Utjecaj ojačanja epoksidnom smolom na izvlačnu silu vijka u ploča vlaknatica i iverica koje se rabe u proizvodnji namještaja

The study aimed to increase the screw withdrawal strength of medium density fiberboard and particleboard used in furniture strength by using epoxy resin in the screw pilot hole. Therefore, the effects of pilot hole diameters, screw diameter, and amount of epoxy resin on screw withdrawal strength of medium density fiberboard and particleboard from face and edge were investigated. According to TS EN 13446, 50 mm × 50 mm specimens were cut from commercial medium density fiberboard and particleboard boards. A static load was applied parallel to the screw direction. The screw withdrawal strength of medium density fiberboard was higher than the screw withdrawal strength of particleboard because of its density. Besides, the screw withdrawal strength of medium density fiberboard and particleboard samples with a 3.5 mm screw diameter was higher compared to those with a 4.5 mm screw diameter. A decrease in pilot hole diameter and an increase in the amount of epoxy resin provided higher screw withdrawal strength of materials. Using 20 % epoxy resin of the volume of the pilot hole resulted in two times better screw withdrawal strength values. The study showed that a higher amount of epoxy resin, smaller pilot hole diameter, and smaller screw diameter contribute to better screw withdrawal strength of both medium density fiberboard and particleboard from the face and edge.Cilj ovog istraživanja bio je povećati izvlačnu silu vijka u ploča vlaknatica i iverica koje se rabe u proizvodnji namještaja, i to upotrebom epoksidne smole u pilot-rupama za vijke. Stoga je ispitan utjecaj promjera pilot-rupa, promjera vijka i količine epoksidne smole na izvlačnu silu vijka na plohi i rubu ploče vlaknatice i iverice. Uzorci dimenzija 50 mm × 50 mm prema TS EN 13446 izrađeni su od komercijalne srednje guste ploče vlaknatice i ploče iverice. Statičko opterećenje djelovalo je paralelno na smjer vijka. Zbog razlika u gustoći ploča izvlačna sila vijka bila je veća za srednje gustu ploču vlaknaticu nego za ploču ivericu. Osim toga, izvlačna sila vijka promjera 3,5 mm u srednje gustoj ploči vlaknatici i ploči iverici bila je veća od izvlačne sile vijka promjera 4,5 mm. Smanjenje promjera pilot-rupe i povećanje količine epoksidne smole omogućilo je veću otpornost materijala na izvlačenje vijaka. Upotrebom 20 % epoksidne smole u odnosu prema volumenu pilot-rupe rezultiralo je dvostruko boljim vrijednostima izvlačne sile vijka. Istraživanje je pokazalo da veća količina epoksidne smole, manji promjer pilot-rupe i manji promjer vijka pridonose boljoj izvlačnoj sili vijka na plohi i rubu srednje guste ploče vlaknatice i ploče iverice

Manufacturing sandwich-type panels from eastern redcedar and southern pine

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Usporedba CoC certifikacije u sektoru proizvođača finalnih drvnih proizvoda u SAD-u tijekom recesije i u postrecesijskom razdoblju

In this paper we examine changes in perceptions, attitudes, and participation in chain-of-custody (CoC) certifi cation in the U.S. value-added, or secondary wood products sector between the period of the Great Recession (2007) and post-recession (2014). Data were collected for two studies conducted in 2008 (for 2007 annual data) and 2015 (for 2014 annual data) using web-based surveys administered by various value-added wood product associations on behalf of the researchers. Results show that understanding of CoC certification, purchases of certified raw materials, and costs to sell certified products increased over this period. The primary reasons for getting involved in certification changed from market driven (growing markets, increasing sales, and expanding market share) to customer driven (customer request) suggesting that respondents were attempting to use certification to become more competitive during the recession when many companies in the U.S. went out of business and employment in the sector declined. Nearly 100 % of respondents in both studies said that they planned on continuing sales of certified wood products.U radu je opisano istraživanje promjena u percepciji, stajalištima i sudjelovanju u certifikaciji lanca sljedivosti (CoC) u sektoru proizvođača fi nalnih odnosno sekundarnih proizvoda od drva u SAD-u u razdobljuod velike recesije (2007.) do postrecesije (2014.). Podaci su prikupljeni izdvaju istraživanja koja su provedena u 2008. (godišnji podaci za 2007.) i 2015. (godišnji podaci za 2014.). Istraživanja su realizirana uz pomoć web-anketa što su ih za istraživače provele različite udruge proizvođača finalnih drvnih proizvoda. Rezultati pokazuju da su se razumijevanje CoC certifikata, kupnja certificiranih sirovina te prodajna cijena certificiranih drvnih proizvoda u navedenom razdoblju povećali. Glavni su se razlozi za uključivanje proizvođača u certificiranje promijenili i nisu više potaknuti tržištem (rastućim tržištima, povećanjem prodaje i širenjem tržišnog udjela) već zahtjevima kupaca. To upućuje na zaključak da se ispitanici pokušavaju koristiti certifikatom kako bi postali konkurentniji u vrijeme recesije, kada su mnoge tvrtke u SAD-u obustavile poslovanje, a zapošljavanje se u sektoru smanjilo. Gotovo 100 % ispitanika u obje studije izjasnilo se kako planiraju nastaviti prodaju certificiranih proizvoda od drva

