H. Hargitai

6603090541

Publications - 28

Advantages of Corrosion-Resistant Overlay Welding on Steel S355J2N

F. Tancsics Nikoletta Légmán H. Hargitai László Varga

Publication Name: Applied Sciences Switzerland

Publication Date: 2025-04-01

Volume: 15

Issue: 7

Page Range: Unknown

Description:

In this paper, the effects of overlay welding of S355J2N steel were studied. We examined how the technological advantages of overlay welding can be taken into account to improve the service lifetime and applicability of components made from traditional S355J2N structural steel during the planning step. Increasing the service life of structures exposed to environmental influences is essential, especially on surfaces exposed to abrasive and chemical corrosion. The direct aim of the investigation was to present a comprehensive picture of technological advantages of the corrosion-resistant overlay welding on steel S355J2N. We mainly analysed experiments with powder-coated wire electrodes which are based on protective gas and robot technology usage. With various mechanical tests, we searched for the minimum number of layers that provides sufficient protection against corrosion. The aim of this paper is to present achieved results during development of a welding technology of a reliably functioning product with increased corrosion resistance.

Open Access: Yes

DOI: 10.3390/app15073832

Investigation of the Tribological Effects of Nano-Sized Transition Metal Oxides on a Base Oil Containing Pour Point Depressant and Viscosity Modifier

I. Szabó Kevin Szabó H. Hargitai

Publication Name: Chemengineering

Publication Date: 2025-02-01

Volume: 9

Issue: 1

Page Range: Unknown

Description:

This study investigates the tribological effects of nano-sized metal oxides (ZrO2, CuO, Y2O3 and TiO2) in Group III type base oil containing 0.3% pour point depressant (PPD) and 5% viscosity modifier (VM) to enhance friction and wear performance. The homogenized lubricant samples with varying concentrations of oxide nanoparticles (0.1–0.5 wt%) on a linear oscillating tribometer performed static and dynamic frictional tests. Optical and confocal microscopy surface analysis evaluated the wear of the specimen, and SEM and EDX analyses characterized the wear tracks, nanoparticle distributions, and quantification. The cooperation between PPD and nanoparticles significantly improved friction and wear values; however, the worn surface suffered extensively from fatigue wear. The collaboration between VM and nanoparticles resulted in a nanoparticle-rich tribofilm on the contact surface, providing excellent wear resistance that protects the component while also favorably impacting friction reduction. This study found CuO reduced wear volume by 85% with PPD and 43% with VM at 0.5 wt%, while ZrO2 achieved 80% and 63% reductions, respectively. Y2O3 reduced wear volume by 82% with PPD, and TiO2 reduced friction by 20% with VM. These nanoparticles enhanced tribological performance at optimal concentrations, but high concentrations caused tribofilm instability, highlighting the need for precise optimization.

Open Access: Yes

DOI: 10.3390/chemengineering9010001

Tribological investigation of the effect of nanosized CuO and TiO2 on a base oil containing Komad 323 dispersant

I. Szabó Márk Marsicki H. Hargitai

Publication Name: Jurnal Tribologi

Publication Date: 2024-09-01

Volume: 42

Issue: Unknown

Page Range: 103-128

Description:

This article investigates the impact of copper(II) oxide (CuO) and titanium dioxide (TiO2) nanoparticles in Group III base oil with 8 wt% Komad 323 dispersant. Nanoparticles underwent ethyl oleate surface modification. Tribological properties were assessed using a linear oscillating tribometer, continuously monitoring static friction. Friction integral values were derived from extensive data acquisition. Wear analysis employed digital optical and confocal microscopy, complemented by scanning electron microscopy for wear-type characterization and energy-dispersive X-ray spectroscopy for additive quantification in the wear track. Results indicate CuO nanoparticles' poor compatibility with Komad 323, resulting in increased friction (2-13%) and substantial wear reduction (39-50%) at low CuO concentrations (≤0.3 wt%). Higher concentrations (≥0.4 wt%) reduced friction (21-35%) but led to surface fatigue and increased wear rates. Elemental composition analysis of the wear track revealed that the surface contains 1.43-3.17 norm.wt% copper. Conversely, TiO2 in synergy with the dispersant, formed a boundary layer, exhibiting lower friction by 11-14%. TiO2 formed a high wear resistance boundary layer at titanium concentrations of 0.33-0.39 norm.wt%, which resulted in 44% wear volume reduction. Applying both nanoparticles reduced the wear scar diameter of the test specimens by 3-12%.

