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Article #51: Aluminum Casting Technologies

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Aluminum Casting Technologies and Cost Hydrodynamics
effectiveness To develop a simulation technique to
Aluminum is the established metal of assist industry in design and
choice for the production of light weight optimisation of dies and products.
components in the automotive, aerospace This year has seen extensive developments
and transport industries. Casting liquid in the Smoothed Particle Hydrodynamics
aluminum alloys into metal moulds using (SPH) code along with testing undertaken
processes such as gravity, low pressure to improve the robustness and speed of
and high pressure die casting is a cost modelling. Enhancements were also made to
effective means of producing complex the visualisation techniques used to
shapes that require minimal machining. display results from SPH's three
Australia's automotive industry supports dimensional (3D) simulation results. 3D
a strong local aluminum die casting SPH isothermal simulations and animations
industry, producing parts that include of parts from Nissan and Metaldyne
automotive transmission housings, showing complex filling patterns were
cylinder heads, inlet manifolds and completed. Observations by staff at
engine sumps.(Ref: Nissan Casting of the casting's filling
Growth in world automotive markets for pattern during production were consistent
aluminium die cast components is creating with the SPH modelling predictions.
significant opportunities and challenges Water analogue images from a clear
for the Australian industry, which is perspex model of a servo piston die
positioning itself as a global player. casting part and digitised short shots of
Through partnerships between our research an aluminium casting were completed for
organisations and key automotive validation with flow predictions from
participants such as Nissan and Ford, SPH. The validation process and further
CAST has developed innovative and novel computational speed improvements will be
technologies that have benefited our completed next year. Further developments
partner's productivity. In turn, these of the SPH code particularly in the areas
technologies have created IP that is of heat transfer, solidification, surface
poised on the verge of commercialisation. oxide prediction, robustness and speed
An example featured is CASTcoat a project are planned in future work.
that began as postgraduate research at Tailoring of reform's New Die Coat for
CSIRO and The University of Queensland. LPDC and GDC
It was developed further under CAST To commercialise the die coat technology
project funding at CSIRO with industrial for low pressure and gravity die casting
trials at Nissan, Ford, Merne Products, and further improve die coat properties.
Castalloy and others. Now it is a Industrial trials were carried out
provisionally patented technology. (Ref: successfully in several low pressure and
Cycle Time Reduction gravity die casting plants. Its
Automated Fault Detection in Aluminium performance was enhanced in low draft
Die Casting angle areas of the die by application of
Modelling of Fluid Flow Inside a Die a sealer. Two provisional patents
Cavity Using Smoothed Particle covering inventions related to have been
Hydrodynamics lodged.
Tailoring of CAST's New Die Coat for LPDC Integrated Gravity Die Design Methodology
and GDC To develop an integrated die design
Integrated Gravity Die Design Methodology methodology for gravity die casting that
Improved Quality Aluminium Automotive can achieve optimal die filling, optimal
Castings feeding and yield, and dimensional
Reduction in Metal Pressure in the HPDC stability.
Process A new design of feeders to address the
Cycle Time Reduction root cause of shrinkage porosity defects
To increase productivity of high pressure in an inlet manifold casting was
die casting by reducing casting machine implemented on a customer's die and
cycle time by 30%. resulted in excellent outcomes. A study
More than a 20% reduction in cycle time was completed on the use of "squeeze
has been achieved and implemented on pins" to reduce or eliminate shrinkage
selected parts at two industry partner defects in a gravity test die. The
plants. The project has involved squeeze pin technique demonstrated that
identification of opportunities to reduce surface shrinkage can be effectively
the process cycle time, performing eliminated and associated internal micro
research to prove the concept and then shrinkage can be significantly reduced in
carrying out the actual trial to prove the locations tried. The squeeze pin
the theoretical findings. This concept was extended to include
necessitated the involvement of shopfloor application as a mechanical squeeze/shear
staff in order to implement changes to gate to reduce fettling requirement. The
the process. Such trials are often in mechanism implemented on a test die
conflict with the day to day production allowed the shearing of the gate before
of parts and only through true full solidification, with adjustment to
cooperation has it been possible to produce variable gate widths.
