International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

A mathematical model is proposed, describing the movement of a gas bubble in a viscous liquid medium under the action of the Archimedean force. In addition to Archimedean forces and fluid viscosity it takes into account the influence of temperature and pressure of the fluid and of the gas in the bubble. Solutions have been obtained for the movements of a gas bubble in the conditions of a solidifying casting, considering the influence of the bubble size, the pressure in the liquid and the viscosity of the medium on the speed of movement. Software based on the FORTRAN language has been created, which implements the solutions of the model for specific values of the input parameters. The capabilities of the model are illustrated by numerical experiments under different conditions.

A mathematical approach is presented for estimation of inertia of thermocouples in unsteady heat transfer processes. The approach allows to estimate the systematic error in measured data and to make a first-order correction, bringing the measurement data significantly closer to the real ones. The efficiency of the method is illustrated by computer simulation of two examples from foundry practice. The symmetry of heat transfer processes is used to identify an important and determining parameter of the inertia of the thermocouple.

Simulation of gravity filling a metal mold with aluminum alloy (EN AC-46400 AlSi9Cu1Mg)

In this issue the main new opportunities in MAGMASOFT® 6.1 /last version of software package MAGMASOFT/ are presented and illustrated. The presentation will introduce you in all general innovations as general innovations in geometry perspective, new options for heat treatment of castings, new possibilities in continuous casting and a new innovation – MAGMA ECONOMICS. With the last option you can now also keep an eye on costs and emissions. With MAGMA ECONOMICS you can add a decision criterion to your decision base. Calculate the costs or look at the carbon footprint and make more informed decisions.

The latest version of MAGMASOFT software package – MAGMA6.1 is used to simulate and optimize a casting formation. The alloy AlSi7Mg was used for this purpose. The casting is intended for the production of a wire connector for high voltage power transmission networks. Die casting method is used. The results obtained from the stimulation of pouring and crystallization of the casting are presented. Based on the located defects and the analysis performed, changes of the technology were made, which ultimately ensure the formation of a defect-free and soundness casting.

In recent years, natural disasters have occurred almost annually in Japan, causing great damage. Power outages in disasterstricken areas have occasionally forced victims to resort to outdoor campfires or indoor candles for lighting. Prolonged bad weather during such events makes it difficult to safely secure lighting, which could have a negative influence on people’s health. To address this issue, we used white light-emitting diodes (LEDs) as the light source and fabricated handmade lanterns by filling a 500 mL plastic bottle with tap water and adding 1–2 drops of milk. In this study, an LED light source casing was constructed using a three-dimensional printer, achieving a stable light scattering effect. Red, green, blue, and yellow LEDs were used for the lantern, considering people’s preferences for colored handmade lanterns. An additional light source case was easily made from cardboard, and a bamboo light source case was also constructed.

Composite structural modifications based on hydraulic inorganic binders and foam glass aggregate fractions were prepared. Formwork moulds were developed for the moulding of composite test bodies using different technological approaches. A series of experimental specimens meeting the requirements for standard laboratory tests were obtained. The role of the technological regimes used in the formation of the structural characteristics and performance of the composites is examined. The existing possibilities for further modification and potential application of the obtained composite materials are analysed.

The article presents a comparison of different computational approaches used to study the surface treatment of a NiCrMoV steel with 0.55% Carbon content by a plasma jet. Metallographic observations show formation of martensite layer due to high cooling rate by heat transfer into the bulk steel. Heat affected zone (HAZ) was 1 mm deep and 10-12 mm wide. The treated surface maximum hardness was measured at 763 HV0.1 whereas untreated steel was at 210 HV 0.1. The computation indicates a hardening sink near the surface that went undetected in the experimental observations. The ability of the different computational approaches to explore the process related phenomena and to give reliable results is put into discussion.

High-speed machining (HSM) significantly influences the thermal dynamics of the cutting process, particularly in the toolworkpiece interaction zone. At elevated cutting speeds, the reduced tool-workpiece contact time minimizes heat transfer to the workpiece, concentrating thermal energy in the cutting zone. This results in localized material softening, reduced cutting forces, and enhanced process efficiency. This study investigates the thermal effects of HSM by experimentally turning C45 steel using a cubic boron nitride (CBN) tool at cutting speeds ranging from 800 m/min to 1800 m/min. Cutting forces were measured and analyzed in conjunction with temperature distributions within the cutting zone and tool. The experimental results were compared against predictions from the analytical Oxley machining model and numerical simulations using DEFORM software. The analysis revealed the dependence of cutting speed on cutting zone thermal properties, providing insights into material behavior under high-speed conditions. Furthermore, the study identified optimal cutting speeds that balance thermal effects and cutting process stability. These findings contribute to the definition of appropriate high-speed machining parameters, ensuring effective heat dissipation and stable tool performance.

Diamond is currently one of the main reserves for the development of microelectronics. It is with it that tangible progress of this industry is possible, allowing it to reach new technical frontiers, associated primarily with an increase in the speed and power of electronic components. Of the many laser technologies for processing materials in the production of electronic components, the following processes are distinguished: cutting, ablation and welding. For short and ultra-short laser pulse durations, the above processes are applicable under certain conditions, e.g., the thickness and linear size of the element are mainly in the micrometer range. High accuracy of part processing is achieved by using the size of the laser spot on the surface > 0.5 μm and a power density of about 109 W/cm2. This can be realized by increasing the uniformity of the laser beam, controlling the pulse shape, and selecting the wavelength of the laser radiation. Laser ablation, especially on metal structures, is implemented using nano-, pico- and femptosecond pulses. If the laser power density values are much higher than the threshold for ablation, treatment occurs at 120 fs < tp <150 fs using wavelengths of 800 and 1064 nm. The features of laser ablation in metals, semiconductors, and dielectrics are to reduce the threshold power flux density if the pulse duration is reduced from nano- to femtoseconds. The main promising areas of predominant application of diamond and diamond-containing materials in the production of components of electronic equipment are presented.

Plasma-based ion implantation (PBII) is a surface modification technique that applies a negative high-voltage pulse to a sample immersed in plasma. PBII is suitable for samples with complex geometries, as its ion sheath conforms to the sample’s shape, ensuring uniform ion implantation. Due to its precise controllability, PBII is widely used industrially for surface modification and has promising applications for sterilization. We previously used PBII with oxygen gas to successfully sterilize heat-resistant spore. Here, we evaluated the use of PBII with HHO as the process gas for sterilization. Sterilization exceeding 7D was achieved at 10 min and 3 Pa. The enhancement of the sterilization efficacy was attributed to the synergistic effect of plasma and thermal energy, which emerged as a consequence of a temperature increase exceeding 100°C due to adjustments in pulse width and delay time. These results indicate the possibility for temperature control in PBII technology, which has potential application in sterilization processes.

An coupled analytic-numerical model for calculation of distortions arising by welding fabrication is introduced. Target of the analytical model is the calculation of the inherent strains after the local thermal-mechanical influence of the welding or thermal straightening process. Following the fabrication processing chart the strains are loaded on an elastic FE-model of the structure and the residual stresses and distortions of the whole structure are calculated. The consideration of welding and thermal straightening scenarios, inclusively the assembling stages, is done by taking into consideration the intermediate variation of the strain state in the FE-model of the structure at every processing step. The important physical relations are demonstrated. The model is intended to be used for solving industrial tasks, i.e. intending acceptable precision and calculation time as well as low simulation costs.