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Number of results: 20
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Abstract

An overview of the bibliography regarding the connection of knowledge about precious metal alloys and aspects of the use of computer aided technologies to the optimization of the jewelry casting processes is presented. An analysis of the usability of selected CAx systems was made: 1) for spatial design, called Rhinoceros 6 and 2) CAE system: NovaFlow & Solid (NF&S). The authors describe own research including data acquisition and evaluation of temperature variations during solidification of the selected Au-Ag-Cu alloy, with the identification of the phase transformations of this alloy. The intensity of heat exchange was changed (cooling of specimens under ambient temperature conditions – "normal" intensity and with the furnace – very slow cooling). The problem of completing the simulation database was pointed out and analyzed. Examples of simulations of casting selected jewelry (ring and signet) were given and compared with the result of the experiment realized in real conditions. It was confirmed that the optimization by combining experimental and simulation studies allows for the acquisition of new knowledge, and also facilitates the creation of new artistic designs of jewelry as well as performing the feasibility check, and then optimizing the chosen technology.

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Authors and Affiliations

Z. Ignaszak
J. Wojciechowski
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Abstract

The paper indicates the significance of the problem of foundry processes parameters stability supervision and assessment. The parameters, which can be effectively tracked and analysed using dedicated computer systems for data acquisition and exploration (Acquisition and Data Mining systems, A&D systems) were pointed out. The state of research and methods of solving production problems with the help of computational intelligence systems (Computational Intelligence, CI) were characterised. The research part shows capabilities of an original A&DM system in the aspect of selected analyses of recorded data for cast defects (effect) forecast on the example of a chosen iron foundry. Implementation tests and analyses were performed based on selected assortments for grey and nodular cast iron grades (castings with 50 kg maximum weight, casting on automatic moulding lines for disposable green sand moulds). Validation tests results, applied methods and algorithms (the original system’s operation in real production conditions) confirmed the effectiveness of the assumptions and application of the methods described. Usability, as well as benefits of using A&DM systems in foundries are measurable and lead to stabilisation of production conditions in particular sections included in the area of use of these systems, and as a result to improvement of casting quality and reduction of defect number.

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Authors and Affiliations

R. Sika
Z. Ignaszak
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Abstract

The paper refers to previous publications of the author, focused on criteria of casting feeding, including the thermal criterion proposed by

Niyama. On the basis of this criterion, present in the post-processing of practically all the simulation codes, danger of casting compactness

(in the sense of soundness) in form of a microporosity, caused by the shrinkage phenomena, is predicted. The vast majority of publications

in this field concerns shrinkage and feeding phenomena in the cast steel castings – these are the alloys, in which parallel expansion

phenomenon does not occur as in the cast irons (graphite crystallization). The paper, basing on the simulation-experimental studies,

presents problems of usability of a classic, definition-based approach to the Niyama criterion for the cast iron castings, especially of

greater massiveness, for prediction of presence of zones of dispersed porosity, with relation to predictions of the shrinkage type defects.

The graphite expansion and its influence on shrinkage compensation during solidification of eutectic is also discussed.

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Authors and Affiliations

Z. Ignaszak
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Abstract

The paper refers to earlier publications of the author, on identification of properties of thermomechanical, chemically hardened core/mold sands. In that earlier period, first version of the original DMA apparatus, produced by a Polish company Multiserw-Morek, was used. The Hot Distortion (HD) study results, published by the author in 2008, referred to phenomena accompanying a thermal shock in real conditions of thermal interaction of a liquid alloy on a mold, in reference to a shock possible to obtain in laboratory conditions, without use of liquid alloy as a heat source, with analysis of solutions applied in the DMA apparatus. This paper presents author’s observations on testing a new, innovative version of the LRu-DMA apparatus, containing a module allowing the Hot Distortion (HD) study. Temperature of specimens achieved in the case of the gas burner heating reaches values definitely above 800°C on the heated side and 610°C on the other side. Using an electric radiator, with maximal temperature of 900°C allows obtaining temperatures in between 225-300°C.
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Authors and Affiliations

Z. Ignaszak
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Abstract

The paper concerns the problem of discontinuity in high pressure die castings (HPDC). The compactness of their structure is not perfect, as

it is sometimes believed. The discontinuities present in these castings are the porosity as follow: shrinkage and gas (hydrogen and gas-air

occlusions) origin. The mixed gas and shrinkage nature of porosity makes it difficult to identify and indicate the dominant source. The

selected parameters of metallurgical quality of AlSi9Cu3 alloy before and after refining and the gravity castings samples (as DI - density

index method), were tested and evaluated. This alloy was served to cast the test casting by HPDC method. The penetrating testing (PT) and

metallographic study of both kinds of castings were realized. The application of the NF&S simulation system allowed virtually to indicate

the porosity zones at risk of a particular type in gravity and high-pressure-die-castings. The comparing of these results with the experiment

allowed to conclude about NF&S models validation. The validity of hypotheses concerning the mechanisms of formation and development

of porosity in HPDC casting were also analyzed.

