Edward Chlebus

Wrocław University of Science and Technology | WUT · Institute of Production Engineering and Automation

Purpose: The current study examined magnesium alloy AZ31B specimens manufactured with Additive Manufacturing method (selective laser melting - SLM) to investigate the applicability of this technology for the production of medical devices. Methods: Osteoblast cells and bacterial biofilm growth ability on specimen was examined and the effect of su...

Purpose This paper aims to discuss the results of material tests conducted on specimens manufactured from AZ31 alloy powder by selective laser melting (SLM) technology. The manufactured specimens were then subjected to porosity assessment, microstructure analysis as well as to mechanical and corrosion tests. Design/methodology/approach SLM process...

In the present study, a commercially pure (CP) Ti and Ti–Re alloys containing 2 and 4 wt% of Re were manufactured by selective laser melting (SLM) and characterized in terms of microstructure, strength and fatigue crack propagation resistance. On the contrary to a homogenous lath-type martensitic α′ microstructure with no signs of directional solid...

Standard experimental research works are aimed at optimization of Selective Laser Melting (SLM) parameters in order to produce material with relative density over 99% and possibly the highest scanning speed. Typically, cuboidal specimens with arbitrarily selected dimensions are built. An optimum set of parameters, determined on such specimens, is u...

The intensive growth and development of additive manufacturing affects all operations across the production chain. This article focuses on aspects of changes in logistics and supply chains during the transition from or replacement of traditional manufacturing with additive manufacturing, in new or existing enterprise. Today, hardware being shipped...

This paper presents results on processing AZ31 magnesium alloy with Selective Laser Melting technology. The process optimization was performed according to the Design of Experiments methods. The porosity analysis shown that fully dense specimens were achieved. Thanks to the Analysis of Variance (ANOVA), the impact of changed parameters on the poros...

Selective laser melting (SLM) is a fast growing, Additive Manufacturing (AM) technology, that creates opportunities for manufacturing complex geometries (both monolithic volumes and spatial structures) directly from metal powders and CAD 3D computer model. Therefore, the SLM technology is recognized as a manufacturing technology of the future. Many...

The purpose of this study was to design a 3D geometry of mini-plate for mandibular angle fracture, based on biomechanical properties, that will be possible to manufacture with additive technologies (AM). Three types of internal structures (lattice, cross and honey comb) were selected and compare the results of displacement and von Mises stress dist...

Selective laser melting (SLM) is a fast growing, Additive Manufacturing (AM) technology, that creates opportunities for manufacturing complex geometries (both monolithic volumes and spatial structures) directly from metal powders and CAD 3D computer model. Therefore, the SLM technology is recognized as a manufacturing technology of the future. Many...

Purpose This paper aims to present the way of modifying surfaces of 316L stainless steel elements that were manufactured in the selected laser melting (SLM) technology and then subjected to mechanical and electrolytic processing (electropolishing [EP]). The surface of the as-generated and commercial produced parts was modified by grinding and EP, a...

In this study, the effect of rhenium addition (2, 4, and 6 wt pct) and building orientation (0 and 90 deg) on the microstructure and corrosion resistance of Inconel 718 (IN718) alloy processed by selective laser melting (SLM) was investigated. Microstructure characterization showed that the as-built IN718-Re alloys consist of columnar grains growin...

Selective laser melting (SLM) is an additive manufacturing process that enables novel alloy production by combining metals with significantly different physical properties. In this paper, the hot corrosion behavior of Ti–Re alloys fabricated by SLM was studied in a mixture of Na2SO4 and NaCl salts at 600 °C. The morphology and composition of the co...

Unlike conventional manufacturing techniques, additive manufacturing (AM) can form objects of complex shape and geometry in an almost unrestricted manner. AM's advantages include higher control of local process parameters and a possibility to use two or more various materials during manufacture. In this work, we applied one of AM technologies, sele...

Nowadays, a CoCrMo alloy is widely used in medicine due to its high corrosion resistance and biotolerance. The possibility to change its mechanical properties (σt, σ0.2 and elongation ԑf) means a large extension of properties in accordance with the requirements of the end-user and could lead to an increase in the attractiveness of a CoCrMo alloy fo...

