Showing papers in "Journal of achievements in materials and manufacturing engineering in 2008"

TOPSIS and fuzzy multi-objective model integration for supplier selection problem

Abstract: Purpose: The problem includes the three objective functions: minimizing the total cost, the net rejected items and the inverse total value of purchasing (TVP), while satisfying capacity and demand requirement constraints. Design/methodology/approach: The model is established for supplier selection problem and later the proposed single objective model is used to calculate the optimum order quantities among the selected suppliers. A numerical example is given to illustrate how the model is applied. Findings: In this article, we proposed a single objective function to solve the fuzzy multi-item multi-objective model in order to calculate the optimum order quantities to each supplier. Practical implications: Single objective function, which is able to consider the relative importance of the goals, is proposed to solve the model. A numerical example is given to illustrate how the model is applied. Originality/value: This approach is able to help the DM evaluate the suppliers in order to find out the appropriate order to each them, and allows purchasing manager(s) to manage supply chain performance on service, cost, quality and etc. the suppliers’ price breaks, which depend on the sizes of order quantities, affects the selection process.

Manufacturing of aluminium matrix composite materials reinforced by Al2O3 particles

Abstract: Purpose: The purpose of the paper is to show and compare of modern method composite materials with aluminium alloy matrix reinforced by Al2O3 particles manufacturing. Design/methodology/approach: Material for investigation was manufactured by two methods: powder metallurgy (consolidation, pressing, hot extrusion of powder mixtures of aluminium EN AW-AlCu4Mg1(A) and ceramic particles Al2O3) and pressure infiltration of porous performs by liquid alloy EN AC AlSi12 (performs were prepared by sintering of Al2O3 powder with addition of pores forming agent – carbon fibers). Findings: The received results show the possibility of obtaining the new composite materials with required structure joining positive properties composite materials components. Practical implications: Tested composite materials can be applicate among the others in automotive industry but it requires additional researches. Originality/value: Worked out technologies of composite materials manufacturing can be used in the production of small elements near net shape and locally reinforced elements.

Surface roughness investigation and hardness by burnishing on titanium alloy

Abstract: Purpose: Burnishing is a chip less machining process in which a rotating roller or ball is pressed against metal piece. It is a cold working process and involves plastic deformation under cold working conditions by pressing hard. The burnishing process help to improve surface roughness and hardness. Design/methodology/approach: The methodology adopted was using a multi roller on square titanium alloy material by designing various sliding speed/ spindle speed, feed rate and depth of penetration. Findings: The roller burnishing is very useful process to improve upon surface roughness and hardness and can be employed. It will help to impart compressive stress and fatigue life can be improved. The titanium alloy is a difficult to machine material and burnishing is difficult process for this grade material. A low surface roughness and high hardness was obtained for the same spindle rotation, feed rate and depth of penetration. Research limitations/implications: There are some limitations in increasing the operating parameters. It may develop flaw and micro cracks on the surface.

Oil, grease and used petroleum oil management and environmental economic issues

Abstract: Purpose: This paper undertakes to answer the question of how used petroleum oil and grease enter groundwater or to the drain becoming both environmental and economic problems to utility companies. Design/methodology/approach: Laboratory methodology was based on modern instrumentation validated further with experimental investigation. Petroleum-contaminated soil samples were analyzed for oil and grease (O/G) content, total petroleum hydrocarbons (TPH), and volatile aromatic compounds: benzene, toluene, ethylbenzene, and xylenes (BTEX) and naphthalene. Gas chromatography-Mass Spectrometry (GC/MS) was used to analyse BTEX and naphthalene analytes. Findings: The results show that total petroleum hydrocarbon fraction (TPH) accounted for oil and grease (O/G) and the ratio of [TPH]/[O/G] ranged from 12% to 50%. The results of volatile organic fraction (BTEX) accounted for only a small part of total TPH and the ratio of [BTEX]/[TPH] ranged below 1%. The concentration of four samples for TPH test exceeded the regulatory limit of 500 ppm for hydrocarbons. The gas chromatography-flame ionization detector (GCFID) method appear to offer the best basis for standard TPH test in soil and groundwater verification of site cleanup. Research limitations/implications: In the future it will be possible to apply the procedures to other more complicated cases e.g. used oil containing more than 1000 ppm total halogens, which is regulated as hazardous waste. Practical implications: Promising directions for adaptation of appropriate pre-treatment standard processes for recycling programs, pollution prevention and reduction of maintenance cost. Originality/value: The gas chromatography-flame ionization detector (GC-FID) methods appear to offer the best hope for standard TPH test in soil and groundwater verification of site cleanup. Implementation of management standards and a permit policy for O/G and used oil generators will be issued to each facility.

