Quality Of Castings Research Articles

Press Casting Quality Prediction and Analysis Based on Machine Learning

In an industrial mass production pattern, quality prediction is one of the important processes when guarding quality. The products are extracted periodically or quantitatively for inspection in order to observe the relationship between process variation and engineering specification. When these irregularities are not instantly detected by lot sampling inspection, lot defectives are produced, and the defective cost increases. Failure to identify defects during sampling inspection leads to product returns or harm to business reputation. Press casting is a common mass production method in the metal industry. After the metal is molten at a high temperature, high pressure is injected into the mold, and then it is solidified and formed in the mold. Thus, pressure stability inside the mold is one of the key factors that influences quality. The melting point of aluminum alloy is normally around 650 °C, but there was no sensor that could withstand this high temperature. To combat this, we developed a high temperature resistant sensor and installed it into pressure casting mold grounded on the principles of fluid mechanics and experts’ suggestions in order to realize the impact of pressure change on the mold. To our limited knowledge, it was a seminal study on predicting mold’s casting quality via in-mold pressure data. We propose a press casting quality prediction method based on machine learning. By collecting the in-mold pressure data in real time. Savitzky-Golay Filter is used for data smoothing, and first-order difference is taken to extract the time interval of an actual injection of molten metal in-to the mold. We extract the key data that influence the quality and employ XGBoost to establish a classifier. In the experiment we prove that the method achieves good accuracy of quality prediction and recall of defectives for in-mold pressure. Via this model, we not only can save large amount of time and costs, but also can carry out maintenance warnings in advance, notify professionals to stop produce defective products, reduce the shipping risk and maintain reputation so as to strengthen its competitive edge.

Numerical simulation for EMS induced solidification and inclusion behavior in bloom caster CC mold with bifurcated SEN

A three-dimensional mathematical model has been developed to investigate solidification and non-metallic inclusions behavior in bloom caster mold with bifurcated submerged entry nozzle (SEN) under the influence of in-mold electromagnetic stirring (EMS). An enthalpy porosity approach is applied for the solidification analysis and the stochastic tracking model is used to track the motion of non-metallic inclusions. A numerical investigation has been carried out to study the influence of the stirrer current intensity on turbulent flow, shell generation and inclusion transport. The complex interplay of the induced flow with the inertial impinging jet from the SEN has been investigated. The effect of inclusion density and size on the removal rate of non-metallic inclusion has also been analyzed. The results show that in-mold EMS plays a significant role in solidification and inclusion behavior. With current intensity of 375 A, the inclusion removal rate is higher than that of 0 A, 300 A and 450 A stirrer current. This research suggests that the optimal current intensity of EMS gives a better internal quality of the continuous casting (CC) bloom mold.

Investigation on characteristic and formation mechanism of porosity defects of Al–Li alloys prepared by sand casting

Porosity defects and interfacial reaction are very serious problems in sand casting Al–Li alloy, which greatly affect the quality of castings. In this work, the characteristic and formation mechanism of the porosity defects in the sand casting Al–Li alloys were systematically investigated by scanning electron microscopy, transmission electron microscopy, energy spectrometry, and inductively coupled plasma mass spectrometry, in order to provide a theoretical basis for the prevention and control of the pore defects in the sand casting Al–Li alloys. The results found that the Al–Li alloys prepared by metal mold and graphite mold as casting molds had almost no pore defects and interfacial reaction layers, with the porosities of 5.81% and 5.05%, respectively, while the sand casting Al–Li alloys with furan resin, phenolic resin, and sodium silicate binder as binders all had serious pore defects and interfacial reaction layers, with the porosity of 15.67%, sharply weakening the mechanical properties of the Al–Li alloy casting. The types of the pore defects were mainly reactive pores and intrusive pores, and the interface reaction layer was mainly composed of LiAlO2 and C–H–O organics. The formation mechanism of the pore defects in the sand casting Al–Li alloys was caused by the reaction between Li and the hydroxyl groups in the binder of the sand mold to generate a large amount of hydrogen, which intruded into the melt or was sucked into the melt.

