A Review of Different Sawing and Drying Techniques Used in Processing Small-diameter Logs

Ratnasinga, J.; Abdullah, Aznor Marlina; Ramasamy, Geetha; Seng, Chee

doi:10.3923/jas.2013.341.347

Cited by 6 publications

(2 citation statements)

References 8 publications

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“…Different methods are implemented during wood processing to reduce the effect of LRGS that helps to increase the quality of the wood (Archer 1987;Kubler 1988;Yang and Waugh 2001;Ratnasinga et al 2013;Gril et al 2017). The application of specific sawing patterns (Johansson and Ormarsson 2009;Ratnasinga et al 2013) and methods that include prolonged storage in the open air and underwater sprays, burying and soaking in water (Nogi et al 2003). These methods lead to the relaxation of LRGS at high temperatures, which is induced by boiling, steaming and smoking (Tejada et al 1997;Nogi et al 2003;Severo et al 2010;Pelozzi et al 2014;Rodrigues et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Reduction of growth stresses in logs of Hieronyma alchorneoides Allemão from fast-growth plantations using steaming and heating: effects on the quality of lumber

Moya

2021

Annals of Forest Science

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& Key message Growth stresses are usually present in the fast-growing trees of forest plantations and can be evaluated along stem diameter. Growth stresses are relaxed after tree felling and during sawing and drying, and are manifested in the lumber quality. Different methods have been employed to reduce the effect of growth stresses, such as steaming and heating treatments. Excellent growth and yield in forest plantations of Hyeronima alchorneoides were observed, but they showed difficulties in the primary sawing process and a high incidence of wood warping during the drying process. Steam and heat treatments on the log were used to study their effects on H. alchorneoides sawlog and to evaluate lumber quality. & Context Growth stresses in Hieronyma alchorneoides Allemão trees growing under fast-growth conditions show high and negative effects on the lumber quality (increased warps and splits or checks). Therefore, steaming and heating treatments have been applied to reduce these effects on the lumber. & Aims The main objective of the present work was to evaluate the effects of steaming and heating treatments on sawlogs of Hieronyma alchorneoides from the fast-growth plantations to reduce the longitudinal surface growth stress. & Methods Twenty-six trees ready for felling in the third thinning were sampled and commercial logs measuring 2.5 m long were extracted from them at different heights. These logs were used to investigate the effect of steaming and heating treatments and the growth stresses were measured before and after treatment. Crooking due to sawing, colour and wards, splits and checks were measured. & Results The results showed that the internal temperature of the logs was approximately 85 °C after the heating treatment, and it was nearly 90 °C after the steaming treatment. It resulted in a reduction of 1500 με (micro-deformations) before the treatment to 1000 με after the treatment. Therefore, crooking due to sawing decreased significantly in logs or semi-logs. The parameters such as colour, luminosity (L*), redness (a*) and lightness (b*) decreased in heartwood while L* increased and a* and b* decreased in sapwood, which led to the decrease in quality of the lumber, the magnitude and incidence of the defects in treated logs. & Conclusion As compared to untreated logs, the best performance was obtained with steaming treatment, followed by the heating treatment. The difference found between steaming and heating can be attributed to the temperature in the internal part of the log, which was more than 90 °C in steaming treatment; meanwhile, in the heating treatment, the internal temperature of the log was slightly lower (80-85 °C). Therefore, glass transition can be more easily reached by steaming treatment than by the heating treatment.

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Section: Introductionmentioning

confidence: 99%

Reduction of growth stresses in logs of Hieronyma alchorneoides Allemão from fast-growth plantations using steaming and heating: effects on the quality of lumber

Moya

2021

Annals of Forest Science

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“…The others work on the effects of drying conditions on the dried products [ 5 , 11 , 12 , 14 , 15 , 26 , 27 , 28 , 29 ]. A few published articles investigated moisture equilibrium relationship, drying kinetics, drying time reduction, drying process optimization, and energy efficiency in lab-scale and industrial-scale driers [ 10 , 18 , 21 , 24 , 30 , 31 , 32 , 33 , 34 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Chanpet

Rakmak

Matan

et al. 2020

Heliyon

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Kiln drying of rubberwood lumbers is a complex transport phenomenon for realistic modeling and simulation. To decouple this complexity, researchers usually divide their research into two parts. The first one is single-lumber drying kinetics to describe how wood lumber responds to its surface conditions. Then they combine this drying kinetics with a lumped transport model or dispersion model or computational fluid dynamics. The mathematical models are then solved numerically to predict the industrial kiln drying behaviors. This work focuses on the drying kinetics of stacked rubberwood lumbers using hot air at different air velocity (0.5, 1.5, 2.5, 3.5, 4.0 m/s), relative humidity (6–67% relative humidity (RH)) and temperature (60–100 °C). The drying kinetics followed the conventional drying theory. However, the two drying periods, namely constant and falling rate (CRP and FRP), were not distinct. As the air velocity increased, the transition from CRP to FRP is faster. The middle of the transition period (at critical moisture content, CMC) moves closer to the fiber saturation point (FSP). The overall mass transfer coefficients in the falling rate period for stacked rubberwood drying were lower than those predicted by the Ananias correlation. Hence, a modified formula was proposed, representing the overall moisture transfer coefficients as a function of air velocity, temperature, relative humidity, and lumbers thickness for the range of variables under investigation satisfactorily. In general, the drying rate and the overall moisture transfer coefficient increased with increasing air velocity, drying temperature, and decreasing RH. Relative humidity directly affects the driving force of moisture transfer rate because higher RH is associated with higher equilibrium moisture content. A lumped parameter model for kiln drying was also developed. After being integrated with the estimated mass transfer coefficient, the model can predict the moisture profiles in lab-scale kiln drying satisfactory, although the model needs more validation data. These kinetic parameters and correlation for stacked rubberwood drying can be used in more complex models and process optimization in future research.

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Application of the steaming step during kiln drying of lumber of two tropical species with high growth stress presence

Moya

2021

Drying Technology

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A Review of Different Sawing and Drying Techniques Used in Processing Small-diameter Logs

Cited by 6 publications

References 8 publications

Reduction of growth stresses in logs of Hieronyma alchorneoides Allemão from fast-growth plantations using steaming and heating: effects on the quality of lumber

Reduction of growth stresses in logs of Hieronyma alchorneoides Allemão from fast-growth plantations using steaming and heating: effects on the quality of lumber

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Application of the steaming step during kiln drying of lumber of two tropical species with high growth stress presence

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