Hardwood sawmillers and roundwood exporters work closely with their resource suppliers to ensure a consistent supply of logs that are good enough to produce sufficient volumes of higher-grade material for returns to exceed the cost of production.
However, a significant challenge when harvesting and using hardwoods like eucalyptus, oak and European beech in sawn applications is managing the internal tensile forces released during felling that inevitably result in end-splitting.
Philip Boardman of Alternative Structures in Centurion, Gauteng, says the combination of internal stresses and external factors affecting the quality of the wood does not end there. “There are no shortcuts when you work with hardwoods. For example, warping and splitting during sawing and horizontal checking during drying reduce the recovery of sawn products,” he comments.
Over the years, eucalyptus growers and sawmillers on every continent have invested significantly in researching the best methods for stopping or minimising end-splitting in newly-felled logs by applying sealants, embedding steel S- or C-hooks or anti-split plates, or strapping.
Boardman says it is internationally accepted that applying a device to the developing split, either at or immediately after felling and cross-cutting, minimises end-checking during log handling and transporting to the processing plant.
The usual methods
“Roundwood suppliers of hardwoods for sawn products, exports and mining timber in Southern Africa tend to use steel S-hooks or anti-split plates. These are time-consuming to remove, and if the processing machine operator is not careful, it will damage the saw blade,” he explains
“The usual method is to trim and discard the log ends containing the anti-split devices. It is a loss of valuable materials, and the splitting continues,” he explains. Another factor to consider is that wood high in tannic acid, such as oak, reacts with the metal and produces dark stains that reduce the products’ value.
Boardman’s company, Alternative Structures, supplies services and solutions for technical forestry and sawmilling problems. It represents several international and local manufacturers, including the award-winning Austrian company Latschbacher and its brands, WinforstPro and Signumat
The WinforstPro electronic tree, log and lumber tracking tags and monitoring software are popular in Brazil, the USA, and Europe. The Signumat’s forest equipment includes felling wedges, sliding calliper, dendrometers and split-stoppers.
“The Signumat split-stoppers are perfect alternative solutions for southern Africa’s hardwood harvesters and processors,” asserts Boardman.
There are two types of split stoppers, and both are simple, lightweight “staples” made of fibreglass-reinforced plastic. The Premium is made of virgin composite materials, while the Eco has a small percentage of recycled material.
“They are quick and easy to install with a single blow of the Signumat Premium hammer. The logs and timber fitted with the devices can be processed in sawmills without damaging saw blades or harming the machine operators”.
Signumat stops splits
The 11cm long Premium model is highly tensile, designed to penetrate wood easily and does not fade when it encounters moisture or during long-term storing. Latschbacher has patented the wave-shaped tip and barbs that securely hold the staple. The two intermediate crossbars distribute the tensile load equally across the area.
“The extremely stiff end crossbars disappear completely in the wood when applied by one hammer blow, making the Premium and Eco split-stoppers suitable for sawn lumber and logs,” explains Boardman. He says speed and accuracy matter when working with hardwoods, and “the only hammer for the job is the purpose designed Signumat Premium hammer”.
The hammer has a flexible joint that reduces the penetration resistance of wood by about 30%. It assists the user to apply a split stopper with a single blow even if the impact is not parallel to the log surface.