Investigations for deducing wall thickness of aluminium shell casting using three dimensional printing

Abstract: Purpose: of the present study is to verify the feasibility of decreasing the shell thickness in rapid shell casting based upon ‘three dimensional printing’ technology in order to evaluate the dimensional accuracy for aluminum castings. Rapid prototyping has been in evidence for the past twenty years and is being widely used in diverse areas, from the building of aesthetic and functional prototypes to the production of tools and moulds for technological prototypes Design/methodology/approach: Further consistency with the tolerance grades of the castings has been checked as per IT grades along with mechanical properties of the aluminium castings. Starting from the identification of component/ 87benchmark, technological prototypes are produced with different shell thicknesses. Measurements on a coordinate measuring machine allowed calculating the dimensional tolerances of the castings produced. Findings: The research proved that the shell thickness having value less than the recommended one is more suitable from dimensional accuracy and economic point of view. The result indicates that at 5 mm shell thickness, hardness of the casting is improved by 3.79%. Further production cost and production time has been reduced by 54.6% and 55.4% respectively in comparison to 12 mm recommended shell thickness. Practical implications: The analysis procedure is better for proof of concept and for the new product, for which the cost of production for dies and other tooling is more. Originality/value: The 3DP technique at different shell thicknesses (12 mm to 2 mm) provided satisfactory results, limited at present to the field of light alloys. This process ensures rapid production of pre-series technological prototypes and proof of concept at less production cost and time.

Microstructure evolution and phase composition of high-manganese austenitic steels

Abstract: Purpose: The aim of the paper is to determine the influence of hot-working conditions on microstructure evolution and phase composition of new-developed high-manganese austenitic steels. Design/methodology/approach: Determination of processes controlling strain hardening was carried out in continuous compression test using Gleeble 3800 thermo-mechanical simulator. Evaluation of processes controlling work hardening and occurring after deformation at 900°C were identified by microstructure observations of the specimens solution heat-treated after plastic deformation to a true strain equal 0.23, 0.50 and 0.91. Phase composition of steels was confirmed by X-ray diffraction analysis. Findings: The steels have a fine-grained austenite microstructure with many annealing twins to a temperature of about 1000°C. The initiation of dynamic recrystallization occurs already after true deformation equal 0.29. Participation of fine grains arranged in a matrix of dynamically recovered grains essentially increases after increasing true strain to 0.5. Fully dynamically recrystallized microstructure of steel can be obtained after the true strain equal 0.9. The conditions of hot-working influence phase state of investigated steels. Steel no. 1 keeps stable austenite microstructure independently from conditions of plastic deformation. Steel with initial bi-phase microstructure keeps a certain portion of eyet dependant on conditions of hot-working. Research limitations/implications: To determine in detail the hot-working behaviour of developed steels, a progress of microstructure evolution in subsequent stages of multi-stage compression test should be investigated. Practical implications: The obtained microstructure – hot-working conditions relationships and stress-strain curves can be useful in determination of power-force parameters of hot-rolling for sheets with fine-grained austenitic structures. Originality/value: The hot-working behaviour and microstructure evolution in various conditions of plastic deformation for new-developed high-manganese austenitic steels with Nb and Ti microadditions were investigated.

