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It is currently known that in certain circumstances pre-rounding of cutting blades can significantly increase tool life. Despite many data on the beneficial effect of drag-finishing on the durability of metalworking tools, it is not entirely clear whether similar benefits appear when machining wood-based panels. The results of some pilot study are quite promising but the real impact of cutting blades pre-rounding (it is about blades made of various standard cemented carbides), on tool life in particleboard milling are very rarely studied. The study aims to fill this gap in the knowledge system. The experimental research was carried out using a CNC milling machine equipped with a single-blade milling head with replaceable blades. It turned out that the positive effect of the drag-finishing of cutting blades on tool life in particleboard machining depends on the structure and hardness of carbide. A significant extension of the tool life (about 50%) was observed only in the case of particularly hard carbide (2240 HV10). There was no significant advantage for the softer type of carbide (1800 HV10). [ABSTRACT FROM AUTHOR]

The stochastic nature of tool wear during wood machining, owing to the dynamic properties of the biological material and its dependence on various factors, has raised significant industrial and research concerns in recent years. Explicitly, the tool wear is a product of the interaction between wood properties (such as hardness, density, and contamination level) and machining parameters (such as cutting speed, feed rate, and rake angle) alongside ambient conditions (such as temperature and humidity). The objective of this review paper is to provide an overview of recent advancements in the field of wood machining. To begin with, it highlights the important role of wood properties and ambient conditions influencing tool wear. Furthermore, the paper examines the various mechanisms involved in the wood-machining process and discusses their cost implications from an industrial perspective. It also covers technological advancements in the characterization of tool wear and explores the relationship between this parameter and other machining variables. It provides critical and analytical discussions on various methods for enhancing tool wear, including heat treatment, cryogenic treatment, thermochemical treatment, coating deposition, and hybrid treatments. Additionally, the paper incorporates statistical analysis to achieve two objectives. Firstly, it aims to identify the most significant wood property that affects tool wear and establish the correlation between this parameter and wood properties. Secondly, it investigates the effect of heat treatment parameters and carbide characteristics on tool wear as well as their correlation. Lastly, the review provides recommendations based on relevant literature for prospective researchers and industrial counterparts in the field. These recommendations aim to guide further exploration and practical applications in the subject matter. [ABSTRACT FROM AUTHOR]

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Walnut (Juglans regia L.) is widely used in wood furnishings, and machinability is a key factor for improving product quality and enterprise benefits. This work focused on the influence of the rake angle, depth of cut, and cutting speed on the cutting force and machined surface roughness during the straight-tooth milling of walnut. On the basis of the experimental findings, a mathematical model was created using a response surface methodology to determine the relationship between the cutting force and the cutting conditions, as well as the relationship between the surface roughness and the cutting conditions. Variance analysis was used to study the significant contributions of the interactions of various factors and two-level interactions to the cutting force and surface roughness. The optimized combination of milling conditions, resulting in lowest cutting force and surface roughness, was determined to be a rake angle of 5°, a depth of cut of 0.6 mm, and a cutting speed of 45 m/s. [ABSTRACT FROM AUTHOR]

The cutting process of oak (Quercus robur) was investigated by means of a novel testing approach. A unique testing device, enabling nearly linear stand-alone cuts, was used. The specimens climatized to 6 different moisture content levels were machined within cutting velocities ranging from 5 to 80 m·s−1, at 5 cutting fibre angles from along to across the grain, and at different uncut chip thicknesses of up to 0.5 mm. The precise quartz sensor utilized for observing cutting forces enabled insights into the cutting mechanism involved while wood disintegration. Cutting velocity evolved as a key process parameter strongly influencing cutting force. Evaluation of uncut chip thickness showed a regression that was strongly influenced by particular force components. The friction force generated by "ploughing" the surface was relevant when cutting thin chips. In contrast, the part of force introduced by chip formation affected the process weightily in the case of cutting a thick chip. When cutting parallel to the grain lower forces were observed than cutting perpendicular to grain orientation. Obtained data supported the mathematical force prediction model establishment involving several parameters (e.g. cutting velocity, cutting fibre angle, uncut chip thickness, and moisture content). [ABSTRACT FROM AUTHOR]

