A new comminution device for high-quality chip production

The authors tested a chipper prototype adopting a new comminution device, designed to produce high quality chips when processing delimbed logs. The machine was fitted with innovative tubular blades, mounted on a flywheel. The prototype was powered by a 55 kW farm tractor through the standard power take-off. The machine appeared as efficient as most conventional disc or drum chippers in the same size class, but offered a much better chip quality. Chips were free from any particles longer than 45 mm, and with a very limited content of fine particles (max. 2.5%). Of course, this was achieved when using premium wood raw material, such as delimbed small logs. Performance varied with tree species: poplar was the softest and easiest to chip, whereas robinia was the hardest and required a much larger effort. Diesel fuel consumption varied between 3.4 and 4.3 dm3 per oven-dry tonne.