Band Saws Research Articles

Active runout compensation using the guide elements on metal band saws for a longer tool life and reduced material loss

AbstractAt a time of rising energy and material costs, manufacturing process efficiency is becoming increasingly important. This is one reason why cutting and especially sawing processes, usually the first step in most manufacturing chains in discrete part production, have to be investigated more intensively. Due to problems with runout and poor surface finishes, raw material is conventionally cut to oversize by either circular sawing or band sawing. This oversize has to be removed by following processes, costing extra energy and wasting material. Since the problem of runout increases with increasing tool wear due to higher deflections of the thin and compliant tools, an even larger oversize is required. This paper describes an approach to reduce the need of oversize even with increasing tool wear in band sawing by tilting the saw band in order to compensate for tool deflections during cutting. To achieve this, it is necessary to measure and understand the saw band runout. The next step is to present a system design and controller for tilting the saw band. Finally, tests are carried out to analyse the effectiveness of the system. In addition, the approach allows the use of increased process parameters to the end of the tool life without losing more material. The tool can therefore be used productively for a longer time period.

ПРОЧНОСТЬ И ДЕФОРМАТИВНОСТЬ ДЕРЕВЯННЫХ КОНСТРУКЦИЙ, АРМИРОВАННЫХ ОТРАБОТАННЫМИ ПОЛОТНАМИ ЛЕНТОЧНЫХ ПИЛ

In Russia, the volume of sawn products produced by cutting large-sized logs on band saws is increasingly expanding. The blades of band saws work from 20 to 500 hours and the technology of their secondary use is currently not provided. The creation of an effective method of reinforcing wooden structures with spent band saw blades will increase their load-bearing capacity, rigidity and operational reliability. It is assumed that in terms of the combination of strength indicators and manufacturability, the new reinforced wooden structures will correspond to existing analogues, and in terms of economic indicators they will surpass them. The conceptual novelty consists in the secondary use of man-made waste from woodworking industries in the construction of buildings and structures, which for the first time will allow to justify the effectiveness of the method of reinforcing wooden structures with treated band saw blades at a high theoretical level. The article examines beams made of solid wood with a length of 6 meters with a cross section of 100 × 200 mm, bending tests are performed. Numerical simulation of the plane stress state by the finite element method is performed. The load-bearing capacity of a beam reinforced with spent band saw blades increased by 1.5 times in comparison with an unreinforced beam.

Усталостная прочность ленточных пил

One of the major disadvantages of band saws is their low durability. Breakages during the operation are mostly caused by fractures in notches between the blades of the band as a result of the fatigue phenomenon. The strength of the band saw blades is ensured if the assurance coefficient value is greater than the theoretically determined one. The value of the assurance coefficient of 2 is recommended. A schematic limit-amplitude diagram was used to calculate the durability of band saws. A formula for the estimation of the assurance coefficient was derived. It was used for the calculation of the assurance coefficients of the band saw blades manufactured in accordance with GOST 6532–77, which are applicable in dividing band saw machines. The resulting value of the assurance coefficient was 1.44. The value is extremely low for the band saws because it is much lower than required. Band saw blades should be sharpened regularly to ensure a long and reliable service life. It should be made not only to ensure the required sharpness of the blades but also to remove the defective layers in notches caused by fatigue phenomena. In the article, there are more recommendations for improving the durability of the blades of the band saws. The durability of a new type of band saw with curved aerostatic guides and hard alloy blades was evaluated. Its assurance coefficient was 2.4. Therefore, the machine can be operated reliably for a long time without regular treatment of the notches. Consequently, band saws have low durability due to their increased breakdown rate and low wear resistance. Hence, the costs of their purchase and treatment rise. Therefore, the results presented in the article are practically applicable. For citation: Prokofiev G.F., Kovalenko O.L. Fatigue Strength of Band Saws. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 4, pp. 136–145. (In Russ.). https://doi.org/10.37482/0536-1036-2023-4-136-145

