At Cltech in Kaiserslautern, Minda built a complete cross-laminated timber factory – from the raw wood infeed to the sanding machine © CLTech
When you enter Cltech’s new cross-laminated timber factory in Kaiserslautern, you can see that a carpenter is in charge there. Lots of light, lots of wood and an extraordinary roof structure with thin oak logs characterize the new production halls.
Just six years ago, Jürgen Gottschall was “only” running a timber construction company, which he took over from his father in 2006. Despite – or maybe because of – the increasing number of orders in recent years, the company faced major challenges, including the shortage of skilled workers. For Gottschall, the way out of this dilemma was a much higher degree of prefabrication in combination with the creation of the best possible working conditions for his employees. To achieve these goals, he founded the company Cltech in Kaiserslautern in 2018 with the mainstays of timber engineering, timber frame construction and mass timber construction with cross-laminated timber.
Since then, a 4,500-m²-big wooden hall with two-axis glulam supports and crossbeams made of BauBuche has housed Cltech’s production, which focuses on the highest possible degree of prefabrication in timber frame and mass timber construction. Compared to work on the construction site, the production hall offers more controllable framework conditions and a much more comfortable working environment, which is also clearly evident in the number of staff. The company started out with only eight employees. Today, Cltech employs 75 people. In addition to Gottschall’s own carpentry shop, Cltech also supplies joinery projects of all kinds to wholesalers.
Focus on creating added value
Cltech’s plant manager Tobias Frank (left) and Minda’s authorized officer Hubertus Zeddies inside the new, jointly developed CLT factory © Günther Jauk
When CLT prices soared and lead times became longer and longer in 2020, it became increasingly difficult for Cltech to secure its supply of raw panels. “There were times when we had to source our panels from the Baltic States. When we found out that the lumber for those panels came from Russia and the log wood from China, we just had enough,” master carpenter and authorized officer Tobias Frank says about one of the reasons for building an in-house CLT factory.
“However, we didn’t want a high-performance factory with a capacity of 100,000 m³ a year, but a plant that meets all of our requirements and is also resource-efficient in the use of the raw material wood. Our strength doesn’t lie in quantity, but rather in the high added value and the numerous additional services that set us apart from many competitors,” Frank says, outlining the requirements profile of the new factory. “We visited many CLT production sites and in every one of them, we saw things that we wanted to do differently – and that’s exactly what did in the end,” he adds.
Minda Industrieanlagen, Minden/DE, was chosen as the main supplier and took all of these wishes into account in the joint planning process. In certain areas, the plant specialists rely on long-time partners, with whom they have already successfully carried out several projects, and include their components in the overall plant design. In addition to finger jointing machine manufacturer Howial, with whom Minda already has an official cooperation, partner companies also include Microtec and Oest Maschinenbau, for example.
Fully automated
Minda included a generously sized lamella curing storage area in the plant design © CLTech
The plant installed by Minda starts with three infeed stations for the sorting line, which are directly connected to a dry storage area for up to 2,500 m³ of lumber. While a vacuum lifter lifts layer after layer from the raw lumber packages, the stacking sticks in between are automatically removed. After passing through a curvature measurement unit implemented by Microtec, the lamellas move downwards and in longitudinal transport towards Microtec’s Goldeneye scanner via an assessment wheel, which also enables the manual assessment of the wood. The scanner identifies defects, which are then marked and subsequently cut out.
Next, the pieces enter the Duozink finger jointing machine, which Howial developed specifically for the medium performance range, while retaining the advantages of a compact machine. The minimum input length is 900 mm, and the company estimates the maximum cycle output to be 15 joints per minute.
Tried-and-tested plant technology
The Timber Press E416 pro produces longitudinal single-layer panels with hotmelt glue and makes it possible to avoid cutouts © Günther Jauk
A lift system transports the freshly finger jointed lamellas to a spacious multi-level storage area for curing. “To be on the safe side, we secured the entire storage area with a metal grid at the bottom. This involved a lot of work but is essential in order to guarantee our customers the best possible performance as well as the highest safety standards,” Minda’s authorized officer Hubertus Zeddies says, referring to one of many implemented detailed solutions, which also give a good idea of the company’s philosophy. From the curing storage area, the lamellas pass through a Rex planer, which also rip-cuts them lengthwise if necessary. “This gives us even more flexibility in terms of panel width,” Zeddies says, explaining this additional function.
In the next step, a Minda Timber Press E416 pro joint gluing station produces longitudinal single-layer panels by bonding the narrow edges with hotmelt glue. The mechanization then transports some of the longitudinal layers directly to one of the seven buffer spaces of the laying station. The other panels are rip-cut, turned by 90° and reassembled as crosswise layers, which then also enter the buffer zone in front of the laying station. A vacuum lifter lays the press cake, and an Oest gantry applies the PU adhesive. After that, the panel moves into the Timber Press X 100 pro CLT press for elements which are up to 16 m long and 3.5 m wide. Here, the main pressing pressure is applied vertically.
Avoiding cutouts
What makes the pro version of the Timber Press X 100 so special is its ability to press panels with openings for windows and doors which were already created during the production of the single-layer panels. This concept developed by Minda involves a special production process: The lamellas for the longitudinal and crosswise layers are produced and positioned in such a way that the openings for windows and doors are taken into account right from the start. Already during work preparation, the required lamella pieces are calculated according to the position and size of the openings and grouped into multiples of the same length that can be produced effectively. Once they have left the curing storage, the lamella pieces can be cut to size, positioned and glued to form longitudinal or crosswise layers.
This way, the lamellas, which are not necessary in places where there will be openings for windows and doors, are not manufactured during panel production in the first place, which has several advantages. In addition to saving raw wood, fewer meters of lamellas have to be produced in the finger jointing machine. This results in a higher overall plant capacity, and it also gives Cltech advantages in the joining process.
“Our newest Hundegger machine, a PBA-Drive 3600, machines all cutouts, and when there are no window and door cutouts, we save a lot of machining capacity during the joining process,” Frank says, adding in conclusion: “Minda delivered a plant that uses the valuable raw material wood in an extremely efficient way and also perfectly meets all of our other requirements.”
