Log sorting line for 1 million m³

Holtec was entrusted with the log yard following the positive experience Holzindustrie Rettenmeier had with the company at its Ramstein site, where the log yard’s infeed system had been modernized. “The project impressed us with its smooth processes, intensive support during the offer phase, and a well-thought-out plant design. Those were the decisive factors for renewed collaboration,” Alexander Gebele, Holtec’s managing director, said during the on-site plant tour.

Separation and quality grading

Rettenmeier Baltic Timber processes pine and spruce. From the infeed deck, the logs are transported via step pushers and feeders on the cross conveyor to two sorting decks. The decision to use two lines has several advantages. Truck delivery logistics are made easier because log deliveries are divided into two areas. This significantly increases the availability of logs. Furthermore, the two lines can operate independently of each other.

Maximum availability

Holtec has installed high-end sensors above the control decks. There, they are protected from soiling. “Each sensor replaces eleven of the usual light sensors,” Gebele explains. “They help increase the plant’s availability.” The high-performance sorting line is continuously fed, ensuring high volumes with maximum plant availability.

On the two sorting decks, rollers first align the logs. Each log is rotated by 360° once to inspect the entire surface and assess its quality. The dimension and type of wood are detected and recorded automatically.

As is customary in the Baltic States, the visual quality assessment is carried out by two employees of the VMF Latvia grading association. The ergonomic operator seats are positioned in a way that both of those employees have eye contact.

A house for the log team

The log reception in Inčukalns is not a “booth” like those commonly found in Central European log yards. In Inčukalns, it is actually a house where every member of the log team has their own workspace – and the house also has lounges, a kitchen, and a meeting room.

Everything taken into account – now or never

The goal of automatically cleaning all machines was achieved here as well. A scraper conveyor under the sorting decks removes bark and other pieces of wood. “All of this has to be taken into account from the beginning – it can’t be done later,” Rettenmeier's Chief Technology Officer, Paul Schmid, explains.

The logs’ butts are reduced using a Baljer & Zembrod machine. After that, star allocators and feeders move the logs to the debarking line. A Logrunner accelerates the logs, which are measured using X-ray technology. Logs that cannot be sawn are removed in front of the debarker.

Integration of existing technology

Both lines are equipped with a single-rotor Valon Kone debarker. Holtec integrated an existing machine into the new plant. This did not impact overall performance and, at the same time, it was not necessary to purchase an additional debarker, which significantly reduced investment costs.

After debarking, the logs that come from the two lines are transported to the sorting line via cross conveyors, buffers, and feeders. Holtec is convinced that this decoupling prevents unnecessary gaps on the line, thereby increasing capacity utilization.

Sorting line and bin allocation

Another Logrunner accelerates the logs onto the 350-m-long chain conveyor. Thanks to the integrated Gap Control, gaps between the logs are defined. Round ejectors then sort the logs into one of 108 bins with high accuracy.

Assembly and acceptance

The machine components were supplied by Holtec and temporarily stored on-site. Assembly began in July 2023 and went as planned. A short while later, the first logs passed through the plant, and acceptance followed without delay.

“The result is impressive. The plant combines all typical Holtec machines into a coherent overall layout. This is reflected in its performance, flexibility, and plant availability. The buildings, which have been tailored to the machines, also contribute to an impressive overall impression,” project manager Thomas Schick emphasizes.