European Beech Log Sawing Using the Small-Capacity Band Saw: A Case Study on Time Consumption, Productivity and Recovery Rate

In rural, isolated areas, sawmills are often equipped with one or more small-capacity hand-fed band saws. Even in this situation, the productivity of the band saw must be viewed through the factors that influence it, namely the characteristics of logs and the optimization of the stages and activities carried out. Therefore, time consumption, the structure of working time and the recovery rate in sawing logs into lumber provide important information for users. The structure of the sawing operation for a work team made up of an operator and an assistant was divided into six work stages. The sawing pattern used involves sawing the log up to approximately half of the diameter, then rolling the log with 180° and continuing the sawing, aiming to obtain lumber with a thickness of 40 and 50 mm from the central part of the log. The productivity was 2.45 m3·h−1, the recovery rate was 70.84% and the working time real-use coefficient was 0.37. Research has highlighted the positive correlation between working time and the middle diameter of the logs (R2 = 0.84). The feeding speed was also determined along with the quality of cuts, which was expressed by the thickness uniformity of the lumber and the presence of cutting teeth traces on the newly created surfaces.

Properties of Autoclaved Aerated Concrete in Different Curing Conditions: A Review

Abstract: Autoclaved aerated concrete (AAC) has many benefits for structures, such as heat insulation, sound insulation, fire resistance, reduced dead weight, and many more. AAC products include blocks, wall panels, floor and roof panels, and lintels. Besides its insulating capability, one of AAC's advantage in construction is its quick and easy installation since the material can be routed, sanded, and cut to size on-site using standard carbon steel band saws, hand saws, and drills. Although AAC has been produced for many years, there are still some points that need to be clarified. One of these points is the effect of humidity intrusion on AAC members in areas with high relative humidity levels, like Mediterranean climates. Therefore, various tests associated with the mechanical and physical properties of AAC concrete should be carried out, particularly Compressive Strength test in order to assess the strength of AAC blocks. The current project intends to analyse the physical and mechanical properties of autoclaved aerated concrete blocks at three different curing conditions using an accelerated curing tank to compare the effects of curing on the properties of AAC

Capacity of surface production of band sawing in manufacture of oak floor upper layers

Thin lamellae, corresponding to the layer components of structural glued members, i.e., 2-ply or 3-ply glued flooring, can be manufactured in re-sawing operations of kiln-dried wood blocks or in wet technologies, which currently seem to be more common because of the shorter drying time. The re-sawing process in wet technology is conducted on dedicated thin-cutting band sawing machines with stellite-tipped band saws. The goal of this research was to demonstrate the capacity of surface production (m2/ tool life) of visible layers of oak engineered flooring composites in a function of both a new band saw and a re-sharpened band saw blade. Additionally, the state of teeth of each band saw blade was examined at the end of the tool life. A series of cutting tests were performed in sawmill production conditions. The conducted tests revealed that a three times higher capacity of surface production was obtained for the new tool compared to re-sharpened tool. Additional microscopic observations of some re-sharpened teeth showed deformed plastic characteristics.

Определение времени периодичности заточки (переточки) зубьев ленточных пил

The advantages and disadvantages of band saws in comparison with other sawmills are considered. The necessity of timely grinding (regrinding) of band saws during their operation is emphasized. A method for calculating the time between regrindings of a band saw is proposed, which ensures the required service life of the saw - the time between regrindings of a band saw is determined taking into account the value of the limited endurance of the saw, determined for a given safety factor; the required quality of the lumber output and the reduction of energy consumption - the time between regrinding of the band saw is determined taking into account the amount of blunting of the band saw teeth, characterized by the radius of curvature of their main cutting edge. It is noted that of the two obtained values of the time between saw regrindings, it is necessary to take the smallest value. It is recommended to use the method proposed in the article when calculating the modes of sawing wood on separating and log band saw machines.

