CLT production mechanisation

Ein BSP-Werk für Profis EN A CLT plant for professionals

Exceptional overall concept sets new standards

Log in, finished CLT element out - and all without a forklift. This is how you could describe best wood Schneider's extremely ambitious Greenfield project in just a few words. At the newly founded site in Meßkirch, Germany, the company is implementing a trend-setting, end-to-end production line. Currently the CLT plant is being commissioned. The planned output in the sawmill is 350,000 cubic meters/year. After the final expansion, the CLT production will reach an output of 100,000 m³/year. As in the sawmill, Kallfass also plays a leading role in further processing.

Actually, best wood Schneider “only” wanted to build a cross laminated timber plant at the new Meßkirch site. “Large-format CLT was the only product that we still lacked as a complete supplier for our approximately 5,000 active timber construction customers”, reports Managing Director Ferdinand Schneider during the Holzkurier visit. In addition to solid structural timber (KVH), glulam, glued laminated timber and box girder elements, the family-owned company offers its customers numerous wood fibre insulation systems as well as comprehensive planning and consulting services.

“But then we decided to do it right from the logs and to realise a continuous line from the logs to the finished timber construction products”, says Schneider, describing the process that began seven years ago with the planning phase and continues to this day. According to Kallfass Project Manager Stefan Günther, this constant development and improvement of ongoing projects, both large and small, is characteristic of the company: “Schneider projects are organic and continue to grow. However, these further developments are always constructive, with the best solution coming out on top, regardless of who it comes from”.

The basic idea for Meßkirch was as follows: to implement a continuously automated material flow–from the log feed to the finished and glazed CLT and box elements for walls and ceilings–completely without forklift traffic and almost without manual intervention.

Well-established team

While the sawmill is already rapidly approaching full-load operation, the first expansion stage of the CLT plant is in the middle of the commissioning process. As in the sawmill, Kallfass is responsible for the majority of the mechanisation, the cross laminated timber press and numerous detailed solutions. “In addition, Kallfass, as our vendor of choice, had the planning authority”, adds Schneider, who has already successfully completed numerous projects with the Black Forest system specialists.

Conveyor belts provide the transfer between the sawmill and processing steps down the line. Subsequently, the dried and sorted goods are transported to a Microtec Optiside cup scanner, where the timber is turned to the correct side, if required. In the next processing step, the planer infeed, also from Kallfass, accelerates the goods up to 250 m/min before they are levelled and scanned, and defects are marked. The timber is then packaged in a crosswise offset, strapped if necessary, and fed on roller conveyors to a high-bay warehouse with 1,450 storage locations.

Precise production

For cross-laminated timber production, the pre-planed raw material from the high-bay warehouse is transferred to a finger-jointing line and then to a longitudinal press. Here, white glue or hot melt is used to create an assembly joint. A vacuum lifter removes the assembly joints and transfers them to another part of the Kallfass system.

Whilst the longitudinal layers are directly used to lay a dry press cake in reverse order, cross-layer segments are produced from some of the single-layer boards. “As the longitudinal layer press always produces exactly a multiple of the desired cross-layer length plus kerf, our cross-layer saw does not produce any waste”, emphasises Günther, adding that particular attention is paid to precision when formatting the individual layers and when subsequently arranging the cross-layers and laying the boards. “This means that the panel no longer has to be formatted with a saw after pressing, which saves us time and, above all, material," emphasises Schneider, who runs his panels through a sanding system, a cross-cut saw and a multi-spindle processing machine for the production of any profiles between the press and the joinery systems.

Ingenious details

When laying the dry cake in reverse order, the single-layer boards are sprayed with water on both sides for the upcoming glue application before they are placed in the actual laying station. Apart from the adhesive application system from Oest, Kallfass is also responsible for the entire plant construction, including the subsequent cross laminated timber press. The latter can hold elements measuring up to 3.6 x 16 m and a maximum thickness of 360 mm.

Once the boards have been pressed, sanded and profiled, they move on to one of Technowood's joinery lines, where Kallfass also carries out the mechanisation upstream and downstream of the machines. This includes a specially developed panel turner for CLT, which enables the elements–which may weigh several tonnes–to be turned quickly and safely.

“This means that Kallfass is responsible for the end-to-end material flow–from sorting in the sawmill to the finished panel–and I have to say that all the parts they have implemented run flawlessly”. Schneider praises the installation and the Kallfass team.

