Effect of species and log diameter on the volumetric yield of lumber in northern Brazilian Amazonia: preliminary results

Abstract

Volumetric yield analysis is critical to optimizing performance in the timber industry. In the Amazon and in the Amapá state, this information is still little known and scarce, and therefore this study was developed to obtain and analyze the volumetric yield coefficient of ten commercial tree species and to test the variation by diameter class. We collect data of volumetric yield from for ten commercial species. For each species, the yields in different diameter classes were analyzed, as well as the yield difference between the species. The overall yield obtained for the sawmills (43.95%) and the yield of each species are within the established standards for operations in the industry according to the legal requirements. There were no differences (p ≥ 0.05) in diameter classes for species with the exception of Dinizia excelsa and Handroanthus albus. However, there was no linear increase (p ≥ 0.05) between the diameter and yield of lumber for all species. The species Dinizia excelsa, Hymenolobium petraeum, Ocotea rubra and Vochysia guianensis show a significant difference in yield for the other species due to the higher obtained values, however, they are statistically similar when compared to each other.

Conicity and Yield for Lumber From Commercial Species From the Amazon

“…Conicity has a direct influence on the final yield of wood from logs and has been cited as one of the principal factors responsible for low yields in Amazonian sawmills (Garcia et al, 2012;Mendoza et al, 2017;Lima et al, 2019). In the present study, in spite of using estimated values for percent volumetric yield, effects of conicity are possibly present with respect to yield of wood.…”

“…Garcia et al (2012) also observed variation in volumetric yield between logs for two native tropical species and attributed this result to differences in log conicity, among other factors. Lima et al (2019) stressed that conicity has a strong influence on the variation in final products obtained from logs, for example, logs with small diameters and high conicity can result in products with heterogeneous dimensions. Furthermore, these authors stated that there is an excessive loss of raw material due to excessive conicity because the sawing method takes into account the end of the log with the smallest diameter.…”

“…As a function of this characteristic of the samples, the results were compared to studies wherein indices of yield were obtained for logs without hollows. Lima et al (2019) determined the volumetric yield in sawn wood of 10 commercial species in Amapá using 50 logs per species with an average diameter of the smallest end of 64.2 cm, and an average length of 7.6 m. These authors identified the presence of hollows in just two species, and the average yield of the remaining 8 species varied between 37.8 and 54.1%, with an average of 43.2%. In a sawmill in the state of Roraima, Danielli et al (2016) evaluated log sawing methods and reported a volumetric yield of 31.7% for M. huberi for 40 logs free from hollows with an average diameter of the smallest end of approximately 60 cm, and an average length of 6.7 m.…”

Performance of Small-Scale Sawmilling Operations: A Case Study on Time Consumption, Productivity and Main Ergonomics for a Manually Driven Bandsaw

“…Kehinde et al [39] monitored 52 small-scale sawmills in Nigeria and found a log conversion ratio of about 58%. De Lima et al [11] attributed low yields to species characteristics factors, such as conicity and tortuosity, log diameter, cutting techniques, and the equipment used. In fact, these defects may limit the use of wood and generate excessive waste.…”

“…FAO [7] suggested to consider the average volume of sawn wood produced per shift as a predictor for a rapid comparison of mill performance in small and medium sawmills. De Lima [11] studied the production level for the different sizes of logs in the processing industry of the Amazon region, and Pinto [8] evaluated the impact of raw material and process characteristics on the production performance using the WoodCIM ® optimization software (VTT Building Technology, Espoo, Finland). Wang [12] introduced a new measure that better reflects the sawmilling performance, proposing a new performance index, called the 4-F, which considers the following four factors: product mix, lumber recovery, log processing rate, and log diameter.…”