Production Capacity, Efficiency and Recovery Rates of Cupressus lusitanica and Pinus patula Lumber from Selected “WoodMizer” Band Sawmills in Kericho County, Kenya

Conservation of forests is slowly shifting into a more proactive approach such as efficient lumber conversion in sawmills. This suggests a need to explore the use of modern sawmilling machinery in lumber conversion that produces low residues, wastage, and hence high recovery. This study looked into the production capacity, efficiency, and recovery rates of Cupressus lusitanica and Pinus patula lumber from selected “WoodMizer” band saws (LT15, 20, and 40) sawmilling machinery in Kericho County, Kenya. Wood logs delivered to each respective sawmill yard were categorized into ten diameter classes, ranging from 10 to 59 cm for both species. Volume of four logs from each class and species was evaluated using Huber’s formula, (1995) and converted using through and through sawing techniques into lumber with each “WoodMizer” band saw. Volume of the lumber pieces and residues obtained were measured. The time taken during the conversion process was also recorded in order to determine the efficiency and lumber production capacity of each sawmill machines. Recovery of C. lusitanica gave average empirical values of 43%, 49%, and 53% in comparison with 39%, 34%, and 60% for P. patula using WoodMizer LT15, LT20, and LT40 respectively. P. patula produced the most residues at 61% and 66% compared to C. lusitanica at 57% and 51% per log volume for LT15 and LT20 respectively but less from LT40 (47%) for C. lusitanica and 40% for P. patula logs. WoodMizer LT40 recorded the highest daily production capacity for both C. lusitanica and P. patula (15.9 m3/day and 16.2 m3/day) respectively. This was followed by WoodMizer LT20 at 11.2 m3/ day and 9.6 m3/day for C. lusitanica and P. patula respectively. WoodMizer LT15 had the least production capacities of 8.8 m3/ day and 9.9 m3/ day for C. lusitanica and P. patula respectively. These results suggest adoption of “WoodMizer” band sawmilling in Kenya for sustainable forest resource.

An unusual complex suicide involving a chainsaw and a hanging: a case report

BackgroundSuicides or suicidal attempts with power tools such as band or circular saws are rarely encountered in forensic medicine practice; in the forensic literature, only a few cases have been reported. We present the case of a “combined suicide” (self-injurious actions using different methods and involving various bodily sites) carried out with uncommon deadly methods: chainsaw and hanging.Case presentationA 58-year-old Caucasian man was found dead by his wife, hanging from the basement ceiling of the cellar in which he lived. During the investigation of the crime scene, external examination revealed a wide incised wound in the umbilical area showing the muscular and adipose tissues below. On inspection of the garden around the courtyard, the police found a chainsaw with blood spatter on both the blade and the handle. The blade appeared to be compatible with the abdominal injuries.ConclusionsSince the corpse presented this incised wound, it was crucial to establish the manner and the causes of death, as well as to exclude any third-party involvement. In this case, the presence of multiple injuries, potentially lethal, required a differential diagnosis between suicide or homicide. A detailed post-mortem examination, in association with a precise study of the circumstantial data, led the authors to assume that they were dealing with a “complex suicide.”

Technological aspects of wear-resistant coating treatment on the surface of a cutting tool