Still a lot to do

While the existing line at Schneider is designed for the production of large-format wall and ceiling elements in non-visible quality, the second line will eject elements in visible quality including glaze. Commissioning is scheduled for the coming winter. As a third expansion stage, the Managing Director mentions a production facility for hollow box and rib elements, as used in roof and ceiling constructions, which Schneider summarises under the “Box” product line. This means that the company will have numerous other essential products in its portfolio for its customers.

Schneider describes the planning and implementation of a cross-laminated timber line as extremely complex, whereby he believes there is no ideal solution: “Depending on the objectives and framework conditions, each new CLT plant is always a path of the best compromises, which we realise together with Kallfass in the best possible way”.

“Wir können auch pressen” EN “Pressing is also our forte”

Ever since the initial CLT location in the Carinthian town of Bad St. Leonhard, Kallfass has been responsible for overall mechanisation at Stora Enso. Ždírec in the Czech Republic will now see the opening of the fourth and, henceforth, largest Stora Enso CLT plant. “We're delighted to have found a partner like Kallfass who we known and value since our CLT production was first launched. The overall mechanisation and press concept it has presented has completely convinced us”, says Markus Weiss-Moser, the Project Manager at Stora Enso. Kallfass Managing Director Hans Haist agrees. “We're very proud to unveil our first complete CLT reference project in Ždírec. The plant is among the foremost locations on a global level”.

Fully integrated location

“One enormous advantage of this project is the fact that it's not a completely new greenfield construction in the classical sense, as we can rely on structures that have developed over decades at this location”, says Markus Weiss-Moser. Following its purchase by Stora Enso in 1999, the sawmill has been continually expanded. Sawing capacity (around 550,000 m³ per annum) was expanded two years after the takeover through the addition of solid structural timber production (150,000 m³ per annum). Pellet production also commenced in 2015, with around 80,000 tonnes being produced each year since then.

The addition of cross-laminated timber rounds of the comprehensive package of services the plant provides. The production capacity of the Finnish/Swedish group will, in total, exceed 400,000 m³ per annum as a result.

The zero-joint principle

Cross-laminated timber is manufactured according to the same principle in all four Stora Enso CLT plants. Both longitudinal and transverse layers are produced as single-layer solid wood boards before being joined to create CLT panels. Process reliability is paramount. “Industrial production of more than 100,000 m³ per annum needs to be a very tight operation. Using single-layer boards means we work without loose lamellas. Naturally enough, this high level of quality is also reflected in the approval values the boards must meet”, explains Markus Weiss-Moser.

Minimising interfaces

In Ždírec, practically everything between the outlet of the throughfeed press for single-layer board production to subsequent joining is from Kallfass. “Minimising of interfaces was one of our central goals in the new plant. Having Kallfass as our main machine supplier enabled us to achieve this”, explains Markus Weiss-Moser.

Boards intended for the transverse layer are automatically cut to the desired length and placed in an appropriate intermediate buffer. Creation of the board can commence as soon as all layers are prepared, and the Oest gluing carriage starts to apply glue on the stationary lay-up table. “A special feature deserving mention here is our exclusive use of PU glue in the entire board. This includes the join, edge and surface of the board”, explains Markus Weiss-Moser.

Press number one

The finished layer package is then conveyed into the Kallfass press on a modular belt conveyor. “The conveyor unit is reversible. The great advantage of this is that, should a problem arise during gluing, the incomplete layer package can be moved quickly and easily into the press”, says Hans Haist. “This emergency press operation also enables us to prevent the loss of valuable raw material in rare cases where incidents arise”, adds Markus Weiss-Moser.

The maximum thickness of the layer package is 600 mm. The dimensions of the completed board are between 8 and 16 m in length and 2 to 3.6 m in width. “We're working with four cylinders per press line. This means we can ensure that the pressure required is applied to every square millimetre of the board”, explains Hans Haist. The plant can achieve pressures of up to 1 N/mm2. “Naturally enough, considerably less pressure is required where spruce is the raw material. But we see this as an investment in the future. Who knows which wood types may be interesting in future for cross-laminated timber? This solution means we can react flexibly, regardless of what happens”, says Markus Weiss-Moser.

Following pressing, the individual boards are automatically pushed off at the dry joint and separated again before being transferred to the sanding machine and subsequently trimmed in a total of three portal processing machines from Hundegger.

