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Nicolae Balc

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Papers by Nicolae Balc

Reconstruction of Orbital Wall by Using Hybrid Manufacturing Operations

IOP Conference Series: Materials Science and Engineering

This paper will discuss the solutions and the main parameters used to print a mold that will be u... more This paper will discuss the solutions and the main parameters used to print a mold that will be used in a manufacturing process for a personalized implant in orbital fracture situations. The main purpose of this article is to rebuild the damaged orbit. The new orbit should have dimensions and accuracy similar to one of the original elements. Based on the computed tomography (CT) of the patient, the images are extracted and processed. With that information, a customized implant is manufactured. In this article, a case study of a patient suffering from an orbital fracture is presented. Based on the CT images, a mold was printed on additive manufacturing equipment (AM). The manufacturing parameters being highly correlated with the requirements that are needed for this case such as hardness, accuracy, surface roughness and support removal were chosen based on a series of tests and results from other studies. Another aspect that was analysed was related to the material from which was man...

Investigation onto the reliability of the selective laser melting process

The paper aims to offer the readers knowledge and information, to support new implementation and ... more The paper aims to offer the readers knowledge and information, to support new implementation and use of the SLM technology for practical applications and to obtain good metal parts for end users. The SLM parameters and conditions were evaluated to set up a scale and estimate how reliable the SLM-AM process is, on a particular type of machine. The experimental research was carried out in the last years by the authors, using the Realizer 250 machine. Many times, there is a lack of repeatability and reliability of the SLM process. The paper is presenting a new method to evaluate the repeatability and the surface roughness, when processing four types of powder materials, mainly for medical applications. Specimens were manufactured from four materials considered as being bio-metals: pure Titanium, Ti6Al7Nb, CoCr, and CoCrWMo. All these important features of the SLM parts were for seen by the authors in close relation with the mechanical characteristics of the parts. In this way, a good i...

Investigation of the Interface between Laser-Melted CoCr and a Stainless Steel Substrate

Metals

Recent advances in laser technologies offer significant flexibility in the additive manufacturing... more Recent advances in laser technologies offer significant flexibility in the additive manufacturing domain. Extensive work was focused on material processing using laser-directed energy deposition for repairing parts. This pilot study investigated the use of selective laser melting (SLM) for depositing a superior material such as CoCr on an existing stainless steel base. The interface between these dissimilar materials was analyzed. During fabrication, both metals were gradually mixed in the liquid state as the first CoCr powder layer was melded on the steel base without obvious defects. According to SEM and EDAX, the heat-affected zone has a limited depth (<20 µm). XRD patterns recorded across the CoCr–304 interface show a homogenous mixture of γ(Fe) and α(Co) solid solutions. The microporosity calculated by CT was under 0.5%. Microhardness was measured at and near the interface region, showing that the intermixing zone has high hardness (470–480 HV1), which may be related to the ...

Investigation of the Interface between Laser-Melted CoCr and a Stainless Steel Substrate

Metals

Recent advances in laser technologies offer significant flexibility in the additive manufacturing... more Recent advances in laser technologies offer significant flexibility in the additive manufacturing domain. Extensive work was focused on material processing using laser-directed energy deposition for repairing parts. This pilot study investigated the use of selective laser melting (SLM) for depositing a superior material such as CoCr on an existing stainless steel base. The interface between these dissimilar materials was analyzed. During fabrication, both metals were gradually mixed in the liquid state as the first CoCr powder layer was melded on the steel base without obvious defects. According to SEM and EDAX, the heat-affected zone has a limited depth (<20 µm). XRD patterns recorded across the CoCr–304 interface show a homogenous mixture of γ(Fe) and α(Co) solid solutions. The microporosity calculated by CT was under 0.5%. Microhardness was measured at and near the interface region, showing that the intermixing zone has high hardness (470–480 HV1), which may be related to the ...

