bluuebunny/crossref_metadata_2025 huggingface dataset:
Location Selection and Size Estimation of Resource Buffers in the Critical Chain Project Management Method
Authors: Paprocka Iwona , Czuwaj Weronika
Published: November 2015

Critical Chain Project Management (CCPM) is based on a network planning and the Theory of Constraints. The importance of management of uncertainty and deviations that occur during a project is emphasized. The probability of the project completion in a predefined time limit, or even before the time limit is increased. Literature analysis indicates that other types of buffers must be applied (buffer supporting a project, buffer reacting on a critical path, buffer reacting on a non-critical path) apart of feeding, resource and project buffers. Applying the additional buffers keeps the critical path in the same position and maintains the unchanging due date of the project. Methods estimating size of feeding and project buffers are identified: half of the chain method, square root of fault method, modified method of square root of fault, method taking into account due date of the project. In this paper, a new method estimating a size of resource buffer and selecting a location of resource buffer based on the theory of probability is presented. In this paper, the CCPM method is applied to estimate due date of the mining machine production project.
Analyses of Production Line Controlled with Kanban Methode
Authors: Gavriluță Ana
Published: November 2015

The challenges of choosing methods of material flow control are bigger due to the fact that they authorize the quantity of production in each processing stage so that the products get to the customer at the right moment and in the quantity wanted, while minimizing the costs and stocks of the production system. For this reason, the objective of the research performed in this paper is to determine the impact of Kanban control methods on the performance indicators, total cost and interoperation stock of a production system, given the fact that many system parameters are variable. The main conclusion drawn from the results is that when the input parameters vary within certain limits the control method with the best performance indicators for a production line can be established following the methodology used in this paper. Methodology is a useful tool in the hand of those who design production systems because it allows the choice of the control method which provides the best performances, at least from the viewpoint of two indicators: costs and stocks.
Simulation Aided Production Planning and Scheduling Using Game Theory Approach
Authors: Krenczyk Damian , Olender Malgorzata
Published: November 2015

In the paper the concept of using methods and models of the game theory to solve problems in the area of production planning and control is presented. The problems concerning selection of the most favorable routes from given circumstances and for available set of alternative routes in discrete multi-assortment production systems is presented. Considered in this paper the problems related to the allocation of adequate resources to carry out specific production plan of production orders. Combinatorial complexity of those problems is high especially at the operational level. Therefore heuristic or analytical methods are often used in the process of decision support, without indicating the optimum solution. Conducted research in this area are also related to AI methods. The proposed approach in this paper, is based on the game theory in the production planning. The tools of game theory have been used so far mainly in the area of production planning at the levels of strategic and tactical planning. But recently, arises increasingly interest in using game theory in the field of production planning at the operational level. In this case, the player term is replaced with the agent or object term that represents (not the entity or person as it is in the classical approach) production order, production process or package of production orders.
Taguchi Approach for the Optimization of Cutting Parameters in Finish Turning of Medical Stainless Steel
Authors: Radovanović Miroslav , Slatineanu Laurentiu , Janković Predrag , Petković Dušan , Madić Miloš
Published: November 2015

Optimization of cutting parameters in finish turning of medical stainless steel 316LVM with coated carbide tools using Taguchi method is proposed in this paper. Four cutting parameters namely, insert radius, depth of cut, feed and cutting speed are optimized with considerations of surface roughness as performance characteristic. The effects of cutting parameters on the surface roughness were experimentally investigated. Experimentation was conducted as per Taguchi's orthogonal array. Four cutting parameters with three levels are arranged in L27 orthogonal array. The orthogonal array, measured values of surface roughness, signal-to-noise ratios and analysis of variance are employed to study the surface roughness. Based on the analysis, the optimal cutting parameter settings were determined. Through the confirmation test with optimal cutting parameter settings the effectiveness of the optimization approach are validated. The obtained results have shown that Taguchi method is suitable for optimizing the cutting parameter levels with the minimum number of experiments.
Use of the Information Concerning the Products Manufacturing in Innovative Learning and Education Programme for Health Care Sector
Authors: Ciobanu Gabriela , Harja Maria , Ciobanu Octavian
Published: November 2015

The present paper presents the educational activities of a Leonardo da Vinci project from Lifelong Learning Programme, project called "Launching of Sector Skills Alliance for Training & Apprenticeship of Health Care and Food Supplements Salespersons" (H-CARE). The project aims to provide an innovative and practically oriented training curriculum for Health sector stakeholders, who offer services in assistive technologies, medical devices and food supplements. The curriculum includes information about medical devices, assistive technologies and food supplements, such as products manufacturing, specific characteristics, and potential risks caused by their use.
Modeling the Economic Performance of Industrial Systems Using Mathematical Programming
Authors: Fechete Flavia , Nedelcu Anișor
Published: November 2015