The article presents a method for producing a nanostructured wear-resistant high-hardness coating with high physical, mechanical and strength characteristics, resistance to shock and vibration loads on the surface of spring-spring and tool steels used in the manufacture of cutting tools, including band saws. Technological modes were selected for the entire cycle of coating deposition of the developed compositions that have high adhesion to substrates made of steels of various grades, as well as provide high microhardness due to the nanostructure of the protective coating obtained on the surface. Studies are shown on the example of one of the most common methods of metal cutting — cutting on band-cutting machines, using closed band saws as cutting tools made of spring-spring steels with obtained carbide cutting edges. Since in modern production, structural steels are replacing materials with high physical and mechanical characteristics (hardness, strength, etc.), the cutting process becomes much more complicated and imposes increased requirements on the cutting tool itself. To expand the range of materials to be processed, for which production use of band-cutting machines is possible, it became necessary to create a band saw with higher cutting characteristics. At the same time, the specificity of the operating conditions of the band saw shows that the blade should have such characteristics as increased vibration resistance, resistance to alternating and dynamic loads, and the cutting part of the saw should have increased resistance to shock, dynamic, alternating loads, have high hardness, as well as increased wear resistance. Therefore, one of the ways to solve this problem proposed in the article is to avoid the manufacture of band saws using the “bimetal” technology and use the same material as a tooth and a blade when applying a wear-resistant hard-alloy nanostructured coating on the surface of the cutting edge of the tooth. The practical usefulness of the developed protective nanostructured coatings for increasing the service life of carbide turning inserts is also shown. The work was supported by the Council on grants of the President of the Russian Federation (Agreement СП-399.2019.1).

Improving the quality of the band saw cut

This article is devoted to the study of the dynamic characteristics of the band sawing process to improve their efficiency. The object of study is: band saw, softwood. A screening experiment was carried out when sawing with band saws to identify key influencing factors on the quality of the treated surface (roughness) and sawing force (sawing power). Rational values of key influencing factors were determined. The effectiveness of the sawing regimes with band saws was evaluated. In the course of laboratory tests of the new saw, it was found that the moisture content of the wood has the maximum effect on the quality of the sawing walls. According to the degree of influence of factors, the roughness of the cut depends on the moisture content of the wood, the feed per tooth, the type of cutting relative to the wood grain and the height of the cut. As a result of a multivariate experiment, two regression equations were obtained for the assumed roughness of the cut and the cutting power. The estimation of the significance of the coefficients in the given interval of variation of the influencing factors is carried out.

Research of dynamic processes at cutting forest materials on horizontal band saw equipment

For processing small-scale wood, as well as wood from logging and sanitary logging, small enterprises are created that use fairly large and expensive band saws of various foreign firms and domestic production, which have a high energy intensity of the technological process. In this regard, the development of a resource-saving band saw machine that improves the quality of saw products and reduces the energy intensity of the technological process is an urgent task for the timber processing industry. To study the dynamics of the process of sawing wood on a horizontal band saw, it is necessary to create its dynamic model, which is a mathematical description of the interaction of the cutting process and the equivalent elastic system of the machine. The problem of the quality of wood sawing is both the accuracy of processing and the roughness of the surface to be processed. To assess the accuracy of wood sawing, two indicators were used: average and maximum undulation. As a result of the research, a new design of the band saw was developed using a dynamic model, which ensures resource saving, reducing the energy intensity of the technological process and improving the quality of the resulting saw products.

The possibility to use Bandsaw Dynamic Tensioning in Bandsaw Machines

The authors considered the mechanism of motion transmission to wood-cutting band saws, using the effects of their dynamic tension during operation, within the general statements of the flexible link transmission theory.

К ВОПРОСУ ПОДГОТОВКИ РЕЖУЩЕГО ИНСТРУМЕНТА ПРИ РАСПИЛОВКЕ ЛЕСОМАТЕРИАЛОВ НА ЛЕНТОЧНОПИЛЬНОМ ОБОРУДОВАНИИ

the main drawback of circular sawing machines is the presence of broken teeth in the cut. In case of vibrations, violation of the saw plane, mismatch of the feed direction with the saw planes, and rebasing, these teeth spoil the processing surface. Belt sawing allows you to ensure high quality of lumber on the roughness of their surface at high feed rates; increase productivity by 1.5-2 times due to mechanization and automation of technological operations. One of the most important advantages of band saws is the small width of the cut, which is 1.5-2 times smaller than that of the sawmill; the small thickness of the saw ensures low consumption of wood in sawdust and high volume output of lumber. Sawing wood on band saws, in the vast majority of cases, is characterized by face cutting. Of the 3 forms of chip formation when cutting into the end, for band saws, the most characteristic is the formation of the chip element by chipping it with the stratification of wood along the bottom of the cut. The quality of the surface, in terms of its roughness, in addition to the formation of the chip element, is affected by its location in the interdental space, the presence and degree of compression and transportation of the chip element. The quality of the surface, in terms of its roughness, in addition to the formation of the chip element, is affected by its location in the interdental space, the presence and degree of compression and transportation of the chip element. As a result of studies of the initial conditions for the development of the teeth sharpening scheme, the orientation of the active elements of the blade relative to the middle plane of the saw can be identified as the main ones.