Impact of laser parameters on additively manufactured cobalt-chromium restorations

The Journal of Prosthetic Dentistry

STATEMENT OF PROBLEM The selective laser melting (SLM) process has become popular for the fabrica... more STATEMENT OF PROBLEM The selective laser melting (SLM) process has become popular for the fabrication of frameworks for metal-ceramic restorations, although their surface roughness is greater than with cast or milled frameworks. Limited information is available regarding the surface mechanical characteristics of cobalt-chromium (Co-Cr) SLM-manufactured restorations. PURPOSE The purpose of this in vitro study was to adapt the laser parameters for a remelting strategy, scanning the outer boundary of Co-Cr specimens, to reduce surface roughness and solidification defects, to determine microhardness, to investigate surface morphology and microstructure, and to establish surface mechanical characteristics. MATERIAL AND METHODS Co-Cr specimens were SLM manufactured by using a typical melting (TM) strategy and an adaptive remelting (AR) strategy. The AR strategy involves rescanning 50% of the contour, varying the laser parameters. The roughness parameters considered were Ra and Rz. Vickers hardness was measured by microindentation with a 9.81-N force (ASTM E384-17). The surface morphology was investigated by scanning electron microscopy, the chemical composition by energy-dispersive X-ray spectroscopy, and the phase identification by using X-ray diffraction. The mechanical surface properties measured were the nanohardness, elastic modulus, and dissipation energy. One-way ANOVA with the Tukey procedure was used to compare the groups (α=.05). RESULTS The innovative AR strategy reduced the surface roughness by 45% compared with TM, comparable with their cast counterpart. The smoothest AR surface was obtained by using 75 W and 350 mm/s for the first scanning of the contour, followed by a second remelting with 80 W and 700 mm/s. The microstructure of AR specimens had limited solidification defects, a chemical composition similar to that of raw powder, and a surface microhardness over 600 HV1. A fine grain structure in a single matrix phase was detected both on TM and AR specimens. The mechanical characteristics of the smoothest Co-Cr surface were 218 GPa elastic modulus, 746 HVIT Vickers nanohardness, 21 243 pJ plastic energy, and 26% nanoindentation work ratio. Significant differences were observed between the melting strategies (P<.05) both for surface roughness and microhardness. CONCLUSIONS The laser scanning strategy affects both the surface roughness and the hardness of SLM-manufactured specimens. The results show that using the AR strategy and proper laser parameters can reduce the roughness and increase the surface hardness of Co-Cr specimens made of conventional powder feedstock.

Experimental Study on 3D Printed Parts Made of Continuous Fiberglass Reinforced Polymer

ACTA TECHNICA NAPOCENSIS - Series: APPLIED MATHEMATICS, MECHANICS, and ENGINEERING, Apr 7, 2021

The paper is presenting studies and experiments on 3D printing of composite parts. The novelty of... more The paper is presenting studies and experiments on 3D printing of composite parts. The novelty of the printing process used is that the parts are printed using continuous reinforced fibers in a plastic matrix. Printing with continuous fiber reinforcement offers a few advantages compared to conventional processes as following: short manufacturing time, high strength, and low part weight. The internal structure of the model can be designed according to the part loads and the continuous fiber is disposed only in the layers where it is necessary. In this experimental research, an industrial part was studied and different possibilities of designing the internal structure were analyzed.

Integrating Electronic Components into 3D Printed Parts to Develop a Digital Manufacturing Approach

IFIP Advances in Information and Communication Technology, 2020

Digital manufacturing (DM) processes such as additive manufacturing (AM) technology, allow a high... more Digital manufacturing (DM) processes such as additive manufacturing (AM) technology, allow a high degree of integrability and functionality of printed parts. In this work, we present a proof of the DM concept focused on the integration approach where a product is developed and embedded with sensors. We also take this example one step further and introduce a method that allows 3D printing of heating elements into the specimens. The thermal characteristics of the developed heaters are investigated, and the results detailed. The novelty relates to a heater prototype injected and solidified into a curved 3D printed channel, which can produce a temperature between 23-46°C on the printed surface of the sample both in a dry and wet environment. This research demonstrates that it is possible to construct parts with embedded electrical structures using the described method.

Improving the Quality of the Parts Made by Rapid Metal Casting Process

The purpose of this article is to present researches for optimizing the vacuum casting process, b... more The purpose of this article is to present researches for optimizing the vacuum casting process, by dimensioning the feeding system. To manufacture metallic complex parts through investment casting process using wax patterns, with a good quality surface and a high dimensional accuracy it is necessary to optimize the feeding system. In this study, starting from the classic metal casting process a method to calculate the optimal dimensions of the gating system has been proposed, using mathematical relations for the gate, sprue and feeders. Thus we can say that by applying the feeding system dimensioning algorithm and by correcting the master model dimensions with the shrinkage value, we can manufacture complex metal parts through investment casting with a high precision and a good surface accuracy.

