It’s more than a year since production started up at the £15m state-of-the-art sawmill built by Balcas Timber Ltd adjacent to its existing mills at Enniskillen.
This is the largest of the four sawmill operations run by parent company Balcas Ltd – there’s another in Northern Ireland, one in Co Leitrim and one in Estonia. The company also owns an MDF processing plant in Co Kildare and a pallet manufacturing company near Belfast.
The total volume produced at all four sawmills is around 350,000m³ a year, of which Enniskillen produces 200,000m³ – although the company plans to significantly increase that figure through the new mill’s higher feed speeds and efficiency.
Vollmer has been the favoured sawshop supplier to Balcas for many years, and has equipment at all of the company’s operations.
‘It was essential that the state-of-the-art equipment in the new mill should be supported by precision sawshop equipment,’ said works director Andrew Kidney. ‘Balcas is acutely aware that there is no point in having a high speed mill unless the sawblades are maintained in optimum condition.’
Computer control
The CAE sawline is completely computer controlled and comprises a scanning and optimising system at every position where the wood is repositioned for further sawing. The line begins with automatic log rotation, leading to a skewing and slewing double length infeed which positions logs with millimetre accuracy for the primary log breakdown through a canter and quad bandsaws. The cant is further processed by a CNC curve sawing canter gang, followed by three curve sawing twin bandsaws. Two optimising edgers process the boards and an optimised multisaw trimmer cross-cuts the timber, which is then conveyed to a 100-bin drop sorter.
Curve sawing
Curve sawing technology allows the saws to follow the contour of curved logs – obtaining extra value recovery. The sawn board then straightens during kilning as tensions in the wood are released.
The mill cuts mainly spruce and produces dry graded construction timber as well as fencing and pallet material for the UK and Irish markets.
All blades used in the mill are Stellite-tipped. The bandsaws cut at up to 120m/min, dynamically changing with depth of cut, with the sawblades running at high strain through pressure guides and with oil lubrication. Feed speed through the circular edger saws is 330m/min and the sawblades run in white metal ‘babbitt’ guides (in a cushion of pressurised oil, air and water) to keep them cool and ensure they cut straight and accurately.
‘We find that precision-ground Stellite tips dramatically increase the feed speeds, decrease sawing deviations and extend the running time between blade changes,’ said Mr Kidney.
Sawblades are changed every shift – the mill runs two shifts at present – resulting in 10 bandsaw blades and 10 circular blades arriving every shift at the large sawshop built on a mezzanine floor in the mill. This has been equipped with some of Vollmer’s latest technology, including the RC100 automatic levelling, tensioning and straightening machine, two CA200 CNC bandsaw grinders (one left-handed and one right-handed) and the Depomatic automatic Stellite-tipping machine which is used for bandsaw and circular saw blades.
Enniskillen’s head saw doctor Gerry Neeson and his team of five also run a second sawshop located near the original mill.
The RC100 is the only one in Ireland and has been a great success for Balcas.
‘It brings a level of predictability and repeatability to bandsaw tensioning and ensures uniformity within and between the blades because it measures tension throughout the whole length of the blade,’ said Mr Neeson.
‘When it was installed I tensioned a blade manually to the profile we have developed to tune the performance of the bandsaws. This blade was then run through the RC100 and measured, and the data was used to write a program for the machine. As a result, the RC100 exactly reproduces the tension profile we achieve manually.’
Bandsaw blades are sharpened using the CA200 wet grinding machines. These do not use tooth-shaped cams, but provide complete flexibility in programming the required tooth shape using the CNC control system. Vollmer has also developed a software program that runs on a laptop and aids the design of tooth shapes – with the information then downloaded to the CA200. This system was used by Balcas to fine-tune the blades’ tooth shape to optimise performance.
Circular sawblades are sharpened using Vollmer’s precision wet grinders. The saw doctors at Balcas ensure the blades match the high performance capabilities of the machinery in the sawmill, by preparing the sawblades with an extremely high level of precision. Again, the flexibility of Vollmer’s CNC circular sawblade grinders ensures that these specifications are produced accurately and repeatably, with a fine surface finish.
Plasma technology
The Depomatic at Enniskillen is the second of these fully automatic Stellite-tipping machines owned by Balcas. It uses plasma technology to apply molten Stellite to the teeth, forming it in water-cooled shaping jaws. These achieve a ‘raw’ tooth shape, which minimises the amount of subsequent grinding required.
‘It’s easy to use, being an automatic machine, and it offers the flexibility of applying Stellite to circular sawblades as well as bandsaw blades, simply by changing the support in front of the machine and the copper moulds for the tooth sizes and shapes,’ said Mr Neeson.
It took one year to build the new mill at Enniskillen – and right from the start the aim was to achieve high-speed production and top quality sawn timber. To achieve that, said Andrew Kidney, you need the best technology in the sawmill, supported by the best technology in the sawshop so that the sawblades are perfectly sharpened and tensioned.
‘It is sometimes said that production is only as good as the cutting edge and stability of the blade. In fact, good sawing depends on the many aspects of the process all being tuned and optimised correctly.
‘However, I certainly believe that Vollmer’s equipment plays a key role by engineering a good tooth tip so that we can achieve maximum performance from the equipment in the mill.’