Nowadays, a CoCrMo alloy is widely used in medicine due to its high corrosion resistance and biotolerance. The possibility to change its mechanical properties means a large extension of properties in accordance with the requirements of the end-user and could lead to an increase in the attractiveness of a CoCrMo alloy for applications in other indus...

Selective laser melting of Inconel 718 (IN718) alloyed with rhenium is an attempt to increase high temperature properties of widely AMused nickel superalloy, without losing its processability. As SLM technology uses metal powders of very low fraction (usually 20-65 µm), the creation of new alloys is possible by mixing powders of alloy components wi...

High-density 316 L specimens were fabricated by selective laser melting (SLM). Different processing parameters, including laser power (100, 200 W) and scanning strategies (alternating stripes without and with re-melting after every layer) were employed to evaluate their impact on microstructure and texture of the specimens. Microstructures of the s...

Laser surface alloying (LSA) with rhenium was applied to produce wear and corrosion resistant layers on Inconel 718 alloy. Using a high-power diode laser and 50% overlapping ratio of laser tracks, two kinds of alloyed layers were produced: IN718–14 wt% Re layer with completely dissolved Re powder in substrate, and IN718–28 wt% Re layer with partial...

The paper describes a method of cutting housings of refrigerating appliances with a CO2 laser, as a stage of their disassembly during recycling. The housings are made of laminar “sandwich” composites with low susceptibility to be processed after withdrawal from use. The problems of their utilization result from difficulties to separate the three ma...

The paper addresses the problem of lumpy demand forecasting which is typical for spare parts. Several prediction methods are presented in the article - traditional techniques based on time series and advanced methods which use artificial neural networks. The paper presents a new hybrid spares demand forecasting method dedicated to mining companies....

The role of rhenium in refractory metals and superalloys is well known. This study was performed to investigate the effect of rhenium in stainless steels. Results of al-loying rhenium into 316L alloy was done by consolidation of 316L and rhenium powders and processing of such prepared mixtures with the use of selective laser melting technology. The...

AISI H13 tool steel and selective laser melting technology is being successfully implemented for the production of injection moulds. Due to the complex geometry of injection moulds scanned cross sections has variable sizes. It is therefore important to develop variable parameters allowing to produce parts with a different distribution of scan field...

The paper presents the results of the process development of laser surface modification of commercially pure titanium with rhenium. The criterion of the successful/optimal process is the repetitive geometry of the surface, characterized by predictable and repetitive chemical composition over its entire surface as well as special mechanical properti...

The present article is dedicated to an investigation of a production method of hydroxyapatite (HA) disks with a study of an influence of compression speed (5, 10 and 15 on structure and properties of those disks. Measurements of density, mass loss and shrinkage as well as scanning electron microscopy (SEM) and light optical microscopy (LM) observat...

Lutowanie prętów stojana ze skuwką, z dużą liczbą miedzianych przewodów elementarnych, jest procesem specjalnym, wynikającym ze złożonej konstrukcji lutowanego złącza. W opracowanej technologii lutowania twardego zastosowano regulowany docisk górny pakietu, zmieniany przed rozpoczęciem procesu i bezpośrednio przed jego zakończeniem. Wywierany jest...

Additive manufacturing (AM) technologies are used to produce objects from a wide variety of materials. Technologies that enable processing of metal engineering materials such as selective laser melting have become particularly important. The group of materials pro-cessed in this technology comprises stainless steel, CoCr, titanium and aluminum allo...

The SLM process offers considerable set of advantages in comparison to traditional manufacturing techniques, like low material consumption or possibility to manufacture complex parts. These characteristic qualify SLM process for aerospace applications. Four orientations (0°, 45°, 45°x45° and 90° - in relation to the building direction) of high dens...

Selective Laser Melting allows building structures of unique and complex shape. Nowadays, the technology is successfully applied in the production of components of titanium-, cobalt-chromium and nickel alloys. However, the range of available materials continues to grow. Tungsten could be such a novel material for powder-bed technologies. The produc...

Data exchange between different computer systems in design and manufacturing processes planning is a very important issue of computer aided engineering. Computer Aided Process Planning (CAPP) systems require properly pre-processed design data. Such data refer not only to geometry, but also to additional information such as dimensions, dimensional a...