Gating System Optimization for EV31A Magnesium Alloy Engine Body Sand Casting.

The research presented in this paper aimed to change the existing gating system that would enable the engine body casting, from a new EV31A magnesium alloy, of the required quality. For this reason, the casting process simulations used the MAGMASoft software, followed by the experimental validation of the achieved results. The results achieved in the first stage of the cast computer simulation enabled the identification of potential problems and factors that reduce the casting quality. However, the proposed design modifications eliminated the inadequate delivery of liquid metal to the casting’s critical areas by adequately controlling the mold cavity filling and solidification process. The experiment validated the simulations of the computer casting defects at the various stages. The results enabled the new EV31A magnesium alloy to be implemented in industrial production.

Analysis of Defects Associated with Manufacturing Keys for Brass Musical Instruments

This article deals with the problematics of the production of small castings using gravitational investment casting. These are castings with a relatively complex shape, which are used as parts of trigger assembly for musical wind instruments. During their production, various defects occur which are connected with the casting process. The aim of this article is to describe the defects and suggest possible methods for removing them. The first step was to find and identify these defects using metallographic and EDX microanalysis. Furthermore, a simulation calculation of the casting process was used to determine the influence of the casting geometry on casting quality. Based on these analyses, the most suitable alloy and casting system geometry were proposed for the production of the casting.

IMPROVING THE QUALITY OF MAGNESIUM-SOLUBLE BIOLOGICAL ALLOY FOR IMPLANTS

Formulation of the problem. Currently, biosoluble materials are widely used for the manufacture of implants, among which the most promising are magnesium alloys. Magnesium is a natural element of the body. It is contained in bone and muscle tissue and involved in various metabolic processes. In addition, magnesium and its biocorrosion products have excellent biocompatibility. The main advantage of magnesium alloys is the positive effect magnesium has on the human body, but their quality is not satisfactory for use in the human body. Improved refining and modification processes of liquid melt can increase the properties of magnesium alloys. Purpose of research: to investigate and test various carbonaceous materials for refining and modifying magnesium melt. Method. Optical microscopy, application of standard techniques for determining the mechanical properties of magnesium alloy and special techniques for determining the refining and modifying ability of various carbon-containing materials. Results. The technology of cast magnesium alloys modification for Mg – Zr − Nd system by dispersed graphite powder is proposed. It is shown that the optimal carbon additive in the quantity of 0,05…0,1 % improves the mechanical properties due to grain grinding and additional strengthening of structural components. A complex filter containing equal quantity of magnesite, graphite and limestone is proposed. It provides an increased level of melt refining to obtain high quality casting. It is shown that the use of a complex carbon-containing filter provides not only efficient melt refining, but also its additional modification. In alloy structure the increased quantity of intermetallic γ-phase is observed, that provides increase the microhardness of alloy structural components and promotes increase of its physical-mechanical characteristics. Scientific novelty. The structure and properties of cast magnesium alloy for Mg –Zr – Nd system during modification with dispersed graphite powder and its filtration through carbon-containing materials are investigated. Practical significance. The developed complex technology for processing the liquid melt of magnesium alloys for the Mg – Zr − Nd system allows to increase the yield of suitable casting and improve its quality.

Optimization of ductile iron casting production based on numerical simulation

The research involved numerical simulations in MAGMASOFT® focused on optimising the casting process and solidification of a cast piece type intended for the shipping industry. The paper presents the results of the numerical simulations together with a proposal of changes in the production technology aimed at increasing the casting quality. No serious deficiencies of the proposed technology were found based on the simulation results. However, as regards optimisation of the filling process, it was recommended to adjust the gates shape to prevent metal splashing. It is recommended to optimise filling of the castings in order to achieve a structure free of internal defects, and also to slightly modify the shape in order to eliminate the risk of porosity and cracking.

