|Zbigniew Konopka, Andrzej Wasik
The article describes several variations of the semi-solid metal processing (SSM) technique rendering castings with non-dendritic structure and significantly improved mechanical properties. The metal slurry was produced using the Rapid Slurry Forming (RSF) method. Based on a mathematical description of the RSF process of the metal slurry fabrication, castings were poured from the AlSi7Mg alloy in the form of a slurry with 30 vol. % solid fraction obtained by stirring and melting down of a chill element. Shown is the structure obtained by gravity casting. The temperature was measured during the slurry preparation and solidification of casting. The data obtained experimentally were compared with the theoretically calculated values.
Keywords: metal slurry, aluminum alloys, solidification, non-dendritic structure,
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Mieczysław Kuder, Krzysztof Jaśkowiec
The aim of the study was to determine the possibilities and conditions for the use of a multi-channel digital recorder to control cast iron quality by rapid thermal analysis. A computer program cooperating with a digital recorder was developed. It supports processing of the acquired data "live" or stored in the recorder memory. The program establishes parameters of the characteristic points on the cooling curve responsible for the properties of the iron melt. A series of melts of cast iron with pearlitic matrix and a varied form of graphite was made. Using professional system of thermal analysis and digital recorder, the waveforms of the cast iron solidification process were plotted for samples of standard and reduced wall thickness. The obtained solidification curves were subjected to detailed analysis to determine the critical temperatures, like TL, TElow, TEhigh, R, TS. The chemical composition and structure of the cast iron from experimental melts were examined. The results of measurements were compared using both sets of equipment. It was found that the use of the recorder and high sampling frequency allow carrying out the thermal analysis of cast iron at a high cooling rate and create favourable conditions for control of the production process of thin-wall iron castings.
Keywords: cast iron, thermal analysis, digital recorder, computer program, thin-wall casting,
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Marcin Małysza, Stanisław Pysz, Aleksander Fajkiel, Piotr Dudek, Krzysztof Saja, Michał Woś
Computer programs are now a common tool aiding the engineer’s work on structure design. The design of foundry moulds used in the pressure die casting process, based on the casting design and effectively utilising the ability to create 3D images of solid bodies, allows for quick preparation of technological documentation. The designer of foundry moulds, guided by technological premises, has to create the right conditions for the liquid metal flow and ensure proper die venting and cooling mould pressure. The possibility of early verification of the die cavity design with visualization of how it will be filled with molten metal reduces both time and cost of the casting preparation and implementation into production. There are many programs on the world market that perform simulation and analysis of pouring, solidification, and other phenomena and operations accompanying the casting shaping process. This article presents an analysis of ambient air behaviour under conditions of high pressure die casting. Computer simulations were performed using Flow-3D software on a test casting of simplified geometry. The results were displayed in a visual form for the die with and without the "stepped" venting injector insert.
Keywords: pressure die casting, computer simulation, venting injector insert,
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Waldemar Uhl, Krzysztof Jaśkowiec
In the research part of this study, several types of materials were proposed, including ADI (Austempered Ductile Iron) subjected to four different types of heat treatment, using cast manganese steel and cast nickel-copper steel. The use of these materials should provide adequate performance life to machine parts operating in wastewater treatment plants while also reducing the cost of manufacture. The selected materials were briefly discussed. A mould making technology was developed to make the respective cast parts. Castings were subjected to a finishing treatment and after hardness measurements were transferred to a wastewater treatment plant, where they were assembled to carry out the field tests.
Keywords: innovative foundry materials and technologies, wear resistant alloys, mechanical properties, ADI, turning machine, environmental protection,
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Edyta Rożniata, Robert Dąbrowski, Adam Kokosza, Rafał Dziurka, Jerzy Pacyna
The subject of the study is the analysis of the microstructure and mechanical properties of cast G200CrNiMo4-3-3 steel. The investigated alloyed cast steel, containing approximately 2% C, is nearly an ideal material for the hot mill work rolls, and this is mainly due to its very high abrasion resistance (in roll-gap), combined with very good mechanical and thermal fatigue properties. The performed metallographic examinations allowed establishing the characteristics of the cast steel microstructure in as-cast state and after heat treatment. The results of mechanical tests carried out on the cast G200CrNiMo4-3-3 steel were also reported. Among other things, a static tensile test was performed to determine the strength coefficients and plastic properties. By means of the Charpy impact test made on V-notched specimens, the ductility of the investigated cast steel was tested and the impact energy KV was determined. Hardness measurements were taken by the Vickers and Brinell method.
