The globally positioned Handtmann Group operates 44 Westomat dosing furnaces at their headquarters in Biberach, Germany. Their extensive experience with light alloy dosing technology enabled the casting manufacturer to carry out a successful modernisation program with the help from the StrikoWestofen specialist team. Together, the two partners modernised the tried and tested PneuCo system with a flanged riser tube. This modernisation project led to the desired improvements in dosing system availability and process stability.
The Handtmann Group (Biberach) believe that the three key factors to success are: pioneering technology, innovation and commitment to quality. The light metal casting expert was able to observe all three of these principles during the recent modernisation project. Over a 24 months period, the industrial furnace manufacturer StrikoWestofen, carried out a comprehensive upgrade of 44 Westomat dosing furnaces at Handtmann. The switch to flanged riser tubes with pneumatic measurement of the liquid metal level - PneuCo system, and the installation of the ProDos3 control systems means the furnaces are now well equipped for the challenges ahead.
Small feature, astonishing result: the PneuCo system
To optimise dosing system availability and process stability, and to further minimise the scrap rate, all 44 Westomat dosing furnaces at Handtmann were upgraded with flanged riser tubes that boast replicable conditions and straightforward handling. However, the globally active company did impose one clear condition: Pointing out the extremely good experience they had had with the PneuCo system over the years, they made it clear that they did not wish to sacrifice this when switching from classically casted to flanged riser tubes.
The PneuCo system is an alternative way of evaluating the liquid metal level at the pouring edge of the riser tube. Usually, it is measured using electrodes, or top-stop position. The advantage of the PneuCo system is that it is not subject to wear and tear: the changed pressure at the scanning point is measured to determine the level of the liquid metal in the riser tube. A small flow of air from the output of the pneumatic control is directed to the scanning point in the riser tube. As soon as the rising level of the liquid metal in the riser tube covers the air outlet, the pressure in the PneuCo system rises suddenly. This rise is detected by a pressure switch and transmitted to the dosing control as a dosing contact. This pressure switch process corresponds to the dosing contact used in classical electrode scanning. Light metal foundries benefit in two ways: there are no wear parts for the dosing contact and the scrap rate is minimised by eliminating possible interference with molten metal. Handtmann’s commitment to quality led them to choosing the PneuCo system with flanged riser tubes. The new solution is currently being tested during production and the company is extremely happy with the results.
In addition to the PneuCo upgrade, Handtmann also decided to improve furnace control with ProDos3 – a high precision control system for high pressure die casting. Holger Stephan, who manages the Service and Spare Parts division at StrikoWestofen, explains: "Our ProDos3 with integrated biscuit correction increases the dosing accuracy of the Westomat. In addition, pressure fluctuations can be compensated, and reproducibility improved using a number of different correction factors. The optional web server is another new feature that allows the integration of the ProDos3 control into the local company network. This means that all relevant information, e.g. the furnace pressure and performance data, can be accessed conveniently from your office."
The modernisation programme also included joint testing of new refractory replacement parts for Westomat. A clear reduction in downtime during refractory repairs to the furnace with similar quality results supports Handtmann's three principles. As a result, the product will be used in the future when repairs are carried out on the lining of dosing furnaces. And finally, a new StrikoWestofen heating station increases the level of occupational safety when handling hot ceramic components and a special assembly bench simplifies the fitting of flanged riser tubes with PneuCo.
Stephan added: "We are extremely happy with the successful modernisation programme and are proud that we were able to meet the specific requirements of our customer in such a flexible and cooperative way".