Mathematical programming models and especially their subclass - linear programming models - plays an extremely important role, both in theory and in economic practice. Linear programming, through its results, brought a considerable contribution to improving management methods in economics and it has boosted theoretical research in modeling complex economic systems, study and interpretation of laws and economic processes. Developing and designing a model for achieving the economic performance of the industrial system allows managers making optimal decision and ensures the improvement of their activity. This paper aim is to determine an optimal manufacturing program for an industrial system, so that, by its implementation, to achieve economic performance. The manufacturing program conducted using a computer software will allow this entity to optimize their management decision process by providing information related to physical production that must be executed on each of their the products, or about the unused or overloaded capacity, in order to maximize their profits.
Non-Conventional Technologies for the Manufacturing Systems Use in Biological Wastewater Treatment Process
Authors: Panaitescu Casen , Stoica Monica Emanuela , Fehiman Ciner
Published: November 2015

Manufacture of wastewater treatment technologies is an important issue due to the complexity of design parameters and performance. Biological wastewater treatment is a process in which the intensity of oxygen transfer into water is an issue that has been extensively studied but yet insufficiently resolved. The present paper aims to describe an aeration system developed by the author in the laboratory by means of non-conventional technologies, and subsequently implemented in refinery wastewater treatment plants. The aeration system takes the form of modules, which are equipped with a new type of membrane. The analysis of the system performance revealed that oxygen transfer was 62%, specific adsorption of oxygen was 37 % and the specific oxygen transfer was 7%/m. The advantages of this new system are as follows: compared to existing technologies there is a higher rate of oxygen transfer into water; longer life; there are no dead zones in the basin as a result of their location; possibility of operating on separate sections.
From Fishing Gear to Granulates and Recycled Steel – An Eco Innovation Project
Authors: Storm Birgit Kjærside
Published: November 2015

Plastix A/S, a cleantech company located in Lemvig, Denmark, received in August 2014 funding for the project Retrawl2, which is a part of the EU initiative ECO-Innovation project. Retrawl2 is co-funded by the European Union with the CIP ECO-Innovation initiative of the Competitiveness and Innovation Framework Programme, CIP. The aim of the RETRAWL is to upscale an innovative recycling technology, which transforms used maritime waste into plastic and steel commodities. The plastics are mainly polyamides and polyethylene from nets and trawls, and the steel are mainly carbon steel from taifun wires as parts of the nets and trawls.The suppliers of the used maritime equipment are Danish and other European fishing harbours, where equipment are stored, because it can be a challenge for the fishermen to dispose it. Also ghost nets are collected and delivered for recycling. In order to recycle nets to commodity plastics considerations of the quality of the product has been taken. The nets are made of materials of a high quality, because the abrasion resistance, the tension strength and the chemical resistance need to be high for the use of them in trawl. The quality of the recycled plastics will be high, when they are gently treated under the cutting, separation, washing and extrusion processes. In the processes the gently handling of the polymers is in focus to keep the degree of polymerisation of the polymers, since the strength of the plastics depends on the chain length of the polymers. The quality and the identity of the recycled plastics are verified through infrared spectroscopi, FTIR, differential scanning calorimetry, DSC, measuring the tensile strength and the elongation to break, measuring the melt flow index and the distribution of the grain size. The used fishing nets may have a significant smell of fish from trimethyl amine and rancid smell from oxidized fatty acids. The smell will disappear under the production mainly because of the volatility of trimethyl amine. The fatty acids will be partly degraded under the production, and if there is a remaining part, they will act as plastisizers in polyethylene and polyamide with a minor influence on the strength of the product. In the steel plant the plastic covers of taifun wires are melted off with energy supply from an induction technology. The steel will afterwards be cut in pieces with length up to 1 meter. The capacity of the extrusion line is planned to be 24 ton per day 7 days per week, and on the steel line the capacity is planned to be 8 – 10 ton steel per day 5 days per week. The amount of used fishing equipment for that production will be approximately 40 ton per day. During 2015 another extrusion line will be ready allowing the doubling of the production.
The Experimental Cutting Parameters Fitting in Turning Technological Operations for Selected Polyamide Materials
Authors: Janik Witold , Grabowik Cezary , Ćwikła Grzegorz , Kalinowski Krzysztof , Banaś Wacław
Published: November 2015

