Research Articles

Scots pine (Pinus sylvestris L.) is a fast-growing wood that has been widely manufactured into various furnishing products. To improve the machinability of Scots pine, the cutting force and surface roughness during peripheral milling with helical cutters was assessed via an orthogonal experimental design. Experimental results revealed that the resultant cutting force is positively related to the depth of cut, but negatively correlated with inclination angle of cutting edge and cutting speed. However, surface roughness first declines and then increases with increasing inclination angle, and it also shows an increasing trend with the increasing depth of cut and decreasing cutting speed. Furthermore, the depth of cut significantly contributes to the resultant force and surface roughness, while both the cutting speed and inclination angle have insignificant impacts on the resultant force and surface roughness. Finally, the optimized milling parameters were determined as 62° inclination angle of cutting edge, 45 m/min cutting speed, and 0.2 mm depth of cut, and these parameters are proposed for the quality finishing of Scots pine machining.

Effects of knife-incising and longitudinal kerfing pretreatments were analyzed relative to the high-temperature drying of red pine and pitch pine timbers with cross-sections less than 15 cm. Specimens were prepared as round and square timbers with thicknesses of 9, 12, and 15 cm. They were divided into four groups: control, longitudinal kerf, knife-incised, and a combination of knife-incised and longitudinal kerf. Some results from this study, such as commercial availability and application methods of drying schedules, have immense commercial importance. The incising and kerfing treatment can be used not only to improve drying quality but also as a tool for deriving an optimal drying schedule. The kerfing treatment noticeably reduced the surface checks in square timber. However, the incising treatment caused a phenomenon in which the incisions connect to each other and develop into surface checks. The wood characteristics, such as species, type, thickness, and initial MC, had more influence on determining the drying defects than the pretreatments. For the commercial use of the drying schedule used in this study, it can be useful to determine the appropriate drying time in the third step according to the species, thickness, and shape.

The traditional two-step cultivation mode for fungal cultivation is commonly divided into the seed stage (usually 24 to 48 h) and the production stage (usually 96 to 144 h). The use of two stages prolongs the total production cycle and generates excess wastewater. In this work, an efficient and environmentally friendly one-step fermentation method was applied for the production of fumaric acid by immobilized Rhizopus arrhizus in a stirred-tank reactor. The nitrogen source content and the agitation speed of the reactor were optimized as the two critical factors in the one-step fermentation process; the fumaric acid production of 51 g/L with a yield of 0.42 g/g glucose was comparable with the product from the traditional two-step fermentation process. Furthermore, the total production cycle was shortened to 96 h, and the amount of wastewater was reduced due to the avoidance of the seed culture process. Thus, utilization of the one-step fermentation method to produce fumaric acid was shown to be preferable feasibility and environmental-friendliness. This is a promising method for industrial production of fumaric acid and other high-value biochemicals by fungus.

The design of a stationary disc wood chipping machine was considered, as well as the stress-strain analysis of a cutting knife with a flat and shaped cutting edge, which will produce a dimensional chip. The design consisted of the conceptual design of a cutting knife, a cutting mechanism, and an entire disc chipping machine, which includes cutting tools. The design solution is based on mathematical calculations of the individual parts of the cutting device. Calculations of the cutting mechanism and the cutting tool were performed using the finite element method. The results of the stress analysis found that the maximum stress acting on the edge of the knife during cutting corresponded to the permissible stresses of the knife material and subsequent use in practice. Based on the design and physical parameters of the wood cutting process, the design of the entire chipping machine was simulated and then was modeled using the PTC Creo parametric 5.0 program. Additional finite element analysis was performed using the Creo Simulate 5.0 software.

This research evaluated the possible use of tropical hardwood species (Myrocarpus frondosus and Ocotea porosa) for grilling plank production. Physical, chemical, and organoleptic properties were evaluated and compared with properties of a well-used wood species for grilling planks, western red cedar (Thuja plicata). For chemical analysis, one technique was used: hydrodistillation. Normality tests and analyses of variance (ANOVA) were used for the comparisons between Thuja plicata and tropical hardwoods. The results of the organoleptic, chemical, and statistical analyses demonstrated the possibility of using Myrocarpus frondosus and Ocotea porosa in grilling plank production.