Particle shape and size, density and distribution are important characteristics of the powders processed by additive manufacturing processes e.g. Selective Laser Melting (SLM) or Electron Beam Melting (EBM). Spherical shape of powder particles allows to stably carrying out the process and affects also the manufactured objects properties. Desired mo...

Biocomposite (or bioceramic) materials have become very popular, especially for replacing some human bone parts, such as hip joints, knee joints, and producing implants for dentistry and others. It is supposed that cladding coatings with hydroxyapatite (HA) on a metallic substrate could be a good solution for implants. Production of laser cladding...

Additive manufacturing (AM) allows producing objects with functional internal structures; one of their applications is the production of medical implants (scaffolds), which may substitute bone tissue. The aim of this study is to evaluate, by micro computed tomography (μCT), the geometric accuracy of scaffolds manufactured from Ti–6Al–7Nb alloy by s...

Purpose – The paper presents the results of theoretical considerations and experimental tests concerning microscaffold fabrication by Selective Laser Melting (SLM). Also described are manufacturing technologies for regular lattice microstructure with smallest possible pore sizes and fullest possible order of geometric accuracy retained. Process par...

The paper presents selected results of the adaptation of Lean Manufacturing methods to the mining industry conditions. The research was carried out within the framework of R&D project "Adaptation and implementation of Lean in the copper mines." The article focuses on the key issues related to the Total Productive Maintenance. TPM in a mine accordin...

Purpose In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen...

Microstructural and mechanical properties of Inconel 718 were determined on the specimens manufactured by selective laser melting (SLM) of prealloyed powder. High density (99.8%) cylindrical specimens were built with four orientations (0°, 45 °, 45°×45° and 90°) in relation to the building and scanning directions. Because of directional, dendritic-...

The article presents the technology of laser cladding of metallic powders and a machine for laser microsurfacing developed for this purpose. This specifically designed and manufactured station is based on a three-axis CNC machine, equipped with appropriate laser safety systems and a dust extraction system. A disc laser is used as a source of laser...

Mini-samples technique was utilized to determine mechanical properties of technically pure titanium produced by means of selective laser melting (SLM). Full-field digital image correlation (DIC) measurements and inverse method were applied for crack tip position and stress intensity factors calculations in the case of fatigue crack growth rate t...

Manufacturing technologies using laser radiation energy are gaining increasingly new applications. It results from their numerous advantages, most of all, from the selectiveness of a laser beam within the spatial and temporal domain. Although the laser beam is a very precise tool, it restricts the tolerances of component preparation. If such increa...

It is widely thought that inflammation and osteoclastogenesis result in hydroxyapatite (HA) resorption and sequestrum formation during osseous infections, and microbial biofilm pathogens induce the inflammatory destruction of HA. We hypothesized that biofilms associated with infectious bone disease can directly resorb HA in the absence of host infl...

The paper presents results of processing Ti–Re alloys by consolidating mixtures of powders of both metals with the use of selective laser melting (SLM). Ti-based alloys containing 0.5, 1.0 and 1.5 at% Re were obtained in this way. Optimum process parameters were determined by accepting the criterion of minimum porosity of manufactured parts and max...

Industrial tomography (XCT) is a nondestructive test method that provides information about spatial distribution of X-ray absorption in the analyzed structures. The aim of this paper was to examine the possibility and accuracy of application of XCT method for discontinuity and porosity detection in parts made of 316L stainless steel powder produced...

The titanium–aluminium–niobium alloy is used in bone, dental and articular prosthetics, where high final surface quality is required. Bone scaffolds for tissue engineering require optimized cellular structures to provide pore diameters allowing the growth of osteoblasts. The aim of the presented paper is to estimate the quality of surface treatment...

Monolithic and spatial samples of Ti-6Al-7Nb alloy were prepared by powder-bed selective laser melting and treated in HF and HF+HNO3 baths to improve surface quality and remove loose powder particles trapped in the porous structure of the samples. The HF+HNO3-contg. bath was more efficient (better surface quality, shorter treatment time) than the H...