Basic solutions on shape complexity evaluation of STL data

Abstract: Purpose of this paper is to present basic solutions on shape complexity, based on basic information of the STL data. Design/methodology/approach: Paper presents a few methods of mathematically evaluating the complexity of the shape. Methods vary from very simple based on the number of triangles in STL file, STL file size and the parts volume, to the more complex mathematical evaluation based on the basic relations of the STL data. Findings: We discovered that evaluation of shape complexity based only on basic data of STL data gives us some basic results on part complexity and can be used for further researches. Research limitations/implications: For parts with large block volume/part volume ratio and thinner parts with free form surfaces only the first method is suitable and gives suitable results. Practical implications: In a rapidly developing field of manufacturing technologies choosing the optimal manufacturing procedure is a difficult and crucial decision. Usually the decision is based on experience evaluation that is fast and can be optimal. Usually, this method produces goods results, but in some cases this method can lead to cost increases and reduced economic efficiency without us even knowing that. Therefore, it is crucial, that a fast and simple solution is developed, by which the optimal way of manufacturing can be determined. Originality/value: Choosing maximum efficient manufacturing processes on base of part complexity is a new perspective in manufacturing, which, properly evolved and complied can cause revolution in manufacturing optimization, especially in hybrid manufacturing processes.

Influence of hot-working conditions on a structure of high-manganese austenitic steels

Abstract: Purpose: The aim of the paper is to determine the influence of hot deformation conditions on σ-e curves and structure changes of new-developed high-manganese austenitic steels. Design/methodology/approach: The force-energetic parameters of hot-working were determined in hotcompression tests performed in a temperature range of 850 to 1050°C by the use of the Gleeble 3800 thermomechanical simulator. Evaluation of processes controlling work hardening at 850°C were identified by microstructure observations of the specimens water-quenched after plastic deformation to a true strain equal 0.22, 0.51 and 0.92. Findings: At initial state the steel containing 3% of Si and Al possesses homogeneous austenite structure with many annealing twins. Increased up to 4% Si concentration and decreased to 2% Al concentration result in a presence of some fraction of e martensite plates. For applied deformation conditions, the values of flow stress vary from 250 to 450MPa – increasing with decreasing deformation temperature. A relatively small values of e max deformation at temperatures of 1050 and 950°C allow to suppose that in this range of temperature, to form a fine-grained microstructure of steels, dynamic recrystallization can be used. At a temperature of 850°C, the dynamic recrystallization leads to structure refinement after true strain of about 0.51. Research limitations/implications: To determine in detail the hot-working behaviour of developed steels, a progress of recrystallization as a function of time at deformation temperature should be investigated. Practical implications: The obtained stress-strain curves can be useful in determination of power-force parameters of hot-rolling of high-manganese austenitic steels. Originality/value: The hot-working behaviour of new-devoloped high-manganese austenitic steels containing Nb and Ti microadditions was investigated.

Potential applications of nanofiber textile covered by carbon coatings

Abstract: Purpose: Nanospider technology is modified electrospinning method for production nanofiber textile from polymer solutions. This material can be used as wound dressing and filter materials for example. Carbon coatings deposited onto surface of polymer nanofiber textiles are predicted to improve filtration effectivity of filters and bioactivity of wound dressings. Carbon coatings have been produced by Microwave Radio Frequency Plasma Assisted Chemical Vapor Deposition (MW/RF PACVD) method. Design/methodology/approach: Carbon coatings were deposited on polymer nanofiber textile by MW/RF PACVD method. Nanocomposite obtained in this way was characterized by the contact angle studies and by scanning electron microscope (SEM). Findings: Carbon coatings can be deposited on the polymer nanofibers by MW/RF PACVD method. Content of diamond phase in produced carbon coatings has been confirmed by wetability test. A SEM microscopic images have shown that the spaces between the nanofibers have not been closed by the material of the film.

Finite Element Method application for modeling of PVD coatings properties

Abstract: Purpose: The main subject of this paper is the computer simulation with the use of finite element method for determining the internal stresses in coatings Ti+TiN obtained in the magnetron PVD process on the sintered high-speed steel of the ASP 30 in different temperatures of 460, 500 and 540 °C. Design/methodology/approach: Computer simulation of stresses was carried out with the help of finite element method in ANSYS environment, and the experimental values of stresses were determined basing on the X-ray diffraction patterns. Findings: The presented model meets the initial criteria, which gives ground to the assumption about its usability for determining the stresses in coatings, employing the finite element method using the ANSYS program. The computer simulation results correlate with the experimental results. Research limitations/implications: To evaluate with more details the possibility of applying these coatings tools, further computer simulation should be concentrated on the determination of other properties of the coatings for example- microhardness.