Volume Fraction, Thickness, and Permeability of the Sealing Layer in Microbial Self-Healing Concrete Containing Biogranules

Autonomous repair systems in construction materials have become a promising alternative to current unsustainable and labor-intensive maintenance methods. Biomineralization is a popular route that has been applied to enhance the self-healing capacity of concrete. Various axenic microbial cultures were coupled with protective carriers, and their combination appears to be useful for the development of healing agents for realizing self-healing concrete. The advantageous traits of non-axenic cultures, such as economic feasibility, self-protection, and high specific activity have been neglected so far, and thus the number of studies investigating their performance as healing agents is scarce. Here we present the self-healing performance of a mortar containing a healing agent consisting of non-axenic biogranules with a denitrifying core. Mortar specimens with a defined crack width of 400 μm were used in the experiments and treated with tap water for 28 days. Self-healing was quantified in terms of the crack volume reduction, the thickness of the sealing layer along the crack depth and water permeability under 0.1 bar pressure. Complete visual crack closure was achieved in the bio-based specimens in 28 days, the thickness of the calcite layer was recorded as 10 mm and the healed crack volume was detected as 6%. Upon self-sealing of the specimens, the water permeability decreased by 83%. Overall, non-axenic biogranules with a denitrifying core shows great potential for development of self-healing bioconcrete

Validation of Sustainability Benchmarking Tool in the Context of Value-Added Wood Products Manufacturing Activities

The primary objective of this study was to validate the sustainability benchmarking tool (SBT) framework proposed by the authors in a previous study. The SBT framework is focused on benchmarking triple bottom line (TBL) sustainability through exhaustive use of lean, six-sigma, and life cycle assessment (LCA). During the validation, sustainability performance of a value-added wood products’ production line was assessed and improved through deployment of the SBT framework. Strengths and weaknesses of the system were identified within the scope of the bronze frontier maturity level of the framework and tackled through a six-step analytical and quantitative reasoning methodology. The secondary objective of the study was to document how value-added wood products industries can take advantage of natural properties of wood to become frontiers of sustainability innovation. In the end, true sustainability performance of the target facility was improved by 2.37 base points, while economic and environmental performance was increased from being a system weakness to achieving an acceptable index score benchmark of 8.41 and system strength level of 9.31, respectively. The social sustainability score increased by 2.02 base points as a function of a better gender bias ratio. The financial performance of the system improved from a 33% loss to 46.23% profit in the post-improvement state. Reductions in CO2 emissions (55.16%), energy consumption (50.31%), solid waste generation (72.03%), non-value-added-time (89.30%), and cost performance (64.77%) were other significant achievements of the study. In the end, the SBT framework was successfully validated at the facility level, and the target facility evolved into a leaner, cleaner, and more responsible version of itself. This study empirically documents how synergies between lean, sustainability, six-sigma and life cycle assessment concepts outweigh their divergences and demonstrates the viability of the SBT framework

A Systematic Literature Review for Better Understanding of Lean Driven Sustainability