Kallfass Sonderlösungen für Deckenelement-Werk

Leimholzwerk spielt alle Stücke EN Glued timber plant has it all

With the “best wood CLT Box Ceiling”, Best Wood Schneider from Eberhardzell in Germany, has successfully combined the positive properties of BSP and BSH. The combination of glued-laminated timber and ribbed beams results in a structurally effective and at the same time space-creating timber element which is comparatively low in weight. Finish-trimmed and glazed, the result is a high degree of prefabrication with quick installation times on site.
Explained in a few short sentences here, these wooden box elements are the result of many years of development work, which also posed major challenges in terms of machine and plant engineering too. “We produce exclusively to order and offer our customers a wide range of products and finishing steps,” explains Schneider Project Manager Andreas Schilling and adds: “In addition, there is the complex arrangement of the production lines over a number of levels.” Schneider realised the plant over three storeys with numerous interim levels – the timbers are transported back and forth for the individual processing steps between the levels at 0 m, 6.5 m and 12.5 m by two lifts, before the automatic transfer of the finished elements to a high-bay warehouse. “This arrangement saves building land and above all means shorter distances within production,” says Managing Director Ferdinand Schneider, explaining the advantages of this arrangement.

New production process

As one of the main suppliers, the tradition-steeped Swabian company Kallfass was commissioned for much of the planning work and also supplied large system components for all three levels of the production system. The Kallfass installation begins on the top floor where the single-layer boards are taken in. Elements which are later used for the transverse layers of the BSP, which is up to 1.25 m in width, are cut to length by a chop saw. The transverse layers are then lowered by a lift table and rotated through 90°. The downstream lay-up station uses longitudinal and transverse layers as well as a glue application station to produce the 16 m long layer package, which is transferred to the CLT press of another manufacturer.

After the press the boards seem to be spoilt for choice – but they always end up exactly where they are supposed to be, in dependency on each order. “A roller conveyor on rails installed by us picks up the boards and, in accordance with the instructions from the master computer, brings them to the glazing line, planer, trimming centre or to the storage and retrieval system realised by us,” says Kallfass Managing Director Hans Haist, explaining the options. The latter is fully automated, places the components in interim storage and links the individual processing steps with each other. For example, the storage and retrieval system also charges the rib element production system, whereby Haist does not wish to provide further details about this part of the installation, with the following reasoning: “For the production of the ribbed ceilings we developed and realised a process with Schneider which had not previously existed in this form before.” The rib elements can be finish-trimmed and/or sanded and glazed after production – just like the BSP elements.

Ready-made laminated beam ceilings

On the middle floor, 6.5 m above ground level, Schneider produces the laminated beam elements. This is dealt with by Kallfass and it transfers them on – depending on the order – for further processing or stretch foil wrapping, after which the elements are moved on to the high-bay warehouse immediately downstream.
In the same way as for the box elements, Schneider also offers its customers glazing for the laminated beam ceilings. If this is required, an inclined lift, also from Kallfass, brings the parts to the ground floor. Here, Schneider employees rectify any surface damage before the elements run through a two-stage sanding and glazing process. On this level Kallfass is responsible for the complete mechanised solution between the machines.

The glazed elements are transferred back to the middle floor again by the same inclined lift, where they are also packetised, packaged and placed in storage. From the high-bay warehouse the packages are transferred via a conveyor system to a central truck loading station, which was realised by Kallfass some years ago.

Maximum flexibility

In the event of a fault – for example, the failure of one of the two glazing lines – Schneider can reschedule the elements along the running line at any time. “This maximum flexibility in terms of production, namely that every element can run through all possible production stages and can be fed in and out at any point was demanded by Schneider and was one of the biggest challenges of this project,” stressed Haist. That this worked out successfully and all other promises made by Kallfass were fulfilled to the satisfaction of Schneider is perhaps best confirmed by the follow-up order: In Meßkirch, Best Wood Schneider is currently realising a production line which is envisaged to set new standards, especially in terms of logistics – from log deliveries to the finished BSP, the aim is to completely dispense with stackers. The systems from Kallfass will once again play a central role here too.

Alles aus einer Hand EN Everything from a single source

Kallfass, located in Baiersbronn/Germany, is well known as a mechanisation specialist. The same applies to the fact that the mechanical engineering company equips cross laminated timber systems. With this in mind, we can refer to some well-known projects. Recently Kallfass has added a CLT press (Cross Laminated Timber) and a CLT turning device.

The mechanical engineering company Kallfass from the Black Forest has already been involved as a supplier in several cross laminated timber projects in Austria and Germany. The most recent work completed was that of Stora Enso in Gruvön/Sweden. Construction work on this site began in 2018 and the system has been running in automatic mode since the beginning of 2019.

