant is identical to the old one, but it is state-of-the-art, as ordered by Zahnd. When it comes to the new drum chipper, we modified and repositioned essential components and included some new features with maintenance- and wear-reducing properties,” Patrick Wicharz tells us. He has been the area sales manager for Switzerland at Bruks Klöckner since the summer of 2023.

These features include replaceable metal strips under the chopping blades or replaceable metal sheets near the counter blades, for example. “In the event of damage or wear, we don’t have to replace the entire rotor. Only individual parts have to be replaced or turned. This increases the service life of the rotor and minimizes downtime and maintenance times,” Wicharz explains.

Quick assembly

“Bruks Klöckner was responsible for the entire planning, delivery, assembly and commissioning of this textbook plant, with the exception of the control system. “We put the entire disposal system into operation within just four months,” Felber says. “Our system is linked to the higher-level control system. With plants of this size, we usually also supply the control system and offer various services as well as maintenance. In this project, though, Zahnd took on this task because the sawmill has its own technical department. We provided detailed functional descriptions based on which Zahnd was able to create its own PLC programs,” Wicharz adds.

“The collaboration with Sägewerk Zahnd was excellent and based on trust already in the planning phase. For example, they filmed the entire sawmill with drones and sent us the 3D data so that we could do the planning in 3D,” Keßler tells us.

Professional collaboration

Sägewerk Zahnd is very satisfied with both the quality of the material used and the service provided by Bruks and praises the collaboration based on trust. “Bruks understood our needs and requirements and implemented them in an excellent way. The results met our expectations. The machines are running reliably and efficiently,” Damien Zahnd, member of the management of the family business, emphasizes. “The collaboration with Bruks was professional and efficient. Clear agreements were made, and all the deadlines were met. Despite the limited time available, everything went very well,” Zahnd says in conclusion.