The existing manufacturing technology of small mechanisms elements (gears, gear racks, displacers, bushings, precise mechanical parts, implants) is based on standard material removal techniques (turning, milling etc.). The problem is a variety of a polyamide materials chemical composition. Each additive has a significant influence to the material machinability in technological process. In a result it changes also resistance for melting of material in heat influence area. The method is based on automatically adaptation of parameters with author GRIP NC software and repeatable check of outer layer surface quality in various conditions and cutting strategies. Siemens NX Manufacturing module was used as a tool for operation simulation, parameters correction and G-code post processing tool. Fast G-code Generations gives possibility not only of parameters correction (that can be easily made in G-code itself) but also to optimize trajectory. Iterative comparison of surface roughness and chip flow monitoring were the main criteria that decided of cutting speed modification. On the output of the proposed method the proper cutting parameters table was prepared as well as a set of manufacturing recommendations. The case study is oriented to three polyamide modified materials: ERTHALON 6 PLA PA 6G, ERTALON LFX PA 6G (oil additive) NYLATRON GSM IPA 6 (MoS2 additive). Each material has a different set of fitted cutting parameters. Achieved results could be the guidance and provide proper outer surface roughness for (rough and finish) cutting operations like: axial and radial turning, threading and cutting.
Optimal Solution of Multi-Pass Turning Processes by Means of the Differential Evolutionary Algorithm for Constraint Problems
Authors: Korlos Apostolos , Kosmanis Theodoros I.
Published: November 2015

The implementation of the Differential Evolutionary Algorithm for the solution of a multi-pass turning optimization problem is presented in this paper. The optimization of a multi-pass turning process is a highly demanding problem due to the number of constraints imposed. A specific variation of the Differential Evolutionary Algorithm appropriate for the treatment of constrained problems is used. It is based on the separation of candidate solutions into those that satisfy all constraints and those that do not and the simultaneous execution of two optimization algorithms. Numerical results from the minimization of the production cost of a popular multi-pass turning problem with six degrees of freedom, namely cutting speed, feed rate and depth of cut of rough machining and finishing, validate the methodology. The selected problem is characterized by a number of equally stepped roughing passes and a final finishing pass of the cutting tool in order to obtain the desired metal part removal from the initial workpiece.
Orthogonal Cutting of Ti6Al4V Alloy Using Experimental and Theoretical Analysis
Authors: Korlos Apostolos , Friderikos Orestis , Mansour Gabriel , David Constantine , Sagris Dimitrios
Published: November 2015

The current paper deals with the orthogonal cutting of Ti6Al4V alloy. Initially, the cutting process is simulated using the Finite Element Method (FEM). Various cutting conditions including cutting speed and feed rate are considered. Based on this computational analysis the chip creation mechanism is studied. The simulation results describe adequately the chip generation and flow, delivering quantitative data concerning temperature and stress distribution, as well as chip geometry. In addition, orthogonal cutting experiments are conducted on a CNC lathe machine with the same cutting conditions. The experimental results are compared with the analytical ones and useful conclusions regarding the chip formation can be drawn.
Analysis of Cutting Parameters Influence on the Machined Surface Roughness Obtained by Turning of a Heat Treated Bearing Steel
Authors: Rotariu Constatin , Mitsi Sevasti , Paraschiv Dragos , Lupescu Octavian , Lungu Sergiu , Bădănac Ana , Popa Mădălina , Popa Sorin
Published: November 2015

In this paper we analyze the influence of cutting parameters on the surface quality, surface roughness respectively, processed by turning when heat treated bearing steel, also called hard turning, and processing by turning of bearing steel without heat treatment. We set parameters of the cutting regime influencing the achievement of roughness surfaces which must be within the predetermined requirements if bearing rings exceeding 500 mm in diameter. This analysis will be done by statistical methods using the software Minitab 14.
Research about Surface Quality of Polytetrafluoroethylene (Teflon) after Inner Turning
Authors: Pascu Cristina Ileana , Popescu Iulian , Vintilescu Alexandru
Published: November 2015

For this study with high originality, a teflon bushing with outer diameter of 58 mm and 32 mm internal diameter has been turned. After inner turning with various cutting feeds, the part has been cut in half to measure roughness. The roughness parameters Ra, Rz and Rq have beeen measured with an electronic roughness tester Mitutoyo, Japan, SJ-201 P. The micro-asperity images for each of the 6 samples performed are presented in the paper. Diagrams with the variations of roughness parameters are also given in this study. The trend is the increasing of roughness values with feed increasing, but some abnormalities also appear in samples 3 and 4 for Ra and Rz. At sample 5 for Rz parameter and sample 6 for Rq parameter a decreasing of values occurs, although geometrically there should be with ascending tendencies. It follows that in teflon turning the cutting process is not uniform, although there are no marks on the blade. However, because this material is not metallic, it does not have a uniform structure, which influences the resulted roughness. This is the cause of the anomalies established by these experiments.
Effect of the Injection Moulding Parameters on the Creep Properties in Polypropylene/Carbon Nanotubes Composites
Authors: Cantaragiu Alina Mihaela , Stan Felicia , Fetecău Cătălin , Sandu Ionuţ Laurenţiu
Published: November 2015

