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PROGRAMMING AND VERIFICATION OF MILLING OPERATIONS FOR CNC MACHINES WITH HORIZONTAL ROTARY AXIS
No full textThe paper analyses the programming of CNC milling machines with horizontal rotary axis. These
are usually machines for rapid prototyping of rotating symmetrical and/or asymmetrical parts. The paper analyses the available programming software, which can be one of the standard CAD/CAM systems or a specialized CAM system. In addition to the analysis of the programming method procedure, the verification of the program by simulating the removal of material and simulating the operation of a virtual machine according to a given program was also considered. Verification of programming methods was realized by machining several characteristic parts, on developed 3-axis desktop CNC milling machine - Multiprodesk, that has two translational and one horizontal rotary axis.Conference proceedings [Elektronski izvor] : 60th Anniversary of the Association of Production Engineering of Serbia
/ 40th International Conference of Production Engineering ICPES 2025 - Serbia 2025, Nis, Serbia, 18th - 19th
CIP - Каталогизација у публикацији
Народна библиотека Србије, Београд
621.7/.9(082)(0.034.2)
621.7/.9:669(082)(0.034.2)
681.5(082)(0.034.2)
005.6(082)(0.034.2)
004.896(082)(0.034.2
COMPARISON OF LASER INTERFEROMETER SYSTEMS FOR MEASURING POSITIONAL ACCURACY OF MACHINE TOOLS
No full textLaser interferometers have become indispensable tools in the high-precision calibration of machine tools, offering sub-micron resolution and enhanced measurement reliability. Since the introduction of stabilized helium–neon (He–Ne) lasers in the 1960s, manufacturers like Hewlett-Packard (HP), Renishaw, and Lasertex have developed systems with increasingly advanced capabilities. This paper presents a technical and historical comparison of three key interferometric systems: HP’s 5525A, Renishaw’s XL-80, and Lasertex’s HPI 3D. The analysis includes specifications such as laser stability, resolution, environmental compensation, and dynamic measurement capabilities. The HP 5525A, although historically significant, lacks modern portability
and software integration. In contrast, Renishaw’s XL-80 offers compactness, advanced environmental compensation, and compatibility with international metrology standards. Lasertex’s HPI-3D introduces next generation capabilities, such as real-time vibration analysis, nanometric resolution, and full 3D geometric evaluation. The comparative findings suggest a clear technological evolution toward higher precision, modularity, and software-driven diagnostics in laser interferometry.Conference proceedings [Elektronski izvor] : 60th Anniversary of the Association of Production Engineering of Serbia
/ 40th International Conference of Production Engineering ICPES 2025 - Serbia 2025, Nis, Serbia, 18th - 19th
CIP - Каталогизација у публикацији
Народна библиотека Србије, Београд
621.7/.9(082)(0.034.2)
621.7/.9:669(082)(0.034.2)
681.5(082)(0.034.2)
005.6(082)(0.034.2)
004.896(082)(0.034.2
APPLICATION OF LOGISTIC REGRESSION FOR IDENTIFICATION OF DROSS FORMATION CONDITIONS IN CO2 LASER CUTTING
No full textDross formation is an issue of multifold importance in laser cutting. In this study, based on data from two crossed experimental designs with 52 trials, a machine learning model, that is, multiple binary logistic regression, was developed to identify dross formation conditions in CO2 laser cutting. The model inputs were laser power, cutting speed, and oxygen pressure, and the corresponding dependent variable took the value of 1 (in the case of dross formation) or 0 (in the case of no dross formation). Statistical indicators showed a good predictive ability of the developed logistic regression model to discriminate between dross formation and no dross formation classes. It was revealed that the most decisive input regarding dross formation is the cutting speed. Upon the development of the logistic regression model, laser cutting process windows were created, and further analysis and interpretation of the experimental results were performed
APPLICATION OF RULE BASED PARAMETRIC COMPUTER PRODUCT DESIGN
No full textThe use of Computer-Aided Design (CAD) systems is now ubiquitous in modern industry. Virtually no manufacturing company develops new products without some level of computer assistance. However, conventional constraint-based CAD modelling can be time-consuming—particularly in the context of Industry 4.0, where speed and automation are increasingly critical. This challenge is especially evident in companies that produce families of similar parts, where designers must repeatedly generate models from scratch.
Parametric modelling offers a solution by enabling automation in the development of new products. It allows external data tables to drive CAD models, making them interactive and accessible through web-based applications (e.g., via the World Wide Web). Such systems empower users without CAD expertise to interact with product models, thanks to embedded design rules that enforce constraints and automate calculations. These rules ensure product parameters remain within predefined limits or are derived from existing values.