Programming Solutions for the User Interface of Virtual Machine Tools

The paper presents some possible solutions for creating elements of the human machine interface o... more The paper presents some possible solutions for creating elements of the human machine interface of complex virtual equipments. This ongoing research is a part of a complex project of designing virtual machine tools, which could be very useful in training the students and/or CNC operators. .After analyzing some possible software solutions, the paper shows two Java-related solutions: usage of the old Java2D class collection and a more modern one based on the recent GUI class collection known as Java FX 2.0. For every solution the paper presents the code of two classes necessary for creating two common controls, a push button and a rotating wheel. As the virtual equipment is created mainly for teaching purposes, the designing solution helps the trainees also by suggesting the possible controls that should be used in their training stage.

Researches on the Buckling Test of a Tripod Components Used in Emergencies

The tripod used for emergencies has been analyzed in different positioning cases of its legs to ... more The tripod used for emergencies has been analyzed in different positioning cases of its legs to its symmetry axis (the symmetry axis being the support of the buckling force), simulating different accidentally scenarios within the rescue interventions. Each case has been three times analyzed, to each analyze being related one type of material(Al2014, Al6082 and carbon fiber); the analysis have been performed by the help of finite element analysis, using ANSYS software. Key words: Buckling, FEM, ANSYS, tripod

Modern technologies in manufacturing : selected, peer reviewed papers from the 12th International Conference on Modern Technologies in manufacturing (MTeM) October 14-16, 2015, Cluj-Napoca, Romania

Synthesis and Characterization of Nano Hydroxyapatite Used for Immobilizing Heavy Metals

3 University Craiova, 13 A. I. Cuza, 200585, Craiova, Romania The specific objectives of this stu... more 3 University Craiova, 13 A. I. Cuza, 200585, Craiova, Romania The specific objectives of this study are to synthesize and characterize nano-scale hydroxyapatite particles in laboratory for use in immobilizing heavy metals. Nano hydroxyapatite (HAP) was synthesized by reacting CaCl 2 and Na 2 HPO 4 as raw materials, a precipitation reaction occuring at the room temperature. Crystal phases were determined by X-ray diffraction (XRD). Scanning electron microscope (SEM) was applied to investigate the morphology. The microstructure of the HAP products was further observed by transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) with energy- dispersive X-ray spectroscopy (EDX). The purity and chemical composition of the as-synthesized powder was analyzed by FTIR. Soil contamination by heavy elements represents therefore a worldwide environmental concern mainly because these elements can be transferred to the hydrosphere and biosphere, thereby p...

Static Analysis to Redesign the Gripper, Using Creo Parametric Software Tools

Within this paper is presented the optimizing activity of a clamping jaw used for gripping and fi... more Within this paper is presented the optimizing activity of a clamping jaw used for gripping and fixing revolution or/and prismatic work-pieces, by the help of CREO design software, using Creo Parametric and Creo Simulate modules. The article approaches a case study, within two loading situations of the gripper jaw, mounted on an industrial arm robot, are presented. Also, CAD and finite element method (FEM) advantages have been presented.

Investigation on Feed Rate Influence on Surface Quality in Abrasive Water Jet Cutting of Composite Materials, Monitoring Acoustic Emissions

Advances in Manufacturing Engineering and Materials, 2018

The paper deals an experimental study on cutting composite materials (CFRP) using abrasive water ... more The paper deals an experimental study on cutting composite materials (CFRP) using abrasive water jet cutting (AWJC) process. The influence of the feed rate on surface roughness is studied using acoustic emission (AE) monitoring. For monitoring the process two acoustic emission sensors was mounted, on the CFRP workpiece and on the cutting head. This monitoring technique has proved that, between process parameter (feed rate and amplitude of AE signal) is a clear connection. The surface roughness can be predicted using online monitoring with acoustic emission (AE).