The goal of this paper is to study the time-dependent properties of multi-walls carbon nanotubes (MWCNTs)-filled polypropylene (PP) composites using the instrumented indentation technique. Two types of the indentation test, the 3-step and the 5-step indentation tests, were considered to investigate the creep response during sharp indentation. In order to characterize the state of distribution of MWCNTs, the Scanning Electron Microscopy (SEM) technique was used. It was found that the maximum indentation depth decreases with the increase in the MWCNTs concentration. At lower MWCNTs concentration, the effect of injection pressure on the creep displacement is not significant. Comparison of the creep displacements from 3-step and 5-step loading histories indicates a noticeable decrease in creep displacement when the 5-step loading history is used.
Study of the Formability of Light Metallic Materials
Authors: Girjob Claudia , Racz Gabriel , Bologa Octavian , Biris Cristina
Published: November 2015

There is a continuing interest in using laminated materials for the production of lightweight parts, the resulting parts having the same functionality and even an increased stiffness and length of operation compared to conventional materials. The present paper aims to study the forming behavior of the laminated materials that requires the unfolding of tests to determine the tensile mechanical properties and the intrinsic properties, determining the forming limit curves by means of the Nakajima test and the analysis of the behavior at unconventional incremental forming.
Aspects of Searching some Possibilities to Diminish the Processing Errors at Stamping Process
Authors: Olaru Sergiu Constantin , Nagîţ Gheorghe , Ripanu Marius Ionuţ , Manole Vasile
Published: November 2015

Processing errors in the process of stamping, represent some of the most important aspect that requires attention when you want to process parts with a simple configuration. Reducing errors increase the quality of stamped parts, therefore the processing industry of blanks from metal sheets attaches great importance to them. Given the international quality standards it is required to study in detail the problem of eliminating these errors. As a result the results of researches on the establishment of a special portable device to eliminate the clearance between the sheet metal and the guidance rulers of the material in die in order to reduce the deformations of the sheet metal trough successive actions dies. Are presented the proposed constructive solution, its advantages and experimental measurements at stamping with the use of the proposed solution.
On Correlation of Pulses and Tool Elongations at Micro-Electrical Discharge Machining Aided by Ultrasonics
Authors: Ghiculescu Daniel , Marinescu Nicolae , Klepka Tomasz , Carutasu Nicoleta
Published: November 2015

The paper deals with Finite Element Method (FEM) of thermal and mechanical-hydraulic components of material removal mechanism at micro-electrical discharge machining aided by ultrasonics (μEDM+US), due to EDM and US contribution. The dimensions of craters produced by single discharges under μEDM+US conditions are determined with different pulse durations in order to establish a machining strategy with correlation of pulses and tool elongations.
Finite Element Modeling of an Ultrasonic Horn Integrating the Tool for Micro-Electrical Discharge Machining
Authors: Marinescu Niculae , Ghiculescu Daniel , Klepka Tomasz , Alupei-Cojocariu Ovidiu Dorin
Published: November 2015

The paper deals with a strategy to obtain a complex conical ultrasonic horn, which integrates the tool for micro-drilling through ̵̵̼̳̹̳̱̼̈́͂˰̴̸̷̵̹̳̱̓͂˰̸̷̱̳̹̹̽̾̾˰˸ڌ̝̔̕˻̥̣˹˰̵̴̲̱̓˰̿̾˰̖̹̾ite Element Method (FEM) modeling. This approach comprises more than 20 stages, starting with preliminary determination of a basic profile stepped horn through mathematical relations. The next stages are based on Comsol Multiphysics FEM modeling, changing gradually different horn constructive elements and integrating the tool and their clamping parts. The entry data for horn geometry determination were the dimensions and own frequency of transducer subassembly, joining ultrasonic horn. Finally, the CAD file of horn was transferred to CAM file and CNC machined. Horn real own frequency obtained was very close to the result provided by FEM modeling.
Influence Factors Hierarchization in Electrochemical Discharge Machining (ECDM) Using the Random Balance Method
Authors: Nioaţă Alin , Ciofu Florin
Published: November 2015

In the case of electrochemical discharge machining (ECDM), the number of influence factors is very high, and the complete determination of a mathematic pattern is very complicated, as proved by the time passed since the application of this processing technology and absence (for the time being) of such a system. The paper presents the method of random balance which allows influence factors hierarchization, depending on the amplitude of the effect they have on the response variable. The main influence factors will be considered: current intensity, voltage, electrode-tool – workpiece pressure, electrolyte supply intensity, relative velocity between the electrode-tool and the workpiece, electrode-tool thickness. The following response functions (performance criteria) were determined: processing productivity, processed surface roughness, flatness deviation. The experiment was made on an electrochemical discharge machining (ECDM) processing machine with a electrode-tool, stratified disk by introducing the electrolyte in it. The semi-finished material is alloy steel X40CrMoV5-1, and the material of the electrode-tool is generally use steel S235JR.
Ultrasonic Assisted Machining for Hard-to-Cut Materials
Authors: Cotargă Elena Adina , Popa Marcel Sabin , Sattel Stefan , Preja Dan , Vereș Ovidiu Virgil , Jugrestan Claudiu Ioan
Published: November 2015

