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Analyzing Joinery for Furniture Designed for Disassembly
End-users can design personalized furnishing products using remote web-based CAD systems. However, if these designs fail to incorporate design for disassembly (DfD) principles, the furniture’s subsequent repair, reconfiguration, recycling, and disposal can be significantly hindered. To address this drawback, this study supports DfD, a strategy that enables the creation of easily repairable, reusable, and recyclable furniture to reduce waste and environmental impact. Consequently, this review aims to classify and evaluate available furniture joinery systems for their suitability within DfD frameworks, ultimately promoting their implementation within CAD environments. To this end, various solutions were evaluated, including traditional joints, dowel/biscuit, hammered, directly screwed, snap-on, expandable, and cam/bolt fasteners. Based on a literature review and practical observations, the analyzed joinery systems were categorized into non-disassemblable, conditionally disassemblable, and fully disassemblable categories. Only the fully disassemblable solutions effectively align with DfD principles. The study postulates a preference for expandable and cam/bolt fasteners in furniture designs, noting that although snap-on fasteners can potentially support DfD, this outcome is not always ensured. To guarantee that the designed furniture adheres to the DfD principles, the following eight furniture design guidelines were formulated: develop web-accessible disassembly instructions, prioritize access to fast-wearing components, prioritize modularity, standardize parts in modules, label components, enable independent component removal, use materials that withstand repeated disassembly, and employ fully disassemblable joints.
Impact of seat and back angle settings on seating furniture quality: an experimental study
Impact of Seat and Back Angle Settings on Seating Furniture Quality: An Experimental Study. The fundamental measure of the quality of seating furniture is seating comfort. Sitting comfort is described in the literature by the discomfort coefficient D, calculated from the pressure values and distribution measured between the human body and a sitting furniture "body support system". The work aims to experimentally verify the influence of selected anthropometric features on sitting comfort. The research was carried out on 12 people using a piezoelectric sensor mat and a model of adjustable sitting furniture. The study investigated how different seat and backrest inclination variants impact pressure distribution. The test results are the values of the contact pressures and discomfort coefficients D for nine combinations of the backrest and seat inclination related to the anthropometric characteristics of the tested group of people. The results indicate that anthropometric factors, such as body mass index (BMI) and user gender, significantly impact objective seating comfort. These findingswill help optimize the seating furniture dimensions at their design stage
Withdrawal Resistance of T-Nuts in Various Furniture Materials
T-nuts are factory installed in the holes of the ready-to-assemble furniture components. There is a risk that the t-nut spontaneously falls out during transport or storage and get lost; the t-nut can also be pushed into inaccessible spaces during assembly. These complications can make furniture assembly impossible. For this reason, sufficient force to hold the t-nut in the hole is essential. The article presents the test results of the forces holding the t-nuts in five furniture materials (softwood, Oriented Strand Board, plywood, and particleboard in two variants). The M6 t-nuts with four prongs were installed in predrilled 8 mm holes. The resistance to withdrawal of the t-nuts was measured with a universal testing machine. The tested materials could be divided into three groups in terms of the risk of the t-nut falling out: softwood and plywood – low risk, F = 1113.2-1158.0 N; OSB and particleboard – moderate risk, F = 592.3-645.5 N, particleboard with a pad – high risk, F = 645.5 N. The results show that the withdrawal resistance is not correlated with the density of the wood material, and that it decreased with the degree of wood material processing – the less processed the material, the greater the resistance to withdrawal of the t-nuts.
Price calculation of wooden bariatric beds
Abstract In the field of interior and furniture, the pursuit of comfort has always been based on the anthropometric dimensions of the user. When optimizing the dimensions of the bed for the needs of today’s population, we start from the forecasted values of the relevant body dimensions, i.e. height and weight. Based on previous research, we can conclude that the anthropometric dimensions of the adult Slovak population after reaching the age of adulthood have increased statistically significantly by approx. 4.5–5% since the last measurements in 1987, from the point of view of the body growth process. In connection with the aforementioned findings, it is necessary for furniture companies producing bed furniture to adjust their calculation procedures for price formation depending on the needs of users, in order to forecast their financial situation. The goal of the work is to determine the cost increase for bariatric respondents, based on the determined dimensions of the wooden bed compared to a standard manufactured bed, and to determine the calculation formula for single-piece production. The results show that increasing the dimensions of the bed will increase the total costs by approximately 70%.