The stochastic nature of tool wear during wood machining, owing to the dynamic properties of the biological material and its dependence on various factors, has raised significant industrial and research concerns in recent years. Explicitly, the tool wear is a product of the interaction between wood properties (such as hardness, density, and contamination level) and machining parameters (such as cutting speed, feed rate, and rake angle) alongside ambient conditions (such as temperature and humidity). The objective of this review paper is to provide an overview of recent advancements in the field of wood machining. To begin with, it highlights the important role of wood properties and ambient conditions influencing tool wear. Furthermore, the paper examines the various mechanisms involved in the wood-machining process and discusses their cost implications from an industrial perspective. It also covers technological advancements in the characterization of tool wear and explores the relationship between this parameter and other machining variables. It provides critical and analytical discussions on various methods for enhancing tool wear, including heat treatment, cryogenic treatment, thermochemical treatment, coating deposition, and hybrid treatments. Additionally, the paper incorporates statistical analysis to achieve two objectives. Firstly, it aims to identify the most significant wood property that affects tool wear and establish the correlation between this parameter and wood properties. Secondly, it investigates the effect of heat treatment parameters and carbide characteristics on tool wear as well as their correlation. Lastly, the review provides recommendations based on relevant literature for prospective researchers and industrial counterparts in the field. These recommendations aim to guide further exploration and practical applications in the subject matter.

This work focused on changes in surface roughness under different cutting conditions for improving the cutting quality of beech wood during milling. A response surface methodology and an adaptive network-based fuzzy inference system were adopted to model and establish the relationship between milling conditions and surface roughness. Moreover, the significant impact of each factor and two-factor interactions on surface roughness were explored by analysis of variance. The specific objective of this work was to find milling parameters for minimum surface roughness, and the optimal milling condition was determined to be a rake angle of 15°, a spindle speed of 3357 r/min and a depth of cut of 0.62 mm. These parameters are suggested to be used in actual machining of beech wood with respect of smoothness surface. [ABSTRACT FROM AUTHOR]

This work focused on changes in surface roughness under different cutting conditions for improving the cutting quality of beech wood during milling. A response surface methodology and an adaptive network-based fuzzy inference system were adopted to model and establish the relationship between milling conditions and surface roughness. Moreover, the significant impact of each factor and two-factor interactions on surface roughness were explored by analysis of variance. The specific objective of this work was to find milling parameters for minimum surface roughness, and the optimal milling condition was determined to be a rake angle of 15°, a spindle speed of 3357 r/min and a depth of cut of 0.62 mm. These parameters are suggested to be used in actual machining of beech wood with respect of smoothness surface.

This paper presents an FEA modeling strategy for predicting the cutting forces generated during linear wood machining. The objective is to determine both the forces and paths of cracks propagating in elastoplastic and anisotropic materials. The model combines a bilinear representation of the material strain-stress relation and the Hill yield function. The proposed procedure also integrates the displacement extrapolation method to evaluate the stress intensity factors. It establishes the cutting forces from the contact pressures between the tool and the chip. These pressures are determined using the penalty method. The validation phase compares the model predictions with average experimental forces and shows correspondence levels higher than 91% and 92% for low (0.085e10−3 m/s) and high (6.8 m/s) wood-feeding speeds, respectively. The developed model maintains a high precision degree over a large range of feeding-velocity. This study demonstrates that the resistive force between the chip and the tool surface is a function of both the rake angle φ and the coefficient of friction (COF). The friction force prompts a self-energizing effect, which increases the resistive force. On the other hand, larger φ amplitudes reduce this effect. Furthermore, the rake angle φ defines the crack propagation mode. Larger φ amplitudes favor the opening mode, whereas smaller values promote the shear mode. The COF amplitude also influences the surface quality, with larger COFs producing more profound cutting dimples. Thus, reducing the COF should result not only in lower cutting forces but also in a better surface quality of machined parts. [ABSTRACT FROM AUTHOR]

Previous methods for the investigation of high-speed cutting processes for bio-based materials failed since essential principles for the investigation of dynamic processes have not been taken into account. The novel self-developed device, based on the principle of a rotor arm, enables a detailed analysis of cutting processes. The rotor arm has a diameter of 4 m, enabling precise analysis of cutting processes. The device enables analysis of speeds up to 100 m/s of the more or less linear cutting process. Stiffness of the set-up, the natural frequency of the system, and a series of cuts per test may cause a convoluted signal demanding dynamic calibration of the measurement chain. The newly developed device enables the conduction of single cuts per examination at relatively high speed. Thus, the influence of the previous cut is eliminated. Previous research has not provided a possibility to study linear cutting processes at the mentioned velocity. The accuracy of the device was proven within various examinations. A correction based on real chip thickness measurement was applied. Finally cutting of beech, using a wide set of parameters, was examined. The cutting forces of the beech sample increased linearly with chip thickness. Nevertheless, the influence of velocity showed non-linear progression. The smallest force was observed at 20 m/s. From this cutting speed, force always increased when velocity was changed. [ABSTRACT FROM AUTHOR]