Rejection Analysis of Casting Defect Using Statical Quality Tools

Abstract: In the industry different type of casting component are produced, nowadays increasing demand of high-quality casting component at right time. For the quality casting component required skill and knowledge. In small industry use trial and error technique defect analysis it is used for reduced rejection percentage of casting compound but this process is time consuming and economical and also this process has less control on rejection of casting components the main aim is produced defect free components at right time and increase the quality of casting components, in this paper used statistical quality tools and Auto-cast simulation software for finding root cause of casting defect. Ishikawa diagram, why-why analysis and brain storming this are statistical quality tool used for rejection analysis casting. Using statistical quality tools cover defect like sand drop, sand fusion, blow hole cold shut etc. but leakage defect root cause not found using statistical quality tool. For minimize leakage defect use auto-cast simulation software find out the root cause. Taking the corrective action and reduced rejection percentage of casting defect of RDP Carrier.

The effect of conditions of directional crystallization on the structure of cast blades made of nickel superalloys

The characteristics of gas turbine engines depend on the structural state of the material of the turbine blades and are largely determined by the technology of their manufacture. Identification of the specific defects of casting is an important goal aimed at improving the quality of blade castings since the castings of turbine blades with a monocrystalline structure made of high-alloyed nickel superalloys (NS) are subject to increased requirements for macro- and microstructure. We present the results of studying the effect of directional crystallization parameters on the morphology of the dendritic structure of NS and their tendency to form casting defects of the single-crystal structure. The structure of alloys in single-crystal blade castings and the effect of technological parameters on the dispersion of the structural components of NS were analyzed upon casting of turbine blades with <001> axial orientation on installations with liquid-metal cooling. It is shown that the parameters of the dendritic cells of castings vary in height from 220 to 330 μg and volume fraction of micropores changes from 0.02 to 0.2%. Electron probe microanalysis revealed that the phase and local elemental compositions of the alloy in the areas of the blade tip and isolated grains are identical. The appearance of isolated grains that violate the monocrystalline structure of castings is observed when the rate of NS cooling decreases. To increase the temperature gradient and reduce the probability of formation of extraneous crystals in castings ahead of the crystallization front, optimized temperature-speed modes of casting and directional crystallization are proposed. The obtained results can be used in the development of temperature-velocity parameters of the process of directional crystallization of blades of promising turbines made of new superalloys.

A Study of Supply Chain Management in Foundry Industry with Special Reference to Kolhapur District

To Survive and thrive within an increasingly competitive market place and to succeed on sustainable basis, organization must adopt the new techniques and business models like supply chain management. A supply chain management consists of all the stages involved directly or indirectly in fulfilling the customer request. The supply chain not only includes the manufacturers & supplies, but also transporters, warehouse, retailers & customers themselves. Kolhapur is a leading foundry cluster, in providing quality castings to its customers majority of the foundry units in the cluster cater to the automotive sector along with other sectors such as pumps/valves, sugar, textiles, etc. Productivity is reduced due to the occurrence of defects in the foundry. These defects occur in various processes of manufacturing. The rejection percentage is not within the company standards in some places. The purpose of any business is to reduce supply risk at lower cost, provide timely delivery, increase customer service, the proper managing the flow of information and product with compressed cycle time and reducing overall operational cost. . Keywords: Supply chain, foundry ,process, defect free, procedure,policies

Effect of Flow Field Optimization of an Asymmetric Multi-Strand Tundish on the Quality Consistency of Cracking Con-Rod Steel.