A Method for Modeling the Individual Convenient Zone of a Human
When designing products to fit a specific user, it is essential to know the user’s upper limb range and strength capabilities at each point of the range space. This is particularly relevant when those capabilities are atypical, e.g., in cases of nonstandard body dimensions, disability, or old age. In this paper, we describe a new method to measure and model the strength capabilities at each point of any person’s upper limb range and then present this information in the form of an Individual Convenient Zone (ICZ) model, which is helpful in virtual product prototyping (CAD) for a specific user. The proposed new method includes creating a database of multiple, detailed, spatial-force characteristics, quickly identifying and modeling the ICZ of any human, and analyzing the ergonomics of a product using a digital human model in combination with the ICZ model. The paper also describes an example of how the proposed methodology can be used to customize kitchen furniture design to the ICZ of a specific senior. The expected result of incorporating ICZ into the design is a better fit between the designed product and the user’s needs, supporting user-centered design methodology. Using ICZ enables the involvement of end-users in product design (participatory design). This is particularly important when designing for people with mobility impairments who are more sensitive to nonergonomic solutions. The ICZ modeling method described in this article may have broader applications beyond kitchen furniture design; it could be used to design workspaces and other similar areas where humans reside and perform manipulation activities.
Effective Adsorption of Phenoxyacetic Herbicides by Tomato Stem-Derived Activated Carbons
Six activated carbons from tomato (Solanum lycopersicum L.) stems (TS-AC) were synthesized by carbonization and chemical activation using potassium hydroxide (KOH) and sodium hydroxide (NaOH) at temperatures of 550, 650, and 750 °C. These TS-ACs were then evaluated as adsorbents to remove 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) from aqueous solutions. The adsorption kinetics of both herbicides followed the pseudo-second-order model, closely correlating with the mesopore volume of the TS-AC. The Langmuir isotherm accurately described the adsorption process for both 2,4-D and MCPA. The porous structure of TS-AC, characterized by micropore volume and specific surface area, significantly influenced the maximum adsorption capacities. The adsorption of both herbicides was pH dependent, but ionic strength had no significant effect. Regeneration testing, conducted over three cycles, showed less than a 15% reduction in herbicide adsorption capacity. This study demonstrates that agricultural waste, specifically tomato stems, can be effectively valorized by using simple activation techniques in TS-AC that are efficient adsorbents to remove organic pollutants, such as herbicides, from aqueous media.
Design and comparison of a suitable dust separation technique during the machining process in a CNC machining center
Design and comparison of a suitable separation technique during the machining process in a CNC machining center. The paper deals with the issue of chip extraction from the milling process in a CNC machining center. The paper aimed to compare the particle size distribution of dust generated in the milling process of natural wood (beech, oak, and spruce) and MDF on a 5-axis CNC machining center. The particle size distribution was evaluated using sieve analysis of samples from the total weight of the captured dust. The results showed that the processing of natural wood is mainly characterized by the formation of coarse dust fractions (2 mm - 1 mm sieves), while the processing of MDF was associated with the formation of fine dust fractions with a size below 100 μm. Another of the objectives was to compare the separation values on the fractional separation curves of selected mechanical separators and filters with the size distribution of dust particles and to propose a suitable separation technique that meets the criteria of "best available technique" (BAT) in the processing of natural wood and MDF, as well as to point out the creation of and the production of harmful dust fractions, which arise mainly during the processing of MDF. We intended to assess whether the introduction of the given technology with the given material mix will also require modifications on the side of the extraction device.
Designing chairs for users with high body weight
The relationship between the functional dimensions of the furniture and a user’s anthropometric dimensions is crucial for safety and functionality. The weight and dimensions of the user’s body significantly affect the functional dimensions of the furniture, especially for overweight users. This paper is focused on the concept of chair structural design, which is suitable for bariatric users, including the application of additional reinforcing structural components. Such components are expected to improve the stiffness and strength properties of the chair structure, and it provides the possibilities to a chair design with improved ergonomic parameters. To increase rigidity and reinforce the frame structure of a chair for obese users, the side stretchers, middle braces inserted under seat and armrests are used. The main goal of the different structural designs of chair frames is to minimize internal forces acting in the structural components of the chair. The finite element method (FEM) was used to determine the internal forces and stress-strain state in the structural elements of the chair, starting with the standard design of the chair frame and comparing different design variants. A synergistic effect is obtained, making the bariatric chair durable and ergonomic, without stigmatizing its users.
