Special Report N°3/2003

Foundry optimisation and automation will be the focus of attention at the international foundry trade fair GIFA, being held in Düsseldorf from 16 to 21 June this year. Manufacturers of foundry machinery and equipment will be presenting technologies which improve productivity and flexibility in production, reduce environmental impact and lower energy consumption.

Foundry technology is already very advanced today. "But simulation can further optimise the production process and increase throughput by up to 20 percent," says Dr. Wolfgang Andree, head of Foundries and Forming Plants at ABB Process Industries GmbH in Dortmund. One way to introduce transparency and uncover quality problems in foundries is to use modern simulation, control and data mining techniques. As part of foundry process monitoring, all important measured values and information are stored and evaluated by computer programs. "Mathematical/statistical analysis of all stored data allows us to uncover relationships which are not immediately apparent," explains the automation expert.

Simulation tools make the production process transparent and highlight organisational bottlenecks. From the findings obtained, measures can be developed which, if implemented consistently, can not only help improve quality of production and lower energy consumption but also reduce scrap rates. "In combination with advanced process control technology, such tools also can lead to changes in outdated administrative procedures and greatly increased transparency throughout a company ," says Andree.

ABB has developed special integrated solutions for melting shop operations and will be presenting these in Düsseldorf.

From automatic charging to processor-controlled melting, these integrated solutions allow the use of lower-quality, lower-cost scrap, such as zinc-coated materials or swarf.

Modern process control systems can help optimise melting shop operations by increasing productivity while still meeting high quality and environmental demands.

The company Otto Junker from Simmerath also specialises in enhancing melting and casting processes to achieve better metallurgical parameters. The main aim is to obtain closer compositional tolerances and increase the purity and homogeneity of the cast metal. High process reliability and cost-efficient use of resources (energy, manpower, raw materials) are other targets.

"There’s healthy competition among the various melting processes, even though the trend towards medium-frequency furnaces is unmistakable," says Dr. Trauzeddel, senior engineer at Otto Junker. This trend is being reinforced by advances in inverter technology, energy reduction, process control and customised solutions.

Simulation programs and 3-D design are being used to optimise equipment for increased efficiency, improved metallurgical conditions and reduced environmental impact. This will be demonstrated at GIFA by a 6-t medium-frequency furnace equipped with a continuously variable 25° back-tilting system.

Higher process reliability can be achieved through the use of early warning, remote diagnostic and intelligent process control systems. One example which will be on display in Düsseldorf is a laser-optical crucible monitoring system which continuously measures local temperatures in the crucible wall in order to determine lining wear and detect cracks and washouts.

Advances have also been made in moulding sand preparation. "The trend is definitely towards medium-to-large, flexible and highly efficient equipment," says Dipl.-Ing. B. Hohl, foundry product manager at Maschinenfabrik Gustav Eirich in Hardheim. At GIFA, the manufacturer of moulding sand preparation equipment will be introducing, among other things, a newly developed modular system which promises to allow particularly fast, cost-effective installation and start-up.

The company has added to its range of high-intensity vacuum mixers: EVACTHERM® combines the three main steps of mixing, cooling and tempering in a single machine. Comparisons with conventional processes show significantly improved properties of the moulding sand, says Hohl. The quality improvement goes hand in hand with increased productivity. In addition, the process reduces dust emissions and makes very efficient use of raw materials.

But it's not just individual machines which will be on display in Düsseldorf: some exhibitors have further developed and optimised the foundry process itself, such as KURTZ GmbH from Kreuzwertheim. The foundry equipment manufacturer will be presenting a low-pressure process capable of producing high-quality castings. "Based on design for casting, this process ensures controlled solidification and results in a pore-free microstructure", explains Lothar Hartmann, the company's sales manager.

In addition to the standardised requirements of volume production, KURTZ has in recent years focused on two special applications of this technology – rapid prototyping, allowing production-like casts of new parts to be made quickly and cost-effectively, and specialised machines, for example, for the high-volume production of engine blocks.

The challenge in rapid prototyping is to prevent pressure variations during the filling of the open moulds which could lead to piping. In contrast to closed moulds, which generate back-pressure during mould filling as a result of differing venting conditions, the metal meniscus during casting in core assemblies is open and reacts to even minor pressure variations.

KURTZ’s pressure control system based on proportional valve technology guarantees smooth transitions at different rates of increase. This significantly improves the quality of the casting process.

One major advantage is the high flexibility of the pressure control system, which can be used in a wide range of furnaces and machines, according to the Kreuzwertheim-based manufacturer. The pressure build-up can be precisely controlled both on small 100 kg furnaces as well as on large-capacity furnaces.