Open Access: Yes

DOI: DOI not available

Effect of Energy Density on the Mechanical Properties of 1.2709 Maraging Steel Produced by Laser Powder Bed Fusion

I. Fekete Gusztáv Fekete István Hatos H. Hargitai

Publication Name: Materials

Publication Date: 2024-07-01

Volume: 17

Issue: 14

Page Range: Unknown

Description:

The unusual combination of the fundamentally contradictory properties of high tensile strength and high fracture toughness found in maraging steel makes it well suited for safety-critical applications that require high strength-to-weight materials. In certain instances, additive manufacturing (AM) has produced materials that may be desirable for safety-critical applications where impact toughness is a key property, such as structural parts for the aerospace industry or armor plates for military applications. Understanding the influence of process parameters and defect structure on the properties of maraging steel parts produced via laser powder bed fusion (LPBF) is a fundamental step towards the broader use of AM technologies for more demanding applications. In this research, the impact energy of V-notched specimens made of 1.2709 maraging steel produced by LPBF was determined via Charpy impact testing. Specimens were produced using different processing parameter sets. By combining the process parameters with the porosity values of the parts, we demonstrate that an almost full prediction of the impact properties can be achieved, paving the way for significantly reducing the expenses of destructive testing.

Open Access: Yes

DOI: 10.3390/ma17143432

Effects of selective laser melting building directions and surface modifications on surface roughness of Ti6Al4V alloy

Tünde Anna Kovács Hassanen Jaber J. Kónya H. Hargitai

Publication Name: Discover Applied Sciences

Publication Date: 2024-01-01

Volume: 6

Issue: 1

Page Range: Unknown

Description:

Abstract: In this paper, the effect of building direction relative to the substrate (0°, 45°, and 90°) on the surface roughness of Ti6Al4V samples produced by selective laser melting (SLM) has been investigated. After SLM, the samples were subjected to different surface modifications, including acid etching (E) with HF, sandblasting (S) with Al2O3 and sandblasting + etching (SE). Surface roughness of the prepared samples were investigated by Alicona Infinite Focus optical microscopy and Scanning Electron Microscopy (SEM). It was found that there is an inverse relationship between surface roughness and building directions. Additionally, the results showed that the acid etching process increases the surface roughness of the samples at 45° and 90°, while the surface roughness decreases at 0°. Furthermore, the results showed that sandblasting and sandblasting followed with acid etching (SE) effectively reduced the surface roughness of the samples at all building directions. In summary, the acid-etched Ti6Al4V surfaces manufactured at 90° showed a superior surface roughness (Ra = 4.25 ± 0.21, Rz = 29.63 ± 2.34 μm) among the specimens, which is encouraged osseointegration of implants.

Open Access: Yes

DOI: 10.1007/s42452-024-05656-0

Novel Technique for Reducing Geometrical Inaccuracies of Clamped Workpiece During Machining: A Hybrid Method

Dániel Ledenyák Tamás Rosta H. Hargitai

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 269-276

Description:

The aim of this paper is to provide a novel technique in production technology, which ensures the adequate tightening torque of workpiece by a vise connector to minimize the effect of elastic deformation, therefore geometrical inaccuracies roughness, during machining process. This effect emerges if the clamping force is excessively high, resulting in a deformed workpiece with a slightly convex surface. Once this surface is machined and the clamping force is released, the material returns to its initial shape and the newly machined flat surface will be concaved, resulting geometrical inaccuracy. The method is based on a simple workpiece, where the elastic deformation is numerically modelled and experimentally measured as a function of different clamping heights and tightening forces. During the experiments, the workpiece is tightened by bolts, step by step, and in each step, the deformation of the surface is measured with a coordinate measuring machine equipped with a Touch Probe Measurement system. This measurement process is followed by finite element modelling, where the same system, with identical boundary conditions (load, constraints, material properties), are computationally created to compare the numerically and experimentally obtained results. As a result of evaluating various cases, a user-friendly database was established that provides recommendations for specific geometry, position, and capture height. Our model can also propose a minimum clamping height if geometry, position, and maximum force(s) are specified during machining.