Laser technology of micro-metallurgy of powders (Selective Laser Melting, SLM) is applied to manufacture three-dimensional metal objects of any shape. These objects are manufactured by melting powder of metal layer by layer with a high-power laser. Each melted layer has a contour marked with a cross-section by a 3D model of the manufactured object....

The paper presents the possibility of using reverse engineering in forensic science. Available reverse engineering technologies and examples of their use as a helpful forensic research tool are reviewed. A method of reconstruction of objects using computed tomography technology was described, as well as an example of the application of this method...

This paper presents the characterization of a commercial nationwide Wi-Fi hotspot network. We examine a 5 month long log of user activity and traffic volume collected by a wireless network service provider operating hotspots in restaurants, serviced apartments, hotels and airports all over Australia. We categorize users based on their account time...

The Gram-positive coccus, Staphylococcus aureus, is the leading etiologic agent of limb and life-threatening biofilm-related infections in the patients following the orthopaedic implantations. The aim of the present paper is to estimate the ability of S. aureus to form biofilm on titanium alloy (Ti-6Al-7Nb) scaffolds produced by Selective Laser Mel...

316L stainless steel was electropolished in 3 electrolytes consisting of H2SO4, H3PO4 and org. additives (Et3N, OHCH2CH2OH, (COOH)2, PhNHAc, glycerol) at 55°C and anodic current d. 20 A/dm2. In the Et3N-contg. bath, the roughness Ra was 0.063–0.065 µm and in the OHCH2CH2OH, (COOH)2 and PhNHAc-contg. bath, 0.091–0.096 µm. The bath consisting H3PO4...

316L stainless steel was electropolished In 3 electrolytes consisting of H3PO4 and org. additives (Et3N, OHCH 2CH2OH, (COOH)2, PhNHAc, glycerol) at 55°C and anodic current d. 20 A/dm2. In the Et3J-contg. bath, the roughness Ra was 0.063-0.065 μm and in the OHCH2CH 2OH, (COOH)2 and PhNHAc-contg. bath, 0.097-0.096 μm. The bath consisting H3PO4 and gl...

In its first part, the paper describes the mechanism of constitutional liquation and specifies the conditions favourable to this phenomenon. Then, two case studies of service failure caused by non-equilibrium liquation in AlCu4MgSi alloy and in stainless steel X46Cr13 are analysed. Components made of these alloys were subject to solution annealing...

Additive layer-based selective laser melting technologies (SLM), provide a new range of possibilities for ob- jects manufacturing. In the present study the alumina/ titania Al2O3/TiO2 coatings were applied onto SLM-manufactured substrates by the atmospheric plasma spraying method. The microstructure and porosity of coatings were examined by scannin...

Patients after trauma or tumor removal often require restoration of cranio-maxillo-facial bone functions and aesthetics. Additive manufacturing technologies offer an efficient solution in production of custom-designed implants for specific clinical cases. Their capabilities also allow for manufacturing objects with complex geometries, including tis...

This paper presents processes of numerical data processing and objects digitalizing in recycling of household appliances. General description of technological line designed for refrigerators recycling. Processes of refrigerator housing scanning and scanned data processing are presented. Algorithm of scanning process, data filtration and key paramet...

The paper presents results of studies on Selective Laser Melting. SLM is an additive manufacturing technology which may be used to process almost all metallic materials in the form of powder. Types of energy emission sources, mainly fiber lasers and/or Nd:YAG laser with similar characteristics and the wavelength of 1,06 - 1,08 microns, are provided...

This paper presents proposed new design solutions for hip endoprosthesis stems characterised by reduced stiffness as a result of application of internal lattice structures obtained using generative production techniques. The conducted analysis showed the possibility of achieving lattice structures inside implants as well as the possibility of contr...

W artykule przedstawiono technologię laserowego napawania proszków metali oraz opracowaną dla niej obrabiarkę do laserowego mikronapawania proszków. Zaprojektowane i wykonane stanowisko bazuje na trzyosiowej obrabiarce CNC, którą wyposażono w odpowiednie układy bezpieczeństwa laserowego i pyłowego. Jako źródło energii laserowej wykorzystano laser d...