This study presents new machining types of advanced materials. Super alloys, ceramics and fiber reinforced plastics started being used on a large scale in the last period, this making necessary the development of new machines and machining processes. This paper describes different methods of ultrasonic machining and makes a comparison between them. By ultrasonic machining can be understood a process that involves axial vibrations with a high frequency and low amplitude, for improving the machining conditions like chip flute removal, tool wear and temperature reducing. In this paper, are presented three different ultrasonic machining methods. In the first one, the cutting process is made by abrasive slurry inserted between the tool and the workpiece, in the second one is made by a rotating diamond-brazed tool and in the last one is made by a special drill. This paper aims to study the current status in this field in order to make a research program through collaboration between the Technical University of Cluj-Napoca and the tool company Gühring KG by which to develop ultrasonic drilling.
Comparative Analytical Solutions to the Problem of Profiling the End Mill Cutter to Generate Helical Surfaces
Authors: Frumuşanu Gabriel , Teodor Virgil , Oancea Nicolae
Published: November 2015

In this paper, we present, comparatively, two analytical methods for profiling the tools delimited by revolution surfaces, used to generate helical surfaces with constant pitch. The first method lays on a complementary theorem used for tools profiling, namely the Minimum distance theorem. A specific algorithm for applying it has been developed, in order to profile the tools delimited by revolution surfaces, which generates helical surfaces with constant pitch by enwrapping. The methodic is referring, here, to a tool whose symmetry axis is incident and, at the same time, normal to the helical surface axis – the end mill cutter. The other analytical method here applied grounds on Nikolaev classical theorem. We also present an example of application for both methods, in the case of profiling the end mill cutter used to generate a helicoid with circular frontal generatrix. The tool axial sections are determined and compared in a numerical representation.
Multi-Objective Optimization of Laser Cutting Using ROV-Based Taguchi Methodology
Authors: Madić Miloš , Radovanović Miroslav , Coteata Margareta , Janković Predrag , Petković Dušan
Published: November 2015

Multi-objective optimization of laser cutting for simultaneous improvement of performance characteristics is of great practical importance. In this study a range of value (ROV)-based Taguchi methodology is proposed for multi-objective optimization of laser cutting, i.e. surface roughness, kerf width and burr height in CO2laser cutting of AISI 304 stainless steel. Laser cutting experiment was conducted based on Taguchi’s L27experimental design by varying the laser power, cutting speed, assist gas pressure and focus position at three levels. In the proposed methodology based on the experimental data signal to noise ratios as per Taguchi’s method were calculated for each experimental trial upon which decision matrix was defined. Subsequently, multi-criteria decision making problem was solved by the ROV method. The proposed ROV-based Taguchi methodology has relatively simple computational procedure and can be easily applied by engineers for solving different multi-objective optimization problems that occur in real manufacturing environment.
Roughness of Small Diameter External Cylindrical Surfaces Obtained by Ram Electrical Discharge Machining
Authors: Slătineanu Laurenţiu , Coteaţă Margareta , Schulze Hans Peter , Dodun Oana , Mircescu Ciprian , Beşliu Irina
Published: November 2015

In order to obtain small diameter external surfaces by ram electrical discharge machining from plate workpieces, tubular tool electrodes could be used. In such a case, one can appreciate that the obtained surface is a simple concatenation of cavities appeared as a consequence of electrical discharges developed between the asperities existing initially on the active surface of the tool electrode and surface to be machined of the workpiece. The analysis of the surface generation as a consequence of the electrical discharge machining process showed that due to the surface tensions, a leveling phenomenon could be taken into consideration. An experimental study of influence exerted by some input factors on the surface roughness parameter Ra was designed and achieved. One noticed that the increase of the pulse on time, pulse off time and peak current intensity determines an increase of the surface roughness parameter Ra. By mathematical processing of the experimental results, an empirical model type power function was determined. The examination of the machined surface by means of an optical microscope showed the existence of microcavities generated by the electrical discharge, while the material melted and re-solidified was placed as a bordure of the microcavities.
Direct Diode Laser Surface Melting of Nodular Cast Iron
Authors: Janicki Damian
Published: November 2015

A nodular cast iron (NCI) has been surface melted using the high power direct diode laser (HPDDL) with a quasi-rectangular laser beam spot and the uniform distribution of power. The effect of a heat input and a shielding gas on the quality of surface melted layers (SMLs) has been investigated. The microstructure of the SMLs has been assessed by optical microscopy, scanning electron microscopy and X-ray diffraction (XRD). Comparative erosion tests between the SMLs and as-received NCI have been performed following the ASTM G 76 standard test method. The HPDD laser surface melting of the NCI enables to produce non-porous layers having a hardness up to 1000 HV. It has been determined that the hardness of SMLs depends on the amount of cementite and residual austenite in the fusion zone. The SMLs produced in an argon atmosphere contain higher volume fraction of austenite, than those produced in nitrogen, and consequently have the lower hardness. With increasing heat input the hardness increases, as the result of more complete dissolution of graphite and the higher amount of cementite. The SMLs exhibited significantly higher erosion resistance than the as-received NCI for erodent impact angle of 30°, and slightly lower at 90°.
Effect of the FCAW Welding Process and Post Weld Heat Treatment on the Properties and Microstructure of the Weld Joints of Heat Treated 4330V Steel
Authors: Górka Jacek , Miłoszewski Michał
Published: November 2015

