Author: kallfass

Hegener-Hachmann Sawmill

The 12 October 2019 saw commissioning of the new sawmill at Hegener-Hachmann. This involved probably the most flexible production processes every realised in a medium-sized sawmill enterprise, posing a planning and technical challenge to all involved.

“Hanxleden 4.0 online sawmill – innovative, resource-efficient sawmill concept for SME” was the project title of the approx. € 11 million investment made by Hegener-Hachmann, Schmallenberg/DE. The new construction took exactly a year from October 2018 to October 2019. After a further twelve months, the planned cutting volume has, in terms of figures, been achieved – but right from the outset.

Exploiting as many resources as possible

Hubertus Hegener-Hachmann heads the company in what is now the fourth generation. He receives significant support in this role from Markus von Weichs who, as his business partner, is primarily responsible for purchasing logs. Having started as a forestry business with an originally small sawmill as a sideline, Hegener-Hachmann had a used head saw and a circular saw when he invested in the first expansion in 2007. “We decided in favour of a completely new construction to ensure the sustainability of our business and, insofar as possible, to be able to cut a broad variety of log types, including in part from our own forestry. Among other things, this enabled us to continue production independently at the location during the production phase. Our goal is to ensure careful and effective use of the resources used during the entire production process”, says Hegener-Hachmann. “We want to process everything at a single location. As a medium-sized enterprise, we can only continue to exist on a broad basis”. What he means by this is not only classic sawn timber such as the raw material for solid structural timber, construction timber or landscaping timber. Hegener-Hachmann is well known in the region for his solid wooden flooring consisting of hard and softwood that goes by the name of “Gutshofdiele”. Larch, Douglas fir and Norway spruce are also processed.

As the entire endeavour is regarded as somewhat of a supra-regional flagship project in terms of flexibility, efficiency and conservation of resources, it received ERDF funding from the Ministry for Environment, Agriculture, Conservation and Consumer Protection of the State of North Rhine-Westphalia as part of the “Ressource NRW” call for projects. This covered 50 % of the components eligible for funding.

What has been created is a modern sawmill with a planned annual cutting capacity of at least 40,000 m³ for soft and hardwood. This has proven highly complex in terms of the processes involved. When it came to the cutting technology, Hegener-Hachmann chose an inclined log bandsaw with a chipper-canter for logs up to 10.5 m in length and with a diameter of 1.3 m. Around 70 % of the timber comes online from the log yard for cutting without presorting. Hegener-Hachmann placed his trust in the know-how of Kallfass (in Baiersbronn, Germany) when it came to mechanisation and the sorting and stacking system. “Aside from the economic viability of the investment, what was decisive for us was the supplier we placed our faith in to accompany us on this journey. The Kallfass solution also impressed us very much, and the company gave us a commitment to realise the project within the estimated time” reasoned Hegener-Hachmann. “Online cutting and the wide variation in product dimensions posed major challenges for us”, remembers Kallfass Managing Director Hans Haist. Kallfass also provided the control unit for the sorting system. “The demanding timbers and varied dimensions meant our programmers were faced with a difficult task“, explains Haist.

A lot of things are possible

The log is in all cases precut on the bandsaw and, following trimming, conveyed on to the Combimes BNK and/or head saw in the Kallfass sorting and stacking plant. However, two other options are also available: “Products with a length exceeding 6 m and a thickness of more than 105 mm, blocks or individual high-quality pieces can be conveyed into special discharge 1 on the head saw or special discharge 2 behind the BNK. These can then be lowered with care to the lower level using a hoisting unit”, explains Hegener-Hachmann. 

50 boxes and multiple occupancy

Timbers with a thickness of up to 105 mm, a width of 300 mm and a length of 6 m are fed into the Kallfass sorting system at Hegener-Hachmann. 50 inclined boxes are available here. With inclined boxes, the timber slides down more gently onto the chain conveyor during emptying. This is primarily an advantage where hardwood is involved. “Due to the enormous diversity of our products and the numerous wood types involved, the computer frequently assigns three different types to a single box if necessary”, says Hegener-Hachmann. In this case, the box is emptied when the filling level is reached and the dimensions which are not required are fed once again over a return run and sorted anew.

The timbers to be stacked are separated and assessed again by a worker with regard to quality in the transverse run-through. Inappropriate workpieces can be ejected or shortened here again. The boards are then fed through the Kallfass CNC multiple circular cross-cut saw. This cuts the timbers with zero and four variable saws, depending on requirements. “Cutting is perfect and realised with millimetre accuracy”, confirms the operator. This is followed by layer formation and packet assembly. Haist estimates the output to be up to ten layers or 60 boards a minute during cycling in. The packing system is equipped with eight magazines with automatic stick placement.

Finished packages are lowered using a hoisting unit. Space conditions mean that they are deposited on a roller conveyor located on one side. This pivots the package (which is on rails) through 90°. The package is then strapped and prepared for shipping. Half packages or packages that need to be unpacked without sticks after drying can be picked again using the connected tilt stacker during a renewed passage through the stacking plant.

Both the Hegener-Hachmann sawmill and Kallfass confirm their satisfaction with implementation and commissioning. The focus now is on ensuring together the continuous improvement of in-house processes and the data flow.

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.