Open Access: Yes

DOI: 10.3233/ATDE240555

Experimental Wear Analysis of Nano-Sized Titania Particles as Additives in Automotive Lubricants

Árpád Tóth I. Szabó Hebah Abdallah H. Hargitai

Publication Name: Micro

Publication Date: 2023-09-01

Volume: 3

Issue: 3

Page Range: 715-727

Description:

This study focuses on the wear effects of nano-sized titania as a potential engine lubricant additive. Titanium dioxide nanoparticles have promising wear-reducing properties and significant tribological potential. In this article, titania nanoparticles were homogenized in Group III automotive oil at five different concentrations (0.1; 0.2 … 0.5 wt%). The nanodoped oil samples were tested on a linear oscillating tribometer with oil circulation. Based on the tribological results, titania nanoparticles increased friction by 20–32% but can reduce the wear area by up to 32%. According to the confocal microscopic examination, wear volume can be reduced by up to 57% with titania nanoparticles. Titania nanoparticles improved the repeatability of tribological measurements. A scanning electron microscopy examination of the wear track revealed that the characteristic wear of the tribological system was abrasive, but a significant amount of adhesive wear was also observed. Energy dispersive X-ray spectroscopy analysis found that the nanoparticles fill the deeper trenches of the wear. The worn surface uniformly contains TiO2 particles and the quantified normalized titanium concentration was between 0.56 and 0.62%.

Open Access: Yes

DOI: 10.3390/micro3030050

Tribological Investigation of the Effect of Nanosized Transition Metal Oxides on a Base Oil Containing Overbased Calcium Sulfonate

Árpád Tóth I. Szabó H. Hargitai

Publication Name: Lubricants

Publication Date: 2023-08-01

Volume: 11

Issue: 8

Page Range: Unknown

Description:

In this study, copper(II) oxide, titanium dioxide and yttrium(III) oxide nanoparticles were added to Group III-type base oil formulated with overbased calcium sulfonate. The nanosized oxides were treated with ethyl oleate surface modification. The tribological properties of the homogenized oil samples were tested on a linear oscillating tribometer. Friction was continuously monitored during the tribological tests. A surface analysis was performed on the worn samples: the amount of wear was determined using a digital optical and confocal microscope. The type of wear was examined with a scanning electron microscope, while the additives adhered to the surface were examined with energy-dispersive X-ray spectroscopy. From the results of the measurements, it can be concluded that the surface-modified nanoparticles worked well with the overbased calcium sulfonate and significantly reduced both wear and friction. In the present tribology system, the optimal concentration of all three oxide ceramic nanoadditives is 0.4 wt%. By using oxide nanoparticles, friction can be reduced by up to 15% and the wear volume by up to 77%. Overbased calcium sulfonate and oxide ceramic nanoparticles together form a lower friction anti-wear boundary layer on the worn surfaces. The results of the tests represent another step toward the applicability of these nanoparticles in commercial engine lubricants. It is advisable to further investigate the possibility of formulating nanoparticles into the oil.

Open Access: Yes

DOI: 10.3390/lubricants11080337

Surface Modification of Silica Nanoparticles with Ethyl Oleate for the Purpose of Stabilizing Nanolubricants Used for Tribological Tests

Árpád Tóth I. Szabó Nóra Mike-Kaszás Gábor Bartus H. Hargitai

Publication Name: Ceramics

Publication Date: 2023-06-01

Volume: 6

Issue: 2

Page Range: 980-993

Description:

Long-term sustainability and decreasing amount of fossil oil reserves require a partial or complete transformation of traditional lubricating oils. The use of silica nanoparticles as a lubricant additive has a huge tribological potential, which has already been discussed in numerous articles. Nanosized silica shows excellent results in reducing friction and preventing wear, but they quickly aggregate and settle after homogenization in oils. For long-term stable dispersion of lubricating oils containing nanoceramics, the surface of the particles was modified with ethyl oleate. The surface modification, the ethyl oleate applied to the surface of the nanosilica, was confirmed by Fourier-transform infrared spectroscopy. Group III based lubricating oil was prepared using the surface-modified nanosilica. The particle size of the nanoparticles in the lubricating oil dispersion was examined by dynamic light scattering. Oscillating tribometer measurements were performed with different concentrations (0.1; 0.2; 0.3 wt%) of nanolubricants. Based on the tribological results, the friction coefficient of the surface-modified nanosilica is more stable, its wear is 15% lower compared to the reference. There is no significant change in the magnitude of the friction coefficient. It can be concluded that the ethyl oleate surface modification method may be suitable for tribological investigations of the acting mechanisms of nanoparticles.

Open Access: Yes

DOI: 10.3390/ceramics6020058

Effect of Surface Modifications on Surface Roughness of Ti6Al4V Alloy Manufactured by 3D Printing, Casting, and Wrought

Péter Pinke Tünde Anna Kovács Hassanen Jaber J. Kónya H. Hargitai

Publication Name: Materials

Publication Date: 2023-06-01

Volume: 16

Issue: 11

Page Range: Unknown

Description:

This work aimed to comprehensively evaluate the influence of different surface modifications on the surface roughness of Ti6Al4V alloys produced by selective laser melting (SLM), casting and wrought. The Ti6Al4V surface was treated using blasting with Al2O3 (70–100 µm) and ZrO2 (50–130 µm) particles, acid etching with 0.017 mol/dm3 hydrofluoric acids (HF) for 120 s, and a combination of blasting and acid etching (SLA). It was found that the optimization of the surface roughness of Ti6Al4V parts produced by SLM differs significantly from those produced by casting or wrought processes. Experimental results showed that Ti6Al4V alloys produced by SLM and blasting with Al2O3 followed by HF etching had a higher surface roughness (Ra = 2.043 µm, Rz = 11.742 µm), whereas cast and wrought Ti6Al4V components had surface roughness values of (Ra = 1.466, Rz = 9.428 m) and (Ra = 0.940, Rz = 7.963 m), respectively. For Ti6Al4V parts blasted with ZrO2 and then etched by HF, the wrought Ti6Al4V parts exhibited higher surface roughness (Ra = 1.631 µm, Rz = 10.953 µm) than the SLM Ti6Al4V parts (Ra = 1.336 µm, Rz = 10.353 µm) and the cast Ti6Al4V parts (Ra = 1.075 µm, Rz = 8.904 µm).

Open Access: Yes

DOI: 10.3390/ma16113989

Laser powder bed fusion and casting for an advanced hybrid prototype mold

Martin Zobač I. Fekete J. G. Kovács B. Zink István Hatos Dániel Török Tatyana Ageyeva Róbert Boros H. Hargitai

Publication Name: Journal of Manufacturing Processes

Publication Date: 2022-09-01

Volume: 81

Issue: Unknown

Page Range: 748-758

Description:

One of the factors limiting the throughput of injection molding is cooling time, which is the most significant part of the total cycle time. The cooling efficiency of molds can be considerably improved with additive manufacturing techniques. A 3D printed injection mold with conformal cooling channels reduces cooling time by 30–40 %. However, the cooling efficiency of these molds can be further improved with a multi-material approach and the use of materials with excellent thermal and mechanical properties. In this study, we propose a hybrid mold insert made of steel and copper, produced with the combination of Laser Powder Bed Fusion (L-PBF) and casting. The steel shell that contains conformal cooling channels was printed by L-PBF. Then this shell was cast with copper. We found that the hybrid mold insert we developed has lower residual cooling time and heat extraction is more uniform than the conventional printed steel insert. The developed hybrid mold insert enables a reduction of residual cooling time by 15 %.