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Authors and Affiliations

Z. Ignaszak
J. Hajkowski
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Abstract

The paper presents an analysis of SPC (Statistical Process Control) procedures usability in foundry engineering. The authors pay particular attention to the processes complexity and necessity of correct preparation of data acquisition procedures. Integration of SPC systems with existing IT solutions in area of aiding and assistance during the manufacturing process is important. For each particular foundry, methodology of selective SPC application needs to prepare for supervision and control of stability of manufacturing conditions, regarding specificity of data in particular “branches” of foundry production (Sands, Pouring, Metallurgy, Quality).
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Authors and Affiliations

Z. Ignaszak
R. Sika
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Abstract

The impact of casting conditions on microstructure a and mechanical properties was described, especially for cast products from AlSi9Cu3 alloy. Particular attention was paid to the parameters of dendritic structure: DAS 1 and DAS 2. Selected mechanical properties (by static tension test) of test castings made using basic technologies of casting: GSC - gravity sand casting, GDC - gravity die-casting and HPDC - high-pressure die-casting, are presented for cast-on test bars and cast separately. Casts were made of the same alloy AlSi9Cu3. Fractures and the zone near the fracture (after static tension test) was subjected to VT - visual tests, PT - penetration tests and metallographic tests. The condition of porosity (fracture zone) was also assessed. The analysis of virtual results was performed using the NovaFlow & Solid system together with the database and they were compared to experimental tests. This way of validation was applied in order to assess the correlation between the local rate of cooling and the size of DAS for GSC, GDC and HPDC technologies. Finally, the correlation between the parameters of structure and mechanical properties with regard to the impact of porosity was signalized.

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Authors and Affiliations

J. Hajkowski
Z. Ignaszak
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Abstract

What is the limit of improvement the structure obtained directly from the liquid state, with possible heat treatment (supersaturation and aging)? This question was posed by casting engineers who put arbitrary requirements on reducing the DAS (Dendrite Arm Spacing) length to less than a dozen microns. The results of tests related to modification of the surface microstructure of AlSi7Mg alloy casting treated by laser beam and the rapid remelting and solidification of the superficial casting zone, were presented in the paper. The local properties of the surface treated with a laser beam concerns only a thickness ranging from a fraction to a single mm. These local properties should be considered in the aspect of application on surfaces of non-machined castings. Then the excellent surface layer properties can be used. The tests were carried out on the surface of the casting, the surface layer obtained in contact with the metal mould, after the initial machining (several mm), was treated by the laser beam. It turned out that the refinement of the microstructure measured with the DAS value is not available in a different way, i.e. directly by casting. The experimental-simulation validation using the Calcosoft CAFE (Cellular Automaton Finite Element) code was applied.

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Authors and Affiliations

J. Hajkowski
P. Popielarski
ORCID: ORCID
Z. Ignaszak
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Abstract

The paper is focused on properties testing of materials used in form of iso-exo sleeves for risers in ferrous alloys foundry. They are grainyfibrous

materials, containing components which initiate and upkeep exothermic reaction. Thermo-physical parameters characterizing such

sleeves are necessary also to fill in reliable databases for computer simulation of processes in the casting-mould layout. Studies with use of

a liquid alloy, especially regarding different sleeves bring valuable results, but are also relatively expensive and require longer test

preparation time. A simplified method of study in laboratory conditions was proposed, in a furnace heated to a temperature above ignition

temperature of sleeve material (initiation of exothermic reaction). This method allows to determine the basic parameters of each new

sleeve supplied to foundries and assures relatively quick evaluation of sleeve quality, by comparison with previous sleeve supplies or with

sleeves brought by new providers.

