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1

Industrial Application of Deep Neural Network for Aluminum Casting Defect Detection in Case of Unbalanced Dataset

Awtoniuk Michał, Majerek Dariusz, Myziak Artur, Gajda Cyprian

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 5

120--128

EN

We have developed a deep neural network for casting defect detection. The approach is original because it assumes the use of data related to the casting manufacturing process, i.e. measurement signals from the casting machine, rather than data describing the finished casting, e.g. images. The defects are related to the production of car engine heads made of silumin. In the current research we focused on the detection of defects related to the leakage of the casting. The data came from production plant in Poland. The dataset was unbalanced. It included nearly 38,500 observations, of which only 4% described a leak event. The work resulted in a deep network consisting of 22 layers. We assessed the classification accuracy using a ROC curve, an AUC index and a confusion matrix. The AUC value was 0.97 and 0.949 for the learning and testing dataset, respectively. The model allowed for an ex-post analysis of the casting process. The analysis was based on Shapley values. This makes it possible not only to detect the occurrence of a defect but also to give potential reasons for the appearance of a casting leak.

2

Structure of Precision Castings Made of the Inconel 713C Alloy

Łyczkowska K., Adamiec J.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

19--24

EN

Inconel 713C alloy belongs to the group of materials with high application potential in the aerospace industry. This nickel alloy has excellent features such as high strength, good surface stability, high creep and corrosion resistance. The paper presents the results of metallographic examinations of a base material and padding welds made by laser beam on the Inconel 713C alloy. The tests were made on precisely cast test plates imitating low - pressure turbine blades dedicated for the aerospace industry. Observations of the macro- and microstructure of the padding welds, heat-affected zone and base material indicate, that the Inconel 713C alloy should be classified as a hard-to-weld material. In the investigated joint, cracking of the material is disclosed mainly in the heat-affected zone and at the melted zone interface, where pad weld crystals formed on partially melted grains. The results show that phases rich with chromium and molybdenum were formed by high temperature during welding process, which was confirmed by EDS analysis of chemical composition.

3

Monitoring of Manufacture Stability of Large Turbine Blades Using Infrared Thermography (IRT) in Investment Casting Technology

Herman A., Vrátný O., Kubelková I.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

9--14

EN

With increasing technology development, an increasing emphasis is placed on the precision of products, but cannot be guaranteed without a stable production process. To ensure the stability of the production process, it is necessary to monitor it in detail, find its critical locations and eliminate or at least control it. With such a precise manufacturing method as investment casting, such a process is a must. This paper therefore deals with monitoring the production process of wax models of large turbine blades using infrared thermography. The aim was to evaluate the critical locations of this production and to propose recommendations for their elimination or, at the very least, significant mitigation of their impact on the final quality of the large turbine blade casting.

4

The Althoff-Radtke Test Adapted for High Chromium Cast Iron

Kopyciński D., Siekaniec D., Szczęsny A., Sokolnicki M., Nowak A.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

61--64

EN

The paper presents results of the possibility of adapting the Althoff-Radtke test for High Chromium Cast Iron. The Althoff-Radtke test is a clump attempt used for steel. The Althoff-Radtke test has four different lengths of clamp which qualifies it as a test to quantitatively take into account different kinds of shrinkage ΔL. The length of the slot of the cracked corner and the length of each staple (50 - 350 mm) are the parameters tendency to cast cracks. Castings of white cast iron have a high tendency to hot cracking due to the large range of solidification temperatures, unfavorable kinetics parameters of shrinkage, and especially a lack of expansion before shrinkage. Shrinkage of high chromium white cast iron is similar to the shrinkage of cast steel, and is approximately 2%. Therefore it is important to test susceptibility to hot cracks. Research was carried out under industrial conditions. Four melts were performed, one of the initial chemical composition and the other three modified by different amounts of Fe-Ti, respectively, 0.25%, 0.5% and 0.75% Fe-Ti. The propensity for hot cracking was based on the observation of the dark surface in the corner of the sample. The study shows that the Althoff-Radtke test can be adapted to determine the tendency for hot cracking of high chromium cast iron. It should however be noted that the test results can not be compared with those for other alloys.