Circular saw blades, either with carbide or diamond inserts, are customarily embedded in wood working machines once they permit a precise and efficient manufacturing of wooden products starting from raw-shaped solid wood chunks or laminate panels, allowing efficient processes and improving the overall industrial quality and competitiveness of the final product. However, the parameters associated with blade design must be defined with caution, aiming to avoid undesirable cutting performance and consequent relevant detrimental impacts on both processes and equipment. Thus, based on the literature, the present investigation intends to collect and gather a consistent information set regarding the effect of changes in tool design parameters on manufacturing, particularly in the case of wood machining by circular saw blades with reinforced tips. The general outlook provided aims at pointing out essential frameworks and practical guidelines for a better comprehension of the most adequate criteria to be used in the design and choice of tools for each specific manufacturing condition.

Southern pine and spotted gum are two of Australia's most important locally produced commercial timbers. However, internationally, they are amongst the most problematic species to glue cost-effectively, especially for sawn-laminate-based structural engineered wood products, such as glulam and cross-laminated timber. This study investigated the efficacy of different pre-gluing wood surface machining preparations on the tensile shear strength of lap shear samples prepared from both species. Surface machining methods tested included planing, face milling, and sanding post-planing with 40 and 80 grit sandpaper. Wood face milling is not currently used commercially in Australia and has not previously been adequately tested on Australian commercial timbers to improve wood adhesion. Planing is currently the most common method used internationally for preparing wood surfaces for gluing. For both species, face milling with fast feed speed (45 m/min), slow cutter speed (57 m/s), and sanding treatments post-planing resulted in significantly higher tensile shear strength compared to planing for lap shear samples that had been subjected to an accelerated weathering process. Performance differences in tensile shear strength between surface machining methods are likely to be related to the effects of these machining methods on surface roughness, fibrillation, and sub-surface cell damage. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of rotation speed and vibration response of a circular saw on the sawing process of Douglas-fir wood. An idling test was conducted on a guided circular saw to determine its stable operation speeds and vibration behavior. Short-time Fourier transform analysis was performed on saw idling test data, and variation of excited frequencies of the blade as a function of rotation speed was obtained. The saw blade critical speeds and the rotation speeds that correspond to saw flutter instability were identified. Then experimental cutting tests were conducted at different cutting conditions and the effect of rotation speed and saw vibration response on cutting power consumption and sawing accuracy was investigated. The results showed that conducting a saw idling test and vibration response analysis can identify the saw critical and flutter speeds, which is essential for identifying the optimum rotation speed of circular saw. There was a significant increase in power consumption when cutting at super-critical and super-flutter speed. The effect of rotation speed on sawing accuracy is complex and nonlinear. This effect interacts with feed speed, which makes it difficult to generalize sawing accuracy versus rotation speed in the circular sawing process. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the surface roughness values of Turkish red pine samples obtained from the seven natural growth areas in Turkey. The samples were cut with a circular saw, planed with a thickness machine, and sanded with a sanding machine (with No. 80 sandpaper). After the samples were processed as radial and tangential surfaces in the machines, their surface roughness values (Ra, Ry, and Rz) were measured in accordance with ISO 4288 (1996). According to the statistical results, the lowest surface roughness values were in the samples obtained from the Muğla and Samsun areas on the tangential surfaces that were processed with the thickness machine.

Specimens taken from Pinus nigra Arnold were subject to surfacing techniques by being cut with a circular saw, planed with a thickness machine, and sanded with a calibrating sanding machine (with P80 grit sandpaper). First, their surface roughness values were measured; then, the specimens were processed in the machines in a radial and tangential process. Afterwards, the change in shear strength (adhesiveness resistance) was analyzed as a result of bonding with various adhesive types (PVAc, PU) and pressure applications (0.45 N/mm² or 0.9 N/mm²). Approximately 600 specimens were prepared with the purpose of identifying the effect of variables on the bonding performance, and they were subjected to shear testing. The greatest shear strength achieved for both the tangential and radial surfaces in terms of cutting was observed in specimens processed in the thickness machine, on which polyvinyl acetate adhesive and 0.9 N/mm². pressure were applied. Specimens bonded with polyvinyl acetate adhesive displayed higher shear strength in general in comparison to those bonded with polyurethane for both tangential and radial surfaces.