РЕШЕНИЕ ЗАДАЧИ СНИЖЕНИЯ ВЛИЯНИЯ БОКОВОЙ СИЛЫ НА УСТОЙЧИВОСТЬ ПИЛЬНОГО ПОЛОТНА

The accuracy of the thickness of lumber is one of the most important indicators of sawing. It is inextricably linked with saw stabilization in the plane of the greatest stiffness. The aim of the study is to eliminate the influence of lateral force on the saw blade and the thickness of the resulting lumber. The issue of eliminating the influence of lateral force in frame sawing and sawing on band saws belongs to the constructive decision in combination with the analytical one according to classical methods. Therefore, the most important issue in the development of a new machine is to identify the presence of a huge range of frequencies of natural and parametric oscillations of saw blades. Previously, these frequencies could not be analytically found to the full extent and, respectively, the tuning out the machine operating frequencies of the possible oscillation frequencies of saw blades could not be carried out. Due to the complexity and the science intensity of the problem solving, it is not conceivable without modern numerical methods of calculation. Among them are the fnite element method, modern software of NX and ANSYS, as well as other original programs. One of such methods, which allow to reduce the influence of lateral force, is determination of stability of the plane form of bending by the Eulerʼs method. The technical solution presented by a fundamentally new saw block with a circular translational motion of the blades reduce dramatically the impact of lateral force on the accuracy of sawing in conjunction with a number of other advantages. At the same time, the issue of ensuring the dynamic stability of the blades both when sawing and at idling speed is solved. It is necessary to point out that with circular translational motion the tooth side cutting edges are under alternating load when scraping over the cut surface. There fore, the tooth cutting element is a subject of increased strength requirements. The angles of their sharpening were adjusted in order to preserve the integrity of the corners of the teeth tips. The possibility of strengthening the teeth lateral cutting edges of saw blades made of steels of different grades was investigated. The reasons of wear and corrosion, both the elements of the saw module and its operating part (blade teeth) were studied and it was decided to supply the teeth with a hard alloy of the stellite type as the most optimal. However, this provision requires additional targeted feld tests. Preliminary calculations showed that the daily productivity of a machine with circular translational motion of the blades (model M2005) in comparison with saw frames increases by 2–4 times; in comparison with band saw equipment of any class by 3–6 times; and in comparison with the circular saw equipment (for small and medium enterprises) by 2–4 times. Analyzing the design scheme and the dynamics of the saw modules, it is possible to fnd a number of advantages of the multi-saw unit presented as part of the machine. The simplicity and reliability of the design allows us to hope for high functional characteristics. Among those we should highlight the following:increasing the accuracy of sawn products due to the rigidity of short blades, increasing the productivity, improving the quality of treated surfaces, as well as reducing the energy consumption, relatively light weight and dynamic balance of the main units with increased mobility of equipment and the absence of a massive foundation. For citation: Blokhin М.A., Podlesny D.A., Rodionov O.A. Solving the Problem of Reducing the Influence of Lateral Force on the Saw Blade Stability. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 2, pp. 118–128. DOI: 10.37482/0536-1036-2020-2-118-128