4330V is a high strength, high toughness, heat treatable low alloy steel for application in the oil, gas and aerospace industries. It is typically used for large diameter drilling parts where high toughness and strength are required. The research describes the effect of preheat temperature, interpass temperature, heat input, and post weld heat treatment on strength, hardness, toughness, and changes to microstructure in the weld joint. Welding with the lower heat input and no post weld heat treatment resulted in optimal mechanical properties in the weld metal. Austempering at 400 °C resulted in optimal mechanical properties in the HAZ. Increasing preheat and interpass temperature from 340 °C to 420 °C did not improve Charpy V-notch values or ultimate tensile strength in the weld metal or heat affected zones. The higher temperature increased the width of the heat affected zone. Austempering at 400 °C reduced HAZ hardness to a level comparable to the base metal. Both tempering and austempering at 400 °C for 10 hours reduced toughness in the weld metal.
Some Features of the Surface Micro- and Macroprofile Formation at Flat Face Grinding with Spindle Axis Inclination
Authors: Kundrák János , Fedorovich Vladimir , Pyzhov Ivan , Markopoulos Angelos P. , Klimenko Vitaly
Published: November 2015

The work described in this paper pertains to the identification of some features of micro- and macroprofile formation of surfaces to be machined with flat face grinding, with inclination of the spindle axis. The question of the formation of machined surface profile at through-feed grinding and multiple-pass scheme are considered by using computer-aided simulations in COMPASS environment. More specifically, for flat face through-feed grinding, a generalized empirical equation exhibiting the dependency of concavity from the outer diameter of the face grinding wheel, the spindle axis inclination angle and the width of the surface of the workpiece is acquired. Furthermore, based on the maximum allowable value of flatness deviation and with pre-determined grinding wheel diameter and workpiece width, it is possible to identify the maximum inclination angle at which concavity falls within acceptable limits. For the case of multiple pass flat face grinding, the role of factors such as inclination angle of spindle axis, cross-feed and diameter of the grinding wheel on the height of residual ridges on the surface of the parts is determined through the proposal of an empirical equation. With the aforementioned equations the machinist may reasonably prescribe machining conditions in practice. The conducted research contributes to the expansion of ideas regarding technological possibilities of improvement of flat face grinding.
Selection Tool for Dissimilar Materials Joining
Authors: Ulianov Cristian , Araya Kenta , Lupescu Octavian , Badanac Ana
Published: November 2015

Considering the advances of lightweight materials, such as Aluminium, Magnesium and composite materials, as well as their growing use in various applications, the demand for dissimilar materials joining methods is increasing, as more modern hybrid structures in various industries are using these novel materials which need to be joined either between them or with traditional ones. The paper presents the results of a project aimed to develop a simple and efficient tool for the selection of suitable joining methods for a large variety of dissimilar materials, and capable to provide a summary of technical information, including process parameters and limitations, required equipment, joint structural performances, etc. for each selected method. The dissimilar joining selection tool DIJO-S was developed using Excel environment, which is very accessible to most of the users, user friendly and visually attractive by using the functions of Visual Basic. After processing the input data, the selection tool provides not just the summary of the suitable joining methods, but also detailed process fiches, which support the user for selecting the best feasible option.
Design Methodology of Sliders Used in Laminating Tools for Decorative Products
Authors: Măgurian Daniel , Oancea Gheorghe
Published: November 2015

The paper presents a design methodology for a slider assembly from tools used in laminating process of decorative parts with big curvature and negative draft. In usual cases are used a single active part to laminate parts. For laminating process of this surface are designed a slider assembly with three active parts. All these three active parts have their own heating-cooling systems. That means a good temperature control in each point on surface. The results are a laminating process without scratches, signs or imperfections. In the paper are also presented the working method of slider assembly and all the main steps in design from concept direction to clash analysis.
Internal Energy Use in Calculating the Lifetime of 2P Armor Steel
Authors: Zichil Valentin , Judele Adrian , Albut Aurelian , Schnakovszky Carol , Sava Alexandre , Lozovanu Petru
Published: November 2015