Open Access: Yes

DOI: 10.1016/j.jmapro.2022.07.034

Investigation of the Applicability of Y2O3–ZrO2 Spherical Nanoparticles as Tribological Lubricant Additives

Máté Zs Leskó Árpád Tóth I. Szabó H. Hargitai

Publication Name: Lubricants

Publication Date: 2022-07-01

Volume: 10

Issue: 7

Page Range: Unknown

Description:

Long-term environmental goals will motivate the automotive industry, component suppliers, and lubricating oil developers to reduce the friction of their tribosystems to improve overall efficiency and wear for increased component lifetime. Nanoscale ceramic particles have been shown to form a protective layer on components’ surface that reduces wear rate with its high hardness and chemical resistance. One such ceramic is yttria (Y2O3), which has an excellent anti-wear effect, but due to its rarity it would be extremely expensive to produce engine lubricant made from it. Therefore, part of the yttria is replaced by zirconia (ZrO2) with similar physical properties. The study presents the result of the experimental tribological investigation of nanosized yttria–zirconia ceramic mixture as an engine lubricant additive. Yttria-stabilized zirconia (YSZ) nanoparticle was used as the basis for the ratio of the ceramic mixture, so that the weight ratio of yttria–zirconia in the resulting mixture was determined to be 11:69. After the evaluation of the ball-on-disc tribological measurements, it can be stated that the optimal concentration was 0.4 wt%, which reduced the wear diameter by 30% and the wear volume by 90% at the same coefficient of friction. High-resolution SEM analysis showed a significant amount of zirconia on the surface, but no yttria was found.

Open Access: Yes

DOI: 10.3390/lubricants10070152

Examination of welded joint of titanium alloy used in oral surgery

K. Kulcsár J. Kónya H. Hargitai

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2020-08-25

Volume: 903

Issue: 1

Page Range: Unknown

Description:

The additive manufacturing of customized Ti-6Al-4V (Grade 23) implants, which in the present research concerns the dental and maxillofacial surgical field, may require complex manufacturing technology due to their complexity and assembly. In practice, additively manufactured titanium implant elements are supplemented by threaded sleeves that allow disassembly. These turned elements made from Grade 5 material quality rolled preform are joined by laser micro-welding with Grade 1 material. This special process for implant production is still not widespread in current manufacturing practice, and there is no technical recommendation for the manufacturing parameters of these implants. The aim of our research is to explore the possibilities and limitations of additive process in the manufacture of custom-made implants and to provide guidelines for optimal manufacturing and welding parameters. In the initial phase of the research, preliminary experiments were conducted with the conventional and additive manufacturing of cylindrical test specimens and with the production of combined products by micro-welding. The specimens were subjected to tensile testing, the weld was examined by CT, and the fracture surfaces were studied by optical microscope and scanning electron microscope.

Open Access: Yes

DOI: 10.1088/1757-899X/903/1/012016

Influence of local porosity on the mechanical properties of direct metal laser-sintered 1.2709 alloy

I. Fekete István Hatos Dóra Harangozó H. Hargitai

Publication Name: Strojniski Vestnik Journal of Mechanical Engineering

Publication Date: 2020-01-01

Volume: 66

Issue: 6

Page Range: 351-357

Description:

Powder bed metal printing has demonstrated its potential for the direct manufacturing of complex parts. It has great flexibility compared to conventional manufacturing. There are also some difficulties and problems, e.g., because the process stops during production. When the process is restarted, the first layer may be thicker due to technological limitations. In this paper, the effects caused by the presence of these thicker layers were investigated. The possibility of re-melting the layers to reduce porosity were also analysed. A tool steel powder grade 1.2709 was used to produce samples with an increased thickness of melted layers.