Adhesion between Biocomposites and Different Metallic Structures Additive Manufactured

Coatings, 2021

This study was concerned with the adhesion of resin cement to metal surfaces obtained by selectiv... more This study was concerned with the adhesion of resin cement to metal surfaces obtained by selective laser melting process (SLM), and how it could be improved the bond strength at the biocomposite-metal junction. The SLM substrates were manufactured out of pure titanium (Ti), Ti6Al7Nb, and CoCr alloys. The metallic surfaces were covered with 5 types of biocomposites: 2 commercially resin-modified glass-ionomer cements (GC Fuji Plus and KETAC CEM) and 3 types of in-house developed materials. These biocomposites were mechanical characterized under compression and bending trials. The biocomposites-metal adhesion was settled both on as built metallic surfaces and after they were sandblasted with alumina. All the sandblasted SLM surfaces presented higher adhesion strength in comparison with the untreated specimens. The CoCr specimens show the highest bonding value. Additionally, the morphological aspects of joining interfaces were investigated using a scanning electron microscope (SEM). Th...

Avoiding carbon fibre reinforced polymer delamination during abrasive water jet piercing: a new piercing method

The International Journal of Advanced Manufacturing Technology, 2021

This paper presents a new method of piercing the carbon fibre reinforced polymer (CFRP) with abra... more This paper presents a new method of piercing the carbon fibre reinforced polymer (CFRP) with abrasive water jet (AWJ), which can avoid delamination. The method consists of adding the abrasive particles in the water jet at the very beginning of jet formation, thus obtaining a mixed abrasive water jet during the first impact with the composite work piece. A new cutting system was designed and set up based on the proposed piercing method and was compared with a conventional AWJ cutting system. The main added values brought by this paper are: it validates our original concept; provides synthetic analyses, the effects of the AWJ homogeneity, and the abrasive inlet angle on the CFRP delamination, and it brings a complete set of recommendations on how to overcome the industrial difficulties caused by the delamination of the composite materials, during the piercing with AWJ.

Additive manufacturing for repairing: from damage identification and modeling to DLD

Rapid Prototyping Journal, 2020

Purpose This paper aims to decrease the cost of repairing operations, of the damaged mechanical c... more Purpose This paper aims to decrease the cost of repairing operations, of the damaged mechanical components, by enabling the strong automation of the process and the reduction of manual labor. The main purpose of the hybrid repair process is to restore the original shape of the mechanical parts, by adding and removing material according to the mismatch between the damaged object and the virtual model, to restore its geometrical properties. Design/methodology/approach The DUOADD software tool translates the information collected from a 3D scanner into a digital computer aided design solid model, which can be manipulated through Siemens NX computer aided manufacturing (CAM), to obtain the tool paths, for the Direct Laser Deposition (DLD) technology. DUOADD uses octrees to effectively analyze the damaged region of the mechanical part and then to discretize the volume to be added to export CAM-compatible information as a 3D model, for additive operations. Findings DUOADD is the missing l...

Challenges of additive manufacturing in production systems

MATEC Web of Conferences, 2019

Additive Manufacturing (AM) has become indispensable in the context of digitalization and Industr... more Additive Manufacturing (AM) has become indispensable in the context of digitalization and Industry 4.0 and is said to be a mega trend of the 21st century. The technology offers immense opportunities to revolutionize the production of parts and components in all industries. Despite of the outstanding technical possibilities, the industry-wide adaptation rate is low. The current approach of looking at AM from a mostly technological view is a major reason for this. The challenge is to efficiently integrate 3D printing and other additive processes into existing manufacturing processes and systems. AM must be perceived as a multidimensional topic and viewed from different perspectives, two of which are the AM technology and the planning and management of production systems. These two perspectives have to be addressed simultaneously and cross-linked. In order to use AM to tackle some of the most challenging problems in modern manufacturing systems like increasing variant diversity, shorte...

Sweat glands module with integrated sensors designed for Additive Manufacturing

MATEC Web of Conferences, 2019

Lead by the results of our previous work, in which we designed the sweat glands prototype accordi... more Lead by the results of our previous work, in which we designed the sweat glands prototype according to AM (Advanced Manufacturing) requirements, in this study we aimed to integrate the previously manufactured channels into a stereolithography (SLA)-manufactured module, in order to avoid support structures inside the channels and the model cavities. That was achieved by distributing the channels in the manner which approximates the sweat glands distribution on an equivalent real body part and to be able toadjust the sweat quantity, to the estimated sweat rates found in the literature. The manufactured module has integrated humidity and temperature sensors, which will allow an accurate quantitative assessmentof the thermoregulation of the individual modules and the sweat glands prototype as a whole.

