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Debarking at Sawmills & Plywood Mills

Rotor debarking is the most commonly used method of debarking in the sawmill and veneer industry (e.g. plywood and LVL). It is the most cost-effective method when we consider the volume of wood normally used in these production units. Among the known methods, rotor debarking is the least damaging to the wood, which makes it an excellent choice for the sawmill and plywood industries.

Debarking at sawmills

The debarkers at sawmills are positioned either at the location of the infeed or at the beginning of the log sorting line before the timber is sorted according to diameter. In the Nordic countries, Russia, and North America, the debarker is usually found in the front of the saw line, whereas most in Central and South European as well as South American sawmills place it in the log sorting line.

Debarking at the saw infeed

Positioning the debarker in the saw line requires the machine to function reliably, as the entire line process is dependent on it. Saw line debarking enables:
  • Optimization of the debarking speed according to log size (the wood has usually been sorted by diameter)
  • Feeding of wood into the debarker end-to-end without space in between logs (which are usually turned top end first)
  • Transferral of wood into the saw line as cleanly as possible (the debarked logs do not need to be lowered to the ground at any stage)
Storing wood at a log yard is also easier as wood is debarked only in the sawline. Logs are not as slippery when the bark is still on. The bark also protects the wood for as long as possible prior to sawing. It slows the drying of the wood in warm conditions and reduces surface damage caused by loaders.

Debarking in the log sorting line

Positioning the debarker in the log sorting line improves sawing results thanks to more accurate log measurement. In the log sorting line, the wood is always debarked before measuring, so bark percentage does not come into consideration. Instead, measurements are always correct.

However, the ideal positioning of the debarker depends on the pricing method used in the respective timber markets. In Central Europe, for example, sawmills pay for actual wood with bark not included. In this case, it is recommended to debark the wood before the measurement that defines the payment.

The third reason for positioning the debarker in the log sorting line is the sawmill’s capacity requirement. At a log yard, the operating time of the debarker is flexible and can be increased as necessary, thereby ensuring a sufficient supply of wood for the sawmill.

We regularly supply single-rotor or tandem rotor debarkers to sawmills all over the world. See machine series VK5000, VK8000, and Kodiak in particular.

Debarking at veneer and plywood mills

In veneer production, it is essential to avoid damaging the surface and ends of the wood during debarking. Rocks and other impurities in the bark that enter the peeling knives cause the knives to wear out more rapidly and reduce the quality of the veneer. Debarking the wood before peeling means the knives are kept in considerably better condition. It ensures an uninterrupted production process, excellent level of quality, and minimal knife maintenance costs.

Due to the considerably higher price of top veneer, the wood’s most valuable part is its surface. The difference is significant when compared to the production of sawn timber, for example, which usually involves producing woodchips of the surface layers.

In veneer production, the raw material is usually soaked before it is cut into veneer. For the debarking process, it is better to position the debarker after the soaking phase where possible. This means the debarking tools and feed rolls do not need to place as much pressure on the wood. Debarking is recommended after soaking, particularly in areas where the wood is likely to freeze in winter. Some wood species, such as birch, must always be soaked before debarking.

We have decades of experience throughout the world debarking the species of wood used by the veneer and plywood industry. For example, the most common debarker in veneer and plywood mills that process birch is manufactured by VK – machine model VK8032PLY. Other hardwood and softwood species are normally debarked with our single-rotor debarkers, such as VK90, VK100, VK110, VK1092, and the VK8000 series.

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