Dynamical flexibility of discrete- continuous vibrating mechatronic system

Abstract: Purpose: The application of approximate method for solving the task of assignment the frequency-modal analysis and characteristics of flexibly vibrating mechatronic system, because for considered case of boundary conditions exact and approximate methods for the coordinates are equivalent. Design/methodology/approach: Formulate and solve the problem in the form of a set of differential equations of motion and state equations of the considered mechatronic model of an object Galerkin’s method was used. The considered flexibly vibrating mechanical system is a continuous beam, clamped at one of its ends. An integral part of the mechatronic system is a transducer perfectly bonded to the beam surface. Findings: The parameters of the transducer exert an important influence on the values of natural frequencies and on the form of the characteristics of the discussed mechatronic system. Research limitations/implications: The linear mechanical subsystem and linear electrical subsystem of the mechatronic system were analyzed and the theory Euler-Bernoulli is used for the beam; however, this approach is sufficient for such systems. Practical implications: Global approach is presented in the domain of frequency spectrum analysis. The methods of analysis and the obtained results my give grounds for designing and investigating this type of mechatronic systems. Originality/value: The mechatronic system created from mechanical and electric subsystems with electromechanical bondage has been considered. This approach is different from those considered so far.

Mechanical alloying for fabrication of aluminium matrix composite powders with Ti-Al intermetallics reinforcement

Abstract: Purpose: The aim of this work is to report the effect of the high energy milling processes, on fabrication of aluminium matrix composite powders, reinforced with a homogeneous dispersion of the intermetallic Ti3Al reinforcing particles. Design/methodology/approach: MA process are considered as a method for producing composite metal powders with a controlled fine microstructure. It occurs by the repeated fracturing and re-welding of powders particles mixture in a highly energetic ball mill. Findings: Mechanical alloying, applied for composite powder fabrication, improves the distribution of the Ti3Al intermetallic reinforcing particles throughout the aluminium matrix, simultaneously reducing their size. Observed microstructural changes influence on the mechanical properties of powder particles. Research limitations/implications: Contributes to the knowledge on composite powders production via MA. Practical implications: Gives the answer to evolution of the powder production stages, during mechanical alloying and theirs final properties. Originality/value: Broadening of the production routes for homogeneous particles reinforced aluminium matrix

Identification of composite materials at high speed deformation with the use of degenerated model

Abstract: Purpose: Composite materials on account of some their characteristics have application in a construction of ballistic shield. An example of the ballistic shield is laminate with the mix-structure materials such as layer pressed of aramid cloths on matrix polymer. Because of the shield’s assignment the aramid cloths are exposed to impact loads caused by an energy made by impact force of cumulated mass (bullet). Previous analyses of the effect are based on linear-elastic reaction of resisting forces between the materials of a bullet and a shield. The article exemplifies the procedure of mechanical properties analysis in the punch effect of the ballistic shield with the use of some of the non-elastic models. Design/methodology/approach: In the article the theoretical analysis of punch effect in the quasi-static load condition based on some of the degenerated models is also presented. Findings: The results of the analysis make aware of demand for designing safety ballistic shields.

Preparation and study of model magnetorheological fluids

Abstract: Purpose: The aim of this work was preparation of the model magnetorheological (MR) fluids. Basic properties of prepared MR fluids, as their response to an external magnetic field and their stability, were investigated. Moreover (furthermore) few results concerning stabilizing effect of various additives are presented. Design/methodology/approach: Model MR fluid was prepared using three type of carriers: silicone oil OKS 1050, synthetic oil OKS 352, mineral oil OKS 600 mixed with carbonyl iron powder CI HQ. Furthermore, to reduce sedimentation Aerosil 200 and 972, Arsil 1100 and Arabic gum were added as stabilizers. MR effect was measured using device working as Couette’s viscosimeter equipped with coil generating magnetic field. Sedimentation was measured by simply observation of changes in boundary position between clear and turbid part of MR fluid placed into glass tube. Findings: Influence of the additives presence on the MR effect was determined. The presence of additives did not diminish the magnetic effect but even increased the dynamic viscosity in existence of an external magnetic field. The stability of MR fluid was improved by adding additives to the formulation. Moreover, increasing stabilizer concentration further enhanced the MR fluid stability. The best result was achieved in case of Aerosil 9782 at 2 % content. Research limitations/implications: MR fluids with excellent properties can be applied in various fields of civil and safety engineering, transportation and life science. However, due to sedimentation, MR fluid response to magnetic field is restricted and in an extreme situation could lead to the fail that is why further efforts must be still made in order to obtain even better results. Originality/value: This article provides set of new data about improvement of MR fluid stability in the presence of selected stabilizers and contains few remarks how the formulation of MR fluid affect its properties.

