Machines. Technologies. Materials.
Vol. 18 (2024), Issue 8

Table of Contents

  • MACHINES

    • Options for methods of experimental investigation of planetary gear sets

      pg(s) 243-244

      Planetary power transmission are characterized through more complex design and kinematics parameters compared to involute gear trains with parallel shafts. It has been established that their components should be measured and monitored more frequently in order to avoid intensive wear. The paper presents a design project of an advanced experimental device for measuring vibration and wear of planetary gear components. As it is well known, approaches to direct measuring of wear and vibration parameters are difficult to be implemented in these gear trains. The application possibilities of a measurement system that includes a micro-electro-mechanical system, a temperature sensor and wireless modules assembled in a planetary gear trains have been considered. The advantages of micro-electro-mechanical measurement systems have been analyzed precisely. The main characteristics of micro-electro-mechanical sensors are low power consumption, small size and good control and monitoring capabilities. A suitable advanced methodology for the experimental study of planetary gears has been created as well. Conclusions and recommendations have been deduced.

  • TECHNOLOGIES

    • Applications of Lasers in Metal Processing: A Comprehensive Overview

      pg(s) 245-247

      Lasers have found extensive applications in metal processing, including cutting, welding, drilling, surface treatment, cladding, marking, additive manufacturing, and peening. Each application involves different physical phenomena and mathematical principles, and requires different laser parameters and processing conditions. The mathematical models and equations presented here provide a fundamental understanding of these applications.

    • Effects of gamma irradiation processing with two dose rates on the thermal properties of ebony wood

      pg(s) 248-251

      Gamma radiation treatment for the destruction of biological pests is a widely applied method, due to its high efficiency, penetrating power of gamma rays, the ability to control the absorbed dose, speed and absence of toxic residual products. The application of gamma irradiation processing for preservation and conservation of artefacts made of wood requires knowledge of the possible radiation effects on the structure of its components and the selection of an appropriate absorbed dose and dose rate. Тhe present study is devoted to the side effects of gamma irradiation decontamination on the structure of two ebony woods dated to different radiocarbon ages. The changes induced by gamma irradiation at two dose rates: 0.037 Gy/s and 1 Gy/s with absorbed doses from 5 to 25 kGy using differential scanning calorimetry are presented. The effects of the absorbed dose, the dose rate and the age of the samples on the observed radiation effects are considered. Higher effects on the enthalpy of water loss were registered in the younger ebony wood after irradiation at low dose rate. Slight changes of the temperatures of water loss were found in the younger ebony wood sample. No significant changes in the temperatures of thermal decomposition in both ebony wood samples were measured.

    • Sensorless Scalar Speed Control of Three Phase Induction Motors by Using SPWM Strategy

      pg(s) 252-256

      Nowadays, development trends in induction motor electrical drives indicate that the next generation of electrical drives will include sensorless speed control. Speed control systems of induction motor drives without using mechanical sensors for speed measuring have the advantage of being low cost, and they are very robust due to the absence of mechanical component. In most cases, induction motor electrical drives used in industry do not require high speed dynamics. This paper gives sensorless scalar speed control of squirrel cage three phase induction motors based on slip frequency compensation by using a sinusoidal pulse width modulation strategy. Simulation results were obtained by using the Matlab/Simulink software. The proposed sensorless scalar speed control method is simple and is adequate for low-dynamics applications in industry.