Cracking con-rod is an advanced high-precision connecting structure based on brittle expansion, breaking and reconnection of steel, to solve the problem of assembly circle missing. High carbon micro-alloyed steel C70S6, as a dominant material for the production of cracking con-rod, has extremely strict requirements on non-metallic inclusions in steel and microstructure stability. Continuous casting tundish plays an important role in removing large-sized inclusions and stabilizing casting quality. Aiming at the inconsistent casting quality of C70S6 steel produced by a three-strand asymmetric tundish and the frequent occurrence of slag entrapment problems in Xining Special Steel, the tundish structure was optimized by means of physical modelling combined with numerical simulation, and the quality of the bloom castings and subsequent hot-rolled products before and after optimization were compared based on volume production. The results show that a new flow control design to the tundish can effectively improve the consistency of its metallurgical effect for each of the three strands and the following overall product quality, in which the flow field and temperature field in the tundish are more uniform. This is due to the adoption of a vortex inhibitor and an optimized wall structure according to the measured RTD curve, ink trajectory and numerical simulation on the 3-D streamline contours and temperature distribution in the tundish. The peak concentration of outlet 1 is decreased from 6.5 before optimization to less than 2.0 after optimization, which means the elimination or alleviation of the local short-circuit flow. The maximum temperature difference of C70S6 molten steel measured at the outlets of the tundish three strands is decreased from 2–5 °C to 1–3 °C, which is in good agreement with the numerical simulation results. The difference in columnar crystal ratio of the corresponding bloom castings is decreased from 2.27–3.17% to 1.26–1.85%, and the consistency of central carbon segregation index is also significantly improved. In addition, the difference in oxygen content among the three strand blooms is decreased from 1.7–3.5 ppm to 0.8–1.9 ppm. As a result, the overall mechanical properties and microstructure stability of the hot-rolled products are improved statistically, in which the hardness fluctuation is decreased from 84 HBW to 60 HBW, the inclusion grade of types B + C + D + Ds is reduced to 1.105, and the occurrence rate of Ds dropped to 0.118%. Accordingly, the failure rate of the cracking con-rod is controlled stably within 4‰, and the fracture is generally smoother than that before tundish optimization. In summary, the flow field optimization to a multi-strand asymmetric tundish has a clear effect on improving the overall quality of its bloom castings and rolled products, which should be paid more attention industrially. Meanwhile, the present study provides a reliable theoretical and experimental reference for the improvement of metallurgical effects of an asymmetric-typed tundish commonly used in special steel production.

The Use of Barley Malt as a Binder in Molding Sand Technology.

The aim of this study was to attempt to use barley malt as a natural, organic binder in the technology of molding sand. TGA analysis of the binder was performed, during which temperatures of thermal decomposition of its components were determined. The results of TG/DTG analysis show that a loss of ~75% of mass of the MB binder is organic matter. Over 50% of this is starch. The results indicate the possibility of using a binder made of barley malt as a binding material for quartz sand grains. This fact was confirmed by tests carried out with use of SEM. During the observations, it was found that barley malt forms smooth bridges connecting individual grains of quartz sand. The typical properties of molding sands with barley malt were also determined, compared to sands containing commonly used binders. At the same time, the influence of the content of this binder on flowability, permeability, strength properties, and wear resistance was assessed. It has been found that increasing the binder content in molding mass results in an increase in strength and wear resistance, as opposed to flowability and permeability. Test castings were also made. It was found that the addition of a binder made of barley malt has a positive effect on the surface quality of castings. This was confirmed by roughness measurements of the test castings. At the same time, a tendency to excessive gas evolution during pouring was shown, with higher contents of this binder. Moreover, greater amounts of barley malt in the molding sand (MB 5%) as compared to the lower content (MB 2%) increased the thickness of the burnt layer of the sand by 25%. This is due to the exothermic reaction when more binder is burnt. It is extremely important from the point of view of the regeneration of molding sand.

High quality plate-shaped A356 alloy casting by a combined ablation cooling and mold heating method

High quality plate-shaped A356 plate castings, with length much greater than the feeding distance, are difficult to make by conventional sand casting processes. This article describes our initial work on combining mold heating with ablation cooling in making plate-shaped castings of high internal quality. Our experimental results indicate that shrinkage porosity can be largely eliminated when the mold temperature is higher than 200 °C. Furthermore, the morphology of eutectic silicon is modified, from flake-like in sand casting to coral-like in castings subjected to ablation cooling. As a result, the mechanical properties of the plate casting, especially ductility, are significantly enhanced by the combined effect of mold heating and ablation cooling. Numerical modeling was performed in this study to quantify the cooling conditions involved.