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Authors and Affiliations

Z. Ignaszak
J-B. Prunier
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Abstract

The paper summarizes research realized by the author in laboratory and industrial conditions (foundries of cast steel and cast iron, castings up to 50 tons) on the effects of the chemically hardened molding sands regeneration using hard/soft rubbing in the dry reclamation. A reference was simultaneously made to advisability of application of the thermal regeneration in conditions, where chromite amount in the circulating (reclaimed) molding sand goes as high as above ten percent. An advisability of connecting standard and specialized methods of examination of the reclaimed sands and molding sands made using it was pointed out. A way of application of studies with the Hot Distortion Plus® method modified by the author for validation of modeling of the thermo-dynamic phenomena in the mold was shown.
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Authors and Affiliations

Z. Ignaszak
J-B. Prunier
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Abstract

The paper presents an original method of measuring the actual chromite content in the circulating moulding sand of foundry. This type of

material is applied for production of moulds. This is the case of foundry which most frequently perform heavy casting in which for the

construction of chemical hardening mould is used, both the quartz sand and chromite sand. After the dry reclamation of used moulding

sand, both types of sands are mixed in various ratios resulting that in reclaimed sand silos, the layers of varying content of chromite in

mixture are observed. For chromite recuperation from the circulating moulding sand there are applied the appropriate installations

equipped with separate elements generating locally strong magnetic field. The knowledge of the current ratio of chromite and quartz sand

allows to optimize the settings of installation and control of the separation efficiency. The arduous and time-consuming method of

determining the content of chromite using bromoform liquid requires operational powers and precautions during using this toxic liquid.

It was developed and tested the new, uncomplicated gravimetric laboratory method using powerful permanent magnets (neodymium).

The method is used in the production conditions of casting for current inspection of chromite quantity in used sand in reclamation plant.

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Authors and Affiliations

Z. Ignaszak
J-B. Prunier
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Abstract

A significant development of the foundry industry contributes to the creation of high reliability and operational strength castings so that they meet specific standards in accordance with customers’ needs. This technology, however, is inseparably connected with casting defects in finished products. Cast products are subject to various defects which are considered acceptable or not, which is conditioned by the alloy chemical composition and strength characteristics, that is, generally – qualities to be agreed between the foundry and the customer. It is the latter that led the authors to research on designing a tool enabling the most reliable possible assessment of the emerging casting defects, which after proper consultations can be repaired and the casting – sold. The paper presents an original tool named the Open Atlas of Defects (OAD), developed for the last few years to support the evaluation of cast iron defects using Non-Destructive Testing (NDT) casting defects analysis tools (DCC card – Demerit Control Chart, Pareto-Lorenz analysis and ABC analysis). The OAD tool structure was presented as an integral part of the original system module for acquisition and data mining (A&DM) in conjunction with the possibilities of using selected tools for defect analysis support on the example of cast iron casting.

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Authors and Affiliations

R. Sika
M. Rogalewicz
A. Kroma
Z. Ignaszak
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Abstract

The article presents an example of analysis of the influence of selected parameters deriving from data acquisition in foundries on the occurrence of Gas porosity defects (detected by Visual testing) in castings of ductile cast iron. The possibilities as well as related effectiveness of prediction of this kind of defects were assessed. The need to rationally limit the number of possible parameters affecting this kind of porosity was indicated. Authors also benefited from expert group's expertise in evaluating possible causes associated with the creation of the aforementioned defect. A ranking of these parameters was created and their impact on the occurrence of the defect was determined. The classic statistical tools were used. The possibility of unexpected links between parameters in case of uncritical use of these typical statistical tools was indicated. It was emphasized also that the acquisition realized in production conditions must be subject to a specific procedure ordering chronology and frequency of data measurements as well improving the casting quality control. Failure to meet these conditions will significantly affect the difficulties in implementing and correcting analysis results, from which INput/OUTput data is expected to be the basis for modelling for quality control.

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Authors and Affiliations

Z. Ignaszak
R. Sika
M. Rogalewicz
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Abstract

The paper includes validation studies of the flow module of the NovaFlow&Solid simulation code. Experiments of ductile iron and gray iron casting in a spiral test of castability were carried out. Casting experiments were then carried out in industrial conditions in the Ferrex Foundry in Poznań and the results are the castability spiral length and local cast iron rate during mould cavity pouring. Simulation tests using NovaFlow&Solid Control Volume code were made. The technological castability test was used to determine thermal-physical data through simplified inversion problem. Influence of physical parameters in the database of simulation code on the spiral length obtained as the result of simulation was analyzed. It was found that critical fraction of capillary flow CLFdown has the biggest impact on cast iron castability in the simulation code. The simulations resulted in defining parameters of gray iron GJL 250 and ductile iron GJS-400-15. For the parameters set, the length of castability spiral in simulations was in accordance with casting experiments.