Features of laser welding of wood-cutting band saws

Abstract. Laser welding is the most effective method of joining the ends of band saws according to the high level of existing jointing requirements; using this method allows you to form anesthetic, even and smooth sound weld without deformation. Laser welding has a number of advantages but at the same time the main disadvantage of laser welding is the high cost of equipment and the need for highly qualified maintenance. The paper considers the main features of the method for joining a number of band saws into an endless band saw by laser welding. The specific feature of laser welding is that it produces the highest degree of energy density on a tiny spot. The essence of the laser welding process sis that inartificially generated laser beam is used as a source of thermal energy to per form the work. High cooling rates of the weld (up to 3,000° C/s) and high speeds of welding (up to 120 m/h) of low-carbon steels affect the ir primary and secondary structure. The same factors provide a disordered fine-grained structure, which contributes to an increased resistance of the weld to the appearance of hot cracks. The laser welding of metals operates in three modes, the advantages and disadvantages of these modes being analyzed. Annealing after welding, accompanied by heating to a temperature of 450–470° C and holding for 30 s (recommended by Rentgen – the CR400 steel manufacturer) causes a gradual equalization of the hardness distribution. In the CR400 steel, containing chromium and tungsten at the lower allowable limit (3,5% and 5,3%, respectively), complete recovery of hard ness after annealing is not observed. Fluctuation sin hardness reach 30–35%, which negatively affects the strength of the saw. To eliminate this shortcoming, it is necessary to equalize the hardness, which can be provided by a special thermal strengthening. It is proposed to develop modes of laser thermal strengthening of the weld after the welding process, which will significantly increase the strength of the tool.

Transparent, mechanically strong, thermally insulating cross-linked silica aerogels for energy-efficient windows

Silica aerogels are transparent and excellent thermal insulators; however, application in energy-efficient windows has been elusive. The main reason is fragility that renders handling and processing extremely difficult. One way to overcome the fragility issue of silica aerogels is via cross-linking technology, in which a polymer is applied conformally over their entire skeletal framework. Extremely strong materials may be obtained by that approach; however, the penalty is loss of transparency. This study was designed to reach a compromise among those competing requirements. Aerogels based on co-gelation of tetramethylorthosilicate (TMOS) and 3-aminopropyltriethoxysilane (APTES) were prepared and were cross-linked with a triisocyanate (Desmodur N3200A). The two independent variables, the total silane concentration in the sol and the concentration of the monomer in the cross-linking bath, were varied according to a full-factorial model. The nanostructure was characterized with SEM and SAXS. The porous structure with N2 sorption. Properties of interest with respect to the intended application were the thermal conductivity, the elastic modulus, and the haze. The latter has two components, from the bulk and the surface. Cross-linking places the polymer inside secondary aggregates that behave as core–shell particles with increased scattering, due to refractive index mismatch. Surface haze can be minimized by molding with clean glass plates and careful handling. Guided by our statistical model, we demonstrate optimal samples with bulk densities in the range of 0.25–0.33 g cm−3, porosities in the range of 76–83% v/v, bulk haze around 10%, Young’s modulus in the range of 30–70 MPa, and thermal conductivities in the range of 18–22 mW m−1 K−1. Those samples were strong enough to be machined with conventional tools (band saws, diamond cutters), they displayed sufficient clarity, and their thermal conductivity was lower than that of still air.

Influence of spectral acquisition technique and wood anisotropy on the statistics of predictive near infrared–based models for wood density

Wood density is an important criterion for material classification, as it is directly related to quality of wood for structural use. Several studies have shown promising results for the estimation of wood density by near infrared spectroscopy. However, the optimal conditions for spectral acquisition need to be investigated in order to develop predictive models and to understand how anisotropy and surface roughness affect the statistics of predictive partial least square regression models. The aim of this study was to evaluate how the spectral acquisition technique, wood surface, and the surface quality influence the ability of partial least square–based models to estimate wood density. Near infrared spectra were recorded using an integrating sphere and fiber-optic probe on the tangential, radial, and transverse surfaces machined by circular and band saws in 278 wood specimens of six-year-old Eucalyptus hybrids. The basic density values determined by the conventional method were then correlated with near infrared spectra acquired using an integrating sphere and fiber-optic probe on the wood surfaces by means of partial least square regressions. The most promising models for predicting wood density were generated from near infrared spectra obtained from the transverse surface machined by the bandsaw, via an integrating sphere ([Formula: see text], RMSEP = 23 kg m−3 and RPD = 3.0) as well as for the optic fiber ([Formula: see text], RMSEP = 35 kg m−3 and RPD = 2.1). Surface quality affected the spectral information and robustness of predictive models with a rougher surface, caused by band sawing, showing better results.