5

Opening Material as the Possibility of Elimination Veining in Foundries

Hrubovčáková M., Vaskova I., Benkova M., Conev M.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 3

157--161

EN

The main bulk density representation in the molding material is opening material, refractory granular material with a particle size of 0.02 mm. It forms a shell molds and cores, and therefore in addition to activating the surface of the grain is one of the most important features angularity and particle size of grains. These last two features specify the porosity and therefore the permeability of the mixture, and thermal dilatation of tension from braking dilation, the thermal conductivity of the mixture and even largely affect the strength of molds and cores, and thus the surface quality of castings. Today foundries, which use the cast iron for produce of casts, are struggling with surface defects on the casts. One of these defects are veining. They can be eliminated in several ways. Veining are foundry defects, which arise as a result of tensions generated at the interface of the mold and metal. This tension also arises due to abrupt thermal expansion of silica sand and is therefore in the development of veining on the surface of casts deal primarily influences and characteristics of the filler material – opening material in the production of iron castings.

6

FSW Welding of Aluminium Casting Alloys

Pietras A., Rams B.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 2

119--124

EN

The article contains basic information associated with the impact of the FSW process parameters on the forming of a weld while friction welding of aluminium casting alloys. Research was conducted using specially made samples containing a rod of casting alloy mounted in the wrought alloy in the selected area of FSW tool acting. Research has thrown light on the process of joining materials of significantly dissimilar physical properties, such as casting alloys and wrought alloys. Metallographic testing of a weld area has revealed the big impact of welding conditions, especially tool rotational speed, on the degree of metal stirring, grain refinement and shape factor of a weld. As the result of research it has been stated that at the high tool rotational speed, the metals stirring in a weld is significantly greater than in case of welding at low rotational speeds, however this fails to influence the strength of a weld. Plastic strain occurring while welding causes very high refinement of particles in the tested area and changing of their shape towards particles being more equiaxial. In the properly selected welding conditions it is possible to obtain joints of correct and repeatable structure, however in the case of the accumulation of cavities in the casting alloy the FSW process not always eliminates them.

7

The Effect of Shell Thickness, Insulation and Casting Temperature on Defects Formation During Investment Casting of Ni-base Turbine Blades

Raza M., Irwin M., Fagerström B.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 4

115--123

EN

Turbine blades have complex geometries with free form surface. Blades have different thickness at the trailing and leading edges as well as sharp bends at the chord-tip shroud junction and sharp fins at the tip shroud. In investment casting of blades, shrinkage at the tip-shroud and cord junction is a common casting problem. Because of high temperature applications, grain structure is also critical in these castings in order to avoid creep. The aim of this work is to evaluate the effect of different process parameters, such as, shell thickness, insulation and casting temperature on shrinkage porosity and grain size. The test geometry used in this study was a thin-walled air-foil structure which is representative of a typical hot-gas-path rotating turbine component. It was observed that, in thin sections, increased shell thickness helps to increase the feeding distance and thus avoid interdendritic shrinkage. It was also observed that grain size is not significantly affected by shell thickness in thin sections. Slower cooling rate due to the added insulation and steeper thermal gradient at metal mold interface induced by the thicker shell not only helps to avoid shrinkage porosity but also increases fill-ability in thinner sections.