To date, this is the largest project for Kallfass in the area of cross laminated timber applications. The company not only supplied the entire mechanical equipment—from the feeding of packages to the acceptance of the finished pressed elements—but was also responsible for the overall layout and the complete safety control system. The fact that Stora Enso has selected Kallfass as its supplier is probably also due to the fact that Kallfass has already been involved in the Austrian CLT plants in Ybbs and Bad St. Leonhard, Austria. The total capacity in Sweden totals 100,000 m³/year.

Large packages also possible

Stora Enso also operates a sawmill in Gruvön, Sweden which supplies the raw materials for the laminated timber elements. The sawn timber (dried and battened or pre-planed) is transported by truck to the Kallfass feeding station. This feeding station is also designed for large packages up to 5.8 m long, 2 m wide, and 3 m high. A vacuum-operated de-stacking device separates the packets layer-by-layer. If stacking strips are available, a brush automatically scrapes them off and collects them. The Kallfass mechanism separates the layers and feeds the boards piece by piece to Finscan's quality scanner. In this area, the strength and the moisture of the timber is also measured. Any unsuitable workpieces are ejected from the process.

Two paths for the boards

“The scanner provides us with the information whether there are cracks on the front sides or knots in the base of the finger joints. If this is the case, we trim the front sides," says Kallfass Managing Director Hans Haist. The boards pass through a front end cross-cut with adjustable servo stop. Subsequently, the zero line is changed and the same process takes place on the other side of the board. If the scanner also finds undesirable wood features in the centre of the board, these pieces are ejected to an upper level where a cross-cut system made by PAUL Maschinenfabrik GmbH cuts out these areas. “However, this concerns only about 5% of the total quantity. Most of it goes straight on to the Grecon finger-jointing system”, describes Kallfass Project Manager Helge Widmann.

The Kallfass mechanisation cycles both the long workpieces and the cross-cut lengths from 800 mm upwards at a rate of up to 50 boards per minute. They travel in the direction of the finger-jointing system with the continuous press. Subsequently, the mechanisation takes over the finger-jointed lamellas again downstream of the moving cross-cut saw. These lamellas are between 8 and 16 m long. The applied adhesive can now cure on a 25 m long buffer section before Kallfass feeds the lamellas into the Rex planing machine. After the lamellas are pre-planed, they are cycled in the direction of the board press: First, a system provided by OEST Mineralölwerk GmbH, applies a layer of adhesive to the the lamellas. Subsequently, these lamellas are fed into the glueing press made by DIMTER GmbH. The single-layer boards produced in this way are then taken over again by a Kallfass system.

This is where the paths split: A VOITH crane picks up the longitudinal layers and transfers them to the intermediate storage. Previously, a chop saw, installed downstream of the glueing press, has already cut the longitudinal layers to the width required by the order. In order to make the best possible use of the DIMTER press, the longitudinal layers are always produced in 16 m lengths wherever possible. If shorter boards are required, Kallfass has developed a special system to recycle the remnants of the longitudinal layer.

Transverse layers measuring up to 1.5 m are stacked by Kallfass to a height of 2 m and are also transported by a VOITH crane to a second storage area. These processes are fully automated. A controller determines the suitable storage location.

Sawed with millimetre precision

Now, the longitudinal and transverse layers are combined to form a layer package. The longitudinal layer already has the right format. The transverse layers, measuring up to a maximum of 1.5 m long, come from five buffer locations and are transferred to a 16 m long conveyor. Several boards are placed one after the other on this conveyor until the required board length is reached. If the length is exceeded, a saw cuts the transverse layer accordingly. The timber offcut then becomes the beginning of the next layer. Subsequently, vacuum systems alternately lift the single-layer boards onto a conveyor belt upstream of the press until the layer package is completely assembled. “Several CTL boards can also be laid on top of each other using a dry joint”, explains Widmann.

Downstream of the MINDA CLT press, Kallfass again takes over the multiple press layer package, separates the elements by means of a push-off process, and transports the elements to the grinding machine. Downstream, they are supplied to a VOITH crane, temporarily stored or transported to one of the three Hundegger machining centres.

In the interview Widmann mentions two more figures regarding the safety concept: “At the Stora Enso factory in Gruvön, 1.2 km of fencing and 82 safety doors were installed”.