Gyors prototípus előállítása lom eljárással

Fiatal Műszakiak Tudományos Ülésszaka, 2002

The "Laminated Object Manufacturing" (LOM) give the results to the manufactured piece of 3D model... more

Reconstruction of Orbital Wall by Using Hybrid Manufacturing Operations

IOP Conference Series: Materials Science and Engineering

This paper will discuss the solutions and the main parameters used to print a mold that will be u... more This paper will discuss the solutions and the main parameters used to print a mold that will be used in a manufacturing process for a personalized implant in orbital fracture situations. The main purpose of this article is to rebuild the damaged orbit. The new orbit should have dimensions and accuracy similar to one of the original elements. Based on the computed tomography (CT) of the patient, the images are extracted and processed. With that information, a customized implant is manufactured. In this article, a case study of a patient suffering from an orbital fracture is presented. Based on the CT images, a mold was printed on additive manufacturing equipment (AM). The manufacturing parameters being highly correlated with the requirements that are needed for this case such as hardness, accuracy, surface roughness and support removal were chosen based on a series of tests and results from other studies. Another aspect that was analysed was related to the material from which was man...

Investigation onto the reliability of the selective laser melting process

The paper aims to offer the readers knowledge and information, to support new implementation and ... more The paper aims to offer the readers knowledge and information, to support new implementation and use of the SLM technology for practical applications and to obtain good metal parts for end users. The SLM parameters and conditions were evaluated to set up a scale and estimate how reliable the SLM-AM process is, on a particular type of machine. The experimental research was carried out in the last years by the authors, using the Realizer 250 machine. Many times, there is a lack of repeatability and reliability of the SLM process. The paper is presenting a new method to evaluate the repeatability and the surface roughness, when processing four types of powder materials, mainly for medical applications. Specimens were manufactured from four materials considered as being bio-metals: pure Titanium, Ti6Al7Nb, CoCr, and CoCrWMo. All these important features of the SLM parts were for seen by the authors in close relation with the mechanical characteristics of the parts. In this way, a good i...

Investigation of the Interface between Laser-Melted CoCr and a Stainless Steel Substrate

Metals

Recent advances in laser technologies offer significant flexibility in the additive manufacturing... more Recent advances in laser technologies offer significant flexibility in the additive manufacturing domain. Extensive work was focused on material processing using laser-directed energy deposition for repairing parts. This pilot study investigated the use of selective laser melting (SLM) for depositing a superior material such as CoCr on an existing stainless steel base. The interface between these dissimilar materials was analyzed. During fabrication, both metals were gradually mixed in the liquid state as the first CoCr powder layer was melded on the steel base without obvious defects. According to SEM and EDAX, the heat-affected zone has a limited depth (<20 µm). XRD patterns recorded across the CoCr–304 interface show a homogenous mixture of γ(Fe) and α(Co) solid solutions. The microporosity calculated by CT was under 0.5%. Microhardness was measured at and near the interface region, showing that the intermixing zone has high hardness (470–480 HV1), which may be related to the ...

Investigation of the Interface between Laser-Melted CoCr and a Stainless Steel Substrate

Metals

Recent advances in laser technologies offer significant flexibility in the additive manufacturing... more Recent advances in laser technologies offer significant flexibility in the additive manufacturing domain. Extensive work was focused on material processing using laser-directed energy deposition for repairing parts. This pilot study investigated the use of selective laser melting (SLM) for depositing a superior material such as CoCr on an existing stainless steel base. The interface between these dissimilar materials was analyzed. During fabrication, both metals were gradually mixed in the liquid state as the first CoCr powder layer was melded on the steel base without obvious defects. According to SEM and EDAX, the heat-affected zone has a limited depth (<20 µm). XRD patterns recorded across the CoCr–304 interface show a homogenous mixture of γ(Fe) and α(Co) solid solutions. The microporosity calculated by CT was under 0.5%. Microhardness was measured at and near the interface region, showing that the intermixing zone has high hardness (470–480 HV1), which may be related to the ...

