170 research outputs found
The development of a tool to promote sustainability in casting processes
The drive of the manufacturing industry towards productivity, quality and profitability has been supported in the last century by the availability of relatively cheap and abundant energy sources with limited focus on the minimisation of energy and material waste. However, in the last decades, more and more stringent regulations aimed at reducing pollution and consumption of resources have been introduced worldwide and in particular in Europe. Consequently, a highly mature and competitive industry like foundry is expecting challenges that an endeavour towards sustainability can turn into significant opportunities for the future. A tool to undertake a systematic analysis of energy and material flows in the casting process is being developed. An overview of the computer program architecture is presented and its output has been validated against real-world data collected from foundries
The capability enhancement of aluminium casting process by application of the novel CRIMSON method
The conventional foundry not only frequently uses batch melting, where the aluminium
alloys are melted and held in a furnace for long time, sometimes as long as a complete shift,
but also uses the gravity sand casting process where the molten aluminium alloys are
transferred using a ladle from furnace to pour station and are poured into a mould. During the
filling of the mould, the turbulent nature of the liquid metal gives rise to massive entrainment
of the surface oxide films which are the subsequently trapped into the liquid and act as micro
cracks. Also the long exposure time of the liquid surface to the surrounding environment
during melting, transferring and filling will increase the level of hydrogen absorption from
the atmosphere. The abovementioned factors are often the main reasons for casting defect
generation. In this paper the novel CRIMSON aluminium casting method is introduced which
has a number of advantages. Instead of gravity filling method, it uses the single shot upcasting
method to realize the rapid melting and rapid counter-gravity-filling mould operations
which reduce the contact time between the melt and environment thus reducing the
possibility of defect generation. Another advantage is the drastic reduction of energy
consumption due to shortened melting and filling time. A simulation software, FLOW-3D, is
used to compare this new method with the conventional gravity casting process. A tensile bar
case is used as a sample to simulate the filling process
The improvement of aluminium casting process control by application of the new CRIMSON process
All The traditional foundry usually not only uses batch melting where the
aluminium alloys are melted and held in a furnace for long time, but also uses
the gravity filling method in both Sand Casting Process (SCP) and Investment
Casting Process (ICP). In the gravity filling operation, the turbulent behaviour
of the liquid metal causes substantial entrainment of the surface oxide films
which are subsequently trapped into the liquid and generate micro cracks and
casting defects. In this paper a new CRIMSON process is introduced which
features instead of gravity filling method, using the single shot up-casting
method to realize the rapid melting and rapid filling mould operations which
reduce the contact time between the melt and environment thus reducing the
possibility of defect generation. Another advantage of the new process is the
drastic reduction of energy consumption due to shortened melting and filling
time. Two types of casting samples from SCP and ICP were compared with the new
process. The commercial software was used to simulate the filling and
solidification processes of the casting samples. The results show that the new
process has a more improved behaviour during filling a mould and solidification
than the two conventional casting processes
Improvements in energy consumption and environmental impact by novel single shot melting process for casting
The CRIMSON (Constrained Rapid Induction Melting Single Shot Up-Casting) method uses a rapid induction furnace to melt just enough metal for a single mould rather than bulk melting used in traditional casting process. The molten metal is then transferred to a computer – controlled platform to complete the counter-gravity up filling. The highly controlled metal flow is pushed into the mould to finish the pouring and solidification. In the present paper the energy saving capability of CRIMSON approach is compared with conventional sand casting process. The paper focuses on the energy and resource efficiency optimization of casting stages through simulation and life cycle assessment analysis simulation for proposing alternative means for the better performance of such processes. It is proven that the CRIMSON process can produce high quality castings with higher energy efficiency and lower environmental impact
Assessment of casting filling by modeling surface entrainment events using CFD
The reliability of cast components is dependent on the quality of the casting process. During this highly transient filling phase the prevention of free surface turbulence and consequential oxide entrainment is critical to ensure the mechanical integrity of the component. Past research has highlighted a number of events that lead to entrainment of surface oxides. Using FLOW-3D, flow structures that result in surface entrainment events have been simulated and an algorithm developed that allows entrainment and defect motion to be tracked. This enables prediction of the quantity and motion of oxide film generated from each event. The algorithm was tested experimentally and compared to experimental data from previously published work. A quantitative criterion is proposed to assess the damage of each type of event. Complete running systems have also been studied to understand how they could be assessed for quality of filling based on the flows within them