The main objective of this work was to evaluate the effects of two machining processes on European oak wood surface characteristics. The relationships between wettability, free surface energy and machining methods were studied. Sawing and slicing, with or without sanding, were used to prepare surfaces prior to testing whether they produce surfaces with different characteristics. For the wood surfaces machined by slicing and sawing, there was a significant difference in contact angle measurements. This indicates that the influence of machining processes such as slicing and sawing on contact angle value is remarkable. Sanded surfaces showed good wettability and high process roughness.

In this paper, the optimization of computer numerical control (CNC) machining parameters were conducted using the Taguchi design method on the surface quality of massive wooden edge glued panels (EGP) made of European larch (Larix decidua Mill). Three machining parameters and their effects on surface roughness were evaluated. These parameters included tool clearance strategy, spindle speed, and feed rate. An analysis of variance (ANOVA) was performed to identify the significant factors affecting the surface roughness (Ra and Rz). Optimum machining parameter combinations were acquired by conducting an analysis of the signal-to-noise (S/N) ratio. Optimal cutting performance for the Ra and Rz was obtained for the cutter at a tool clearance strategy of an offset 16000 rpm spindle speed and 1000 mm/min feed rate. The surface roughness, both the Ra and Rz, increased with increasing feed rate. Optimal cutting performance for Ra and Rz was obtained for a tool clearance strategy of an offset 16000 rpm spindle speed, and 1000 mm/min feed rate cutting settings. Based on the confirmation tests, Ra decreased 2.2 times and Rz 1.8 times compared to the starting cutting parameters.

In this study, samples were subjected to the following surface treatment techniques: sawing with a circular saw, planing with a thickness machine, and sanding with a sanding machine (with No. 80 sandpaper). After samples were treated radially and tangentially with machines, their surface roughness values (Ra, Ry, and Rz) were measured according to ISO 4288. When statistics related to surface roughness values (for Ra, Ry, and Rz) were analyzed, it was found that surfaces processed with the thickness machine exhibited the smoothest surfaces. Also, according to the same statistical tables, the lowest surface roughness values were found for surfaces cut tangentially.

The objective of this study was to understand better the cutting forces and chip formation of Scots pine (Pinus sylvestris L.) with different moisture contents (MCs) and machined in different cutting directions. To that end, an orthogonal cutting experiment was designed, in which Scots pine was intermittently machined using a tungsten carbide tool to produce chips. The cutting forces were measured and the chip shapes were quantitatively described. Four conclusions can be drawn: (1) with increasing MC, the average cutting forces initially decreased and then stabilized, while the angle between the direction of the main and the resultant force continuously decreased. (2) The average cutting forces in the 90°–0° cutting direction were lower than the same forces in the 90°–90° cutting direction. (3) During machining, the dynamic cutting forces fluctuated less in the 90°–0° case. However, the dynamic feeding forces showed a decreasing trend in both the 90°–0° and the 90°–90° cases. (4) The process applied produced granule chips and flow chips, while less curly flow chips with a higher radius of curvature were more easily produced from samples with high MCs in the 90°–0° cutting direction. [ABSTRACT FROM AUTHOR]

Until today cutting processes were mainly optimized by trial and error to increase yield and surface quality. However, optimization of the cutting process, e.g. reduction of the saw kerf width, improvement of surface quality as well as tool optimization, requires a basic understanding of the interaction between tool and workpiece. However, knowledge-based optimization of cutting processes is lacking from a valid cutting model considering the complex and inhomogeneous structure of wood. Subsequently, out of this analytical description an applicable semi-empirical model, likewise in the metal working industry, is necessary. But, the validation of a cutting force model requires the existence of consistent cutting force values. However, utilization of data from previous studies is impossible as important information about data processing, cutting parameters as well as wood properties is lacking. To enable a validation of the cutting force model, a standardized and reliable method for the examination of cutting forces had to be developed. For slow dynamic cutting processes (6.8 m/s), a pendulum was modified enabling the examination of different cutting directions. For high-resolving cutting force measurements, a force sensor (90 kHz) was mounted between machine table and knife holder allowing force measurements in three directions. [ABSTRACT FROM AUTHOR]

The main objective of this work was to evaluate the effects of two machining processes on European oak wood surface characteristics. The relationships between wettability, free surface energy and machining methods were studied. Sawing and slicing, with or without sanding, were used to prepare surfaces prior to testing whether they produce surfaces with different characteristics. For the wood surfaces machined by slicing and sawing, there was a significant difference in contact angle measurements. This indicates that the influence of machining processes such as slicing and sawing on contact angle value is remarkable. Sanded surfaces showed good wettability and high process roughness. [ABSTRACT FROM AUTHOR]