Global trends and factors, such as the increased level of globalization, climate change, resource scarcity, and awareness of social and environmental responsibilities, as well as fiercer competition and lower profit margins in all industries, force organizations to act to retain, regain, or sustain their competitive advantages for long-term survival. These trends and factors are historically known to bring about innovations that drive the evolution of industries. Sustainability is considered to be such an innovation to achieve fiscally sound, environmentally conscious, and socially progressive organizations and supply chains. This study reviewed 477 past articles published in five major databases from 1990 to 2018. The purpose of the study was to assess the current state-of-the art in the subject of lean-driven sustainability. Based on the exhaustive descriptive and contextual analysis, synergies, divergences, and the extent of two-way permeability of lean and sustainability concepts from the perspective of intra- and inter-organizational operations were identified along with future research opportunities. Fundamental strengths and weaknesses of both concepts, existing strong synergies and untapped potential, along with their key contributors, the potential-use cases of lean tools to derive sustainable solutions are highlighted in this review

Surface Quality of Wood Plastic Composites as Function of Water Exposure

The objective of this study was to evaluate the surface quality of experimentally manufactured wood plastic composite (WPC) samples exposed to water soaking. Eastern redcedar (Juniperus virginiana L.), which is one of the invasive species in Oklahoma, USA, and recycled plastic were used to manufacture WPC samples. Three types of samples, namely with 0%, 3% and 6% nano-clay were soaked in water for up to one month. Stylus-type equipment was employed to evaluate their surface roughness as a function of water exposure. Two accepted roughness parameters, average roughness (Ra) and mean peak-to-valley (Rz), were used to determine changes in the surface quality of the specimens due to water exposure. Average roughness values of 1.5 µm and 4.1 µm were determined for the samples with no clay in dry conditions and those soaked for one month in water, respectively. Corresponding values were lower in the case of those with clay in their content. Based on the findings in this work, it appears that the stylus technique can be successfully applied to such samples to quantitatively evaluate their surface quality when they are exposed to water for an extended time span. It is expected that data from this work could help to produce a better understanding of the behavior of WPCs under environmental conditions

Lean and Sustainable Supplier Selection in the Furniture Industry

The furniture manufacturing sector faces intricate challenges in pioneering sustainable supply chains, particularly with lean and sustainable supplier selection. This study focused on integrating key performance indicators (KPIs) associated with lean philosophy and sustainability into multi-criteria decision-making (MCDM) methodologies. The study methodically evaluated 18 criteria spanning economic, environmental, and social dimensions to discern supplier suitability in both leanness and sustainability realms. Through the ENTROPY method, weights were systematically assigned to these criteria. Subsequently, Fuzzy ARAS and Fuzzy TOPSIS methods were adeptly employed to comparatively assess supplier options. Noteworthy findings included the paramount importance of the distance to the customer and labor practices in supplier selection. The quality level, however, carried the least weight, mainly due to comparable performance scores among alternatives. Consistently, Fuzzy ARAS and Fuzzy TOPSIS results converged to pinpoint Supplier 2 as the optimal choice, reflecting its superior Ki and CCi metrics. Central to this research was the introduction of a structured and holistic framework for lean and sustainable supplier selection, a significant leap forward that promises to be an invaluable asset for practitioners and scholars in the furniture industry, supply chain management, multi-criteria decision-making, and policymaking

Volume fraction, thickness, and permeability of the sealing layer in microbial self-healing concrete containing biogranules

Autonomous repair systems in construction materials have become a promising alternative to current unsustainable and labor-intensive maintenance methods. Biomineralization is a popular route that has been applied to enhance the self-healing capacity of concrete. Various axenic microbial cultures were coupled with protective carriers, and their combination appears to be useful for the development of healing agents for realizing self-healing concrete. The advantageous traits of non-axenic cultures, such as economic feasibility, self-protection, and high specific activity have been neglected so far, and thus the number of studies investigating their performance as healing agents is scarce. Here we present the self-healing performance of a mortar containing a healing agent consisting of non-axenic biogranules with a denitrifying core. Mortar specimens with a defined crack width of 400 μm were used in the experiments and treated with tap water for 28 days. Self-healing was quantified in terms of the crack volume reduction, the thickness of the sealing layer along the crack depth and water permeability under 0.1 bar pressure. Complete visual crack closure was achieved in the bio-based specimens in 28 days, the thickness of the calcite layer was recorded as 10 mm and the healed crack volume was detected as 6%. Upon self-sealing of the specimens, the water permeability decreased by 83%. Overall, non-axenic biogranules with a denitrifying core shows great potential for development of self-healing bioconcrete.Materials and Environmen