achieve the project objectives. The final part of the methodology to be
The third year of this project has shown developed is optimal die filling through
the development of true cooperation variable tilt pouring from a ladle. To
between researchers and industrial ensure smooth flow, the variable tilting
partners where the latest research motion can be programmed to match the
findings obtained through modelling and filling rate with changes in the
simulation have been implemented on the instantaneous flow area. Flow evaluation
shopfloor with the help and support of is done by real time X-ray radiography on
staff from Ford and Nissan. The changes, a test die. The effect of die geometry,
once trialed during a production period, especially wall thickness, on die
have been implemented as part of the distortion will be investigated using
process, hence providing ongoing cost computer simulation that models thermal
benefits through a reduction in the time stresses in casting cycles.
required to produce each component. Improved Quality Aluminium Automotive
An example of implementation is a Castings
reduction in cycle time at Nissan on a To improve the overall performance of low
gearbox side cover produced in a twin pressure die casting operations by
cavity die that has shown successful implementing improved tools in design and
production results over many months from process control to reduce casting
an original cycle time of 75 seconds down defects.
to 60 seconds. Whilst research at Ford on Successful development of appropriate
a converter housing casting has shown tooling design and process control has
successful implementation of cycle time been achieved for the low pressure die
reduction from 90 seconds to 74 seconds. casting (LPDC) process to cast small
In future work we will look for further automotive components. A multi-cavity die
opportunities with current stakeholders design was selected and optimised by
and the die casting industry in general, solidification simulation. Several dies
to implement the horizontal deployment of of this design are being used to produce
cycle time reduction across other high-volume, high-integrity parts.
machines and parts. Casting parameters were also investigated
Automated Fault Detection in Aluminium to improve the casting quality and reduce
Die Casting the cycle time. Die trials were conducted
To develop and implement an automatic on an LPDC research die to investigate
fault detection system for surface and the effect of casting geometry and
sub-surface defects. process parameters on shrinkage defects
A fully automated fault detection machine in castings having several fundamental
called CASTvision has been developed and features of cylinder heads. The die trial
a prototype system is ready for extended successfully produced castings with
in-plant on-line trials. This project is shrinkage defects in one particular area
in its third year and exciting results sandwiched in the sand core, as
are now emerging. The results from the predicted. Analysis of castings made on
algorithm, which was designed and the LPDC pseudo-cylinder head research
developed during the second year of the die will be completed to establish
project, have been put to the test this relationships between porosity defects
year. Through prototyping, the CAST team and process parameters.
have designed and developed a working Reduction in Metal Pressure in the HPDC
system, CASTvision. For Ford's converter Process
housing casting the off-line system can To investigate the role of metal pressure
detect and discriminate between defective on the production of quality parts in
and good parts. The prototype system is high pressure die casting.
capable of identifying blocked holes on In the final six months of this project,
any of the holes on this complex casting. effort was focused on innovative
Off-line systems have also been developed technologies. One such technology was
where hot tears and cold shuts can be designed to absorb impact pressure spikes
detected on Ford's structural sump that cause detrimental flashing and the
casting. other technology involved revamping the
Work at Nissan on their pump cover hydraulics of ageing die casting machines
casting has resulted in a CASTvision to improve product quality. A novel shock
prototype system for in-line fault absorbing technology was developed that
detection. The system is able to capture utilised existing casting overflows. Die
images and identify certain categories of casting trials at CSIRO confirmed the
defects on the surface of the part. This effectiveness of this technology in
project has demonstrated that advances in absorbing impact pressure shocks upon
machine vision applied to fault detection cavity filling. Through in-plant trials
of aluminium castings can be taken from at Nissan Casting Plant the limits of
the concept stage through to a working hydraulic valve timing and circuit
prototype very successfully. The next functioning were confirmed. A proposal
step for this project is to take the for a revamp to improve intensification
concepts from single part to multi part pressure response was put forward. The
systems able to handle more complex project concluded in December 2001. Ford
shapes and surfaces. This outcome will be Australia may adopt the reduced pressure
a strong candidate for future operating parameters for the production
commercialisation. of their new Barra model engine sumps
Modelling of Fluid Flow Inside a Die later in 2002.
Cavity Using Smoothed Particle






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