Effects of type of wood, number of blades, and depth and width of cutting were evaluated relative to the noise level during the machining of wooden materials in a spindle moulder. Lombardy poplar, Oriental beech, and medium density fibreboard (MDF) materials, at the thickness levels of 6 mm, 12 mm, 18 mm, 25 mm, or 30 mm, were planed for 20 min for each variable at the feed rate of 5 meters per min and at the cutting depth of 1 mm, 2 mm, or 3 mm with one or four blades. During machining of the samples, the noise levels were measured using a noise level meter. According to the data obtained, the highest noise level connected to the type of materials was measured in the machining of poplar wood, followed by that of beech wood and MDF. As the thicknesses of the materials were increased, increases up to 9 dBA of the noise level were measured. Moreover, machining the materials with one blade instead of four and with a cutting width of 1 mm instead of 3 mm increased the noise level by 2 dBA and 6 dBA, respectively. [ABSTRACT FROM AUTHOR]

Forced structural vibration and cutting tool inaccuracy have been identified to be the primary causes of surface defects in rotary wood planing. This paper presents the development of a control strategy used to compensate for the effects of both vibration and cutting tool inaccuracy on planed wood surface finish. The solution is based on active vibration control and real-time modification of the cutting tool trajectory using an optimal Linear Quadratic Gaussian tracking controller. A small-scale mechatronic wood planing machine, which has an actively controlled spindle unit, has been designed for practical investigation of the proposed technique. Experimental results show that the applied compensation increased the dynamic performance of the machine and the quality of the surface finish produced. [ABSTRACT FROM AUTHOR]

The main objective of this work is to develop a mathematical model to evaluate optimum sanding conditions of Europen black pine (Pinus nigra). Samples were sanded using different of grit size, feed rate, cutting speed and depth of cut. Average surface roughness (Ra) values of each type of specimens were measured employing a stylus type of equipment. Interaction between sanding parameters and surface roughness of the species were analyzed using Minitab software and response surface methodology. Based on the findings in the work feed rate, cutting speed, grit size and depth of cut values of 5,39 m/min, 19,75 m/sec, 220 (grit size) and 9 mm were determined as optimum sanding conditions. [ABSTRACT FROM AUTHOR]

The introduction of lightweight cutting tips in industrial wood machining could lead to machining at much higher speeds and thus greatly increase efficiency. One possible way to achieve this is through lightweight ceramic composites. An Al 2 O 3 ceramic matrix was selected and reinforced with particles resulting in a density of approximately one quarter of the currently used heavy tungsten carbide tools (density of >15 g/cm 3 ). Furthermore, a coating was applied to the ceramic cutting tools in order to increase the stability of the cutting edge. A combination of reduced coefficient of friction, frictional forces and a resulting decrease in temperature can lead to a reduction in chipping at the cutting tip. Chipping has always been the major drawback of ceramic cutting tools for industrial wood cutting. A ceramic composite containing 25 vol% of submicron and nano sized SiC particles shows good mechanical properties with HV 2 =21.5 GPa and K Ic =4.5 MPa m 1/2 . This composition performed very well in industrial cutting trials on laminated beech. The cutting performance was increased further by use of an industrially available coating on the tools. The quality of the cut wood surface has always been difficult to characterize when comparing cutting tool materials and is often performed qualitatively by experienced carpenters by touch. The surface quality of the machined laminated beech was for the first time quantitatively characterized using Gelsight 2.5D tactile sensing. [ABSTRACT FROM AUTHOR]

In this study a number of work-piece variations were evaluated whilst limiting the cutting conditions. Eight wood species controlled at four moisture levels were machined along and across the wood grain. The tool used during cutting was designed to resemble a rip saw tooth with zero rake angle and narrow edge width. Each work-piece variation machined in the cutting tests was subjected to mechanical tests that evaluated bending properties across the grain and shear properties along the grain. The regression model establishes a relationship between the bending properties for cutting forces across the grain, as well as shear properties for cutting forces along the grain. F and R² values show that the elastic properties of the wood in bending and shear have less influence on the cutting forces when compared to the strength and toughness. Additionally, density is seen to have less influence on the cutting force along the grain. This is explained by the tool passing through an unquantifiable proportion of early and latewood fibers from the annual growth rings. Cutting across the grain, the tool is forced to machine through approximately the same proportion of earlywood and latewood fibres.

