Aluminium Foundries Research Articles

A comprehensive review on state-of-the-art applications of case based reasoning in aluminum foundries

An Aluminium Foundry offers multiple opportunities for implementing expert systems across various domains, including component design, process planning, rejection reduction, and determining parameter values for Die-to-Die Design to achieve cost benefits. Considering the projected growth of the Global Aluminium Die Casting market at a 15 percent CAGR until 2025, one of the key hurdles to this growth lies in the requirement for substantial investments. This paper explores the diverse applications of expert systems in different aspects of aluminium casting, focusing on the utilization of Case-Based Reasoning (CBR) systems within Aluminium foundries. Case-Based Reasoning, a problem-solving approach, leverages past cases resembling the current problem to guide solutions for new challenges. The review encompasses various expert systems applied in aluminium casting and specifically highlights the application of Case-Based Reasoning systems. Additionally, it identifies gaps within the Die Design Support System for Gravity Die Casting utilizing Case-Based Reasoning, aiming to delve deeper into this particular area for potential improvements.

MQTT protocol for SME foundries: potential as an entry point into industry 4.0, process transparency and sustainability

The foundry industry with its casting processes and conditions create the basis for the quality of the final metallic components. The control of the process parameters is therefore of primary importance. Topics such as Industry 4.0, digitalisation, Internet of Things or Big Data allowing for a new grade of process monitoring but so far are mainly practiced by a few large foundries, which have started early with the digitalisation of their processes due to the high degree of automation already in place. Small and medium-sized foundries on the other hand often struggle with these issues. Concrete, comprehensible solutions are missing from the point of view of many medium-sized foundries without competences in the new IT-related topics. As the innovative backbone of industry, however, SMEs must also find and enter into this new world of manufacturing. Taking the example of, but not limited to, SME aluminium foundries, the topic presented here therefore aims at a basic and practicable approach for the digital monitoring of the most important process parameters during the production of aluminium castings. The Message Queuing Telemetry Transport (MQTT) communication protocol in combination with suitable microcontrollers, sensor technology as well as corresponding professional open-source software could provide a comprehensive, cost-effective infrastructure for real-time monitoring and visualisation of all relevant process data. In the sense of horizontal integration, the work demonstrates an implementable concept for the appropriate integration of the necessary components and their software-technical linking as well as the associated potential for process transparency, reproducibility and sustainability.

Barriers to and Drivers for Improved Energy Efficiency in the Swedish Aluminium Industry and Aluminium Casting Foundries

Industrial energy efficiency is important for reducing CO2 emissions and could be a competitive advantage for companies because it can reduce costs. However, cost-effective energy efficiency measures are not always implemented because there are barriers inhibiting their implementation. Drivers for energy efficiency could provide means for overcoming these barriers. The aim of this article was to study the importance of different barriers to and drivers for improved energy efficiency in the Swedish aluminium industry and foundries that cast aluminium. Additionally, the perceived usefulness of different information sources on energy efficiency measures was studied. The data were collected through a questionnaire covering 39 barriers and 48 drivers, divided into different categories. Both the aluminium and foundry industries considered technological and economic barriers as the most important categories. The most important category of drivers for the aluminium industry was organisational drivers, while the foundries rated economic drivers as the most important. Colleagues within the company, the company group and sector, and the trade organisation were considered the most useful information sources. Important factors for driving work with improved energy efficiency included access to knowledge within the company, having a culture within the company promoting energy efficiency, and networking within the sector. The policy implications identified included energy labelling of production equipment, the law on energy audit in large companies and subsidy for energy audits in small- and medium-sized companies, voluntary agreements that included long-term energy strategies, increased taxes to improve the cost-effectiveness of energy efficiency measures, and EUs Emission Trading System.

New Plant-Technologies for Reducing Carbon Emissions and Costs in Heat Treatment Processes of Aluminium Castings

The sustainable usage of our precious energy resources is one of the most challenging topics in current developments in the field of mechanical engineering. Apart from the use of a product, the requirements for reducing the impact of manufacturing activities are also increasing, not least because of their economic relevance. Energy-intensive processes, such as foundry industries, are particularly affected. In Aluminium foundries, in addition to the melting process and primary shaping, heat treatment is also of particular significance for an eco-oriented redesign of thermal processing operations. In consideration of the efficient use of energy-resources, this study focuses on the development of innovative plant technology for a sustainable heat treatment of aluminium components. In contrast to previously known solutions, the developed gas-heated furnaces (based on a newly designed burner system) can provide the necessary processing heat for the first time in an electrical control quality. Additionally, the control of the developed burner allows for the reliable utilization of hot air, and thus the effective reuse of waste heat. Conducted analyses and verifications of the prototype plant exhibit tremendous potential for reducing the energy consumption, for lowering costs (savings up to 70%) and CO2 emissions (reduction of 60%), without adversely affecting the quality of the components.