Development of advanced cold crucible melting of titanium alloys

Cold crucible is used to melt reactive metal scrap at elevated temperatures for high quality castings or to produce spherical powders for additive manufacturing. The most advanced crucibles have a small exit nozzle to pour the molten alloy through the bottom opening protected by graphite or ceramic material. The nozzle operates at high temperature and typically lasts several minutes, possibly adding contamination to the outflowing liquid metal. This paper presents new efforts to improve the technique with the aim to achieve a stable commercial process by introducing melting of scrap metal in the presence of liquid flux of different compositions to purify the liquid metal and to enhance thermal effectiveness. The crucial modification in avoiding contamination is a new type of the non-consumable nozzle made of copper segments and the second coil to supply a high frequency electromagnetic field in the vicinity of the nozzle. The nozzle entrance is protected by a thin solidified layer of the same alloy as the main melt. The AC electromagnetic field adds heating at the outflow, modifies the velocity field, gives a possibility to extract particles, and precludes entrainment of slag into the final casting or into the produced powder. The electromagnetic force permits to control the outflow rate and to increase the superheat of the metal at the outlet. The presence of flux permits shielding of the liquid metal from direct contact with the water-cooled side segments of the crucible. The paper demonstrates the effectiveness of numerical modelling to predict and investigate a variety of options in advancement of the cold crucible technique. Figs 8, Refs 13.

Assessment of the Quality and Mechanical Parameters of Castings Using Machine Learning Methods.

The aim of the work is to investigate the effectiveness of selected classification algorithms and their extensions in assessing microstructure of castings. Experiments were carried out in which the prepared algorithms and machine learning methods were tested in various conditions and configurations, as well as for various input data, which are photos of castings (photos of the microstructure) or information about the material (e.g., type, composition). As shown by the literature review, there are few scientific papers on this subject (i.e., in the use of machine learning to assess the quality of the microstructure and the obtained strength properties of cast iron). The effectiveness of machine learning algorithms in assessing the quality of castings will be tested using the most universal methods. Results obtained by classic machine learning methods and by neural networks will be compared with each other, taking into account aspects such as interpretability of results, ease of model implementation, algorithm simplicity, and learning time.

Investigating sodium phosphate binders for foundry production

The results of theoretical and practical research on the synthesis of sodium phosphates from its inorganic salts and the use of these phosphates as binders for the manufacture of molds and cores are presented.In order to find variants of sodium phosphate synthesis, the processes of interaction of orthophosphoric acid H3PO4 with sodium salts of different types (Na2CO3 carbonate (salt of chemically weak acid), NaCl chloride (salt of chemically strong acid) and tripolyphosphate Na5P3O10 (polyphosphoric salt)) were analyzed. The regularities of the formation of sodium phosphates in all three systems and the conversion of these phosphates when heated in the range from 20 to 1000 оС have been researched.For the first time, thermodynamic parameters were established and the process of obtaining sodium phosphate through the chemical interaction of orthophosphoric acid with sodium chloride was implemented in the laboratory.It has also been shown that the chemical interaction of sodium tripolyphosphate with orthophosphoric acid forms the strongest binder, which is a disodium pyrophosphate Na2Н2P2O7.Synthesized sodium phosphates have an optimal set of functional properties for using in foundry technologies. They provide high strength in compositions with refractory quartz filler and have sufficient thermal stability. Experimentally established, foundry cores based on synthesized binders provide high quality cast surfaces and are easily removed from the internal cavities of cast parts.

Interfacial Microstructure and Bonding Area of Sn-based Alloy-GG25 Gray Iron Bimetallic Material Using Flux, Sn, and Sn-Zn Interlayer Compound Casting

A bimetallic casting consisting of GG25 gray iron substrate and Sn-based alloy using the liquid-solid technique has been studied in this paper. Three different pretreatment processes of gray iron surface substrates including flux only, flux and Sn powder, and flux and Sn-8.8% Zn powder eutectic alloy surface treatment were adopted for the aim of improving the quality of tinning, the interfacial structure, and the bonding area of the Sn-based alloy/gray iron bimetallic composite in order to promote the bonding quality of bimetallic castings. Microstructure characterization on the bonding interface was conducted. The novel tinning material for gray cast iron substrate comprising of Sn-8.8% Zn eutectic alloy powder in combination with flux interlayer improved the bonding area, the interfacial bimetal structure, and the shear stress. This improvement is due to the higher interface reaction of Zn with Fe that leads to the formation of a very thin layer of Fe-Zn and Fe-Sn intermetallic phases.