Keywords: cast steel, microstructure, heat treatment, mechanical properties,
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The results of studies of the process of pressure-free granulation of foundry dust were described, including dust generated in the mechanical reclamation of waste bentonite sand (Dust 1), dust generated in the dry mechanical reclamation of waste sand mixture containing approximately 90% of Floster S moulding sand and 10% of core sand with a resol type phenolic resin (Dust 2), and dust generated in the dry mechanical reclamation of waste furan resin-bonded sand (Dust 3). The aim of the studies was to produce granules of specified dimensions and strength parameters. Dust granules were formed from pure bentonite dust and two dust mixtures of the following compositions: mixture 1 - 75 wt. % of dust from the reclamation of various mixed foundry sands and 25 wt. % of dust from the reclamation of bentonite sand, and mixture 2 - 50 wt. % of dust from the reclamation of furan sand mixed with 50 wt. % of dust from the bentonite sand. The moistened bentonite sand dust was used as a binder in the granulation of post-reclamation dust from the technology of loose self-hardening sands. The following parameters of the final product were determined: final moisture content (W), the shattered resistance of granules (Wz) tested immediately after the granulation process and after the lapse of 1, 3, 5, 10 and 30 days of seasoning, and water resistance of granules after the immersion in water for 24 hours. Studies were conducted on granules produced in the granulator pan inclined at an angle of 45° and rotating at four different speeds of 10, 15, 20 and 25 rev/min.
Keywords: moulding sand, loose self-hardening sand, Floster S process, post-reclamation dust, granulation, environmental protection,
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Artur Kudyba, Aleksandra Siewiorek, Natalia Sobczak, Patrycja Turalska
The paper focuses on the experimental investigation of wetting behavior and solderability of commercial lead-free solder on Printed Circuit Board (PCB) covered with an OSP finish (Organic Surface Protectant) characterized by physical (mechanically scratched) and/or chemical (oxidized in air at 260°C for 1 hour) inhomogeneity of the surface finish. The influence of the quality of the PCB finish on the maximum wetting force Fmax, wetting time t0, the contact angle θ, and the parameters characterizing solderability, were studied. The tests were performed by a wetting balance method with SAC305 solder (Sn-3.0Ag-0.5Cu, wt. %) and commercial flux (EF2200) using MENISCO ST88 apparatus allowing direct measurement of the wetting force Fr and wetting time t0 as well as calculation of the contact angle θ values. The measurements were made at a temperature of 260°C for a contact time of 3 s. For comparison, the tests were also performed on PCBs in delivery state showing average Fmax = 0.9 mN, t0 = 0.58 s and θ = 57°. The results have shown that both oxidation and mechanical damage of the OSP finish have a significant worsening effect on solderability. Scratched OSP finish had an average Fmax = -1.03 mN and θ = 78°. Such surfaces were non-wettable with corresponding values of Fmax = -4.7 mN and θ = 120° for oxidized samples and Fmax = -4.04 mN and θ = 111° for those scratched and oxidized.
Keywords: surfaces, coatings, electronic characterization, defects, surface properties, solderability, wetting balance test,
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Katarzyna Szczepaniak-Lalewicz, Michał Woś
An attempt was made to develop a mathematical model and apply this model in numerical analysis to the drying process of multi-layer ceramic moulds used in investment casting. The numerical analysis carried out in a FLOW-3D program was meant to serve later as a tool in the development of an optimal method for drying multi-layer ceramic moulds used in the investment casting of titanium alloys. The proposed two-dimensional physical "non-condensable gas model" enabled simulations including the gas constant and specific heat.
Keywords: ceramic moulds, drying, numerical analysis,
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