Factors Affecting the Metal Recovery Yield during Induction Melting of Aluminium Swarf

Machining operations of cast parts usually generate considerable amounts of waste in the form of chips (usually 3–5% of the casting weight). Traditionally, swarf is sold to scrapers and remelters, but this option is quite expensive because the selling price is roughly 30% of the acquisition price of the commercial 2nd melt raw material. For most aluminium foundries that incorporate machining operations in their products, reusing aluminium chips as raw material for the melting stocks is perhaps the best option as waste management policy in what concerns to economical and technical aspects. Nevertheless, aluminium swarf is a low density product (0.25 kg/dm3) and is usually covered by a thin film of aluminium oxide and machining fluid. Melting such a product without suitable previous preparation leads to very low metal recovery rates, high energy consumption, gases and smoke generation and very low quality of the final product. During the last years, the authors have developed a high efficient and environmentally friend aluminium swarf recycling technique, using direct incorporation in aluminium melts. The influence of processing parameters, namely melt temperature and holding time, melting atmosphere, swarf briquetting pressure and melting charge composition in the metal recovery yield and dross generation was studied and characterized, and the optimal processing parameters were established. The microstructure of the final product obtained in those conditions was evaluated and is also presented. It is shown that the recycling efficiency depends on the swarf conditioning, the melting technique and the melt treatment methodology. Swarf moisture reduction, induction melting under protective atmosphere and a specially developed degassing technique were found the most important factors influencing the recycling process. By using the developed technique, cast ingots with microstructure and sanity similar to commercially available AlSi12Cu1 2nd melt raw material were successfully obtained with minimal dross formation and metal recovery rates around 90%, without using traditional salts and fluxes.

Energy conservation in aluminium foundries by waste heat recovery from solidifying molten metal

This paper presents a unique attempt to preheat the raw materials by recovering the waste heat from solidifying molten metal in shape castings of aluminium using sand moulds. Finite element analysis of the problem using ANSYS has also been done, results of which show satisfactory agreement with the experimental results. By using this preheating method, it is proved that around 16% of heat recovery could be realised, which is a substantial achievement in this field. Since energy generation has negative environmental impacts, this attempt is a definite contribution to the solution of global environmental problems such as climate change. Patent has been applied for this work and hence minimum details have been provided.

AlB 3 master alloy to grain refine AlSi10Mg and AlSi12Cu aluminium foundry alloys

The potential of AlB3 master alloy in the grain refinement of AlSi10Mg and AlSi12Cu foundry alloys was investigated and compared with that of the AlTi5B1 master alloy, the standard grain refiner for most aluminium foundries. The latter refines the grain structures of both alloys. However, this performance is not nearly as good as that obtained in wrought aluminium alloys with the same grain refiner. The Ti-free AlSi10Mg and AlSi12Cu alloys, on the other hand, exhibit very small grains for the entire range of holding times when inoculated with AlB3. This implies a remarkable grain refining efficiency, typical of grain refined wrought aluminium alloys, as well as a strong resistance to fading of the grain refinement effect. Lack of Ti in the melt allows the entire B to form AlB 2 particles, the perfect substrates, shortly before α-Al starts to crystallize. Aluminium castings can enjoy grains as small as those of the wrought alloys, well below 200 μm, with an addition of 0.02 wt% B provided that their Ti content is controlled.

Production of Al–B alloy by heating Al/KBF 4 powder blends

Al–B master alloys have received considerable attention in recent years owing to their potential as efficient grain refiners for aluminium foundry alloys. While they are generally produced via the halide salt route in bulk alloy form, their use in the form of compacted alloy tablets would be more attractive in aluminium foundries. In the present work, the response to thermal exposure of Al/KBF 4 powder blends was investigated in an effort to explore the potential of powder metallurgy processing in the production of Al–B master alloys. KBF 4 starts to react with aluminium at temperatures as low as 490 °C, well below the melting point of aluminium. Reduction of KBF 4 salt by aluminium produces AlB 2 particles in aluminium grains and KAlF 4 salt dispersed in between. The former are in the form of clustered stringers marking the counters of the original powder grains in mixed Al/KBF 4 samples. AlB 2 particles are dispersed more homogeneously in ball-milled samples owing to the dispersion capacity of the high energy milling process. No evidence of the AlB 12 phase, often reported to be present in Al–B master alloys, was noted in heat treated powder blend samples.