Casting Defects in Sand-Mold Cast Irons—An Illustrated Review with Emphasis on Spheroidal Graphite Cast Irons

Cast irons are known to be easy to shape by sand casting due to their high eutectic fraction. Despite this fact, together with cost benefits, obtaining good quality castings is not an easy task, although it depends on the level of defects allowed in each case. Casting defects are here reviewed and classified into three classes according to their known main origin: (1) related to the sand mixtures used to make the molds; (2) associated with the mold design and the geometry of the castings; (3) related to the casting alloy itself. The present work is an illustrated description of these defects, with details of their origin when well established, and of known remedies. In addition, an attempt has been made to clarify the possible cross-effects of the above three origins.

Outcomes of Paediatric Distal Radius Metaphyseal Fractures

Background: Manipulation and cast immobilisation is the accepted gold standard for management of distal radius metaphyseal fractures in children, with the use of Kirschner wires (K-wires) in cases with potential instability. The primary aim of this study was to determine the outcome of these fractures treated with our current management protocol. We also sought to identify possible risk factors for redisplacement. Methods: A retrospective study was conducted on 61 children with displaced distal radius metaphyseal fractures under the age of 16 years. Fifty-three patients were treated with manipulation and casting only, while eight patients had K-wire fixation. The primary outcome measured was redisplacement during follow-up. Initial complete displacement, an associated ulna fracture, the quality of reduction, cast and padding indices were assessed as possible risk factors for redisplacement. Results: A redisplacement rate of 18.8% was reported. We found a statistically significant association between redisplacement and non-anatomical reduction (P = 0.001), cast index (P = 0.030) and padding index (P = 0.031). Non-anatomical reduction resulted in 23.6 times more likelihood of redisplacement (P = 0.008) compared to anatomical reduction. Complete displacement and the presence of an ulna fracture had no effect on redisplacement. Conclusions: Our current treatment protocol is safe and effective based on the redisplacement rate of 18.8% which is marginally lower than current standards reported in the literature. Poor casting technique and non-anatomical reduction were found to be significant predictors of redisplacement. We suggest that K-wires be used if anatomical reduction is not achieved in older children with limited remodelling capacity.

Перемішування металевих розплавів як засіб підвищення ефективності функціонування агрегатів «ківш – піч». Повідомлення 1. Способи та системи перемішування рідких сплавів у металургійних агрегатах (огляд)

Based on the global trends in the metallurgy, the features of the further development of technologies for the cast metal productions are predicted. At the same time, there is considered the constant tightening of requirements for energy and resource saving, environmental and work safety, with the simultaneous need to improve the quality of casting, widening the range of obtained alloys and products from them. Also, ensuring reliable operation and expanding the functional capabilities of “ladle – furnace” units has particular importance, since they provide the complex out-of-furnace processing of melts, including averaging on temperature and chemical composition (at alloying and modifying too), removal gases and non-metallic inclusions, etc. It is noted that for the successful implementation of the listed technological operations, “ladle – furnace” units are equipped with additional devices and systems for heating the melt, vacuuming, blowing with inert gas (argon) and electromagnetic stirring. A comparative analysis of different methods of liquid metal stirring (by gas blowing and under the action of an external alternating electromagnetic field) showed that electromagnetic stirring is more effective and appropriate, especially at manufacturing relatively small batches of high-quality and special alloys on metallurgical mini- mills. At that, the most common at metallurgical enterprises and among research developments are electromagnetic stirrers of travelling magnetic field.There are indicated that applications of such stirrers have certain limitations due to physical characteristics. It relates to the need (in most cases) to supply them with a low frequency, making changes to the design of operating metallurgical aggregates for installation of the stirrer, as well as with not always rational hydrodynamic modes of melt stirring.The requirements concerning the development and application of electromagnetic stirrers for “ladle – furnace” units were formulated. Such devices should be simpler in design and operation, ensuring their long-term reliable working at obtaining a wide range of high-quality alloys. Keywords: “ladle – furnace” unit, metallic melt, gas blowing, electromagnetic stirring.