Once a large and diverse timber processing operation, Bucina DDD is now almost wholly concentrated on particleboard production and its value-added derivatives. At the heart of that process is the first continuous press of its kind in the world.
The company is located in Zvolen, a fairly small town of around 35,000 inhabitants (although one of the top four towns in Slovakia) in the west of the country.
The takeover of Bucina Zvolen, a state-owned company, by Kronospan Holdings Ltd of Cyprus in 2003, was just the beginning of a remarkable transformation for this long-established wood processor.
At that time, Bucina had facilities for the manufacture of particleboard, impregnated decor paper and melamine faced particleboard (MFC), as well as a large sawmill and a finger-jointing factory.
In fact, as is often the case, the residues produced by the sawmill gave Bucina the impetus to build the particleboard line in the first place.
In the old communist era the 70ha site had provided employment for around 2,800 workers, in the way that politics and sound financial management had of conflicting with each other under that system. Today the figure is a more realistic 300.
At the heart of the particleboard line when Kronospan assumed control was an elderly 12-opening press of 1,880×5,500mm and the line had a capacity of around 900m3/day, or 300-350,000m3/year.
Meanwhile, far away from Slovakia, another company acquired by Kronospan Technical Holdings was Shanghai Wood Based Panel Machinery Co Ltd (SWPM) of Shanghai, China.
The international panel making giant assumed control of SWPM in 2004,
taking over this manufacturer of a wide range of machinery used in panel production, from fibre refiners to presses to stacking systems.
Central to SWPM’s product range, in more ways than one, were the single- and multi-opening hot presses used in the making of all kinds of primary panel products (as well as short-cycle presses).
At the time of Kronospan’s purchase, SWPM was well into its journey of developing the first continuous hot press for panel manufacture to be built
outside Europe.
Bringing Kronospan’s considerable expertise in panel making together with SWPM’s expertise in machinery design and manufacture, it was not long before that continuous press really began to take its final shape.
The first unit to be built was fully assembled and extensively tested in SWPM’s own factory in Anting Industrial District, Shanghai.
The second continuous ‘ContiPlus’ press to be made in Anting was shipped to Slovakia to begin erection in Bucina’s factory in Zvolen in March 2007.
Installation, carried out by engineers from China together with Kronospan’s own experienced technicians, was completed in August of that year – an impressive timescale, especially for the first installation of its kind.
Start-up of the line began in September, with the first board being produced on September 22 and full three-shift commercial production beginning in November 2007 – and continuing at the time of my visit in early March 2009.
Bucina was able to utilise part of an original building on the site, which had been used for storage, for the production line but the forming station, supplied by Dieffenbacher, required greater height than that structure offered and so the factory was extended in length with a higher roof. Construction of the steel structure for this extension commenced in January 2007. The old building was re-clad with metal sheeting to match the new extension.
Meanwhile, the original multi-opening press line continued to produce particleboard, in a separate building adjacent to the building used for the new ContiPlus, right up until the continuous press
could take over production. The multi-opening line was then closed down and has not been re-started since, although it is still there.

Before the press
The wood supply for Zvolen is not a problem and comes from the forests of Slovakia, which can be seen all around the factory.
The wood preparation and pre-production stages were renewed in 2006, before installation of the ContiPlus press commenced. The replacement dryer has a capacity of around 1,400m3/day.
That original Rudnick and Enners primary chipper line is fed with a mixture of logs and sawmill slabs by a Volvo grab loader. The four knife ring flakers were from Pallmann. There is a knife sharpening workshop adjacent to the flaker room.
From after the dryer to the end of the production line, everything is new.
That includes the Pal oscillating chip screens and the two concrete dry silos and three similar wet chip silos.
Bucket elevators by MUT take the dry chips up to the top of the dry silos, from where they are transferred to the two Pal/Imal dry bins – one for core and one for surface layers. These bins feed the rotary blenders from the same Italian suppliers to mix the resin with the wood particles.
Resin comes from other Kronospan group factories and is brought by rail directly into the mill site.
Beside the dry bins is a Trasmec conveyor for returning mat side trim directly back to the core layer for recycling.
Trasmec also supplied a large contract of conveyors to Kronospan’s Bolderaja mill in Riga, Latvia (see WBPI Feb/March 2009, p16).
