Widely used in the material preparation stages of textile, papermaking, pulp, and engineered wood products industries. The main raw materials for this machine are small-diameter wood, bamboo, wood veneer, and logging residues after debarking. However, it is not sufficiently capable of uniformly cutting excessively coarse (over 350mm), excessively fine (under 30mm), excessively short (under 250mm), excessively thin (under 5mm), or irregular materials (undecomposed stumps, branches, etc.), or it may only cut the raw material on its original shape. It also lacks sufficient layered cutting capability for bamboo with a wall thickness less than 5mm. This type of forestry machinery processes the residues from logging and wood processing into craft wood chips. Wood chips are mainly used as raw materials for pulp, hydrolyzed wood chips, and engineered wood products.
Overview: In the 1870s, the first wood chippers produced and used in developed forestry countries in Northern Europe and North America were equipped with only 3-4 cutting blades. In the 1940s, multi-blade chippers with six or more cutting blades appeared. In the 1950s, a new type of multi-blade chipper with a spiral cutter disc emerged, further improving the performance of wood chippers. In the 1970s, the Forestry Machinery Research Institute of the Ministry of Forestry of China developed a mobile combined chipper that could simultaneously complete chipping, wood chip screening, and pneumatic delivery of qualified wood chips to a loading bin or transport vehicle, thus greatly improving the productivity of wood chipping.
Classification: Wood chippers are broadly classified into two types: stationary and mobile. Stationary chippers are mostly used in factories; mobile chippers are generally used in forest areas. According to the structure of the working parts, they are divided into drum chippers and disc chippers; according to the feeding method, they are divided into inclined feed and horizontal feed types.
① Drum Chipper This type of chipper is mainly used for cutting branches, small-diameter timber, bark, and strips with a diameter or thickness of less than 120 mm. The resulting wood chips are used as raw materials for fiberboard and pulp. Its cutting mechanism consists of a rotating drum with several flying knives mounted on it. As the flying knives rotate, they process the wood into decorative wood chips. The drum has multiple square through holes on its outer edge to allow the wood chips to exit smoothly. The feeding mechanism consists of a feeding interface, upper and lower feeding rollers, and a feeding gap adjustment mechanism. The wood entering through the feeding interface is pressed down by the upper and lower feeding rollers and fed to the cutting mechanism at a certain speed, controlling the size of the wood chips. When processing thicker wood, the feeding gap is adjusted by the feeding gap adjustment mechanism. After screening, larger wood chips must be re-crushed between the blades and the baffle. This type of chipper produces wood chips of lower quality.
② Disc chipper. Consists of a cutter disc, cutting blades, bottom blades, and cutter disc blades. The cutter head has grooves on the front for mounting cutting blades, arranged radially at an angle of 10° to 15°. Wedge-shaped adjusting blocks are placed at the bottom of the blades to adjust the blade's extension and wear depth; a spacing adjusting block is installed at the rear to adjust the compensation length of the blades after sharpening. A through-cutting slit runs along the blade direction on the cutter head, allowing the shaved wood chips to rotate to the other side. Blades are evenly distributed along the outer edge of the cutter head; the airflow generated by the blades blows the wood chips out of the discharge port. After screening, excessively large chips are sent to a further crusher for further grinding. This machine has three types: few-blade, multi-blade, and spiral-face blade. The first two types produce wood chips with poor uniformity. The spiral-face blade chipper, because the entire cutting surface is in contact with the cutter head during the cutting process, has lower unit pressure, resulting in neater cuts, fewer wood chips, less cutter head wear, and consistent chip length. The qualified wood chip rate can reach approximately 97%. Development Trends: Manufacturers of wood chippers worldwide are now focusing on improving cutting mechanisms, blade quality, and clamping methods to reduce sharpening and clamping time. The global decline in forest resources has spurred the development of mobile chippers for logging areas; the adoption of combined logging area chippers and whole-tree chipping machines will further enhance economic efficiency.
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