Évaluation des pertes causées par les défauts de bois sur le rendement matière au sciage

Abstract

Improving material yield and visual grade of sawn timber remains a major problem for primary wood processing units in Cameroon which face significant losses caused by wood defects. It is with a view of reducing these sawing losses as the present study, which deals with "the evaluation of losses caused by wood defects on sawing material yield” was carried out. Its general objective assessment of losses caused by wood defects on sawing material yield in order to propose solutions to limit these losses and valuation methods for unavoidable waste. This study took place at Ets ARAFAT.COM in Ebolowa. The evaluation was carried out on 45 logs of six species: Padouk, Doussié, Iroko, Koto, Ayous and Sapelli, that were sawed during the data collection period. The methodology consisted of the identification of faults on the logs, the focus was on major faults. The percentage of a fault is found by dividing the number of logs of gasoline with this fault by the total number of logs of gasoline. After taking measurements of the logs before sawing, the volume with sapwood and volume under sapwood were calculated, which allowed us to assess the volume of sapwood. At the end of all sawing operations, the products obtained were cubed as well as the parts rejected due to defects, which made it possible to estimate the proportion of each waste. The yield was calculated by dividing the sum of the volumes of debits obtained on the sum of the volumes of the logs. It appears from the results obtained that the defects major ones identified are sapwood, cracks, and rot. The sapwood volume represents 11.80% of their average volumes with sapwood. By its negligible quantity, the sapwood is perceived as a defect that influences sawing performance. The average volume of cracks and rots generated by sawing these specimens represents 37.99%. The total yield of sawing is 40.04%, for waste production of 59.96% of which 49.79% is due to wood defects. It is therefore important to take into account the wood defects during the logging of logs. Waste recovery is not very advanced in the sawmill, it is just limited to firewood and local sales for various purposes, hence the need for a study on further recovery and even recycling of waste.