The modelling of oxide film entrainment in casting systems using computational modelling
As Campbell stated in 2006, “the use of entrainment models to optimise filling systems designs for castings has huge commercial potential that has so far being neglected by modellers”. In this paper a methodology using computational modelling to define entraining events and track the entrained oxide films is presented. Research has shown that these oxide films present within the casting volume are highly detrimental to casting integrity, thus their entrainment during mould filling is especially undesirable. The method developed for the modelling of oxide entrainment has been validated against previously published data by Green and Campbell (1994) [31]. The validation shows good quantitative correlation with experimental data. However there is scope for further development which has the potential to both improve the accuracy and further validate the technique
The challenges for energy efficient casting processes
Casting is one of the oldest, most challenging and energy intensive manufacturing processes. A typical modern casting process contains six different stages, which are classified as melting, alloying, moulding, pouring, solidification and finishing respectively. At each stage, high level and precision of process control is required. The energy efficiency of casting process can be improved by using novel alterations, such as the Constrained Rapid Induction Melting Single Shot Up-casting process. Within the present study the energy consumption of casting processes is analyzed and areas were great savings can be achieved are discussed. Lean thinking is used to identify waste and to analyse the energy saving potential for casting industry
Effect of batch initial velocity on the glass furnace efficiency
Glass manufacturing is a heat intensive process. There is a direct coloration between the batch distribution techniques and the furnace energy consumption, productivity, and quality of the glass manufactured. All four major segments (float, container, fibre, and specialty glasses) would benefit from using an optimised batch distribution technique where possible. Oscillating batch chargers (OBC) have been in use since the early 70s, despite their superior batch shape, coverage, and in turn positive effects on the energy consumption (Soleimanian, TMS 2013) and productivity of the furnace they are almost exclusively used in container glass manufacturing. The OBC’s main difference compared with other charging methods is its ability to directly influence the batch initial velocity. This paper reports on results achieved in two CFD models (in Flow 3D and GFM) used to study effect of the machine on the overall energy consumption in the doghouse and the melt space
Quality assesment of casting filling method
The reliability of cast components is dependent on the quality of the casting process. This can be characterised by the robustness (repeatability) and specific fluid flow characteristics within the running system. During this transient filling phase the prevention of free surface turbulence and thus oxide entrainment is critical to the mechanical integrity of the component [1,2,3]. Past research has highlighted that return waves are major causes of free surface entrainment [4]. To reduce the entrainment occurring during the transitional filling of the runner a steady quiescent flow must be developed.
Using FLOW-3D(1), the Froude number was extracted to allow the quantitative assessment of air entrainment for four different designs of sump at the end of the runner. The results show that, for the designs used, the addition of a correctly designed sump can be advantageous. However, an incorrect design may reduce the Froude number but can greatly increase the persistence of the return wave and entrainment and is therefore extremely detrimental to the cast component. Additionally, the in-gate design is of utmost importance in controlling the back pressure and thus the persistence of the back wave between the in-gate and the downsprue exit. This has a direct effect of the level of oxide entrainment
Redesign of an industry test for hot tearing of high performance aluminium casting alloys using casting simulation software
Hot tearing propensity in aluminium alloys is commonly measured using dog-bone and ring tests. Hot tearing occurs as a result of a number of factors including; level of stress and strain, hot spots and nucleation sites. This paper presents the results of a study to redesign a dog-bone type hot tear test using casting simulation software to ensure that the location of the tearing was always in the same location. In the simulation of the original five fingered die both the stress and strain were sufficiently high for hot tearing but there was no defined hot spot implying that the random hot tear locations would result depending upon suitable nucleation sites. A number of design iterations were carried out to produce more focussed hot spots and to ensure that the die was easy to manufacture and use, and was economically viable
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