There are four mat formers, supplied by German machinery supplier Dieffenbacher – two for surface and two for core layers – and these are the latest models, containing devices to prevent glue lumps appearing in the mat. These formers are key to the surface quality of the particleboard and Kronospan says its aim is to upgrade particleboard surface quality to that of MDF. This will allow for the use of low grammage paper, foil or melamine paper. These upgraded surface qualities are being produced across Kronospan’s factories in Bischweier, Szczecinek, Riga, Jihlava, Sebes, etc as well as here in Zvolen, says the company.
They are thus the same type of formers that Kronospan employed in all its new particleboard lines. Core layer forming is mechanical, while surface layers are wind-formed and graded in their thickness, with the finest particles on the surface.
The forming conveyor is dampened with an Imal mat spray before the bottom surface layer is formed. A GreCon IR3000 moisture meter is positioned above the surface layer, as well as magnets to remove any ferrous metal.
The same arrangement is repeated after the core layer and again after the top surface layer is formed.
Another Imal mat spray dampens the top surface of the mat.
A Dieffenbacher weighbridge is located right after the forming and this gives immediate feedback to the former for fine control of mat weight.
There is also a GreCon traversing mat density gauge BWQ 3000, followed by a Wagner Magnete ferrous metal extractor and then a Cassel non-magnetic-metal detector which can actuate the mat dump if metal is detected.
Taking centre stage in the production hall is the grey bulk of Shanghai’s finest, the ContiPress continuous press.
Overall responsibility for the press installation was taken by SWPM. The Chinese company was also responsible for putting together the package of Dieffenbacher formers and the press line; and for all the electrical systems from gluing to packaging of the finished product. The only exceptions to this were the Imal gluing controls (urea formaldehyde glue is used), the actual operation of the Dieffenbacher formers, the diagonal cross-cut saw (also supplied by Dieffenbacher) and the Steinemann sander.
Kronoplus Technical AG had overall responsibility for the project management at Zvolen.
There is a separate gas-powered energy system made by Intec (a Dieffenbacher group company) just for the press, installed outside the factory building adjacent to the press. The rest of the pre-existing energy system is fuelled by wood but was of insufficient capacity for the large continuous press.
Quality control on the line was the sole responsibility of GreCon, while Minimax and GreCon together supplied the fire protection for the press.

The ContiPlus press
The continuous press is eight feet wide and 45.1m long. Its design speed is around 1.2m/second which is said to be adequate for particleboard production.
The press is equipped with simple on-off valves for the hydraulic cylinders, rather than the more complex servo valves. These simple valves are
considered to be more robust, to consume less energy and to be reliable and easy to maintain without special
engineering skills, explained a senior Kronospan Group engineer.
An unusual feature of the press set-up is that all the hydraulics are located at ground level, rather than the more common practice of positioning them on top of the press.
The reason for this is that it keeps the hydraulic system away from the intense heat and fumes above the press and also makes it far easier for maintenance staff to keep a more frequent eye on the systems and to carry out any necessary repairs or servicing.
For access to the drive chain above the press, SWPM has created a spacious chamber at the top of the press with access doors every eight metres. This allows service personnel access to the chains, and the stainless steel belt, without the need to disassemble any of the upper part of the press. The fact that the hydraulic system is not above the press helps in this regard, too.
In further attention to detail for servicing, all bearings are external to the press for easy maintenance access.
There are also unusual features to the press itself. For instance, the thermal oil heating system for the platens at the press entry – in fact the whole infeed area – is said to be of unique design and has a patent pending.
The way in which the sections of the hot platens are joined together is the subject of another patent application.
Keeping a continuous press clean is another important factor in its smooth, reliable and safe operation. Thus the Ceatec fume extraction system features a water spray inside the trunking to catch particles and prevent their accumulation, which could block the ducts. It also absorbs some of the free formaldehyde in the fumes. Ceatec also supplied the dust extraction systems.
Because of the nature of a continuous press, a considerable amount of oil is required to keep the hundreds of moving parts running smoothly.
Thus SWPM has developed a patented process to ensure that any excess/used oil comes to the outside of the press where it is collected and removed and drained to collection pots in the pit beneath it.