Synthesis of mechanical systems including passive or active elements

Abstract: Purpose: In this work there is presented basic method of synthesis of active and passive mechanical systems realization. The principal aim of the research is to work out a method of structure and parameters searching i.e. structural and parametric synthesis of a discrete model of mechanical system on the base of desired requirements. The requirements refer to dynamic features of the system, particularly its frequency spectrum. The purpose of this paper is also comparison of reduction of vibrations in mechanical systems by use the passive and active elements. Design/methodology/approach: In this work used unclassical method of polar graphs and their relationship with the algebra of structural numbers. This method enables analysis without limitations depending on kind and number of elements of complex mechanical system using electronic calculation technique. Findings: Use of active elements into the elimination of vibration offers the possibility to overcome the limitations of the methods of passive elimination of vibration, such as, in particular, low efficiency in case of low-frequency vibration. Practical implications: The results represented this work in form of polar graphs extend the tasks of synthesis to other spheres of science e.g. electric systems. The practical realization of the reverse task of dynamics introduced in this work can find uses in designing of machines with active and passive elements with the required frequency spectrum. Originality/value: Thank to the approach, an unclassical method of polar graphs and their relationship with the algebra of structural numbers, can be conducted as early as during the designing of future functions of the system as well as during the construction of the system.

Surface roughness analyses on hard martensitic stainless steel by turning

Abstract: Purpose: The purpose of this research paper was to analyze the surface roughness produced by turning process on hard martensitic stainless steel by Cubic Boron Nitride cutting tool. The work piece material was hard AISI 440C martensitic stainless steel. Design/methodology/approach: The experiments were designed using various operating parameters like cutting speed, feed rate and depth of cut. These operating parameters are predominantly used in carrying out

Laser texturization in technology of multicrystalline silicon solar cells

Abstract: Purpose: This paper presents technology of multicrystalline silicon solar cells with laser texturization step. The texturing of polycrystalline silicon surface using Nd:YAG laser makes it possible to increase absorption of the incident solar radiation. Moreover, the additional technological operation consisting in etching in 20% KOH solution at temperature of 80oC introduced into technology of the photovoltaic cells manufactured from laser textured wafers allows for significant improvement in their electrical performance compared to cells produced from the non-textured wafers after saw damage removal. Design/methodology/approach: The topography of laser textured surfaces were investigated using DSM 940 OPTON scanning electron microscope and LSM 5 Pascal ZEISS confocal laser scanning microscope. The reflectance of produced textures was measured by Perkin-Elmer Lambda spectrophotometer with an integrating sphere. Electrical parameters of manufactured solar cells were characterized by measurements of I-V light characteristics under standard AM 1.5 radiation. Findings: Solar cells manufactured from laser-textured polycrystalline silicon wafers demonstrate worse electrical performance than cells manufactured from the non-textured wafers after saw damage removal as well as wafers textured by etching in alkaline solutions. Etching of textured surface in 20% KOH solution at temperature of 80oC subsequent to laser processing shows to have a greatly increased impact on electrical performance of solar cells. Research limitations/implications: Continued etching to remove laser induced defects cause the texture to flatten out reducing it optical effectiveness. Originality/value: This paper demonstrates, that laser processing is very promising technique for texturing multicrystaline silicon independent on grains crystallographic orientation compared to conventional texturing methods in technology of solar cells.