In this study, a parametric CAD model of a universal press was developed using the commercial software Autodesk Inventor. The model integrates custom design rules and maintains full associativity with data stored in an external table. Automated regeneration of the assembly model was tested by altering input parameters, and the system's rule-enforcement functionality was validated. If rule conditions were violated, the CAD system triggered a user-defined notification window designed by the product developer.
This approach demonstrates a practical method for automating product development workflows, which can be customized to meet specific client requirements
On energy efficiency of tankers: EEDI, EEXI and CII
No full textThis paper aims to extensively analyze the energy efficiency of large tanker fleets, focusing on their compliance with the International Maritime Organization (IMO) requirements through the evaluation of design and operational indices. Despite an increase in energy efficiency studies, few have assessed large tanker fleets and their subgroups systematically, leaving a significant gap regarding the impact of regulations on different tanker sizes. The paper evaluates the energy efficiencies of tankers concerning Energy Efficiency Existing Ship Index (EEXI), Energy Efficiency Design Index (EEDI), and Carbon Intensity Indicator (CII), differentiating ships by size and type. It further explores and provides the potential reductions in speed and power for each subgroup of tankers, required to meet current and future energy efficiency requirements. The outcome shows that regulatory measures like EEDI, EEXI, and CII have significantly improved energy efficiency, but compliance remains challenging, with only 14.8% of ships meeting the EEXI criteria, especially for smaller ships, which face greater power reductions than larger ones. The results also indicate that the considered fleet of tankers does not operate at more than 60% of the available engine power and that the ships are already sailing at 8% lower speed than for which they were designed
Inverse Iterative Methodology for Welded Joints Characterization in Construction Designing and Comparison to Classical Approach
No full textTraditional approach in structural designing and strength assessment that
observes structure without welded joints is sufficiently accurate in terms of elastic response,
in comparison to yield strength. The main idea of this paper is to show that it is necessary to
consider welded joints and all their regions in the elastic-plastic domain. This methodology
proposes obtaining of mechanical properties of welded joint regions using inverse iterative
procedure developed by the authors of this paper. Taking into account tensile testing of
specimens containing welded joints, strain field was obtained using Digital Image
Correlation. Finite Element Method model of test specimens is formed using the same
parameters as in the experimental one (such as welded joint geometry, boundary conditions,
loads, etc.). Strain fields of all regions of welded joint (parent material, weld metal, and heat
affected zone) are imported into finite element model, setting ground for development a new,
improved, finite element model. Consequently, material properties of all three welded joint
regions were obtained. Demonstration of the proposed procedure is shown in the analysis of
two significant structures: (i) a pipeline (membrane stress), and (ii) a girder of a bucket
wheel excavator (bending of plates). Based on this analysis it was shown within the plastic
deformation domain the differences in stresses (and structural behavior in overall) between
structure with and without welded joints are considerable, while there is no difference in the
elastic domain. Stress concentration factors are formulated for each analyzed type of
structure, in order to quantify those difference
Reconfigurable control system for machine tools with a switchable kinematic and variable execution flow of the kinematic algorithm
No full textThis paper introduces the development of a control system for reconfigurable machine tools, featuring switchable kinematics and a variable execution flow of kinematic algorithms. The research highlights the importance of a low‐cost, adaptable solution for retrofitting aging CNC machinery, enhancing their flexibility and modularity. By leveraging open‐architecture platforms like LinuxCNC, the system incorporates direct and inverse kinematic functions designed to support multiple kinematic configurations without necessitating axis reinitialization or workpiece repositioning. Validated through real‐world experiments, the proposed system offers significant benefits for both educational and research purposes.Editor of chief: Assistant Professor Dejan Branković, PhD
Executive editor: Milivoj Stipanović, BsC
COBISS.RS-ID 14261145
Ballistic impact of fragment-simulating projectiles on steel targets: A multi-approach study
No full textPenetration mechanics, a subfield of terminal ballistics, examines the impact of projectiles (penetrators) on targets (obstacles) [1–3]. This study investigates the ballistic impact of fragment-simulating projectiles (FSPs) on homogeneous steel plates, a topic relevant to assessing the efficiency of fragmentation warheads and projectiles, as well as target vulnerability and protection. Three complementary approaches—experimental, analytical, and numerical—are employed to analyze the penetration process.
Extensive experimental research has been conducted [4, 5] and supplemented with new results. Two steel target plates, 1.25 mm and 2.20 mm thick, were perforated using blunt, deformable cylindrical projectiles with a diameter of 4.70 mm and two distinct masses—1.090 g and 1.912 g. Given the geometric characteristics and material properties of both the penetrator and the target, the dominant penetration mechanism was identified as plugging. Impact and residual velocities of the FSPs were measured, alongside the geometric properties of deformed penetrators and perforation holes in the target plates.