Open Access: Yes

DOI: 10.5545/sv-jme.2020.6573

Displacement-based failure analysis of metal matrix syntactic foam

I. Zsoldos I. Kozma Dóra Harangozó H. Hargitai

Publication Name: Wit Transactions on Engineering Sciences

Publication Date: 2019-01-01

Volume: 124

Issue: Unknown

Page Range: 161-173

Description:

Metal matrix syntactic foams are being used more and more widely thanks to their relative density as well as their perfect energy-absorbing characteristics. Multiple studies concern the economical production of these materials – particularly, how energy absorption as a physical characteristic can be increased. Many studies examined the effects of material choice as well as cell size and wall thickness of reinforcing materials on compressive strength. However, there are only estimated models about descriptions concerning decaying processes of samples from different material composition and geometrical variation. In this study, we introduced an “in situ” examination in order to model the decaying process. We upsetted aluminium-ceramic composite foams cyclically. We reconstructed the geometry of the sample with microcomputed tomography (μCT) technology and digital image processing at certain specified points of the compression test. During the complete decaying process, the process was evaluated with volume change and number of broken hollow particles, as well as elementary particle displacements, orientation and sphericity of the reinforced material.

Open Access: Yes

DOI: 10.2495/MC190161

Conformal cooling with heat-conducting inserts by direct metal laser sintering

István Hatos B. Kocsis H. Hargitai

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2018-11-30

Volume: 448

Issue: 1

Page Range: Unknown

Description:

With the development of layer manufacturing technologies injection mold inserts with conformal cooling channels can be manufactured. If the cooling channels can be placed along the geometry, the heat removal is uniform and effective. In tight mold regions, formation of cooling channel is not possible or not efficient. The combination of conformal cooling and heat conductive insert can be an ideal solution for the effective cooling.

Open Access: Yes

DOI: 10.1088/1757-899X/448/1/012027

Effect of locally increased melted layer thickness on the mechanical properties of laser sintered tool steel parts

I. Fekete T. Ibriksz István Hatos András Lajos Nagy B. Kocsis H. Hargitai

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2018-10-18

Volume: 426

Issue: 1

Page Range: Unknown

Description:

Additive technologies have several advantages over conventional manufacturing, such as the freedom of geometry of the products and internal structures. There are also some limitations and problems, deriving from stopping the process during the production. By restarting the process, the building often continues with a thicker starting layer due to the deposition of two or more layers. The effect of skipped melting of layers is investigated in this paper. Maraging steel powder (MS1) was used in direct metal laser sintering (DMLS) process to produce samples with increased thickness of melted layers. The layer thickness was increased in 20 μm steps up to 160 μm with 0.5 mm offset between the increased thickness layers. Porosity caused by the uneven melting was measured by optical microscope, mechanical tests were carried out to quantify the effect of skipped layers and fractured surfaces were observed under SEM. We have found that the yield strength and tensile strength are not affected if the layer thickness is slightly increased locally in the laser sintered part, while even a small increase in porosity greatly reduces the total elongation of the specimen. The decrease of impact energy due to the porosities shows similar correlation with the decrease of percentage elongation at break. However, the Charpy impact test is much more sensitive to layer skipping, the lack of melted layers lowers the impact strength significantly.

Open Access: Yes

DOI: 10.1088/1757-899X/426/1/012014

Surface modification and wear properties of direct metal laser sintered hybrid tools used in moulds

I. Fekete J. G. Kovács T. Ibriksz Mária B. Maros István Hatos H. Hargitai

Publication Name: Journal of Mechanical Engineering

Publication Date: 2018-01-01

Volume: 64

Issue: 2

Page Range: 121-129

Description:

Injection moulding is one of the most productive plastic forming processes. Product development and the reduction of production time require new solutions in tooling design and manufacturing. Direct metal laser sintering (DMLS) allows moulds to be built with special cooling systems, which offer curved cooling lines that can follow the geometry of the part (conformal cooling). One disadvantage of DMLS, its high cost, can be dramatically reduced with the building of hybrid structures. With conventional tool steels as the base plate and only the special geometry of the part sintered on the top, the final geometry can be manufactured after sintering by conventional process technologies. We produced hybrid structures by direct metal laser sintering maraging steel (MS1) powder onto the surface of commercial mould steels and studied the effect of different heat treatments on porosity, tribological behaviour and the microstructure. The transition zone was also characterized.