A concentração de calor na superfície da madeira, resultante do seu processamento mecânico, promove o desgaste prematuro da ferramenta de corte, com consequente efeito sobre o acabamento do material processado, ocasionando o aparecimento de regiões carbonizadas sobre a superfície, bem como provocando maior rugosidade superficial do que as observadas em procedimentos de usinagem com ausência de calor concentrado. O objetivo deste trabalho foi avaliar o efeito da refrigeração da ferramenta de corte na qualidade da superfície da madeira usinada. O mecanismo adotado foi a utilização de dióxido de carbono, em forma de névoa, aplicado diretamente na região em processo de usinagem, de modo que esse fluido atuasse como refrigerante do processo de corte. Para os ensaios, foram adotados madeira de Eucalyptus grandis e operação de corte com serra circular. Para avaliar o estado superficial, adotaram-se, como parâmetros, a rugosidade e a ocorrência de carbonização da superfície. Os resultados mostraram que a aplicação do dióxido de carbono, mesmo em pequenos níveis de vazão (15g min-1 ou 30g min-1), reduziu a carbonização superficial do material processado, bem como os valores de rugosidade superficiais.Heat concentration from wood cutting process promotes the tool premature wear, with consequent effect on the surface processed material, causing burnt areas as well as provoking larger superficial roughness than observed in machining process with absence of accumulated heat. The objective of this research was to evaluate the effect of cutting tool refrigeration during wood machining. The adopted mechanism was the use of pressurized carbon dioxide in fog form applied directly in the cutting area as a refrigeration method. The test was performed using Eucalyptus grandis and as cutting tool, a circular saw. To evaluate the wood final surface the following parameters were adopted; superficial roughness and occurrence of surface carbonization. The results showed that carbon dioxide applied in fog form, even at the smallest level (15g min-1), avoided the superficial carbonization of the processed material, as well as reduced the values of superficial roughness.

Se estudia el maquinado paralelo a la fibra (dirección 90-0) de aromo australiano, utilizando transductor piezo-eléctrico para monitorear los niveles de emisión acústica (EA) generados durante el corte, considerando el tipo de madera (albura y duramen), y además la relación con la rugosidad superficial (Rz) obtenida. Como resultados se encontró una adecuada relación entre la modificación de las condiciones de maquinado con la emisión acústica, en la cual un incremento de los espesores promedio de viruta se traducen en un mayor consumo energético durante el corte. Asimismo, se encontraron niveles superiores de emisión acústica al cambiar el tipo de madera de albura a duramen. Finalmente, entre rugosidad superficial y emisión acústica se encontró una correlación muy buenaWood machining parallel to the grain (90-0 direction) of Blackwood was performed using piezo-electrical transducer to record the acoustic emission (AE) signals generated during the cut process, considering the type of wood (heartwood and sapwood), and the relationship with surface roughness (Rz). A good relationship it was found between cutting conditions and acoustic emission signals, where an increase of the chip thickness results in a major consumption of cutting energy. Also, it was detected an increase of AE signals with the change of wood type, passing from sapwood to heartwood (increase of density). Finally, a good relationship it was found between surface roughness (Rz) and acoustic emission (AE)

Aim of the study: The aim of this study was to evaluate the influence of xylem tissue cell structure, determined through biometry and basic density of the wood from Corymbia citriodora Hill & Johnson on consumption of specific 90º-0º longitudinal cutting force.Area of study: The study area was in the region of the Vale do Rio Doce - Minas Gerais, Brazil.Material and methods: A diametrical board with dimensions of 60 x 18 x 5 cm (length x width x thickness, respectively), with more than 1.3 m from the ground, was removed. In machining trials, a 400 mm diameter circular saw was used, with 24 “WZ” teeth, feed rate of 10 m.min-1, cutting speed of 61 m.s-1, and maximum instantaneous torque of 92.5 N.m. During cutting, test specimens were removed with alternated and parallel 1.5 cm edges in 6 radial positions, which were used for biometric determination of cell structure and basic density.Main results: It was observed that wood basic density, vessel diameter, fiber wall thickness, fiber wall fraction and fiber wall portion were directly proportional to the specific cutting force. In contrast, vessel frequency and fiber lumen diameter proved to be inversely proportional to cutting force.Research highlights: This work provides important values of quantification of influence of xylem tissue cell structure, determined through biometry and physical properties of the wood that may be used to prediction of consumption of specific cutting force.Keywords: wood machining; wood properties; optimization of the process.

