At the end of last year, HWS (Heinrich Wagner Sinto), Bad Laasphe, and INDUGA Industrieöfen und Gießereianlagen GmbH & Co. KG, Cologne, successfully put the first dedicated low-pressure sand casting line for heavy metals into operation at a leading German production plant.
The casting line is designed for 180 flasks per hour and is supplied with metal by two low-pressure casting furnaces. These furnaces operate alternately so that production is not interrupted during recharging of the metal from the melting line. During filling of the moulds, a robot picks up the flask from the line and positions it over the furnace nozzle, through which the metal is then forced from below into the mould. The robot then returns the flask to the moulding line. The whole process takes 20 seconds.
The filling characteristic can naturally be programmed or set as required, since it can be controlled via the filling pressure. A laser sensor ensures that drifts are compensated and the flask is filled precisely and reproducibly.
The figure shows the casting furnace with the pressure and recharging chambers, as well as the riser and nozzle section on which the flask is placed. During flask changing, the pressure is controlled so that the meniscus of the liquid metal is level with the nozzle upper edge. The furnace is equipped with a channel-type inductor that permits precise and automatic temperature control.
The fundamental process was developed in conjunction with the University of Duisburg and brought to production sophistication with respect to the moulding cross-sections and casting dynamics by the customer on a pilot plant.
The advantages of the process lie essentially in the enhanced casting quality and the drastically reduced amount of recycled material, with the corresponding savings. In addition, the casting process is hermetically sealed for a cleaner metal discharge without oxide and slag inclusions and offers a high metering precision. Overall, profitability and process reliability are enormously improved.