Polypropylene is a widely used linear hydrocarbon polymer with diverse applications due to its exceptional physicochemical characteristics and minimal changes during the recycling process. Numerous studies have focused on factors influencing the mechanical properties of polypropylene and its application in composites. However, despite their significance in the agricultural industry, there is limited research on polypropylene baling twines. This study analyses the behaviour of polypropylene baling twine under tensile loading, exploring the influence of fibre friction and twisting angle on the material’s tensile strength. Experimental investigation indicated that tensile strength increases with twisting angle, but only until the angle reaches a critical value. Further increase in the twist angle led to a decrease in tensile strength. The increase in tensile strength is attributed to the rise in the coefficient of friction between fibres in the twine. An experimental approach was employed to evaluate the mechanical characteristics of the twine, including the effect of prestressing by twisting. Understanding these characteristics is crucial for enhancing the quality of polypropylene baling twines and optimising their application in the agricultural industry.

The paper presents theoretical and experimental analyses of the kinetic friction coefficient of a ball bearing in conditions of rotational motion initiated by dynamic impact force. A method has been developed and a measurement system allows the measu...

The application of CAD/CAM technologies in modern production has revolutionized manufacturing processes, leading to significant improvements in precision, efficiency, and flexibility. These technologies enable the design and manufacturing of complex geometries with high accuracy, reducing errors and material waste. CAD/CAM integration streamlines workflows, enhances productivity, and facilitates rapid prototyping, accelerating the time-to-market for new products. Additionally, it supports customization and scalability in production, allowing for cost-effective small-batch and large-scale manufacturing. Without a 3D model of the product, it is not possible to use the advantages of applying advanced CAD/CAM technologies. Recognizing 3D models from engineering drawings is essential for modern production, especially for outsourcing companies in fluctuating market conditions, where the production process is organized with 2D workshop drawings on paper. This paper proposes a novel methodology for reconstructing 3D models from 2D engineering drawings, specifically those in DXF file format, leveraging a genetic algorithm. A core component of this approach is the representation of the 2D drawing as a symmetric adjacency matrix. This matrix serves as the foundational data structure for the genetic algorithm, enabling the evolutionary process to effectively optimize the 3D reconstruction. The experimental evaluation, conducted on multiple engineering drawing test cases (including both polyhedral and cylindrical geometries), demonstrated consistent convergence of the proposed GA-based method toward topologically valid and geometrically accurate 3D wireframe models. The approach achieved successful reconstruction in all cases, with fitness scores ranging from 1.1 to 112.2 depending on model complexity, and average execution times from 2 to 100 s. These results confirm the method’s robustness, scalability, and applicability in real-world CAD environments, while establishing a new direction for topology-driven 3D reconstruction using evolutionary computation.

The paper investigates the effects of roller pressing on the hardness, roughness, and elastic modulus of wooden workpieces. For research purposes, a roller pressing device based on purely mechanical processing was designed and developed. Four different levels of pressing force have been applied to eight different types of wood: cherry, fir, alder, linden, beech, walnut, oak, and ash. The obtained results indicate that the proposed processing method can significantly improve the hardness, elastic modulus, and surface quality of wooden workpieces. The ash sample exhibited the largest relative increase in hardness (175.9%), while the most significant relative increase in the elastic modulus (66.73%) was measured on the linden sample. The largest relative decrease in surface roughness (54.75%) was achieved on the alder sample. For all types of wood except for fir, in which case an increase in pressing force did not produce the desired reduction of roughness, correlation coefficients indicate a strong relationship between the pressing force as an input variable and the elastic modulus, hardness, and roughness as output variables.

In modern material processing industries, the constant need for increased efficiency and precision drives ongoing research aimed at optimizing technological parameters. The presented study aims to analyze excessive wear and chipping of gun drills during the deep drilling process of 24CrMoV5-5 steel. The experiment was conducted on a horizontal deep drilling machine, model T30-2-500 (TBT Tiefbohrtechnik GmbH+Co), under real production conditions. The investigation included the performance analysis of both factory-reground and subsequently reground drills, with the number of tests enabling a detailed comparison across different process regimes. The process parameters were systematically varied in three phases, with a focus on increasing the coolant pressure from 50 to 60 bar, while other conditions, such as spindle speed and feed rate, remained constant. The results indicate that increasing coolant pressure allows for more efficient cooling, stabilization of temperature fluctuations in the cutting zone, and improved chip evacuation, directly leading to reduced chipping and more uniform tool wear. Consequently, this extends the service life of the drills and preserves the high precision of the machined surface. The obtained results provide valuable guidelines for optimizing deep drilling parameters, highlighting the importance of properly adjusted cooling conditions in industrial machining. Future research will focus on integrating additional processes, including variations in cutting speed, the application of different cooling techniques, and the implementation of intelligent tool condition monitoring systems, aiming to achieve an optimal balance between process efficiency and tool longevity.