Filters
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.
Energy Consumption for Furniture Joints during Drilling in Birch Plywood
The purpose of this study is to support eco-design ideas and sustainable manufacturing techniques by examining the energy consumption related to drilling holes for different furniture connections. The experimental model is a simple piece of furniture made from birch plywood with three different types of joints. Eccentric joints, confirmat screws, and dowel measurements of energy consumption with a CNC drilling and milling machine show different values for every kind of connector. The energy consumption was measured using a portable power quality analyzer, specifically the PQ-box 150 manufactured by A:Eberle GmbH & Co. KG Nürnberg, Germany. This device likely adheres to industry standards for energy measurement, ensuring accurate and reliable results. The measurement process involved recording energy consumption at different stages of the machining process, allowing for the analysis of specific cutting work and total energy consumption for various joint types. Dowels exhibit the lowest energy consumption at 0.105 Wh for one furniture joint, confirmat screws at 0.127 Wh, while eccentric joints, despite their higher energy consumption (0.173 Wh), offer enhanced transportability and assembly flexibility of a piece of furniture. Specific cutting power for one selected piece of furniture was 227.89 J/mm3 for dowels, 190.63 J/mm3 for eccentric joints and 261.68 J/mm3 for confirmat screws.
Improving the stiffness of the corner connections in wooden door frames
The research aimed to determine the strength and stiffness of corner joints in interior door frames, depending on their construction and the modifications made to the design of the door frame joints. Initially, two models were compared: model 1, with two connectors using a clamping screw at an angle of 45°, and model 0, with a single connector using a cam joint at an angle of 90°. In all tests, model 1 exhibited significantly better mechanical properties. To improve the performance of model 0, three alternative construction models (A, B, and C) were proposed by changing the position of the door frame mounting holes. In the compression test, model A showed an increased bending moment compared to model 0, while models B and C showed no such improvement. In the tension test, the bending moment values remained at a similar level across all construction variants, including model 0. In terms of bending moment, the best result in compression was achieved by model A (48.26 Nm), and in tension by model B (48.72 Nm). The highest stiffness was demonstrated by model 1 (up to 42.38 kNm/rad), while among the alternative models, model C showed the best result in tension (33.98 kNm/rad). Due to the favourable increase in bending moment under compression in model A and the insignificant changes under tension across all variants, model A is considered the optimal solution. To enhance the strength of the door frame, offset holes can be applied as proposed in this model.
Long-term operation of pulse-jet filters for wood dust
Long-term operation of pulse-jet filters for wood dust. The study specifies the value of flow resistance and separation efficiency of filter material during long-term use in pulse-jet filters for wood dust. The experiments were carried out for one type of material working in two different filtration installations in one furniture factory. The bags were obtained from the installations after working for 67, 133 and 272 days, respectively. All tests were performed on the pilot-scale test stand under identical filtration conditions. Studies have shown that long-term filter material use increases airflow resistance and improves filtration efficiency. The range of these changes depends on the operating conditions of the pulse-jet filters. The obtained results made it possible to determine the properties of the long-term use of filter materials in various filtration conditions.