The aim of this study was to determine the surface roughness values of Turkish red pine samples obtained from the seven natural growth areas in Turkey. The samples were cut with a circular saw, planed with a thickness machine, and sanded with a sanding machine (with No. 80 sandpaper). After the samples were processed as radial and tangential surfaces in the machines, their surface roughness values (Ra, Ry, and Rz) were measured in accordance with ISO 4288 (1996). According to the statistical results, the lowest surface roughness values were in the samples obtained from the Muğla and Samsun areas on the tangential surfaces that were processed with the thickness machine. [ABSTRACT FROM AUTHOR]

This paper investigates and models the effects of wood species, feed rate, number of cutters and cutting depth on power consumption during the wood planning process. For this purpose, the samples were planed at a feed rate of 7 and 14m/min, a cutting depth of 0.5, 1.5, 2.5 and 3.5 mm, and using 1, 2 and 4 cutters, with measurements taken during this process. According to the results, power consumption increased with increasing feed rate, cutting depth and number of cutters. In artificial neural network model, the mean absolute percentage error values between the actual and predicted values were 0.32% for the training data set and 1.15% for the testing data set. In addition, the values of R² were found to be 0.99 and 0.97 in the training and testing data sets, respectively. It is evident from the results that the designed model may be used to optimize the effects of process parameters on power consumption during the planning process of different wood species. Thus, the findings of the current study can be effectively applied in the wood machining industry in order to reduce the time for further experimental investigations, to lower energy consumption and avoid high machining costs. [ABSTRACT FROM AUTHOR]

The roughness of a machined wooden surface is affected by a number of factors such as cutting tool geometry, machine settings and wood structure. The influence of wood structure on wood surface quality is difficult to control since the surface roughness is dependent on the local combination of density, grain direction and moisture content (MC). The greater the variation in wood features, the more difficult it is to find a combination of tools and machine settings that will give a high surface quality. The purpose was to study the impact of a surface wetting treatment before planing in order to reduce torn grain in the wood surface near knots in sawn timber of low MC. The study was based on a total of 120 specimens of Scots pine (Pinus sylvestrisL.). To maximize the variation in grain orientation and density, the specimens contained both clear wood and knots. The results showed that when the surface was moistened before planing, chipped and torn grain in areas of deviating grain close to knots decreased. The response to wetting was rapid, wetting less than 30 s before planing gave as good an improvement as treatment time of 30 min or more. [ABSTRACT FROM PUBLISHER]

Specimens taken from Pinus nigra Arnold were subject to surfacing techniques by being cut with a circular saw, planed with a thickness machine, and sanded with a calibrating sanding machine (with P80 grit sandpaper). First, their surface roughness values were measured; then, the specimens were processed in the machines in a radial and tangential process. Afterwards, the change in shear strength (adhesiveness resistance) was analyzed as a result of bonding with various adhesive types (PVAc, PU) and pressure applications (0.45 N/mm² or 0.9 N/mm²). Approximately 600 specimens were prepared with the purpose of identifying the effect of variables on the bonding performance, and they were subjected to shear testing. The greatest shear strength achieved for both the tangential and radial surfaces in terms of cutting was observed in specimens processed in the thickness machine, on which polyvinyl acetate adhesive and 0.9 N/mm. pressure were applied. Specimens bonded with polyvinyl acetate adhesive displayed higher shear strength in general in comparison to those bonded with polyurethane for both tangential and radial surfaces. [ABSTRACT FROM AUTHOR]

