The number of companies which could draw on the experience of an existing plant when building a new cross-laminated timber factory can be counted on two hands. If you narrow this illustrious circle even further down to those market participants whose experience in producing CLT dates back to the last millennium, even the fingers of one hand are too many. Schilliger Holz is one of those CLT pioneers. The Swiss company has been producing CLT at its headquarters in Küssnacht since 1999 and built Switzerland’s first multi-story wooden residential building, the “Holzhus”, in 1992. Then as now, the company attaches great importance to continuous product development and the highest possible in-house added value.
The company’s portfolio includes lumber and planed timber, beam- and panel-shaped glued timber products as well as wood fiber boards, which will be produced in Switzerland from the accumulating wood chips.
From solid structural timber to CLT
In 2009, Schilliger acquired Klenk’s French site in Volgelsheim. Located directly next to a port on the Rhine, the high-performance site was equipped with a line for large-diameter logs and a chipping-profiling line as well as a planing mill and solid structural timber plant. Ernest, Beat and Roland Schilliger, the fifth generation to run the company, put the cutting volume at 330,000 m³ of log wood per year and shift. “The solid structural timber plant in Volgelsheim was never a profitable business for us, which is why we had been thinking about alternative products for a while,” Schilliger tells us. Eventually, he was forced to start producing CLT at the Rhine site earlier than he had planned. After a major fire at the Swiss headquarters had destroyed the CLT plant in 2017, Schilliger purchased two CLT vacuum presses, which were commissioned within a few weeks and enabled the company to process at least some of the CLT orders. At the same time, the Swiss worked hard to build a new high-performance line in Küssnacht, which went into operation in 2020.
Not a standard plant
Drawing on this experience, Schilliger started planning a new CLT line for the French production site, which now takes the place of the former solid structural timber line. “It was clear to us that the market wouldn’t need another large CLT plant for standard products. That’s why we wanted a plant that would enable us to manufacture other timber construction products, too,” Schilliger says, outlining the basic idea without going into detail. Product quality also played a key role, as the company is known for it far beyond Switzerland’s borders.
Ledinek was chosen as the main supplier. Schilliger emphasizes that a second good plant design was in the running right up to the end, but Ledinek ultimately offered the better overall package.
Numerous possibilities
Specifically, Ledinek supplied a sorting line and a combined production line for CLT, solid structural timber and special products. “This way, we can continue to supply our regular customers with solid structural timber, even though it is certainly no longer the main product for us in Volgelsheim,” Schilliger emphasizes.
The sorting line essentially consists of a Superplan S250-4V for four-sided pre-planing at a maximum feed speed of 250 m/min and a Microtec Goldeneye scanner, which detects wood defects and marks them accordingly. The components installed by Ledinek start with the raw material infeed, where a vacuum lifter lifts the lamella layers and places them on a cross conveyor. At the end of the sorting line, the lamellas can either be stacked and discharged or positioned directly in one of the three storage spaces in front of the optimizing cross-cut saw and the finger jointing machine. According to Ledinek’s sales representative Jaka Bradač, the maximum possible cross-sections of 85 x 260 mm are a special feature of the sorting line, which enables Schilliger to also easily sort raw wood for solid structural timber.
For large cross-sections as well
Ledinek developed the X-Cut S400 L optimizing cross-cut saw in use at Schilliger specifically for high-performance lines which also process elements with large cross-sections of up to 320 x 100 mm. The saw’s maximum feed speed is 400 m/min. A high-performance Kontizink 2500 cycle press with an average nominal throughput of 2,500 m/h guarantees the required finger jointing performance. According to Bradač, this machine can even achieve 3,000 m/h as well. For the next phase of expansion, space has already been reserved for another machine of the same type. A contactless application system is used for gluing the finger joints together with PU adhesives, which are also used for surface gluing. Behind a curing storage area and another Superplan lamella planer, Ledinek installed a second cross-cut saw for the final front side processing of the solid structural timber. Behind the saw, the finished solid structural timber and the CLT lamellas go their separate ways. While the beam-shaped elements are stacked, the CLT lamellas head towards the single-layer panel production.
Load-bearing, bonded edges
Ledinek further developed its two edge gluing machines for longitudinal and crosswise layers specifically to meet Schilliger’s requirements. The Z-Press became the Super Z-Press for longitudinal layers, and the Z-Press CL was further developed into the Super Z-Press CL for crosswise layers. “We extended the press bed of both machines, thereby enabling both hot-melt assembly bonding as well as load-bearing PU bonding without any compromises in performance,” Bradač says about the advantages of the Super models. The Super Z-Press can handle ten lamellas for longitudinal layers with hot-melt glue or five lamellas with PU adhesive, with the latter curing completely inside the press. The Super Z-Press CL can also glue five lamellas per minute with PU adhesive and up to 18 assembly bonds per minute with hot-melt glue.
Once they have left the joint gluing machines, the longitudinal and crosswise layers first enter the respective single-layer panel storage spaces and then the laying station. Here, vacuum lifters lay the press cake, which moves under a permanently mounted, 1,750-mm-wide, all-in-use adhesive application gantry from Oest after each layer.
The last step in the production of the raw panels is done by a third-generation X-Press press for elements which are up to 16 m long and 3.5 m wide. According to Bradač, one of the special features of this press is the maximum possible panel height, which Ledinek increased from 360 to 500 mm.
If several panels are pressed at the same time, they can be separated behind the press before they pass through a sanding machine supplied by Imeas and on to one of the Technowood CNC machines. The production control system used is the X-Lam Manager, which Ledinek developed specially for the management and control of production orders in CLT, solid structural timber and glulam lines.
Drawing on years of experience
For managing director Gregor Ledinek, the high level of complexity and the limited space available in an existing hall were major challenges of this project. “Schilliger’s requirements for the plant were extremely demanding. With our experience and some innovative solutions, we managed to create a convincing plant design and put it into practice.”
An assessment which Schilliger also confirmed during the Holzkurier’s visit to the French production site: “After a few smaller projects in Küssnacht, we knew that Ledinek was good. And so far, everything has worked perfectly in Volgelsheim, too.”