Multilayer and gradient PVD coatings on the sintered tool materials

Abstract: The paper presents investigation results of structure and properties of the multilayer and gradient TiN+(Ti,Al,Si)N+TiN nanocrystalline coatings deposited with the PVD method (CAE -Cathodic Arc Evaporation process) and in the combination of Al2O3 and TiN coatings in the CVD process on the substrate of cemented carbides, cermets, Al2O3+ZrO2, Al2O3+TiC, Al2O3+SiC(w) oxide ceramics and Si3N4 nitride ceramics. The structural investigation includes the metallographic analysis on the transmission and scanning electron microscope, confocal microscope. Examinations of the chemical compositions of the deposited coatings were carried out using the X-ray energy dispersive spectrograph EDS, glow-discharge optical emission spectroscope GDOS, and using the X-ray diffractometer. The investigation includes also analysis of the mechanical and functional properties of the material: substrate hardness tests and microhardness tests of the deposited coatings, surface roughness tests, evaluation of the adhesion of the deposited coatings, cutting properties of the investigated materials. Cutting tests were carried out on the multipoint inserts made from the materials based on cemented carbides, cermets, Al2O3 and Si3N4 ceramics, uncoated and coated with gradient, multicomponent and multilayer hard wear resistant coatings with PVD and CVD processes.

Biogas production with the use of mini digester

Abstract: Purpose: of this paper is to present the construction of a mini digester for biogas production from different energy plants and organic wastes. With the mini digester the amount of biogas production (methane) is observed. Design/methodology/approach: Firstly, the mini digester consisting of twelve units was built and secondly some measurements with energy plants were performed. The measurements were performed with mini digester according to DIN 38414 part 8. Four tests simultaneously with three repetitions can be performed. Findings: The mini digester was built and then parameters such as biogas production and biogas composition from maize and sugar beet silage were measured and calculated. The highest biogas and methane yield was 493 NI kg VS-1 or 289 NI CH4 kg VS-1. Research limitations/implications: The interest in the use of the biogas as a renewable source of energy is increasing and also the scope of substrates for the anaerobic digestion process is on the increase. With the mini digester it is possible to observe the amount of biogas (methane) production and thus the most suitable plant, giving the maximum methane yield, can be determined. Practical implications: The biogas is a renewable source of energy. On big farms the liquid manure and different energy plants can be used for biogas production. That can improve the economical efficiency of the farm and reduce the CO2 emissions. Originality/value: For biogas production a special device, the mini digester, was built. The composition of produced biogas is determined with the gas analyser GA 45.

Manufacturing of hard magnetic composite materials Nd-Fe-B

Abstract: Purpose: This paper presents the material and technological solution which makes it possible obtaining of hard magnetic composite materials: nanocrystalline material – polymer. Design/methodology/approach: For fabrication of composite materials the Nd-Fe-B powder obtained by melt quenching technique was used and for matrix: epoxy resin (EP) or high density polyethylene (HDPE) (2.5 % wt.). Composite materials were compacted by the one-sided uniaxial pressing. The complex relationships among the manufacturing technology of these materials, their microstructure, as well as their properties were evaluated. Materialographic examination of powders morphology and the structure of composite materials were made. Findings: Composite materials show regular distribution of magnetic powder in polymer matrix. Examination of mechanical properties show that these materials have satisfactory compression strength. Research limitations/implications: The advantage of the bonded composite materials is their simple technology, possibility of forming their properties, lowering manufacturing costs because of no costly finishing and lowering of material losses resulting from the possibility of forming any shape. The manufacturing of composite materials greatly expand the applicable possibilities of nanocrystalline powders of magnetically hard materials.

Structure and plasticity of the AZ31 magnesium alloy after hot deformation

Abstract: Purpose: The favourable properties of magnesium account for the fact that it is applied not only in cast structural components but also in those subjected to plastic working. Currently, intensive works are conducted to optimize the processes of plastic working of these alloys The following work concentrates on the analysis of microstructure and plasticity of magnesium alloy AZ31 type during hot plastic deformation process. Design/methodology/approach: After rolling and annealing, alloy specimens were subjected to axial-symmetric compression in the Gleeble 3800 simulator at temperatures ranging from 200 to 450°C at 0.01 and 1.0 s-1 strain rates. In order to analyse the processes which take place during deformation, the specimens after deformation were intensely cooled with water. Structural examination was carried out using light microscopy. Findings: The processes of structural reconstruction such as dynamic recrystallization, which take place during hot - deformation, have been detected. Practical implications: The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated AZ31 type alloy. The results will constitute the basis for modelling the structural changes. Originality/value: The results obtained are vital for designing an effective thermo - mechanical processing technology for the investigated Fe3Al-5Cr alloy.