Internal cooling to produce aluminium alloy slurries for rheocasting

Rheocasting is becoming the choice of the casting industry which relies on the semi-solid processing for high integrity structural parts. It is thus of great technological interest to identify simple methods to prepare slurries at reduced cost. The potential of internal cooling to produce slurries for rheocasting was investigated in the present work for several aluminium casting alloys which are technologically important for aluminium foundries. Alloys quenched directly from the liquid state were predominantly dendritic while the slurry samples quenched after an initial fraction of solid phase was first formed, were dominated by α-Al rosettes and globules. The solidification of the remaining liquid phase occurred through the growth of the α-Al rosettes and globules which have formed during internal cooling before quenching.

Response to thermal exposure of the mechanically alloyed Al–Ti/C powders

Al–TiCp composites have been extensively studied in recent years not only because of their attributes as wear-resistant structural materials but also on account of their potential as very efficient grain refiners. Al–Ti–C alloys of various compositions have already been commercialized as grain refining master alloys and have long been in use in aluminium foundries world wide. The present work was undertaken to investigate the possibility of manufacturing Al–TiCp grain refiner master alloy tablets by the mechanical alloying route. Carbon was mechanically alloyed into Al–Ti alloy powder grains via high energy ball milling. The Al–Ti/C powder blend thus obtained was heat treated to promote the precipitation of TiC. Al4C3 was the first phase to form inside the powder grains upon thermal exposure. The Al4C3 particles which were too small to be identified with the optical microscope until 750 °C, have grown until 850 °C where they have started to react with Al3Ti to produce TiC. A very fine dispersion of TiC particles was thus generated inside the powder particles while the Al3Ti phase has almost vanished.

Benchmarking commercial aluminium sand gating systems

The results of a study to identify the range of commercial gating systems used in American aluminium foundries are reported. Fifteen foundries using green sand moulding methods participated in the study by producing moulds of test castings using their “normal” shop gating systems. The foundries were asked to rig a common test pattern for a target volume of 1,500 pieces per month, produced to a “commercial” quality standard, and with an absence of visible porosity on machined surfaces. Information was also requested on essential melt and moulding media conditions, as well as a selling price for the castings.The evaluations included gating ratio and yield measurements, radiographic evaluations of subsurface quality, machining of cope and drag surfaces to reveal gating induced trapped air and dross, pressure testing of two drilled bosses, and a final liquid penetrant examination of the machined surfaces.Those features in the individual systems that appeared to produce the best results are summarised, as well as some undesirable practices that might have a negative influence upon casting quality.

Effect of inclusions on the tensile properties of Al–7% Si–0.35% Mg (A356.2) aluminium casting alloy

The present study was performed on an A356.2 alloy. Two types of initial materials were used, i.e. fresh and recycled. A total of 13 operations representing those normally applied in aluminium foundries were simulated under dry atmospheric conditions (humidity ∼15%–20%). The molten metal was cast into test bars which were T6 tempered prior to tensile testing. The results show that holding the liquid metal for a long time, i.e. 72 h at 735°C leads to sedimentation of most inclusions towards the bottom of the melting crucible. However, a change in the surrounding humidity may cause absorption of hydrogen and, hence, a large amount of porosity. Degassing using dry argon injected into the liquid metal through a rotary impeller (speed ∼ 160 r.p.m) appears to be the best technique for inclusion removal. The efficiency of this process is significantly improved when it is coupled with filtration using ceramic foam filters (10 and 20 p.p.i). A linear relationship between alloy ductility and logarithm of percentage inclusions has been established. Owing to decohesion between the inclusions/oxide films and the surrounding matrix, cracks are easily initiated at their interfaces, leading to unpredicted failure. © 1998 Chapman & Hall

Assessment of melt cleanliness in A356.2 aluminium casting alloy using the porous disc filtration apparatus technique: Part I Inclusion measurements

The present work was undertaken to study the role of the major operating parameters commonly applied in aluminium foundries, as well as the effect of minor alloying elements on inclusion formation in one of the most widely used Al–Si alloys, i.e., A356.2 primary alloy, using the porous disc filtration apparatus (PoDFA) technique. A set of 23 experiments was conducted (each using a melt of 25 kg of fresh alloy material). In each case, four to six successive PoDFA trials were executed. PoDFA samples containing the unfiltered part of the metal (about 5 mm in thickness) in contact with the PoDFA filter were polished for metallographic examination. Inclusion classification and counting were done using the grid method. The present work summarizes the types and concentrations of non-metallic inclusions as well as aluminium oxide films that can occur in this alloy prior to casting.