Impact of laser parameters on additively manufactured cobalt-chromium restorations

The Journal of Prosthetic Dentistry

STATEMENT OF PROBLEM The selective laser melting (SLM) process has become popular for the fabrica... more STATEMENT OF PROBLEM The selective laser melting (SLM) process has become popular for the fabrication of frameworks for metal-ceramic restorations, although their surface roughness is greater than with cast or milled frameworks. Limited information is available regarding the surface mechanical characteristics of cobalt-chromium (Co-Cr) SLM-manufactured restorations. PURPOSE The purpose of this in vitro study was to adapt the laser parameters for a remelting strategy, scanning the outer boundary of Co-Cr specimens, to reduce surface roughness and solidification defects, to determine microhardness, to investigate surface morphology and microstructure, and to establish surface mechanical characteristics. MATERIAL AND METHODS Co-Cr specimens were SLM manufactured by using a typical melting (TM) strategy and an adaptive remelting (AR) strategy. The AR strategy involves rescanning 50% of the contour, varying the laser parameters. The roughness parameters considered were Ra and Rz. Vickers hardness was measured by microindentation with a 9.81-N force (ASTM E384-17). The surface morphology was investigated by scanning electron microscopy, the chemical composition by energy-dispersive X-ray spectroscopy, and the phase identification by using X-ray diffraction. The mechanical surface properties measured were the nanohardness, elastic modulus, and dissipation energy. One-way ANOVA with the Tukey procedure was used to compare the groups (α=.05). RESULTS The innovative AR strategy reduced the surface roughness by 45% compared with TM, comparable with their cast counterpart. The smoothest AR surface was obtained by using 75 W and 350 mm/s for the first scanning of the contour, followed by a second remelting with 80 W and 700 mm/s. The microstructure of AR specimens had limited solidification defects, a chemical composition similar to that of raw powder, and a surface microhardness over 600 HV1. A fine grain structure in a single matrix phase was detected both on TM and AR specimens. The mechanical characteristics of the smoothest Co-Cr surface were 218 GPa elastic modulus, 746 HVIT Vickers nanohardness, 21 243 pJ plastic energy, and 26% nanoindentation work ratio. Significant differences were observed between the melting strategies (P<.05) both for surface roughness and microhardness. CONCLUSIONS The laser scanning strategy affects both the surface roughness and the hardness of SLM-manufactured specimens. The results show that using the AR strategy and proper laser parameters can reduce the roughness and increase the surface hardness of Co-Cr specimens made of conventional powder feedstock.

Experimental Study on 3D Printed Parts Made of Continuous Fiberglass Reinforced Polymer

ACTA TECHNICA NAPOCENSIS - Series: APPLIED MATHEMATICS, MECHANICS, and ENGINEERING, Apr 7, 2021

The paper is presenting studies and experiments on 3D printing of composite parts. The novelty of... more The paper is presenting studies and experiments on 3D printing of composite parts. The novelty of the printing process used is that the parts are printed using continuous reinforced fibers in a plastic matrix. Printing with continuous fiber reinforcement offers a few advantages compared to conventional processes as following: short manufacturing time, high strength, and low part weight. The internal structure of the model can be designed according to the part loads and the continuous fiber is disposed only in the layers where it is necessary. In this experimental research, an industrial part was studied and different possibilities of designing the internal structure were analyzed.

Integrating Electronic Components into 3D Printed Parts to Develop a Digital Manufacturing Approach

IFIP Advances in Information and Communication Technology, 2020

Digital manufacturing (DM) processes such as additive manufacturing (AM) technology, allow a high... more Digital manufacturing (DM) processes such as additive manufacturing (AM) technology, allow a high degree of integrability and functionality of printed parts. In this work, we present a proof of the DM concept focused on the integration approach where a product is developed and embedded with sensors. We also take this example one step further and introduce a method that allows 3D printing of heating elements into the specimens. The thermal characteristics of the developed heaters are investigated, and the results detailed. The novelty relates to a heater prototype injected and solidified into a curved 3D printed channel, which can produce a temperature between 23-46°C on the printed surface of the sample both in a dry and wet environment. This research demonstrates that it is possible to construct parts with embedded electrical structures using the described method.

Improving the Quality of the Parts Made by Rapid Metal Casting Process

The purpose of this article is to present researches for optimizing the vacuum casting process, b... more The purpose of this article is to present researches for optimizing the vacuum casting process, by dimensioning the feeding system. To manufacture metallic complex parts through investment casting process using wax patterns, with a good quality surface and a high dimensional accuracy it is necessary to optimize the feeding system. In this study, starting from the classic metal casting process a method to calculate the optimal dimensions of the gating system has been proposed, using mathematical relations for the gate, sprue and feeders. Thus we can say that by applying the feeding system dimensioning algorithm and by correcting the master model dimensions with the shrinkage value, we can manufacture complex metal parts through investment casting with a high precision and a good surface accuracy.