8

Porosity of Castings Produced by the Vacuum Assisted Pressure Die Casting Method

Zyska A., Konopka Z., Łągiewka M., Nadolski M.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1

125--130

EN

The paper presents the results of investigations concerning the influence of negative (relative) pressure in the die cavity of high pressure die casting machine on the porosity of castings made of AlSi9Cu3 alloy. Examinations were carried out for the VertaCast cold chamber vertical pressure die casting machine equipped with a vacuum system. Experiments were performed for three values of the applied gauge pressure: -0.3 bar, -0.5 bar, and -0.7 bar, at constant values of other technological parameters, selected during the formerly carried initial experiments. Porosity of castings was assessed on the basis of microstructure observation and the density measurements performed by the method of hydrostatic weighing. The performed investigation allowed to find out that – for the examined pressure range – the porosity of castings decreases linearly with an increase in the absolute value of negative pressure applied to the die cavity. The negative pressure value of -0.7 bar allows to produce castings exhibiting porosity value less than 1%. Large blowholes arisen probably by occlusion of gaseous phase during the injection of metal into the die cavity, were found in castings produced at the negative pressure value of -0.3 bar. These blowholes are placed mostly in regions of local thermal centres and often accompanied by the discontinuities in the form of interdendritic shrinkage micro-porosity. It was concluded that the high quality AlSi9Cu3 alloy castings able to work in elevated temperatures can be achieved for the absolute value of the negative pressure applied to the die cavity greater than 0.5 bar at the applied set of other parameters of pressure die casting machine work.

9

Expert System for Analysis of Casting Defects - ESVOD

Elbel T., Králová Y., Hampl J.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1

17--20

EN

The powerful tool for defect analysis is an expert system. It is a computer programme based on the knowledge of experts for solving the quality of castings. We present the expert system developed in the VSB-Technical University of Ostrava called ‘ESWOD’. The ESWOD programme consists of three separate modules: identification, diagnosis /causes and prevention/ remedy. The identification of casting defects in the actual form of the system is based on their visual aspect.

10

Logistyka produkcji z zastosowaniem automatycznego systemu detekcji wad odlewniczych

Świłło S., Perzyk M., Myszka D.

Logistyka

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2014

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nr 6

10186--10191

PL

Artykuł dotyczy nowych rozwiązań z dziedzinie logistyki procesów produkcyjnych. Autorzy przedstawiają system wizyjny przeznaczony do automatycznej inspekcji defektów powierzchniowych. W zależności od konstrukcji wyrobu i techniki wykonania, proces odlewania może generować powierzchniowe defekty takiej jak: pęknięcia lub pory, które w sposób znaczący zmniejszają funkcjonalność wyrobu. Odkąd kontrola wzrokowa stała się powolna i kosztowana, systemy komputerowej inspekcji stały się alternatywa dla tego typu problemów w inspekcji dokonywanej w czasie rzeczywistym. Dlatego też została zaproponowana procedura składająca się z trzech etapów, w celu zwiększenia jakości końcowej wyrobów oraz zwiększenia wydajności procesu odlewania. W pierwszym etapie opracowano technikę obróbki obrazu opartej na metodzie detekcji krawędzi oraz metodę sieci neuronowych. W kolejnym kroku opracowano zaawansowaną technikę oświetlenia, kluczową dla wizualizacji defektów. Na koniec wprowadzono procedurę na automatyczną selekcję oraz kategoryzację rozpoznanych defektów.

EN

The paper presents some new solutions in logistics of production processes. The authors demonstrate a camera based machine vision system for the automatic inspection of surface defects in aluminum die casting. Depending on part design and processing techniques, castings may develop surface discontinuities such as cracks and pores that greatly influence the material’s ability. Since, the human visual inspection is slow and expensive a computer vision system is an alternative solution for on-line inspection. Therefore, a three steps procedure has been developed in order to improve quality and productivity of the manufacturing process. First, the developed vision system uses an advanced image processing algorithm based on edge detection method and advanced learning process, based on the methods of computational intelligence. Second, in addition to the developed image processing algorithm, advanced lighting system has been designed. Finally, the vision system allows the user automatic selection, and classification of the measured defects.