Full-service provider

However, Kallfass cannot “only” supply the mechanisation for a cross laminated timber factory. Since last year the company also has a CLT press in its product range. “We have developed this CLT press in response to numerous customer requests”, explains Haist. Thanks to it modular and stand-alone segmental design, it makes no difference whether the layer package is built up of boards or pre-glued panels. The customer also has flexibility when it comes to the design of the workpiece. The board dimensions range from 7 to 20 m long, 2.2 to 3.6 m wide, and 6 to 60 cm high. The hydraulic system forms the core of the system. It enables an almost isobaric (without pressure difference) pressing process. In addition to vertical pressure, Kallfass also equips the cycle press with cross pressure units on request. The area-dependent pressure control enables a pressure in excess of 1 N/mm² even at maximum plate width.

Kallfass will complete its CLT product range with a further innovation in the future: “We have developed a board turning device for cross laminated timber, which can turn the elements very easily and quickly”, explains Widmann. The turning device handles CLT up to 16 m long, 3.6 m wide and 300 mm thick. It is designed for a weight of more than 10 t. “With this device, CLT can be turned over without any risks and without hurting anyone. For example, in joinery centres, one area of application is for two-sided processing", concludes Haist.

Exceptional overall concept sets new standards

The dried raw material is transported from the sawmill ...

directly to the next hall, using conveyor belts.

There, the timber is assessed, stacked and temporarily stored in a high-bay warehouse. From there it continues to the BSP line or onto the lorry.

Well-established team

Precise production

In the cross-layer production process, the single-layer panels are cut to length using high precision and joined together to form cross-layers.

Ingenious details

Managing Director Ferdinand Schneider (right) together with Kallfass Project Manager Stefan Günther.

Still a lot to do

In the cross-layer production process, the single-layer panels are cut to length using high precision and joined together to form cross-layers.

The cross laminated timber press is just one of many components that Kallfass implemented in best wood Schneider's new CLT plant.

The finished pressed CLT panels are fed to the downstream sanding machine via a travelling roller conveyor.

First successful CLT press delivered to the Czech Republic

Successful project management: Kallfass Managing Director Hans Haist with Stora Enso Project Manager Markus Weiss-Moser and Kallfass Project Manager Helge Widmann (r. to l.) in front of the first Kallfass CLT press.

Fully integrated location

The zero-joint principle

Trimming the transverse layers: Transverse layers produced as single-layer boards are trimmed to the later board width upstream of the lay-up station.

Minimising interfaces

80 press cylinders spread over ten press modules ensure particularly even pressure distribution.

Press number one

Series production begins in 2023

Successful project management: Kallfass Managing Director Hans Haist with Stora Enso Project Manager Markus Weiss-Moser and Kallfass Project Manager Helge Widmann (r. to l.) in front of the first Kallfass CLT press.

Trimming the transverse layers: Transverse layers produced as single-layer boards are trimmed to the later board width upstream of the lay-up station.

80 press cylinders spread over ten press modules ensure particularly even pressure distribution.

Multi-storey production for multi-storey timber construction

A fully automated storage and retrieval system links the individual processing steps with each other.

“For the production of the ribbed ceilings we developed and realised a process with Schneider which had not previously existed in this form before.”

Following the successful project at the headquarters, talks get straight under way about the next major project together in Meßkirch.

A turning device moves the element into the correct position. Since many of the timbers are produced in exposed quality, this is particularly gentle on the material.

Two lifts from Kallfass connect the three levels for the timbers.

Depending on the order, the BSP boards are glazed, trimmed and/or processed further into rib elements.

Kallfass is one of the main suppliers at the Schneider ceiling element plant and supplied numerous special solutions.

Following the successful project at the headquarters, talks get straight under way about the next major project together in Meßkirch: Max (left) and Ferdinand (third from left) Schneider and Andreas Schilling (right) from Best Wood Schneider together with the Kallfass managing directors.

Kallfass presented its new CLT press for the first time last year at the LIGNA Expo in Hanover, Germany.

Kallfass supplied Stora Enso with the entire mechanisation in the cross laminated timber system – the picture shows the separation of the packages in layers.

The scanner (A) detects cracks and knots, the Kallfass saws (B) cut off the front sides accordingly.

Modular design: Kallfass manufactures the CLT press in segments so that it can be adapted exactly to customer requirements

Mechanisation of the longitudinal (left) and cross layers (right) before they are assembled into the layer package.

Turn once, please: To bring the longitudinal layers to the correct side, Kallfass installed a board turning device.

Automation solutions

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