“This is an example of experience in use by us, the panel maker, and a machinery maker who will listen,said the Kronospan engineer. “This kind of attention to detail reduces fire risk dramatically.
“Our relationship with the machinery manufacturer probably speeded up the development of this press considerably.”
Considering the ContiPlus had been running more or less continuously since September 2007 when I visited in March 2009, it was certainly very clean indeed.
Another unusual feature of this press is that the supporting rolls for the
stainless steel belt are all driven, not
‘passively rotated’ by the passage of the steel belt itself.
The advantage claimed for this is that non-driven rolls can become clogged with dust and oil and slip intermittently against the belt, or indeed stop
completely. This can quickly damage a steel belt at a cost of several hundred thousand euros/dollars.
The operator in the control room receives a warning signal immediately any of those driven rolls stops. “That’s one more risk removed,the engineer said.
The control room is equipped with monitors enabling supervision of all aspects of the production line, as well as CCTV cameras monitoring what is going on in all areas of the factory, inside and out. The GreCon equipment has its own monitor screens as well.
The Chinese electricians employed by SWPM are very skilled in this specific area of machine control in a panel
factory, explained the engineer.
As of March, SWPM had sold five ContiPresses in total – and not only
to Kronospan.
Beyond the press
Thickness of the finished board is checked by a GreCon 3000CT sensor.
Dieffenbacher Zaisenhausen was responsible for the diagonal cross-cut saw and the board handling equipment, as well as the three star coolers which boards pass through consecutively.
Sanding involves a 10-head Steinemann Satos machine, with panel handling, cross-cutting and edge trimming being supplied by Kontra of Germany, with electrical controls by SWPM. After the edge trimming, the handling and packaging equipment is by Kronospan group company Polytrans.
The warehouse has a system of sensors set in the floor which enable the control room to know where every pack, and every fork lift or truck, is located, while both the new warehouses, and the new short-cycle press hall, have roofs supported by glulam beams.
The theoretical capacity of the Zvolen production line is 2,375m3 a day (ca700,000m3 a year) but at the present time there is insufficient dryer capacity for that quantity. Current production is closer to 1,400m3 a day (ca400-450,000m3 a year).

The products
The master panels produced at Zvolen are 1,830-2,520mm wide and 8,225-11,235mm long and are made in thicknesses of 6-40mm, with a density range of 620-760kg/m3, depending on thickness of course.
Much of Bucina’s production is surfaced and, market permitting, it is intended, ultimately, to surface the vast majority of production.
There is a small Vits paper impregnation line on site, which was installed by the original Bucina company in its state-owned days. Decor papers come from other Kronospan facilities.
Today, in the new short-cycle press machine hall, there are three presses for producing melamine faced particleboard (MFC).
One is a Wemhöner line installed in 2008. This is 2.5×5.8m. The other two are Siempelkamp presses, 2.2×5.8m, moved here from Kronospan’s Lampertswalde factory in Germany.
The main markets for Zvolen so far are Slovakia, Poland, Hungary and Austria, pursuing the Kronospan philosophy of locating its production facilities close to both raw material supply and to a market relatively uncluttered by the competition.
Market conditions are of course
currently very difficult for Bucina, as for everybody else, but the company is
confident that with its modern, efficient line, it can ride out the hard times. When conditions improve, plans are already laid to raise output to the full potential of around 700,000m3 a year by expansion of the dryer capacity.

More than a mill
The site at Zvolen does not only house the particleboard production line of Bucina, but is also home to another Kronospan group company, Kronovision. This is a training and international meeting establishment for the whole Kronospan group, providing accommodation and specially-designed meeting rooms.
Kronovision also has close cooperation with the University of Zvolen, which is a specialist wood technology university that provides a source of highly-trained staff for the factory.
When Kronospan bought SWPM, many people in the industry were surprised and could not see a logical ‘fit’ between the two companies. Peter Kaindl, director of Kronospan Holdings Ltd, has the answer:
“SWPM’s continuous press was engineered and built with the knowledge and experience of a user, for a user. Therefore this press has unique features to achieve the highest accuracy in terms of thickness adjustments, low maintenance cost and its fire security is much improved.”