Materials Science Forum Vol. 630

Abstract: In the past 3 years, Pyrotek in association with Laval University and the Industrial Materials Institute of the National Research Council of Canada has developed a simulation package proposing a unique approach in the fluid flow calculation of molten aluminum distribution with a combo bag in the ingot head of sheet casting. This paper will summarize the difficulties encountered and the solutions that were adopted to render that simulation tool efficient and consistent. Validation of the model using actual casting tests will be detailed as well as the major change in the simulation package in order to obtain decent calculation times. Some examples of simulations will be given to demonstrate that the initial goal of this project has been achieved by the development of a mathematical simulation tool to design and improve metal distributors used in the sheet casting production.

Abstract: Tomago Aluminium experienced problems with the boiling of cooling water in ingot casting machines, where water splashed onto molten aluminium after mould filling. The boiling problem was particularly severe when new standard moulds were installed. This paper describes the experiments and modelling employed to analyse and identify the cause of the problem and based on the results, modifications to mould geometry were suggested. Subsequent testing in lab and field trials showed that the boiling was suppressed. The first set of modified moulds in service at Tomago Aluminium showed mould life was improved as predicted. Other issues with the modified mould design, which arose in service, are also discussed.

Abstract: Abstract Usual production of modern cast houses includes semi products and re-melt products. Billets, slabs and rod belong to the family of semi products, while T-bars, sows and ingots are incorporated in the category of re-melt products. Re-melt forms have been developed to be easily transported and easily processed in locations even far away from the cast house where these have been produced. Unlike sow and T-bars, ingots need to be stacked in bundles and securely strapped to allow safe and easier handling and transportation. Yet, the ingots can be processed one-by-one by small users or can be loaded into the melting furnace bundle-by-bundle. The shape and weight of pure aluminium ingots of the old prior art were determined with two aims: maximization of the production rate and minimization of the production costs: for many years heavy ingots have been produced by pouring molten aluminium into a chain of open top moulds. The traditional complex shape of the ingots was intended to facilitate de-moulding operations and bundle piling. For the above reasons, the most common ingot weight worldwide has ranged, until now, from 22.5 to 23.5kg. Now a new technology launched by Continuus-Properzi offers bigger hourly production rates and handy, safe and sound ingots of 30 pounds (13.6kg) as well as more compact and stable bundles. These advantages are paralleled by low maintenance costs and a very high yield near to 90%. With similar investment and production costs the new technology can give a 30% yearly production increase and winning ingot characteristics.

Abstract: Surface quality and metallurgical characteristics of extrusion ingot have a significant impact on the extrudability of the billet. Both the type of casting mould and mould maintenance significantly influences billet surface quality. ALBA, like the majority of extrusion ingot producers, uses moulds with graphite technology, where a mix of oil and gas is injected through a graphite ring into the mould to improve billet surface quality. ALBA has a policy of continual improvement in the areas of safety, product quality and productivity to enhance customer satisfaction. During 2008, an extensive campaign was conducted in ALBA’s casthouse to select the optimum type of casting rings for Airslip™ moulds supplied by Wagstaff Inc. The graphite casting rings evaluated must be suitable for the casting conditions and environment within the casthouse at ALBA. This paper details the methodology and the criteria set for the selection of the optimum graphite casting ring type as well as the results achieved. The results of the work showed a preference for L type casting rings, which enhance the quality of the extrusion ingots and extend the service life of the graphite ring.