Engineers Invent New Process to Make Foundries Greener
Engineers at the University of Birmingham, with local company, Ntec, have invented a new casting process that could reduce the energy costs of light-metal foundries. The technology, called CRIMSON, means that foundries need only heat the quantity of metal required to fill a single mould rather than whole batches that use unnecessary energy and create waste.
The UK is at the forefront of light metal casting and investment casting technologies, which are vital to the global aerospace and automotive industries. The energy efficiency of the casting process has never been investigated fully so a new research project run by the University of Birmingham’ School of Mechanical Engineering will identify the energy use in traditional foundry processes and compare it with the University’s new process that aims to reduce costs, energy usage and waste output.
Currently a typical light-metal foundry melts between 100kg to several tonnes of alloy in a range of furnace types. This liquid metal is held at about 700 degrees centigrade in a holding furnace before it is transferred to a ladle and poured into a casting mould. It can take roughly 8 hours for the liquid metal in a batch to be used up and any leftover metal is poured off to be re-used or scrapped for re-melting or refining in a secondary processing plant.
The traditional casting method uses energy to melt and keep the batch at temperature, heat the pouring ladle, and melt the unused metal so it can be recycled or scrapped.
Quality issues can also arise when the liquid metal reacts with hydrogen, oxygen and water in the atmosphere. An oxide surface layer is created which becomes mixed in during the pouring process, resulting in tiny particles or layers of metal oxide, which reduce the quality of the liquid metal, leading to degraded mechanical properties of the end product.
The new CRIMSON technique uses a high-powered furnace to melt just enough metal to fill a single mould in one go in a crucible. It transfers the crucible into an up-casting station for a highly controlled filling of the mould against gravity. This method only holds the liquid aluminium for a minimum time reducing the energy losses incurred when holding metal at temperature and removing the need for ‘degassing’ as other elements from the atmosphere are not absorbed or thick layers of oxide allowed to form. The castings produced are of a higher quality, leading to a reduced scrap rate and decreased re-melting energy costs.
Dr Mark Jolly, the lead investigator from the University’s School of Mechanical Engineering, says, ‘At the moment in the UK we use the equivalent of every man, woman and child each boiling a kettle twice a day every day of the year just to melt the aluminium for casting. It is hoped that the new process will be able to reduce this energy usage by one third.’
He continues, ‘From an industrial point of view any understanding of the relationship between processing and energy usage is of benefit to both the process engineer and designer in today’s climate of sustainability. By measuring the energy usage of the traditional processing methods we will be able to gain a better insight into how energy can be saved. Our new casting technique will provide an alternative and more energy efficient processing route for foundry designers and engineers.’
Notes to Editors
1. CRIMSON stands for Constrained Rapid Induction Melting Single Shot Method.
2. Dr Mark Jolly has received a grant of £526,000 from the Engineering and Physical Sciences Research Council (EPSRC) to carry out this research project. The total value of the project including partner contributions is £800,000
3. Partners in this project include Cast Metals Federation, Resource Efficiency Knowledge Transfer Network, Ntec, Ford Motor Company, Grainger and Worral foundry, Aeromet aluminium foundry, Federal Mogul Nurenberg GmbH.
For further media information
Kate Chapple, Press Officer, University of Birmingham, tel 0121 414 2772 or 0779 921164.