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Authors and Affiliations

P. Popielarski
ORCID: ORCID
J. Hajkowski
R. Sika
Z. Ignaszak
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Abstract

The validation of each simulation code used in foundry domain requires individual approach due to its specificity. This validation can by

elaborated on the basis of experimental results or in particular cases by comparison the simulation results from different codes. The article

concerns the influence of grey cast iron density curve and different forms of solid fraction curve Fs=f(T) on the formation of shrinkage

discontinuities. Solid fraction curves applying Newtonian Thermal Analysis (NTA) were estimated. The experimental and numerical

simulation tests were performed on the castings, which were made with Derivative Thermal Analysis (DerTA) standard cups. The

numerical tests were realized using NovaFlow&Solid (NF&S), ProCast and Vulcan codes. In this work, the coupled influence of both

curves on the dynamics of the shrinkage-expansion phenomena and on shrinkage defects prognosis in grey cast iron castings has been

revealed. The final evaluation of the simulation systems usefulness should be based on validation experiment, preceded by comparing the

simulation results of available systems which are proposed in given technology.

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Authors and Affiliations

Z. Ignaszak
P. Popielarski
J. Hajkowski
E. Codina
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Abstract

The paper undertakes an important topic of evaluation of effectiveness of SCADA (Supervisory Control and Data Acquisition) systems,

used for monitoring and control of selected processing parameters of classic green sands used in foundry. Main focus was put on process

studies of properties of so-called 1st generation molding sands in the respect of their preparation process. Possible methods of control of

this processing are presented, with consideration of application of fresh raw materials, return sand (regenerate) and water. The studies

conducted in one of European foundries were aimed at pointing out how much application of new, automated plant of sand processing

incorporating the SCADA systems allows stabilizing results of measurement of selected sand parameters after its mixing. The studies

concerned two comparative periods of time, before an implementation of the automated devices for green sands processing (ASMS -

Automatic Sand Measurement System and MCM – Main Control Module) and after the implementation. Results of measurement of

selected sand properties after implementation of the ASMS were also evaluated and compared with testing studies conducted periodically

in laboratory.

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Authors and Affiliations

Z. Ignaszak
J. Kozłowski
M. Perzyk
R. Sika
A. Kochański
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Abstract

The paper presents the results of experimental-simulation tests of expansion-shrinkage phenomena occurring in cast iron castings. The

tests were based on the standard test for inspecting the tendency of steel-carbon alloys to create compacted discontinuities of the pipe

shrinkage type. The cast alloy was a high-silicone ductile iron of GJS - 600 - 10 grade. The validation regarding correctness of prognoses

of the shrinkage defects was applied mostly to the simulation code (system) NovaFlow & Solid CV (NFS CV). The obtained results were

referred to the results obtained using the Procast system (macro- and micromodel). The analysis of sensitivity of the modules responsible

for predicting the shrinkage discontinuities on selected pre-processing parameters was performed, focusing mostly on critical fractions

concerning the feeding flows (mass and capillary) and variation of initial temperature of the alloy in the mould and heat transfer

coefficient (HTC) on the casting - chill interface.

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Authors and Affiliations

J. Hajkowski
P. Roquet
M. Khamashta
E. Codina
Z. Ignaszak
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Abstract

The conducted work shows and confirms how thermal analysis of grey and ductile iron is an important source for calculating metallurgical data to be used as input to increase the precision in simulation of cooling and solidification of cast iron. The aim with the methodology is to achieve a higher quality in the prediction of macro– and micro porosity in castings. As comparison objects standard type of sampling cups for thermal analysis (solidification module M ≈ 0.6 cm) is used. The results from thermal analysis elaborated with the ATAS MetStar system are evaluated parallel with the material quality (including tendency to external and internal defects) of the tested specimen. Significant temperatures and calculated quality parameters are evaluated in the ATAS MetStar system and used as input to calibrate the density curve as temperature function in NovaFlow&Solid simulation system. The modified data are imported to the NovaFlow&Solid simulation system and compared with real results.

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Authors and Affiliations

P-E. Persson
Z. Ignaszak
H. Fransson
V. Kropotkin
R. Andersson
A. Kump

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