Jakościowe aspekty w konstrukcjach meblowych. Poprawa jakości poprzez użycie różnych materiałów konstrukcyjnych
The Brinell Method for Determining Hardness of Wood Flooring Materials
We hypothesize that the ability to recovery the depth of the indentation increases with increasing the hardness of the flooring material. The research was carried out for ten lignocellulosic flooring materials: merbau, oak, maple, red oak, laminated HDF (high-density fiberboard), innovative plywood, beech, pine, peasantry, iroko. The hardness was examined using the Brinell method, and additionally, the elastic indentation of the indenter was measured during the hardness test. On this basis, the permanent (plastic) and temporary (elastic) component of total deformation was determined. Different ability to recovery was found. The harder materials were the higher percentage of elastic indentation in total indentation depth. Moreover, it was found that the measurement of the indentation diameter in wood materials is characterized by high uncertainty and measurements based on the depth of the indentation are more unambiguous and of greater practical importance, especially when testing hard lignocellulosic flooring materials.
Influence of thermal modification and sanding parameters on finest particle content in pinewood dust
Anthropo-Mechanical Cradles: A Multidisciplinary Review
Domestic cradles are beds that are movable but non-mobile for babies up to five months of age. The “anthropo-mechanical” cradle simulates the physiological movement of the human body. The article reviews scientific literature discussing the impacts of swinging on infants, provides classifications of all currently used cradles due to how the child moves, and briefly describes modern technologies within cradle automation. This made it possible to calculate and propose safe motion parameters within mechatronic cradles. The main conclusions of the article are as follows: (1) the scientific literature reports the beneficial effects of harmonic movement on a child, (2) motion analyses substantiating the classifications of all cradles into six types (tilting, yawing, hammock, Sarong, swing, and surging cradle; the classification criterion included the nature of the cradle movement in relation to the planes and anatomical axes of the child’s body), (3) modern technologies allowing for the use of movement with thoughtful parameters, thus, safer for a child, (4) movement within the parameters similar to the motion and speed passively performed by the child in the womb while a mother is walking was considered beneficial and safe, and (5) the use of advanced technology allows for the possibility to devise and create an automatic mechatronic cradle with a child-safe motion. Future innovative anthropo-mechanical cradles that follow physiological human motion parameters can be used safely, with a vertical amplitude ranging from −13 to + 15 mm and a frequency of up to 2 Hz.
Fine dust after sanding untreated and thermally modified spruce, oak, and meranti wood
AbstractAirborne wood dust poses health and safety risks in the construction and furniture industry. The study verified whether the thermal modification affects the share of fine wood dust particles (< 10 μm) generated during spruce, oak, and meranti wood sanding. The experimental research involved nine material variants, including three wood species in three states: untreated, thermally modified at 160 °C, and thermally modified at 220 °C). To collect at least 200 g of each dust sample, a belt sander with P80 sandpaper and a belt speed of 10 m/s was used, along with a dust collector. The collected dust was then separated into fractions using a set of sieves with aperture sizes of 2000, 1000, 500, 250, and 125 μm. A laser particle sizer was employed to measure the sizes of dust particles in the under-sieve fraction (dust with particle sizes smaller than 125 μm). The under-sieve fraction was decomposed into three subfractions, with particle sizes: <2.5, 2.5-4.0, and 4.0–10 μm. Surprisingly the results indicate that sanding dust from thermally modified wood generates a lower average mass share of potentially harmful fine particle fractions than dust from untreated wood. Oak dust contained a higher mass share of fine particles compared to the spruce and meranti dust samples. Dust from thermally modified oak and meranti wood had a lower content of harmful particle fractions than dust from untreated wood. The average mass shares of these dust fractions for modified wood at 160 and 220 °C showed no statictically significant differences (p < 0.05). Conversely, spruce dust had a low content of fine fractions because spruce particles exhibit a more irregular elongated shape. The study considered the extreme temperatures of 160 and 220 °C used in the thermal modification of wood. Therefore, the above statements are assumed to be valid for all intermediate thermo-modification temperatures.