The distinct characteristics of juvenile and mature woods, which are observed particularly in softwoods, have an influence on processing due to their different mechanical resistance properties in relation to cutting operations. In the past, when most of the wood used industrially came from adult trees of natural forests, little importance was given to a distinction between different zones of the tree stem. At present, however, as the supply of mature trees with large diameters from native forests is constantly decreasing, the use of short-cycle trees has become a common practice, through the adoption of species that grow relatively fast, such as pines and eucalyptus. In both softwoods and hardwoods, juvenile wood cells are generally smaller and thinner than in mature wood, and this reflects on their density and mechanical resistance, which should have an effect on the cutting forces developed during processing. The main object of this research was to evaluate orthogonal cutting forces in juvenile and mature Pinus taeda woods. Cutting force magnitude differences were observed for those two regions of the trunk, with parallel cutting forces being 33.4% higher, on average, at the mature wood region for 90-0 cutting, and 12% higher for 90-90 cutting. This result is consistent with the distinct anatomical structures of the material, since the forces developed during machining depend directly upon its properties.As características distintas dos lenhos juvenil e adulto, existentes principalmente na formação das coníferas, influenciam na usinagem devido às diferentes propriedades de resistência mecânica ao corte. No passado, quando a maior parte da madeira utilizada industrialmente era proveniente de árvores adultas de florestas naturais, pouca importância era dada à diferenciação de zonas no tronco. Atualmente, no entanto, com o decréscimo constante do suprimento de árvores adultas de grandes diâmetros, provenientes de florestas nativas, tornou-se comum o aproveitamento da madeira de ciclos curtos, através da adoção de espécies de crescimento relativamente rápido, como exemplo os Pinus e os eucaliptos. Tanto nas coníferas quanto nas dicotiledôneas, as células da madeira juvenil são, geralmente, menores e mais delgadas do que na madeira adulta, refletindo em sua densidade e resistência, o que deverá afetar as forças de corte desenvolvidas durante o processamento. O objetivo principal desta pesquisa foi avaliar as forças de corte ortogonal nas madeiras juvenil e adulta de Pinus taeda. Houve diferenças de magnitude das forças de corte nessas duas regiões, sendo as forças de corte paralela, em média, 33,4% maiores na zona de madeira adulta, no corte 90-0, e 12% maiores no corte 90-90. Esse resultado é coerente com a diferenciação da estrutura anatômica do material, uma vez que as forças geradas durante a usinagem dependem, diretamente, de suas propriedades.

Se estudia el maquinado paralelo a la fibra (dirección 90-0) de aromo australiano, utilizando transductor piezo-eléctrico para monitorear los niveles de emisión acústica (EA) generados durante el corte, considerando el tipo de madera (albura y duramen), y además la relación con la rugosidad superficial (Rz) obtenida. Como resultados se encontró una adecuada relación entre la modificación de las condiciones de maquinado con la emisión acústica, en la cual un incremento de los espesores promedio de viruta se traducen en un mayor consumo energético durante el corte. Asimismo, se encontraron niveles superiores de emisión acústica al cambiar el tipo de madera de albura a duramen. Finalmente, entre rugosidad superficial y emisión acústica se encontró una correlación muy buena. Abstract Wood machining parallel to the grain (90-0 direction) of Blackwood was performed using piezoelectrical transducer to record the acoustic emission (AE) signals generated during the cut process, considering the type of wood (heartwood and sapwood), and the relationship with surface roughness (Rz). A good relationship it was found between cutting conditions and acoustic emission signals, where an increase of the chip thickness results in a major consumption of cutting energy. Also, it was detected an increase of AE signals with the change of wood type, passing from sapwood to heartwood (increase of density). Finally, a good relationship it was found between surface roughness (Rz) and acoustic emission (AE).

This study aimed to evaluate surface roughness of heat treated Eucalyptus grandis wood after peripheral planning and sanding performed in directions to the grain and against the grain. For machining tests, workpieces were collected from two different regions in the radial direction, as follows: internal, nearby the pit; external, nearby the bark. Heat treatment was carried out by heating samples at a maximum temperature of 190ºC, with total treatment duration of 390 minutes. Heat treated and control samples underwent peripheral planning and sanding tests. The quality of machined surfaces was assessed by means of roughness average (Ra) measurements across and along the grain orientation. Results indicated significant differences in surface roughness as a function of machining feed direction, sandpaper grit size, and heat treatment. Surface roughness has not shown any difference in the radial direction.

In this paper, the optimization of computer numerical control (CNC) machining parameters were conducted using the Taguchi design method on the surface quality of massive wooden edge glued panels (EGP) made of European larch (Larix decidua Mill). Three machining parameters and their effects on surface roughness were evaluated. These parameters included tool clearance strategy, spindle speed, and feed rate. An analysis of variance (ANOVA) was performed to identify the significant factors affecting the surface roughness (Ra and Rz). Optimum machining parameter combinations were acquired by conducting an analysis of the signal-to-noise (S/N) ratio. Optimal cutting performance for the Ra and Rz was obtained for the cutter at a tool clearance strategy of an offset 16000 rpm spindle speed and 1000 mm/min feed rate. The surface roughness, both the Ra and Rz, increased with increasing feed rate. Optimal cutting performance for Ra and Rz was obtained for a tool clearance strategy of an offset 16000 rpm spindle speed, and 1000 mm/min feed rate cutting settings. Based on the confirmation tests, Ra decreased 2.2 times and Rz 1.8 times compared to the starting cutting parameters. [ABSTRACT FROM AUTHOR]