Programming Solutions for the User Interface of Virtual Machine Tools

The paper presents some possible solutions for creating elements of the human machine interface o... more The paper presents some possible solutions for creating elements of the human machine interface of complex virtual equipments. This ongoing research is a part of a complex project of designing virtual machine tools, which could be very useful in training the students and/or CNC operators. .After analyzing some possible software solutions, the paper shows two Java-related solutions: usage of the old Java2D class collection and a more modern one based on the recent GUI class collection known as Java FX 2.0. For every solution the paper presents the code of two classes necessary for creating two common controls, a push button and a rotating wheel. As the virtual equipment is created mainly for teaching purposes, the designing solution helps the trainees also by suggesting the possible controls that should be used in their training stage.

Researches on the Buckling Test of a Tripod Components Used in Emergencies

The tripod used for emergencies has been analyzed in different positioning cases of its legs to ... more The tripod used for emergencies has been analyzed in different positioning cases of its legs to its symmetry axis (the symmetry axis being the support of the buckling force), simulating different accidentally scenarios within the rescue interventions. Each case has been three times analyzed, to each analyze being related one type of material(Al2014, Al6082 and carbon fiber); the analysis have been performed by the help of finite element analysis, using ANSYS software. Key words: Buckling, FEM, ANSYS, tripod

Modern technologies in manufacturing : selected, peer reviewed papers from the 12th International Conference on Modern Technologies in manufacturing (MTeM) October 14-16, 2015, Cluj-Napoca, Romania

Synthesis and Characterization of Nano Hydroxyapatite Used for Immobilizing Heavy Metals

3 University Craiova, 13 A. I. Cuza, 200585, Craiova, Romania The specific objectives of this stu... more 3 University Craiova, 13 A. I. Cuza, 200585, Craiova, Romania The specific objectives of this study are to synthesize and characterize nano-scale hydroxyapatite particles in laboratory for use in immobilizing heavy metals. Nano hydroxyapatite (HAP) was synthesized by reacting CaCl 2 and Na 2 HPO 4 as raw materials, a precipitation reaction occuring at the room temperature. Crystal phases were determined by X-ray diffraction (XRD). Scanning electron microscope (SEM) was applied to investigate the morphology. The microstructure of the HAP products was further observed by transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) with energy- dispersive X-ray spectroscopy (EDX). The purity and chemical composition of the as-synthesized powder was analyzed by FTIR. Soil contamination by heavy elements represents therefore a worldwide environmental concern mainly because these elements can be transferred to the hydrosphere and biosphere, thereby p...

Static Analysis to Redesign the Gripper, Using Creo Parametric Software Tools

Within this paper is presented the optimizing activity of a clamping jaw used for gripping and fi... more Within this paper is presented the optimizing activity of a clamping jaw used for gripping and fixing revolution or/and prismatic work-pieces, by the help of CREO design software, using Creo Parametric and Creo Simulate modules. The article approaches a case study, within two loading situations of the gripper jaw, mounted on an industrial arm robot, are presented. Also, CAD and finite element method (FEM) advantages have been presented.

Investigation on Feed Rate Influence on Surface Quality in Abrasive Water Jet Cutting of Composite Materials, Monitoring Acoustic Emissions

Advances in Manufacturing Engineering and Materials, 2018

The paper deals an experimental study on cutting composite materials (CFRP) using abrasive water ... more The paper deals an experimental study on cutting composite materials (CFRP) using abrasive water jet cutting (AWJC) process. The influence of the feed rate on surface roughness is studied using acoustic emission (AE) monitoring. For monitoring the process two acoustic emission sensors was mounted, on the CFRP workpiece and on the cutting head. This monitoring technique has proved that, between process parameter (feed rate and amplitude of AE signal) is a clear connection. The surface roughness can be predicted using online monitoring with acoustic emission (AE).