Armored steel sheets have various uses in civil and military industry. For the last one, especially in aeronautics, a better determination of the lifetime for the fatigue and shock loaded parts, is a major challenge. Several methods for fatigue calculus are known: safe-life, fail-safe, crack propagation method. All of this methods are not considering in any way the shocks that can accidentally occur, so in the calculation of lifetime, the role of impact multiplier is null. The authors propose a corrected formula for the calculus of the lifetime for 2P armor steel, based on the internal energy developed into the test specimens, through the impact multiplier.
Self-Repairing Behavior of Shape Memory Composites
Authors: Santo Loredana , Quadrini Fabrizio , Bellisario Denise , Ciampoli Luigi
Published: November 2015

A shape memory composite plate has been produced by adding a shape memory interlayer between two carbon-fibre epoxy-matrix prepregs. A Small plate has been obtained which was used for testing under bending at different rates up to the final failure. The first test was performed at low rate and final damage was recovered by heating. A second bending test was performed on the self-repaired plate at high rate. As a result, a good shape recovery after damaging has been observed and a fairly good residual stiffness was measured. The residual stiffness after shape recovery was about 80% and the composite plate was able to withstand a second test at higher rate (with a residual strength about 40%). Results show that it is possible to combine shape recovery of shape memory polymers with structural properties of composite materials: the goal is producing composite structural
The Behavior at Corrosion and Fatigue of the Aluminum Alloy, Coated with a Cobalt Base Alloy, Deposited by Thermal Spraying in Electric Arc
Authors: Toma Stefan Lucian , Ionita Iulian , Eva Lucian , Bejinariu Costică , Istrate Bogdan , Toma Bogdan Florin
Published: November 2015

The present investigation has been conducted in order to study the fatigue and corrosion fatigue behaviour of an aluminium alloy (99,5%Al) substrate coated with a 106 MXC deposited by thermal spraying in electric arc. It has been determined that the deposition of such a coating on the aluminum substrate gives rise to significant gains in fatigue life in comparison with the uncoated substrate, when testing is carried out both in air and in a 3,5 wt.% NaCl solution. It has been shown that during testing in air, the fatigue gain ranges between ~131 and 186%, depending on the maximum alternating stress applied to the material. Larger fatigue gains are associated with low alternating stresses. Also, when fatigue testing is conducted in the NaCl solution, the gain in fatigue resistance varies between ~124 and 159%. Fatigue cracks have been observed to initiate at the coating surface and then grow towards the substrate after propagating through the entire coating thickness. Although in the present work residual stresses were not measured, it is believed that the gain in fatigue life of the coating–substrate system is due to the presence of compressive residual stresses within the coating which hinder fatigue crack propagation. The deposition of the coating does not give rise to significant changes in the static mechanical properties and hardness of the aluminum alloy substrate.
Vibroacoustical Diagnosis of Planetary Precessional Kinematical Transmission (Part 1)
Authors: Malcoci Iulian , Bodnariuc Ion
Published: November 2015

An ideal dynamical system should not generate any vibrations, because vibrations mean a loss of energy. Vibration in planetary precessional gear box occurs at bearings, gear wheels, misaligned shafts, imbalance rotating parts, couplings. If damage occurs, not only the dynamic processes change, but also the forces that act on system components. Regarding this aspects, regular vibration measurements on machines provide information about any necessary maintenance. Vibration research was made by using GUNT PT500 Machinery Diagnostic System and vibration signals was evaluated by using GUNT PT500.04 software witch allow to perform correct FFT analysis. Data acquisition was made by using two piezoelectric accelerations sensor type IMI603C01 and one reference photoelectric sensor to record the shaft speed. Sound level was measured by using Brüel & Kjær Sound Level Meter Type 2250 Light that has everything needed to perform high-precision, Class 1 measurement tasks in environmental, occupational and industrial application areas. Obtained and measured results was presented in diagrams and tables to be compared with German standard VDI-2058Limit value for vibration severity and noise level.
Dynamic Characterization of Free Torsional Subsystem by Galerkin’s Approximate Method and its Correction
Authors: Buchacz Andrzej
Published: November 2015

Studying the diagrams of characteristics of complex subsystem of mechatronic one it has been determined that in case of approximate method the resonance frequencies cover with those which have been determined with exact method. However the values of the characteristic in other areas are different. Therefore there is the mistake of approximate method, which in case of studying the single systems does not have any influence because in resonance areas the characteristic values of the system approach to the infinity. However the difference in values of flexibility within two methods has the great influence on the result of complex systems. The main subject of deliberation was to determine the flexibility of the complex system with constant cross section using the exact and approximate that means Galerkin's method. The mechanical and/or mechatronic system composed from many mechanical subsystems having the same length and variable cross section, loaded by the focused moment was analysed. One case of attachment the complex system that means free torsional vibrating bar were examined. That why it was necessary to correct the results of approximate method. The problems presented in this paper, that means the analysis of subsystem of mechatronic and mechanical complex systems is however the introduction to the synthesis of torsional vibrating mechatronic systems with assumed frequency spectrum.
Trajectories and Laws of Motion for a Mechanism with Two Leading Elements and Two RRP Dyads
Authors: Sass Ludmila , Popescu Iulian
Published: November 2015