11

The influence of casting defects on fatigue resistance of elektron 21 magnesium alloy

Pikos I., Kiełbus A., Adamiec J.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2

103--106

EN

The Mg-RE alloys are attractive, constructional materials, especially for aircraft and automotive industry, thanks to combination of low density, good mechanical properties, also at elevated temperature, and good castability and machinability. Present paper contains results of fatigue resistance test carried out on Elektron 21 magnesium alloy, followed by microstructural and fractographical investigation of material after test. The as-cast material has been heat treated according to two different procedures. The fatigue resistance test has been conducted with 106 cycles of uniaxial, sine wave form stress between 9 MPa and 90 MPa. Fractures of specimens, which ruptured during the test, have been investigated with scanning electron microscope. The microstructure of specimens has been investigated with light microscopy. Detrimental effect of casting defects, as inclusions and porosity, on fatigue resistance has been proved. Also the influence of heat treatment's parameters has been described.

12

Technologia wytapianych modeli w zastosowaniu dla stopów miedzi

Rzadkosz S., Kranc M., Garbacz-Klempka A., Kozana J., Piękoś M.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 3 spec.

143--148

PL

Technologia wytapianych modeli należy do najstarszych technologii odlewniczych. Historycznie służyła do odlewania narzędzi, broni i ozdób. Model wykonany z wosku pszczelego oblepiano gliną suszono i wypalano. Otrzymywano odlewy o dużej gładkości powierzchni, dokładności i precyzji wykonania ornamentu. Metodą tą odlewano niewielkie kilkugramowe odlewy jak i wielkogabarytowe pomniki. Współcześnie ta technologia jest wykorzystywana w wielu ważnych gałęziach produkcji zarówno artystycznej, jak i przemysłowej. Szczególnie w przemyśle zbrojeniowym, lotniczym, motoryzacyjnym, energetycznym, budowlanym, a nawet kosmicznym. W pracy przedstawiono wyniki badań i eksperymentów, prowadzonych w zakresie technologii odlewnictwa miedzi i stopów miedzi z zastosowaniem metody wytapianych modeli, zarówno w aspekcie historycznym, jak i współczesnej praktyki przemysłowej. Przykładowo przedstawiono analizę wybranych elementów dawnych technologii, form i odlewów wytworzonych w epoce brązu oraz wyniki badań dotyczące aktualnie produkowanych odlewów dla branży energetycznej. Jakość odlewów została oceniona na podstawie przeprowadzonych badań z zakresu mikrostruktury, składu chemicznego, przewodności elektrycznej i zawartości tlenu.

EN

Investment casting technology belongs to the oldest casting techniques. Historically, it was used for casting tools, weapons and ornaments. A model, made from beeswax, was covered in loam, dried and fired. The casts obtained were characterised by high surface smoothness, accuracy and precision of its ornaments. This method was used for relatively small casts as well as for big monuments. Nowadays, this technology is used in many fields of manufacturing, both artistic and industrial, especially in ornaments, aviation, automotive, power, construction and even space industry. This work presents the results of research and experiments conducted in the field of casting technology of copper and copper alloys, applying the investment casting method, both in its historical aspect and modern industrial practice. An exemplary analysis was presented of the chosen elements of the old technologies, moulds and casts, as well as the results of casts made currently for the power industry. The casts quality was evaluated based on the research of their microstructure, chemical composition, electrical conductivity and oxygen content.

13

Numerical analysis of influence of the mold material on the distribution of shrinkage cavities

Dyja R.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 1

15--18

EN

Production of castings, like any other field of technology is aimed at providing high-quality product, free from defects. One of the main causes of defects in castings is the phenomenon of shrinkage of the casting. This phenomenon causes the formation of shrinkage cavities and porosity in the casting. The major preventive measure is supplementing a shortage of liquid metal. For supplement to be effective, it is necessary to use risers in proper shapes. Usually, the risers are selected on the basis of determination the place of formation of hot-spots in the castings. Although in these places the shrinkage defects are most likely to occur, shape and size of these defects are also affected by other factors. The article describes the original program setting out the shape and location of possible cavities in the casting. In the program is also taken into account the effect of temperature on the change in volume of liquid metal and the resultant differences in the shape and size of formed shrinkage cavities. The aim of the article is to describe the influence that have material properties of the mold on the simulation results.