Adhesion between Biocomposites and Different Metallic Structures Additive Manufactured

Coatings, 2021

This study was concerned with the adhesion of resin cement to metal surfaces obtained by selectiv... more This study was concerned with the adhesion of resin cement to metal surfaces obtained by selective laser melting process (SLM), and how it could be improved the bond strength at the biocomposite-metal junction. The SLM substrates were manufactured out of pure titanium (Ti), Ti6Al7Nb, and CoCr alloys. The metallic surfaces were covered with 5 types of biocomposites: 2 commercially resin-modified glass-ionomer cements (GC Fuji Plus and KETAC CEM) and 3 types of in-house developed materials. These biocomposites were mechanical characterized under compression and bending trials. The biocomposites-metal adhesion was settled both on as built metallic surfaces and after they were sandblasted with alumina. All the sandblasted SLM surfaces presented higher adhesion strength in comparison with the untreated specimens. The CoCr specimens show the highest bonding value. Additionally, the morphological aspects of joining interfaces were investigated using a scanning electron microscope (SEM). Th...

Avoiding carbon fibre reinforced polymer delamination during abrasive water jet piercing: a new piercing method

The International Journal of Advanced Manufacturing Technology, 2021

This paper presents a new method of piercing the carbon fibre reinforced polymer (CFRP) with abra... more This paper presents a new method of piercing the carbon fibre reinforced polymer (CFRP) with abrasive water jet (AWJ), which can avoid delamination. The method consists of adding the abrasive particles in the water jet at the very beginning of jet formation, thus obtaining a mixed abrasive water jet during the first impact with the composite work piece. A new cutting system was designed and set up based on the proposed piercing method and was compared with a conventional AWJ cutting system. The main added values brought by this paper are: it validates our original concept; provides synthetic analyses, the effects of the AWJ homogeneity, and the abrasive inlet angle on the CFRP delamination, and it brings a complete set of recommendations on how to overcome the industrial difficulties caused by the delamination of the composite materials, during the piercing with AWJ.

Additive manufacturing for repairing: from damage identification and modeling to DLD

Rapid Prototyping Journal, 2020

Purpose This paper aims to decrease the cost of repairing operations, of the damaged mechanical c... more Purpose This paper aims to decrease the cost of repairing operations, of the damaged mechanical components, by enabling the strong automation of the process and the reduction of manual labor. The main purpose of the hybrid repair process is to restore the original shape of the mechanical parts, by adding and removing material according to the mismatch between the damaged object and the virtual model, to restore its geometrical properties. Design/methodology/approach The DUOADD software tool translates the information collected from a 3D scanner into a digital computer aided design solid model, which can be manipulated through Siemens NX computer aided manufacturing (CAM), to obtain the tool paths, for the Direct Laser Deposition (DLD) technology. DUOADD uses octrees to effectively analyze the damaged region of the mechanical part and then to discretize the volume to be added to export CAM-compatible information as a 3D model, for additive operations. Findings DUOADD is the missing l...

Challenges of additive manufacturing in production systems

MATEC Web of Conferences, 2019

Additive Manufacturing (AM) has become indispensable in the context of digitalization and Industr... more Additive Manufacturing (AM) has become indispensable in the context of digitalization and Industry 4.0 and is said to be a mega trend of the 21st century. The technology offers immense opportunities to revolutionize the production of parts and components in all industries. Despite of the outstanding technical possibilities, the industry-wide adaptation rate is low. The current approach of looking at AM from a mostly technological view is a major reason for this. The challenge is to efficiently integrate 3D printing and other additive processes into existing manufacturing processes and systems. AM must be perceived as a multidimensional topic and viewed from different perspectives, two of which are the AM technology and the planning and management of production systems. These two perspectives have to be addressed simultaneously and cross-linked. In order to use AM to tackle some of the most challenging problems in modern manufacturing systems like increasing variant diversity, shorte...

Sweat glands module with integrated sensors designed for Additive Manufacturing

MATEC Web of Conferences, 2019

Lead by the results of our previous work, in which we designed the sweat glands prototype accordi... more Lead by the results of our previous work, in which we designed the sweat glands prototype according to AM (Advanced Manufacturing) requirements, in this study we aimed to integrate the previously manufactured channels into a stereolithography (SLA)-manufactured module, in order to avoid support structures inside the channels and the model cavities. That was achieved by distributing the channels in the manner which approximates the sweat glands distribution on an equivalent real body part and to be able toadjust the sweat quantity, to the estimated sweat rates found in the literature. The manufactured module has integrated humidity and temperature sensors, which will allow an accurate quantitative assessmentof the thermoregulation of the individual modules and the sweat glands prototype as a whole.

Gyors prototípus előállítása lom eljárással

Fiatal Műszakiak Tudományos Ülésszaka, 2002

The "Laminated Object Manufacturing" (LOM) give the results to the manufactured piece of 3D model... more