Evaluation of Cutting Time and Waste Generation in Different Band Sawmills in Sri Lanka with Special Reference to Teak Timber

In recent years, due to rising raw material and labor costs, increasing attention is being devoted to improve wood sawing practices. While a high cutting rate is still among the most desired characteristics, other factors such as improved cutting accuracy and surface quality, reduced kerf losses, noise, downtime, and maintenance of the machine are becoming increasingly important. However, band sawmilling have advantages over circular saws which include higher cutting speeds lower kerf waste, and typically lower noise levels. Considering above advantages several Sri Lankan companies have now established band saw milling factories. Thus the key objectives of this study were to evaluate cutting time of band sawmills and to investigate waste generation. Three different band saws (TRAK-MET TTP 600 premium; TM, Wood-Mizer LT20; WM, and Veheran; V) which are commonly used in Sri Lanka were used to this study. Evaluation of cutting time and waste generation in different band sawmills were done with special reference to Teak timber. Results show that the fastest cutting time in WM (mean cutting time of 27s), medium cutting time in TM (mean cutting time of 60s) and the slowest cutting time in Veheran (mean cutting time of 180s). The factors such as tooth profile, setting value, sharpening frequency, status of lubrication, tensioning pressure of the blade and capacity and the condition of the machine may have affected to the fastest cutting time. According to the results of evaluation of saw dust Veheran showed the highest wastage owing to high kerf and factors such as poor lubrication, lower tensioning pressure. Moreover, cutting time negatively correlated with the lubrication and saw tension in band sawmills. Therefore, it can be concluded that proper saw mill management is necessary for reduction of timber wastage and increase the efficiency of the industry. Keywords: Band sawmilling, Waste generation, Teak, Lubrication, Tensioning pressure

An examination of linkages in the sawn wood sector of the Nigerian forest industry: Policy implications for natural resource-based development

Proponents of natural resource-based development have argued that backward, forward and lateral linkages around natural resources can bring about structural change. However, there are very few studies on the development potential of natural resources in developing countries, specifically on non-petroleum related industries. This study examines linkages in the sawn wood sector of the Nigerian forest industry, in particular the saw mill and artisanal metal fabrication sectors which represent forward and backward linkages. Using a qualitative approach to obtain a detailed historical perspective, the study reveals that foreign inputs were gradually replaced by local inputs through the spontaneous efforts of artisans using the Doing, Utilising and Interacting (DUI) mode of learning and innovation to fabricate band saws and accoutrements used by the saw millers. Furthermore, problem solving skills have been acquired by the artisans over the years through the fabrication of these machines and interacting with the production activities of the millers. Export of machines by the artisans to regional low technology demanding countries were revealed. In addition, evidence of lateral linkages in form of movement of the fabricators to the manufacturing sector was also reported. While the sector shows promise for structural change, advances in technological competence of the sector is however being curtailed by a lack of access of the artisans to Science, Technology and Innovation (STI) based modes of learning and innovation and a vibrant iron and steel industry. In addition, production activities are being limited by an inadequate supply of timber due to the country's rapidly degrading forests. This in turn has restricted learning and competence building opportunities. For the industry to attain its full development potential, policy recommendations include revitalising the country's iron and steel sector, commencing the award of degrees in wood products engineering, fostering linkages between the artisans and formal knowledge infrastructure, initiating proper sustainable forest management practices and providing relevant physical infrastructure.