Gaining competitive advantage in the contemporary business world requires entrepreneurs to quickly adapt to the changes occurring in the ever more dynamic environment. The tendency related with transition from competitiveness to cooperation was very distinctive in the World in the last twenty years. Nowadays initiatives in this direction are also u...

This paper presents a description of an expert system developed specially for technological processes planning. Commercially available rulebased shell expert systems do not offer appropriate solutions in the scope of knowledge processing and knowledge representation. Hence authors had developed an own shell expert system devoid of aforementioned dr...

The simulative agent system is going to be capable of independent collection of information required for construction of a simulation model, monitoring and constant data updating, deciding on the necessity of building new updated simulation models, applying changes to data (based on results of a conducted simulation) into class ERP and PDM systems....

Selective laser melting (SLM) is an advanced manufacturing technology providing alternative method of producing complex components directly from 3D computer models. The purpose of this work is to determine the influence of the SLM manufacturing strategy on mechanical properties and microstructure of the as-built Ti-Al-Nb alloy. Specimens of Ti-6Al-...

We have used Euler–Maclaurin summation to develop a recursive scheme for modifying the original approximation for the Euler–Mascheroni constant . Convergence to  resulting from successively employing the proposed scheme has been significantly accelerated while the form of the approximation originally introduced by Euler is still preserved.

The current characterization methodology for Wi-Fi hotspot networks analyzes parameters related to the entire subscriber population. It does not consider the impact of the fluctuating number of subscribers. In this paper we develop a methodology to characterize user specific, population independent parameters of a Wi-Fi hotspot network and apply it...

The production system was defined with regard to system theory. The risk concept was treated as synonym of unreliability. This kind of approach enabled decomposition of the production system into several areas and determination of reliability structure. The paper presents method of the risk value evaluation for serial-production structures and conc...

A novel unique probability distribution, which has a lognormal body and either light or heavy tail, has been fitted to various empirical data sets of Web file sizes. The optimal parameters of this distribution have been determined by the maximum likelihood estimation combined with the optimization algorithm minimizing a goodness-of-fit metric speci...

We have applied the upper truncated Pareto distribution to modeling the probability distribution of the terms of the p-series. The lower and upper bounds of their partial sum have been found and used for approximating its exact value. A relative error contributed by the proposed approximation has been evaluated.

The production system was defined in accordance with systems theory, while the risk was treated as a synonym of unreliability. This approach allowed decomposing the production system into several areas and determining the reliability structure of the production system. This paper presents a method of determining the risk for a production system wit...

Commercial Wi-Fi hotspot operators often categorize their customers depending on price, time and traffic limits. This paper presents the first comparison of user and traffic characteristics of three different categories of commercial Wi-Fi hotspot users. We examine a five month long trace of user activity and traffic collected by a wireless hotspot...

A new probability distribution following from Lavalette's law has been proposed for modeling wireless Internet access session statistics collected in a public nationwide Wi-Fi network. We have derived maximum likelihood estimators for this distribution and found them for three data sets of session duration and traffic volume measurements. Goodness...

This paper presents the first analysis of user and traffic characteristics in a commercial nationwide Wi-Fi hotspot network. We examine a five month long log of user activity and traffic collected by a wireless network service provider operating hotspots in cafes, restaurants, serviced apartments, hotels and airports all over Australia. We analyze...

In this paper we show that daily web session arrivals are nonstationary Poissonian with a rate surprisingly stable, i.e., changing only once per 24 hours in all the examined cases.

We have analyzed measurement traffic statistics for high-speed wireless Internet access sessions collected in a public nationwide Wi-Fi network. By ranking session lengths and traffic volumes we have found a law implying the truncated Pareto distribution. This finding is analogous to the relationship between Zipf's law and the Pareto distribution....

The ring and toroidal cell layouts are commonly used to avoid the so called “edge effect” which may significantly bias performance modeling of wireless mobile systems. Both these layouts are applied to traffic analysis of cells operated in rural, suburban and urban environments. The obtained results are compared and validated against field data.

The manufacture and consumption of market products show ever growing trends, and this means not only the supply and demand volume but also, to a higher and higher extent, searching for new products distinguishable from the variety of products on the market. Thus, it is necessary to find methods of functional, logical and structural combination of t...