Open Access: Yes

DOI: 10.5545/sv-jme.2017.4942

Characterization of internal stresses in hybrid steel structures produced by direct metal laser sintering

J. G. Kovács István Hatos H. Hargitai

Publication Name: Materials Science Forum

Publication Date: 2017-01-01

Volume: 885

Issue: Unknown

Page Range: 196-201

Description:

In this study hybrid structures were produced by direct metal laser sintering of maraging steel (MS1) powder onto the surface of commercial mold steels. The over-sintering method should be analyzed to find the optimum pre- and post-heat treatment to minimize the internal stresses. The internal stress is directly proportional to the deformation if the solid thick part is reduced to thin plate like parts. Based on this recognition the deformation of the plates over-sintered with MS1 could be analyzed in order to explore the internal stresses and the effect of different pre- and postheat treatments were examined.

Open Access: Yes

DOI: 10.4028/www.scientific.net/MSF.885.196

Enhanced injection molding simulation of advanced injection molds

N. K. Kovács A. Suplicz J. G. Kovács T. Tábi B. Zink István Hatos H. Hargitai F. Szabó

Publication Name: Polymers

Publication Date: 2017-01-01

Volume: 9

Issue: 2

Page Range: Unknown

Description:

The most time-consuming phase of the injection molding cycle is cooling. Cooling efficiency can be enhanced with the application of conformal cooling systems or high thermal conductivity copper molds. The conformal cooling channels are placed along the geometry of the injection-molded product, and thus they can extract more heat and heat removal is more uniform than in the case of conventional cooling systems. In the case of copper mold inserts, cooling channels are made by drilling and heat removal is facilitated by the high thermal conductivity coefficient of copper, which is several times that of steel. Designing optimal cooling systems is a complex process; a proper design requires injection molding simulations, but the accuracy of calculations depends on how precise the input parameters and boundary conditions are. In this study, three cooling circuit designs and three mold materials (Ampcoloy 940, 1.2311 (P20) steel, and MS1 steel) were used and compared using numerical methods. The effect of different mold designs and materials on cooling efficiency were examined using calculated and measured results. The simulation model was adjusted to the measurement results by considering the joint gap between the mold inserts.

Open Access: Yes

DOI: 10.3390/polym9020077

Influence of cryogenic attrition ball milling on the particle size of microcrystalline cellulose at different moisture contents

Zsolt András Nánási H. Hargitai László Mészáros

Publication Name: Materials Science Forum

Publication Date: 2017-01-01

Volume: 885

Issue: Unknown

Page Range: 202-207

Description:

In this study the effect of attrition ball milling on cellulose particle size distribution was studied. The effect of moisture content of cellulose and grinding time were examined and grinding was carried out at room temperature and under cryogenic conditions, as well. The grinds obtained were studied with electron microscope, and the characteristic dimensions of ground particles were determined using image processing software. Results revealed that effective size decrease of cellulose particles was achieved at low moisture content at room temperature, while under cryogenic conditions high moisture content was necessary, i.e. frozen moisture enhances grinding efficiency in the latter case.

Open Access: Yes

DOI: 10.4028/www.scientific.net/MSF.885.202

Methodology development for through-plane thermal conductivity prediction of composites

A. Suplicz J. G. Kovács H. Hargitai

Publication Name: International Journal of Thermal Sciences

Publication Date: 2016-02-01

Volume: 100

Issue: Unknown

Page Range: 54-59

Description:

The prediction and tailoring of thermal conductivity of two-phase composites is essential. In this work a new semi-empirical model was developed, which was derived from the rule of mixtures. Furthermore, a new methodology was developed to determine the thermal conductivity of the fillers and the maximum achievable filler content. To validate the new model, polypropylene-based composites were prepared with different fillers, such as talc, boron-nitride and graphite, with 20, 40 and 60 vol% filler content. The results obtained from the proposed model are in good agreement with the experimental data. Various other theoretical models were also introduced and compared to the experiments, but in most cases those underestimate or overestimate the thermal conductivity of composites.

