|
|
|
|
|
|
|
|
|
| CSIRO | SOLVE | Issue 2 Feb 05 | |
|
| |
|
MANUFACTURING
Cool Tool
By Rebecca Thyer
A revolutionary new 'feed' system will cut the cost of making metal parts through high-pressure die casting. Automotive parts manufacturer Lyndon Joss knew he was on to something potentially revolutionary when the CSIRO technicians who came to test their new high-pressure die casting process at his factory told him the dies he had prepared for their trial were far too hot.
'The fact that the new process didn’t require the dies to be preheated to anywhere near the conventional preheat level meant energy and time savings alone were going to be significant,' he says. Mr Joss, managing director of Melbourne-based Excel Pacific Diecasting, is now considering installing the new high-pressure die casting (HPDC) system later this year. The CSIRO-developed (and patented) process, Advanced Thixotropic Metallurgy (ATM), takes a different approach to HPDC by using a revolutionary feed system. It is particularly suited to aluminium and magnesium alloys. ATM is about 10 per cent cheaper to operate than conventional HPDC and does not require major investment in new plant and equipment. As ATM technology produces a higher quality metal product – because the new feed system leads to a more uniform metal distribution – it is expected to be of particular interest to manufacturers of safety-critical automotive components. However, its range of applications should be wide, such as lighter and more durable cases for mobile phones. The new approach to HPDC is said to have the potential to give Australian manufacturers a timely competitive edge against imports by producing higher quality products. Mr Joss says this is critical for local manufacturers: 'Adopting best-practice die casting methods is crucial to the survival of die casting manufacturing in Australia. Using processes our grandfathers used and saying "that’ll be all right" does not work anymore. Cost-efficiency and top quality are the benchmarks which set best-practice manufacturers apart from the overseas and local competition, and ATM is one of the tools now available to us.' ATM is being described in the industry as a breakthrough technology for traditional HPDC. Barrie Finnin, marketing and business development manager for CSIRO Manufacturing and Infrastructure Technology (CMIT), says ATM essentially covers off the die caster’s wishlist: reduced rejection rates and reduced cycle (production) time, which lowers labour and machine costs. It is also a system that can be added to most existing equipment. Conventional HPDC involves molten metal being forced into a cavity through small tunnels or runners. During this process, air can become trapped within the melt. This trapped air appears as porosity in the finished part and can be detrimental to its quality. To exclude the worst of the affected metal and reduce the internal porosity of the part, cavities usually have substantial overflow zones. Additionally, traditional feed systems can contain pre-solidified grains that continue to grow while being forced into castings. Particularly large grains can seriously affect casting properties. Dr Rob O’Donnell, project manager for ATM within the CMIT division, says the use of a revolutionary feed system in the ATM process generates a more uniform product with reduced porosity, and at a lower unit price than traditional casting. 'Using ATM technology, the fill is different,' he says. 'It doesn’t trap the same amount of air during the rapid cavity filling process, as is the case for traditional HPDC processes. Also the ATM technology causes the pre-solidified grains to undergo a process akin to "turbulence", breaking larger particles into smaller ones. 'Breaking up larger bits into fine nuclei enables a more uniform distribution of nucleation sites within the die, and therefore a more uniform product.' As the feed system requires a smaller runner and negligible overflow zones, less metal is used and less is wasted, reducing metal costs and recycling costs, and improving turnaround times. 'In a part that normally costs $1, a die caster can now save between 10 and 20 cents through using less metal, having better efficiency and turnaround times, improved wear on dies and manpower savings,' says Dr O’Donnell. Mr Joss agrees. He says the CSIRO trial proved that significant savings could be made in raw material, energy and manpower costs. Excel Pacific hopes to utilise the process on the automotive parts it manufactures for Holden, Toyota and Ford, where a 'high level of structural integrity and minimal porosity is required'. Dr O’Donnell says that important quality improvements – because of reduced porosity and a more homogeneous microstructure – will give part designers and die casters a real competitive advantage. He also points out that low porosity enables the end product to be heat-treated. This is regarded as a major triumph because products made using the conventional HPDC process cannot be heat-treated. Heat treatments can be used to significantly increase the metal’s ductility and can more than double product strength. 'From a scientific point of view, we love that part. We have the opportunity to manipulate the microstructure so that, where strength is critical, lighter parts can be designed to perform the same task', says Dr O’Donnell. 'We are now introducing this development to component designers and showing them what can be done. It could mean thinner or lighter road wheels, for example.'
The ATM process arose out of research into reducing the amount of metal that needs to be recycled during the HPDC process, without adding to manufacturing costs. From the start, the researchers were aware of the need to achieve a scientific result that met these economic structures. Mr Finnin says CSIRO’s approach was 'a radical rethink of the HPDC runner design. It moves in completely the opposite direction to recent die casting technology'. The result is a process that does not require any major new capital outlay to either trial or use ATM technology. CSIRO simply takes the feed system to potential clients. 'It fits inside their system, meaning there is no need to change their plant,' says Dr O’Donnell. The process has been in low-volume serial production since 2002. Five Australian manufacturers and more than 10 international manufacturers are now trialling the technology, and most are reporting immediate improvements. BSTG (formerly Bridgestone Automotive Ltd) has been working with CSIRO to implement the ATM technology into steering wheel armatures. Commercial production is anticipated to start this year. To use the system permanently, die casters simply remanufacture their runner system. 'Die casters are used to doing this anyway, because these parts get worn out and require periodic refurbishment. They don’t have to go to a lot of effort to recoup the benefits of this system', Dr O’Donnell concludes.
For further information contact: |
IN THIS ISSUE
|
| Home | About Us | eSubscribe | Links | |
|
|
||
|
|
|
Back to main