Thermochemical modification of beech wood with ammonium hydroxide
AbstractFour variants of the thermochemical modification were conducted on beech wood at a temperature of 130 °C, employing NH4OH concentrations of 5% or 10% for durations of either 12 or 24 h. The weight% gain (WPG) and bulking coefficient (BC) were initially calculated. Subsequently, the wood’s degree of discoloration was assessed using the CIELAB-colour-system. Chemical structure alterations were determined through Fourier transform infrared spectroscopy (FTIR), while the compressive strength of the wood parallel to the grain was measured. As the NH4OH concentration increased and the treatment duration extended, the samples displayed simultaneous weight increase and volume reduction. The ΔE* values of the samples ranged from 19.33 to 21.09 units, indicating significant color alteration. FTIR analysis revealed differences between the spectra of the unmodified control sample and the NH4OH-treated samples. The modification reduced in hydroxyl and carboxyl groups within the main and side chains of hemicelluloses. Additionally, a decrease in the absorption peak intensity of the unconjugated carbonyl group at 1740 cm− 1 indicated a relative reduction in hemicellulose content. Compressive strength tests showed that the thermochemical modification improved the modulus of elasticity, increasing it from 10,898 MPa (in the control sample) to a range of 11,663 − 13,390 MPa. Similarly, the compressive strength increased from 77.10 MPa to 81.56-107.19 MPa. Interestingly, this improvement was more pronounced with higher concentrations of NH4OH and prolonged modification durations.
Influence of the number of layers on the strength of beech laminated elements in the three-point flexural test
A chair is a piece of furniture whose elements are loaded with relatively high forces. The strength of these elements is vital for the safety of using this type of furniture. The research aims to test the chair material system made of beech wood. The authors analyzed laminated elements with 9, 11, and 13 layers of veneers. The veneers were 1.23 mm thick, with perpendicular fiber directions in adjacent layers, and bonded with 220 g/m2 of PVAc adhesive. The moisture content of the elements was 6 ± 1%. A three-point bending flexural test was performed to determine the stress-strain response of the tested three variants. A complementary numerical analysis allowed a more precise comparison of the three analyzed laminated elements variants. It was confirmed that all variants exceed the desired minimal values in chair support design. Moreover, the average strength values for tested laminated elements, differing in the number of veneers, were sufficient even with a reduced number of veneer layers. The experiments and numerical analysis results confirmed the usability of the three tested types of beech laminated elements to be used as highly loaded chair elements.
Fungi in Mycelium-Based Composites: Usage and Recommendations
Mycelium-Based Composites (MBCs) are innovative engineering materials made from lignocellulosic by-products bonded with fungal mycelium. While some performance characteristics of MBCs are inferior to those of currently used engineering materials, these composites nevertheless prove to be superior in ecological aspects. Improving the properties of MBCs may be achieved using an adequate substrate type, fungus species, and manufacturing technology. This article presents scientifically verified guiding principles for choosing a fungus species to obtain the desired effect. This aim was realized based on analyses of scientific articles concerning MBCs, mycological literature, and patent documents. Based on these analyses, over 70 fungi species used to manufacture MBC have been identified and the most commonly used combinations of fungi species-substrate-manufacturing technology are presented. The main result of this review was to demonstrate the characteristics of the fungi considered optimal in terms of the resulting engineering material properties. Thus, a list of the 11 main fungus characteristics that increase the effectiveness in the engineering material formation include: rapid hyphae growth, high virulence, dimitic or trimitic hyphal system, white rot decay type, high versatility in nutrition, high tolerance to a substrate, environmental parameters, susceptibility to readily controlled factors, easy to deactivate, saprophytic, non-mycotoxic, and capability to biosynthesize natural active substances. An additional analysis result is a list of the names of fungus species, the types of substrates used, the applications of the material produced, and the main findings reported in the scientific literature.
Enhancing Functional and Visual Properties of Paulownia Wood Through Thermal Modification in a Steam Atmosphere
Paulownia elongata wood is characterized by rapid mass gain, but its limited mechanical strength hinders engineering applications. This study aimed to determine the effect of thermal modification in a steam atmosphere (at temperatures of 180 °C and 190 °C for 12 or 6 h with 3 or 6 h of steam dosing) on wood’s selected physicochemical and aesthetic properties. Color changes (CIELAB), chemical composition (FTIR), density, and compressive strength parallel to the grain were evaluated. The results showed a clear darkening of the wood, a shift in hues towards red and yellow, and an increase in color saturation depending on the treatment parameters. FTIR spectroscopy confirmed a reduction in hydroxyl and carbonyl groups, indicating thermal degradation of hemicelluloses and extractives. Wood density remained relatively stable, despite observed mass losses and reduced swelling. The most significant increase in compressive strength, reaching 27%, was achieved after 6 h of modification at 180 °C with a concurrent 6 h steam dosing time. The obtained results confirm that thermal treatment can effectively improve the functional and visual properties of paulownia wood, favoring its broader application in the furniture and construction industries.
