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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.
Optimizing dimensions in furniture design: A literature review
Wooden furniture design necessitates the integration of both technological requirements and aesthetic considerations. To guide designers in achieving this balance, this article explores how established design principles, such as proportions and preferred numerical sequences, can inform decision-making for both technological and aesthetic aspects. The goal is to demonstrate how these principles can be integrated with modern CAD tools. In reviewing the scientific literature, this study compiled and compared mathematical and non-mathematical models that support dimensional decision-making. These models included ancient canons (Egyptian, Greek, and Roman) alongside those of Leonardo da Vinci, Palladio, Dürer, Le Corbusier, Zeising, McCallum, and Brock. Additionally, the article examines numeral systems used in modern technology, such as Renard’s series and convenient numbers. It is proposed that designers should experiment with geometric design templates to achieve balanced proportions. All geometric design principles contribute to aesthetics, creativity and effectiveness in design. The literature identifies two groups of dimensional design templates: organic, inspired by the human body or the Fibonacci sequence, and inorganic, based on numerical order. It’s impossible to pinpoint a single “optimal algorithm” to support dimensional decisions in design. Specific geometric design principles serve as valuable tools, not the ultimate answer.
Adjustments in production costs linked to the redesign of wooden chairs for the bariatric population
Purpose Current furniture design principles fail to keep pace with the global rise in obesity. This study aims to address this issue by proposing a novel methodology for manufacturing cost estimation of common-use chairs that can accommodate even severely obese individuals. Design/methodology/approach The approach prioritizes universal design principles and user safety while ensuring furniture producers’ economic viability. This study utilizes real-world data to determine the establish appropriate load capacity for common-use chairs. Empirical height and weight data were collected from 7,938 young Slovakian men (aged 18–25) between 2001 and 2023. Additionally, data on Slovakia’s bariatric population, encompassing all genders, were obtained from medical facilities (2020–2024). Findings Considering the 95th percentile weight among bariatric individuals, the authors factored in a 20% design safety margin. This resulted in a target load capacity of 230 kg for all chairs designed for common use – a significant increase from the standard 110 kg capacity. An essential contribution of this study is a method for estimating chair production cost based on its designed load capacity. This method’s calculations reveal that the redesigned chair is estimated to cost 11.6% more than a standard chair. However, considering its ability to cater to broader user needs, this price point remains competitive. Practical implications The research indicates that the standard load capacity of common-use chairs should be substantially increased to accommodate the growing obese population. The study offers a methodology for estimating the cost implications of designing chairs with a higher load capacity, enabling manufacturers to assess the economic feasibility of implementing such changes. Social implications Chairs with higher load capacities improve accessibility for individuals with obesity, promoting their participation in social and professional activities. By accommodating individuals of all sizes, these chairs reduce the risk of falls, injuries and other problems associated with poorly fitting furniture. Originality/value This study links universal design, safety and affordability. The authors used real data from Slovakia to find the right weight limit for these chairs. The study addresses the pressing issue of furniture design failing to keep pace with rising obesity rates. The method helps make chairs that are accessible to everyone. While these chairs cost a bit more, they are affordable considering their expanded user base. The study’s originality lies in its novel methodology and data-driven approach, while its value lies in its potential to address a significant societal issue.
Surveying Quality Management Methodologies in Wooden Furniture Production
Furniture production is a specific industrial sector with a high human labor demand, a wide range of materials processed, and short production runs caused by high customization of end products. The difficulty of measuring the aesthetic requirements of customers is also specific to furniture. This review of academic papers identifies and explains effective quality management strategies in furniture production. The reviewed literature highlights a range of quality management methodologies, including concurrent engineering (CE), total quality management (TQM), lean manufacturing, lean six sigma, and kaizen. These strategies encompass a variety of pro-quality tools, such as 5S, statistical process control (SPC), quality function deployment (QFD), and failure mode and effects analysis (FMEA). The strengths of these quality management strategies lie in their ability to enhance efficiency, reduce waste, increase product diversity, and improve product quality. However, the weaknesses concern implementation challenges and the need for culture change within organizations. Successful quality management in furniture production requires tailoring strategies to the specific context of the furniture production industry. Additionally, the importance of sustainability in the furniture industry is emphasized, which entails incorporating circular economy principles and resource-efficient practices. The most important finding from the literature analysis is that early detection and correction of poor quality yields the most beneficial outcomes for the manufacturer. Therefore, it is essential to strengthen the rigor of quality testing and analysis during the early stages of product development. Consequently, a deep understanding of consumer perspectives on required furniture quality is crucial. The review identified two research gaps: (1) the impact of unnecessary product over-quality on the efficiency of furniture production and (2) the influence of replacing CAD drawings with a model-based definition (MBD) format on quality management in furniture production.
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.
Analysis of the lamella dimensions of the bed slat for the bariatric respondent: A modelling approach
Chair Size Design Based on User Height
General principles derived from anatomical studies of human body sizes should be applied to chair designs. Chairs can be designed for a specific user or a particular group of users. Universal chairs for public spaces should be comfortable for the largest possible group of users and should not be adjustable, such as office chairs. However, the fundamental problem is that the anthropometric data available in the literature either come from many years ago and are out of date or do not provide a complete set of all the dimensional parameters of a sitting human body position. This article proposes a way to design chair dimensions solely based on the height range of the intended chair users. For this purpose, based on literature data, the main structural dimensions of the chair were assigned to the appropriate anthropometric body measurements. Furthermore, calculated average body proportions for the adult population overcome the incompleteness, outdated and burdensome access to anthropometric data and link the main chair design dimensions to one easily accessible anthropometric parameter: human height. This is achieved by seven equations describing the dimensional relations between the chair’s essential design dimensions and human height or even a height range. The result of the study is a method of determining the optimal functional dimensions of a chair for a chosen range of sizes of its future users based only on users’ height range. Limitations of the presented method: the calculated body proportions are correct only for people with a standard body proportion characteristic of adults, i.e., they exclude children and adolescents up to 20 years of age, seniors, and people with a body mass index exceeding 30.
The influence of feed rate during pilot hole drilling on screw withdrawal resistance in particleboard
AbstractScrew withdrawal resistance (SWR) is a metric that assesses the strength of furniture joints made with wood screws. The SWR value is influenced by several factors, such as the size of the screw, the depth to which it is embedded, the diameter of the pilot hole, and the material properties of the furniture components that are being joined together. These factors have been widely studied in the scientific literature. The objective of the research was to investigate the previously unexplored factor of a feed rate during pilot hole drilling and its influence on SWR. This study used three particleboards composed of raw pine material and urea–formaldehyde resins; the boards varied in average density (633, 637, and 714 kg/m3). Blind pilot holes with a diameter of 5 mm and depth of 25 mm were drilled in these boards using three significantly different feed rates (0.033, 0.33, and 3.33 mm/rev.). Subsequently, a confirmat-type furniture screw (7 mm major diameter, 4 mm minor diameter, 3 mm pitch) was screwed into these pilot holes. The ultimate SWR was measured with a universal testing machine. The results showed that the highest feed rate significantly decreases the SWR for all particleboards tested. This phenomenon can be attributed to the fact that a higher feed rate leads to a decreased precision in the internal surface of the pilot hole, consequently diminishing the screw’s anchoring capacity within the hole. The high feed rate, used to increase production efficiency, may significantly reduce furniture durability and usability.
Differences in employee motivation in wood-processing enterprises in selected countries of Central Europe
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%.