14

Examination and elimination of defects in cone casting made of ductile cast iron

Guzik E., Łagowski M., Nowak-Dudek A., Niedzielski B.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 4

43--48

EN

In the scope of existing cooperation with the Foundry of Cast Iron ZM “WSK Rzeszów” Ltd. there was carried out research work of microstructure and mechanical properties in the walls of a cone casting made of ductile cast iron. The particular attention was being put to the search of the potential brittle phases which have deleterious effect on ductility and dynamic properties of highly strained use of the casting prone to the potential risk of cracks during the highly strained use.

15

Klasyfikacja wad struktury metalowych odlewów kompozytowych z nasycanym zbrojeniem

Gawdzińska K., Nagolska D., Szweycer M.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 1s

39--46

PL

Definicja kompozytu [1] określa materiał kompozytowy idealny o doskonałej budowie. W rzeczywistych materiałach kompozytowych mamy na ogół do czynienia z budową niedoskonałą – materiały kompozytowe zawierają różnorodne wady [2, 3–5], szczególnie kiedy rozpatrujemy kompozyty wytwarzane przez odlewanie. Odlewy bowiem charakteryzują się specyficzną budową związaną z przebiegiem procesu ich wytwarzania. W przypadku odlewów z kompozytów metalowych, a szczególnie wytwarzanych przez nasycanie, brak jest klasyfikacji tych wad [2, 4]. Klasyfikacja wad odlewów z materiałów klasycznych (żeliwo, staliwo, stopy metali nieżelaznych) jest niewystarczająca i wymaga uzupełnienia o specyficzne wady wspomnianych tworzyw. Problem ten (zauważony podczas wytwarzania odlewów z metalowych kompozytów nasycanych w Instytucie Podstawowych Nauk Technicznych Akademii Morskiej w Szczecinie oraz w Instytucie Technologii Materiałów Politechniki Poznańskiej) stał się przyczyną podjęcia prac nad stworzeniem takiej klasyfikacji i w efekcie do powstania niniejszej propozycji, która przyczynić się może do poprawy jakości badanych materiałów, a co jest z tym związane, z ochroną środowiska.

16

Surface quality of foundry pattern manufactured by FDM method - rapid prototyping

Hanus A., Špirutová N., Beňo J.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 1s

15-20

EN

The goal of this paper was to verify the possibilities of using 3D models produced by means of the FDM technology for actual foundry production. Experimental models were produced using Dimension sst 768 3D printer. Two types of castings (type I - simple plates, type II - jewellery) were cast in plaster moulds. The models were burnt out at 500 oC. The goal of the experiment was to verify the effect of modifications upon surface quality of the resulting casting. The ABS model was tested with unmodified surface, chemically treated surface, blasted surface and blasted and etched surface together. The results of the experiment have confirmed the assumed effect of both mechanical and chemical modifications of the model surface on casting surface quality.

17

Study of pinholes genesis in iron castings

Elbel T., Hampl J., Senkypl M.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 1