    • Recycled Polypropylene filament: process optimization for 100 per cent recycled FDM material, optimizing properties and printing techniques

      pg(s) 257-261

      The growing environmental concern about plastic waste has prompted research into sustainable recycling of polymer, particularly for widely used polymers such as polyethylene from the spools used in the textile industry in the second half of the 20th century. This study investigates the feasibility and optimization of recycling Polypropylene to make filaments suited for 3D printing applications, notably Fused Deposition Modelling (FDM). The study is divided into three phases: collecting and preparing post-consumer Polypropylene spools, extruding recycled Polypropylene into filaments, and optimizing the filament for 3d printing using FDM Technology.
      Polyethylene spools are cleaned, shredded, and treated to ensure consistent feedstock quality. The extrusion process entailed controlling factors like temperature, screw speed, and cooling rate to produce filaments with constant diameter with less distortion. Following material characterisation, the printability of recycled Polypropylene filaments was evaluated using an FDM 3D printer. The Taguchi method is used to carefully study the influence of printing parameters such as nozzle temperature, bed temperature, print speed, and layer height to determine optimal parameters. The printed examples showed reasonable dimensional accuracy and layer adhesion, with surface roughness values within acceptable limits for practical applications.
      This thorough study plan focuses on recycled Polypropylene as a feasible and sustainable material for FDM 3D printing. The findings indicate that with proper optimization, recycled Polypropylene can match the performance requirements of a variety of applications, helping to reduce waste and promote the circular economy in additive manufacturing. Long-term performance testing and the development of recycling processes will be the primary focus of future research to improve the material’s characteristics and broaden its application range.

    • Status and trends in the development of the industrial robots market

      pg(s) 262-265

      Industrial robots are one of the main driving forces of the fourth industrial revolution and one of the most promising technologies for increasing the degree of automation in modern production. Since their entry into mass industrial production in the 1960s, they have evolved significantly, and today they are being implemented in the construction of high-tech smart manufacturing enterprises. With the development of technique and technology, industrial robots are becoming more productive, flexible, versatile, safe and easy to use, revealing new possibilities for modern industrial ecosystems. As a key tool for improving efficiency and productivity, they enter a number of sectors such as automotive, mechanical engineering, energy, electronic production, food industry, space sector, defense, etc.
      The purpose of this report is to present the status and trends in the development of robotics and its spread among the industrial sectors of the economy. The results of the research show the state of the global robotics market and Bulgaria’s place in it.

    • Review of the development of micro-drilling processes

      pg(s) 266-271

      In the knowledge society (KS) and ”Industry 4.0” (I4.0) in the 21st century and today’s rapidly developing world with a large number of important applications, one of the most advanced and growing areas of manufacturing technologies is micro- and nano-machining (traditional and non-traditional) and micro- and nano-aditive manufacturing. Certainly one of the most important technologies of micro and nano machining is micro drilling. Micro-drilling (MD or D) is type of machining (processing) technology used for the drilling of miniaturized parts of small diameter in micro-scale, i.e. diameter in a range of a few microns to several hundred microns. In this paper is given a brief description of the development of micro-drilling process, as well as the basic division of micro-drilling process.

  • MATERIALS

    • Nanocomposite materials based on industrial thermoplastics for metal-polymer systems with high resource

      pg(s) 272-274

      Methodological approaches to the creation of nanocomposite materials based on thermoplastic matrices of industrial production for metal-polymer systems with high resource are considered. The concept of energy and technological compliance of components is proposed. This concept allows to achieve a synergistic effect when introducing dispersed particles in the nanostate into the thermoplastic matrix due to the formation of a structure with special parameters of characteristics. Examples of practical use of the concept of energetic and technological compliance of components in the creation of nanocomposites for special structures are presented.

    • Development of non-equilibrium thermodynamics models of solid-phase transformations in iron-carbon alloys

      pg(s) 275-277

      The development of metal physics and physical materials science in the coming decades is one of the main driving forces of the new scientific and technological revolution, which will cause significant changes in many sectors of industry and energy, construction and agriculture, military equipment and everyday life. In the work using the principles of nonequilibrium thermodynamics develop new models of solid-phase transformations in iron-carbon alloys: annealing, tempering, γ→α – transformation, graphite formation, carbides transformation. Developed models of solid-phase transformations applied to the management of the structure formation of iron-carbon alloys and optimization of their thermal treatment and identifying the conditions of formation of dispersed (nano) particles of carbides in some of the investigated alloys and possibilities of their transformation.