Bending strength tests were conducted of cross-laminated timber (CLT)-concrete composite slabs according to the shear connection method and carbon fiber reinforced plastic (CFRP) reinforcement. The bending strength of the composite slab that was shear-connected with an epoxy adhesive was 17% higher than that of a composite slab that was shear-connected with a self-tapping screw. In addition, the CLT-concrete slip of the former composite slab was also measured as 20% lower than the latter under the same load, showing a behavior close to that of a full composite. Both shear connection methods generated a failure in a low load-deformation section when there was a defect in the outermost tensile laminae of the CLT. In contrast, the CFRP reinforcement in the tension part of the composite slab suppressed the failure at the defect in the outermost tensile laminae. This reinforcement effect increased the reliability of the bending performance of the composite slab by preventing the failure of the composite slab while in a constant failure mode. Furthermore, the slip of the composite slab decreased 49% after its reinforcement with CFRP, showing a behavior close to that of a full composite.

A sound or a noise that accompanies wood machining processes is introduced by the tool rotation itself, by the friction of moving machine parts, or by wood-tool interaction. The sounds generated during machining with a circular saw could be analysed in order to monitor and possibly control the cutting process. Applying altered cutting parameters while cutting beech wood (Fagus sylvatica L.), which is the most common wood species in the Republic of Serbia, caused acoustic emissions that could be analysed throughout corresponding spectra. As shown in previous studies, altering the cutting parameters, e.g., the feed speed and tool override, resulted in variations in power consumption, surface roughness, and acoustic emission (or acoustic pressure). The aim of this paper was to provide a possible correlation between the applied cutting parameters and the acoustic emission spectra with respect to consumed power and the state of the machined surface. Along with acoustic emissions, the power consumption and surface roughness data were also acquired in order to make a possible relationship. By associating the idle circular saw acoustic spectra with background noise and comparing them with those obtained during machining, it was possible to indicate spectrum areas of particular interest for further analysis.

Polylactic acid is a biodegradable thermoplastic polyester derived from renewable polysaccharides. In this work, softwood fibers were used to reinforce the paper sheet made from polylactic acid fibers, thus addressing the challenges regarding low density, rough surface, and weak strength. The impact of wood fibers and calendering on the physical properties (density, roughness, tensile strength, and folding endurance) of the composite paper were identified. Furthermore, the morphology of papers with different fiber contents and those that had been calendered was characterized with a scanning electron microscope. The use of wood fibers resulted in the improvement of the physical properties of the polylactic acid paper, and the enhanced refining of wood fibers had a favorable role in improving paper density, smoothness, and mechanical strength. The tensile index increased 37.9% when the beating degree of wood fibers increased from 25 to 60 °SR. After calendering, the density, smoothness, tensile strength, folding endurance, and air barrier property of the paper were improved 60.2%, 45.8%, 15.5%, 148.1%, and 79.4%, respectively. The calendering-based papermaking process involving the combined use of wood fibers and polylactic acid fibers would be a promising strategy for designing composite materials for tailorable end-uses.

The feasibility of the dynamic testing was explored for the elastic modulus and shear modulus of full-scale laminated veneer lumber in batches at the production site. In order to do so, dynamic testing and analysis, involving a hammer blow and detection of frequencies, were carried out on the laminated veneer lumber free-plate placed in two ways: suspended and placed on a sponge. The results showed that the mode shape and modal frequency value of the suspended laminated veneer lumber free-plate obtained from the modal test were consistent with those of the specimens placed on the sponge. The elastic modulus and shear modulus values of the laminated veneer lumber free-plate obtained in sponge mode based on the transient excitation method were 3.99% and 3.08% higher than the elastic modulus and shear modulus values of the laminated veneer lumber obtained in suspension mode obtained based on the modal test method. The feasibility and reliability of the elastic modulus and shear modulus values obtained by the laminated veneer lumber free-plate in sponge mode were verified.

The furniture industry is the fastest growing sub-sector in the Malaysian wood-based industry. Although it has grown tremendously over the years, it is characterized by stagnating value-addition. To improve industrial competitiveness, automation and technology application has emerged as a possible solution. A study was conducted to evaluate the influence of company size towards their readiness and adoptability of automation and Industry 4.0. A questionnaire-based survey involving large-, medium-, small-, and micro-sized furniture manufacturers throughout Malaysia was conducted with 160 respondents. The analysis of the results from the survey showed that there was a significant relationship between company size and their readiness for Industry 4.0. The results showed that small- and medium-sized enterprises (SMEs) are more hesitant in adopting technology due to the high cost required and the lack of skilled workers to cope with the new technology, compared to the large sized companies. The factor analysis revealed that the three main groups of the factor affecting decisions towards adopting industry 4.0 are government policy, difficulty in implementation, and expected benefit. This study suggests that providing incentives for the application of automation and technology will be required when the goal is greater uptake of technology among furniture manufacturers.