Blas Mola-Yudego, Gianni Picchi, Dominik Röser, Raffaele Spinelli. (2015). Assessing chipper productivity and operator effects in forest biomass operations. Silva Fennica vol. 49 no. 5 article id 1342. https://doi.org/10.14214/sf.1342

Keywords: mixed models; efficiency; comminution; operator effect; raw material supply; wood chippers

Highlights: A model is constructed to assess the productivity in chipping of wood biomass at roadside; The data includes 172 trials and 67 operators in Italy; The operator effect was included in a mixed model approach; The R2 were 0.76 (fixed part) and 0.88 (incl. operator effects).

Abstract | Full text in HTML | Full text in PDF | Author Info

The present research focuses on the productivity of energy wood chipping operations at several sites in Italy. The aim was to assess the productivity and specifically the effect attributed to the operator in the chipping of wood biomass. The research included 172 trials involving 67 operators across the country that were analysed using a mixed model approach, in order to assess productivity, and to isolate the operator effect from other potential variables. The model was constructed using different predictors aiming to explain the variability due to the machines and the raw-materials. The final model included the average piece weight of raw material chipped as well as the power of the machine. The coefficients of determination (R²) were 0.76 for the fixed part of the model, and 0.88 when the effects due to the operators were included. The operators’ performance compared to their peers was established, and it was compared to a subjective classification based on the operator’s previous experience. The results of this study can help to the planning and logistics of raw material supply for bioenergy, as well as to a more effective training of future forest operators.

Mola-Yudego, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland; NIBIO Norwegian Institute of Bioeconomy Research, P.O. Box 115, 1431 Ås, Norway http://orcid.org/0000-0003-0286-0170 E-mail: blas.mola@uef.fi
Picchi, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy E-mail: picchi@ivalsa.cnr.it
Röser, Forest Feedstocks Group, FPInnovations, Vancouver, British Columbia, Canada E-mail: dominik.roser@fpinnovations.ca
Spinelli, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy E-mail: spinelli@ivalsa.cnr.it

article id 984, category Research article

Christian Rottensteiner, Petros Tsioras, Heinz Neumayer, Karl Stampfer. (2013). Vibration and noise assessment of tractor-trailer and truck-mounted chippers. Silva Fennica vol. 47 no. 5 article id 984. https://doi.org/10.14214/sf.984

Keywords: chippers; noise; whole-body vibration; exposure limit values

Highlights: Truck-mounted chippers were associated with higher vibration values, while tractor-trailer chippers had higher noise level; Chipping hardwood produced higher vibration magnitudes than softwood; Vibration and noise values in most cases did not exceed the exposure limit values set by the European Union.

Abstract | Full text in HTML | Full text in PDF | Author Info

During chipping, machine operators are exposed to whole-body vibration and noise bearing a risk to health. Vibration on the operator’s seat and noise inside the chipper cab was measured and analyzed. The factorial design considered two setup variants (tractor-trailer and truck-mounted) of two chipper models from different manufacturers during chipping of softwood and hardwood tree species. Furthermore, exposure to noise was measured during chipping of hardwood. Vibration and noise during chipping, driving between wood piles, and operational delays were measured separately. The results associated truck-mounted chippers with higher vibration values and tractor-trailer chippers with higher noise levels. The highest vibration levels were recorded while driving on the forest road from one log pile to another and the second highest during chipping. On the contrary, the lowest vibration levels were measured during operational delays with the chipper in idling condition. Chipping hardwood produced higher vibration magnitudes than softwood. Exposure to noise was significantly higher during chipping compared to driving and operational delays. Vibration and noise data were combined with time studies data, for the calculation of eight-hour energy equivalent total values, both for vibration and noise. In all cases, the exposure limit values set by the European Union were not exceeded, with the exception of truck-mounted chippers, which are likely to exceed the exposure action value for vibration.

Rottensteiner, University of Natural Resources and Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Straße 82, 1190 Wien, Austria E-mail: christian.rottensteiner@boku.ac.at
Tsioras, Aristotle University, P.O. Box 227, GR-541 24 Thessaloniki, Greece E-mail: ptsioras@for.auth.gr
Neumayer, Specialist in Occupational Medicine, Wörndlestraße 10, 6020 Innsbruck, Austria E-mail: heinz.neumayer@die-arbeitsmedizin.at
Stampfer, University of Natural Resources and Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Straße 82, 1190 Wien, Austria E-mail: karl.stampfer@boku.ac.at

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