21-26

EN

Purpose: The study concerns the formation of pinholes in castings formed by reaction between a green foundry mould and lamellar graphite cast iron. Great numbers of works have been aimed at clarifying the causes of pinholes formation in iron castings. In spite of this there exists no united opinion on the pinholes formation (genesis) and the authors of this contribution having studied this phenomenon in compacted graphite and spheroidal graphite iron castings were also aimed at lamellar graphite cast iron and they applied for it their knowledge gained in study of reoxidation processes during casting of ferrous alloys. Methodology: Experiments were done on castings of stepped bars moulded in green bentonite mixtures with s graduated moisture and with use of two types of carbonaceous matters. Metal was melted in a 100 kg induction furnace from the same charge. Inoculation was done in a ladle after pouring out from the furnace. Aluminium was dosed in the ladle in some cases and the inoculator kind was changed too. Results: Pinholes were present on castings as small flat pits; on horizontal surfaces sooner singly, on casting edges in clusters. The formation of pinholes wasn't caused by high moisture of moulds but the defect was sensitive to aluminium content in metal. In castings with high aluminium content > 0.01 % the pinholes were present in great numbers, and namely both under low, and also high moistures of moulding mixtures. In melts with low content of Al < 0.01 % the pinholes occurred less extensively only. Practical implications: Conclusions from literature about influence of Al on pinholes occurrence were confirmed in such a way. Study of the defect morphology has shown that the question is a oxidation reaction type of pinholes caused by oxidation of the residual melt between dendrites with formation of CO.

18

Hydrogen analysis and effect of filtration on final quality of castings from aluminium alloy AlSi7Mg0,3

Brůna M., Sládek A.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 1s

5-10

EN

The usage of aluminium and its alloys have increased in many applications and industries over the decades. The automotive industry is the largest market for aluminium castings and cast products. Aluminium is widely used in other applications such as aerospace, marine engines and structures. Parts of small appliances, hand tools and other machinery also use thousands of different aluminium castings. The applications grow as industry seeks new ways to save weight and improve performance and recycling of metals has become an essential part of a sustainable industrial society. The process of recycling has therefore grown to be of great importance, also another aspect has become of critical importance: the achievement of quality and reliability of the products and so is very important to understand the mechanisms of the formation of defects in aluminium melts, and also to have a reliable and simple means of detection.

19

Casting defects analysis by the Pareto method

Borowiecki B., Borowiecka O., Szkodzińska E.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 3 spec.

33--36

EN

On the basis of receive results formed of diagram Pareto Lorenz. On the basis of receive graph it affirmed, that for 70% general number casting defects answered 3 defects (9 contribution – 100% defects). For 70% general number defects of influence it has three type of causes: sand holes, porosity and slag inclusions. The defects show that it is necessary to take up construction gating system. The remaining 8 causes have been concerned only 25%, with general number of casting defects. Analysis of receive results permit to determine of direction of correct actions in order to eliminate or to limit the most defects.

20

Automatic inspection of surface defects in die castings after machining

Świłło S. J., Perzyk M.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 3 spec.

231--236

EN

A new camera based machine vision system for the automatic inspection of surface defects in aluminum die casting was developed by the authors. The problem of surface defects in aluminum die casting is widespread throughout the foundry industry and their detection is o f paramount importance in maintaining product quality. The casting surfaces are the most highly loaded regions of materials and components. Mechanical and thermal loads as well as corrosion or irradiation attacks are directed primarily at the surface of the castings. Depending on part design and processing techniques, castings may develop surface discontinuities such as cracks or tears, inclusions due to chemical reactions or foreign material in the molten metal, and pores that greatly influence the material ability to withs tand these loads. Surface defects may act as a stress concentrator initiating a fracture point. If a pressure is applied in this area, the casting can fracture. The human visual system is well adapted to perform in areas of variety and change; the visual inspection processes, on the other hand, require observing the same type of image repeatedly to detect anomalies. Slow, expensive, erratic inspection usually is the result. Computer based visual inspection provides a viable alternative to human inspectors. Developed by authors machine vision system uses an image processing algorithm based on modified Laplacian of Gaussian edge detection method to detect defects with different sizes and shapes. The defect inspection algorithm consists of three parameters. One is a parameter of defects sensitivity, the second parameter is a thres hold level and the third parameter is to identify the detected defects size and shape. The machine vision system has been successfully tested for the different types of defects on the surface of castings.