Open Access: Yes

DOI: DOI not available

Thermal simulations and measurements for rapid tool inserts in injection molding applications

N. K. Kovács A. Suplicz J. G. Kovács T. Tábi B. Zink H. Hargitai F. Szabó

Publication Name: Applied Thermal Engineering

Publication Date: 2015-06-25

Volume: 85

Issue: Unknown

Page Range: 44-51

Description:

apid prototyping (RP) is a widely used process in the industry to shorten development time. Another advantage of this technology is the ability to create conformal cooling systems, thus not only cooling time and cycle time can be shortened, but also shrinkage, thus warpage can be decreased. The main disadvantage of Rapid prototyping materials is their low thermal conductivity, which strongly influences cooling properties and warpage. The research based on a special developed injection mold for novel rapid prototyping based mold inserts with cooling systems. A method has been introduced to determine the most important thermal parameters for injection molding simulations using rapid tools. Those parameters, which can be measured such as the specific heat and thermal conductivity of the mold materials, are directly implemented into the software. The heat transfer coefficient between the polymer melt and the rapid tool insert surface cannot be measured in a reasonable way, thus simulation software was used to determine that based on indirect calculation derived from real measurements. In the paper, the method was proved with Fused Deposition Modeling (FDM) and Polyjet mold inserts.

Open Access: Yes

DOI: 10.1016/j.applthermaleng.2015.03.075

The analysis of injection molding defects caused by gate vestiges

N. K. Kovács A. Suplicz J. G. Kovács T. Tábi B. Zink H. Hargitai F. Szabó

Publication Name: Express Polymer Letters

Publication Date: 2015-04-01

Volume: 9

Issue: 4

Page Range: 394-400

Description:

Issues of product safety are the most serious problems of an injection molded product due to their risk to human health. Such a safety problem can be the needle-shaped vestige at the gate zone of injection molded products, called a gate vestige. Only observations of the formation of gate vestiges can be found in the literature, but the processing parameters influencing their dimensions, especially their height have not been studied yet. Our goal was to study the effect of various injection molding processing parameters and gate constructions on gate vestige formation.

Open Access: Yes

DOI: 10.3144/expresspolymlett.2015.37

Reinforcing and compatibilizing effect of nano size montmorillonite on high density polyethylene - Polyamide 6 composites

T. Ibriksz H. Hargitai

Publication Name: Iccm International Conferences on Composite Materials

Publication Date: 2013-01-01

Volume: 2013-July

Issue: Unknown

Page Range: 8162-8169

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Development of PA6/HDPE nanocomposite blends

T. Ibriksz János Stifter Endre Andersen H. Hargitai

Publication Name: Materials Science Forum

Publication Date: 2013-01-01

Volume: 729

Issue: Unknown

Page Range: 216-221

Description:

In our experiments polyamide 6/high density polyethylene blends (25/75 wt%) were produced and maleic anhydride grafted polyethylene was used as chemical coupling agent. To get finer microstructure and enhance the mechanical properties the blends were compounded by different nanostructured reinforcements. Two kinds of nanosilicate, the layered structure montmorillonite and the needle like sepiolite were applied in different concentrations and their effect on the mechanical and melting properties were examined. © (2013) Trans Tech Publications, Switzerland.

Open Access: Yes

DOI: 10.4028/www.scientific.net/MSF.729.216

Applications of Macro- and Microfiller-Reinforced Polymer Composites

H. Hargitai Ilona Rácz

Publication Name: Polymer Composites

Publication Date: 2012-03-21

Volume: 1

Issue: Unknown

Page Range: 747-790

Description:

No description provided

Open Access: Yes

DOI: 10.1002/9783527645213.ch23

Development of nanoclay reinforced HDPE/PA6 nanocomposites

T. Ibriksz H. Hargitai

Publication Name: Eccm 2012 Composites at Venice Proceedings of the 15th European Conference on Composite Materials

Publication Date: 2012-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

In our experiments HDPE/PA6 blends (75/25 wt%) were produced and maleic anhydride grafted polyethylene (PEgMA) was used as chemical coupling agent. To enhance the mechanical properties the blends were compounded with the layered structure montmorillonite (MMT) in different concentrations. The effect of PEgMA, MMT and their combination on the mechanical and melting properties were examined in this study.

Open Access: Yes

DOI: DOI not available