The paper deals with the trajectories and lows of motion of a mechanism of type T-RRP that was buil by using the properties of Cardano circles. It has two slides moving along the axis of the system xOy. A second leading element and another T-RRP dyad were added to this mechanism, the resulting mechanism, of type T-RRP-R-RRP. The trajectories of three points of interest were determined, for various (linear) correlations between the movements of the leading elements. The obtained trajectories are similar, but not identical, to the loops of epicycloides, wrapping ellipses. The generated laws of movement were also determined, variable oscillations of the final slide being obtained.
Model for Economic Optimization of the Tool Life and the Cutting Speed at Drilling of the Steel X5CrNiMo17-12-2
Authors: Iacob Marius , Blăjină Ovidiu , Vlase Aurelian
Published: November 2015

In the specialized literature the cost of the machining process has been analyzed using a number of approaches and varying degrees of simplification to determine the optimum tool life and the tool speed. The accuracy of prediction is dependent on the degree of sophistication of the model. The purpose of this paper is the optimization of the cutting tool life and the cutting speed at the drilling of the stainless steels in terms of the minimum machining cost. A more comprehensive nonlinear programming model to minimize the total cost at the drilling of a stainless steel is developed in this paper. The optimum tool life and the associated tool speed are obtained by solving this model. The results can be taken into consideration in the educational studies and in the theoretical technical research. They can be implemented in the manufacturing activity.
Cages for Heavy Bearings: A Patent Study
Authors: Cioară Romeo , Szekely Valentin Gabriel
Published: November 2015

In contextual evolution of the global economy and new technologies, quality, competitiveness, and cost engage companies to focus on continuous improvement and innovation. This approach is highly visible in the bearing industry, due to the emergence and improvement of existing and new types of bearings.The authors of the paper are engaged in a long-term research, which aims to improve the performance of heavy bearings, including identification of new constructive solution. The study is focused on the characteristics and constructive structure of the bearings cages in discussion.In this context, it is logical that the research focuses upon known bearings cages that are currently used [1], as well as unknown or unapplied constructive solutions which are the subject of patents.The critical analysis of various constructive cage solutions for bearings, intended or not for heavy bearings, is a valuable source of inspiration and information towards identification of constructive elements and characteristics useful to develop new technical solutions, by applying integrations, combinations, innovations and development processes [2].In the presented paper several patents are analyzed critically [3, 4, 5], in terms of constructive solutions, manufacturing complexity and presumptive operational energy consumption.
Mechanical Loading System for Tests on Cross-Flow Turbines
Authors: Popescu Constantin , Popescu Daniela , Ciobanu Bogdan
Published: November 2015

Since large hydraulic turbines already have very good energy performance, nowadays the challenge is to study, improve and construct low power turbines. One important step in the design of a new type of turbine is the experimental study based on adequate equipment. In real-life applications, the turbine is loaded by the electricity consumers. Usually experiments try to reply such conditions, when it is possible and by consequence an electrical loading system seems to be adequate for tests on pico turbines. The present paper focuses on the analysis of an electrical loading system and a mechanic loading system to be used for laboratory experiments on pico turbines. The quality of experiments and the extension of graph area recommend without doubt the mechanic loading system to be used for tests on new pico hydro turbines.
Dynamic and Positioning Performances of Linear Electromechanical Actuator
Authors: Nasui Vasile , Banica Mihai , Darabă Dinu
Published: November 2015

This paper presents the dynamic characteristics and the proposed positioning performance of the system to them investigated experimentally. In this research, we developed the positioning system and we evaluated positioning accuracy. The developed system uses a servo motor for motion actuation. In this paper, we focused on studying the dependency of the positioning error – elementary errors – the position of the conducting element for the mechanism of the transformation of the rotation translation movement, representatively the mechanism screw – screwdriver and on emphasizing the practical consequences in the field of design, regulation and exploitation of the correct identification of all the initial errors in the structure of the mechanism, their character and the selection for an ultimate calculus of these which are of a real practical importance.
Design of a Testing Device for Cruciform Specimens Subjected to Planar Biaxial Tension
Authors: Andrusca Liviu , Doroftei Ioan , Barsanescu Paul Doru , Goanta Viorel , Savin Adriana
Published: November 2015

Multiaxial experiments are necessary to determine materials behavior subjected to complex stress state corresponding to real operating conditions under complex loadings. Stresses applied in biaxial experiments are closely to the stresses that materials experience during their function life. Because of reduced acquisition cost, operation cost and maintenance costs devices attached to the universal testing machine are beginning to be used in ever more applications. The present paper examines a new type of mechanism used to test biaxial cruciform specimens in order to evaluate stress state in planar biaxial tensile testing.