One thing you don’t see stacked around the 20-acre sawmill site of Industrie du Bois Vielsalm (IBV) is much in the way of sawn timber: the mill does not cut for stock, but saws logs to individual customers’ specifications and ships the resulting packs out pretty well immediately.
Situated in Vielsalm on the Belgian/ German border, IBV is one of four sawmills owned by Joseph Haas, Roland Jost and Bruno Wilmote. It was established three years ago, when an existing mill was purchased, and since then major investment has been made to develop the facility with the latest sawmilling technology – including a Holtec log cross-cut line two years ago and, last year, a complete Linck sawline integrated with a Holtec log yard.
‘The IBV mill demonstrates the way Holtec and Linck technology can be combined to produce a turnkey operation that delivers quality sawn timber and production efficiency,’ said Justin Peckham, sales director of Woodtech Machinery which represents the two manufacturers in the UK and Ireland.
‘It’s one of the most modern sawmills in Europe and an excellent reference to the capabilities of both companies.’
Export markets
IBV supplies timber importers and larger manufacturers – particularly those involved in making laminated timber beams – in Belgium, Germany, the UK, Ireland, Holland and France. It is the largest and newest of the group of four mills, each of which is equipped for handling different types of logs.
There’s another called IBV at Voneche on the Belgian/French border, which takes only logs of 3m length and produces pallet, fencing and packing case materials; IBH in Harpescheid, Germany, saws logs up to 65cm diameter as well as very small diameter logs; and Reitho in Weywertz, Belgium, handles logs from 10-80cm diameter and 11m and up in length.
In addition to processing logs sourced from forests around the mills, the group also cuts logs imported from Russia. To streamline the supply, the group set up a dedicated sorting line in Liege a year ago, which sorts logs from Russia and feeds them to one of the mills.
The group aims to achieve a total production of one million m³ this year and IBV in Vielsalm is playing a significant role in this. It takes logs, mainly pine, in anything from 2.5-22m in length and 40-45cm in diameter.
‘On arrival the logs are first processed on the Holtec cross-cut line,’ said Alfred Winter, technical director of the group. ‘They are measured by a scanner to assess their curvature and this information is displayed on the operator’s monitor.
‘The butt ends are removed by the first circular sawblade and the logs are conveyed to the second saw. This produces straight boules of the lengths required for the sawline – from 2.5-6.2m – using the information from the scanner as well as the experience of the operator who can override the automatic system.’
After passing through a metal detector – (shrapnel is a hazard in IBV’s source areas) – the logs are automatically conveyed to one of 72 sorting bins according to their length and diameter, and removed by a grabber crane for storage on site until required for a customer’s order.
Logs are processed in batches of the same size, and for feeding material to the mill Holtec has designed a sophisticated handling system that had to overcome two key challenges. The first was the 14m height difference between the log yard and the mill, which was solved by linking the log deck to the mill infeed conveyor via an inclined vertical conveyor.
‘The second factor was the speed of the Linck sawline,’ said Mr Winter. ‘We now run at up to 150m/min – and we will soon increase that – which means we have to feed logs pretty well end-to-end. The problem is that the debarker operates at a maximum of 105m/min, so we needed two of them to keep the sawline running at maximum efficiency.’
Twin-line infeed
Holtec’s solution was to design a twin-line infeed. When logs arrive at the top of the vertical conveyor they are kicked onto one of two conveyors. Each of these has a scanner, which checks which way logs are oriented, and a turning system that rotates them so they are always fed ‘thin end’ first to one of the two debarkers.
After debarking, the logs are combined onto a single conveyor for feeding through the Linck sawline. This begins with yet another scanner – this time an optimising system that accurately measures diameter throughout the length of the log.
The single operator sits in a control room facing away from the mill and looking out over the log infeed system. Banks of video monitors show key parts of the Linck line.
‘Data from the optimising scanner sets all the machinery on the sawline automatically,’ said Mr Winter. ‘Logs are first rotated to achieve optimum yield from the first canter, then rotated 90O for the second canter – resulting in a cant with four flat sides.’
The second canter is followed by a profiler, which cuts notches from the top and bottom of both sides of the cant to prepare it for the first multi-rip. This separates the required number of sideboards, and the cant is then rotated 90O again and a second pro-filer/multi-rip combination cuts the remaining sideboards and the centreboards.
As sideboards and centreboards come off the line they are checked by graders. Those that meet the customers’ requirements go directly to an automatic stacking/sticking machine; those that do not are sent to a separate quality control station at the end of the line. Here, the first of two graders marks defects on the upper face using a fluorescent pen. The boards are then turned over automatically as they are conveyed to an upper level of the line, where a second grader checks the other face.
Because the graders stand at one side of the line they obviously can’t reach the far end of boards. The marks they apply are therefore ‘coded’ to identify the position of the defect. A scanner reads the marks on both sides of the board simultaneously and then examines the relevant area of board for the presence of wane and splits.
‘The scanner determines which of 12 sorting stations the board will be discharged into, depending on how much needs to be cut off the end to produce an acceptable grade based on the lengths required by the customer,’ said Mr Winter.
‘Information about the volume of timber in each station is displayed on the colour monitor by the cross-cut operator. When a station is full the operator releases the timber and the sawblades on the CNC cross-cut automatically adjust based on data from the scanner.’
After cross-cutting, these boards are fed back to join sideboards or centreboards coming off the sawline, and once a pack has been completed – comprising boards of the same dimension and length – they are automatically strapped and stored for a short time until the order is ready for delivery.
By-products
IBV fully utilises all materials coming onto the site. Sawdust and chips (including offcuts from the sawline which are chipped) are graded and sold to paper, particleboard or fibreboard manufacturers; and reject log offcuts are sent to an MDF manufacturer adjacent to the mill.
‘The combination of Holtec and Linck systems gives us the production efficiency and quality sawing capacity we need to supply customers with timber to their specifications,’ said Mr Winter.
‘Co-operation between the two suppliers has been excellent and we have had no problems with the installation. We’re now planning to increase the speed of the line, so that we will be able to meet growing domestic and export demand for our service.’