Various analytical models describing the plugging perforation process were examined. Additionally, a numerical model was developed in Abaqus using a Lagrangian framework with explicit time integration. The Johnson-Cook constitutive and failure models were employed to characterize dynamic stress and material failure. The analytical and numerical results were validated against experimental data, showing good agreement. This validation enables key conclusions regarding the influence of penetrator mass on residual velocity and provides an evaluation of the ballistic limit velocity.NITRA: 451-03-137/2025-03/200105 od 4.2.2025. god
The effect of infill density on fracture toughness results of PLA material
No full textThe main objective of this research is to obtain a comprehensive insight into the influence of infill density on the fracture toughness results of PLA material, used in FDM technology. This paper presents four infill cases (100%; 70%; 40%; 10%) with 0.1 mm layer height. The whole research includes cases from 10 to 100% infill with a 10% increment on three different layer heights (0.3; 0.2; 0.1 mm). The FDM-grade PLA material is brittle hence, the fracture toughness of this material was estimated using the ASTM D5045-14 standard on SENB specimen geometry. This standard requires the plane-strain state near the crack tip to be met to obtain valid results. Three specimens were tested per infill group, all of which met the plane-strain condition. However, when looking at the KIC results from the highest to the lowest infill in all three considered layer configurations, the SENBs start to fail at 50%- onward due to the apparent presence of plasticity. This is evident from the maximum load value in the lower infill cases, where it exceeds the conditional value by more than the limit value of 10%. Therefore, for a better assessment of current results, the J integral approach was also used.contract No. 451-03-66/2024-03/200213 (from February 5th, 2024.
Stance and engagement markers in Serbian university students’ essays
No full textThe aim of the paper is to explore the frequency of use and the types
of stance and engagement markers in ESP students’ essays. Stance markers
include hedges, boosters, attitude markers and self-mentions while engagement
markers, as reader-oriented text features, comprise reader pronouns, personal
asides, appeals to shared knowledge, directives and questions. The presence of
stance and engagement markers was analysed in the essays written by the
first-year students of the Faculty of Mechanical Engineering as part of their
English course task (Ne=220; 41,156 tokens). The results indicate that students
primarily employed stance markers, such as hedges and boosters, to articulate
their perspectives. When engaging with the reader, they mostly utilised reader
pronouns, while other engagement markers had relatively low frequencies.
The prevalence of stance over engagement markers suggests that the students
primarily took care of carefully communicating their attitudes and paid slightly
less attention to communicating with the reader.У литератури се често истиче важност развијања вештина неопходних за потребе
академског писања на страном језику код студената на универзитетском нивоу
наставе, будући да су оне једна од кључних способности да се страни језик
ефикасно користи у различитим друштвеним контекстима. У вези са тим,
важну улогу има и употреба маркера становишта и ангажовања у академском
писању. Маркери становишта односе се на језичка средства којима се исказује
став аутора према неком питању, док маркери ангажовања укључују стратегије
које имају за циљ да наведу читаоце да се укључе у разумевање аргумената
аутора. Маркери становишта обухватају ограде, појачиваче, маркере става и
самопомињања, док маркери ангажовања обухватају заменице које се односе
на читаоца, личне напомене/коментаре, упућивање на општепознате чињенице,
смернице и питања. Циљ рада је да се анализира учесталост употребе и типови
маркера становишта и ангажовања у есејима студената који уче енглески језик
струке. Истраживање је урађено на есејима које су написали студенти прве године
Машинског факултета у оквиру задатка на курсу енглеског језика, у којима је
требало да изложе своје ставове на тему „Аутономна возила у савременом свету
– предности и мане“. Резултати показују да су маркери становишта коришћени
у знатно већем броју од маркера ангажовања, што би могло да значи да су
студенти примарно водили рачуна о томе да пажљиво саопште своје ставове, а
мање пажње су посветили комуникацији са читаоцем. Унутар категорије маркера
становишта, највише су коришћене ограде и појачивачи, а у оквиру категорије
маркера ангажовања најчешће су се јављале заменице које се односе на
читаоца, док су остали маркери ангажовања коришћени са ниском учесталошћу.
Закључује се да су студенти успешно употребили различите маркере, као и
различите лексичке јединице за изражавање становишта и ангажовања, али
да је ипак важно да наставници развијају стратегије за помоћ студентима у
развијању вештина академског писања и прагматичке компетенције.br. 451-03-137/2025-03/200105;
br. 451-03-137/2025-03/20011