The right mix makes the difference

With 235 employees, Georg Fischer Automotive produces around 35,000 tons of castings made from nodular graphite cast iron at its Herzogenburg site in Austria every year. The company specializes in crankshafts, exhaust manifolds, turbocharger housings, brake carriers and differential housings for passenger cars and commercial vehicles. The cast iron for the components is made up of different raw materials in precisely defined proportions. For this purpose, the foundry sends "recipes" to the raw material mixing plant, a large hall shrouded in dark gray dust with 25 separate bunker areas in which mountains of metal and scrap pile up several meters high. Here, containers are filled with the appropriate mixture of different melting materials and sent to the melting furnace via a rail system.

The crane operator as cook

Just like a chef mixes his ingredients, the crane operator mixes the metal types according to the foundry's recipe. The required composition is transmitted to him via the control system and shown on the display in his crane cab. For this purpose, the crane control system communicates with the foundry's charging system via a ProfiBus connection.

During batching, the gantry crane moves at up to 63 m/min through the hall of the basic material mixing plant to approach the storage bunkers.

In manual operation, the crane operator moves to one of the numbered bunkers at a time and picks up the bulk material using a magnet - a maximum of five tons per lifting movement. The display provides information on the mass picked up and the quantity still missing from the current bunker. At the touch of a button, the crane operator can release excess bulk material from the magnet in fine increments and thus precisely dose his ingredients. The casting ingredients are unloaded into material containers; the two container slots provided for this purpose are located in a frame below the crane bridge, i.e. always where the crane is at the moment.

The distances in the 60-metre-long hall, the number of bunkers to be approached and the required charging capacity of 15 t/h necessitate high speeds for the crane and trolley and therefore a robust design. The crane bridge can be continuously accelerated up to 63 m/min via four travel drives, the trolley travel speed is 40 m/min and the hoisting speed is 20 m/min. An SH wire rope hoist from Stahl CraneSystems with a high FEM rating of 3 m (ISO M6) is used as the hoist for this high load.

The crane takes over the night shift

Thanks to the compact dimensions of the trolley and wire rope hoist, the new crane system could be integrated into the existing hall and still provide the required lifting height.

In addition to manual operation during the day, the crane is equipped for automatic operation during the night shift. In this mode, the crane automatically moves to the raw material bunkers specified in the foundry's recipe, picks up the required quantities and fills the material containers according to the specifications. Filling a container in continuous automatic mode takes a maximum of 20 minutes, depending on the composition.

The heart of the crane is a double-girder trolley with special headroom, equipped with CraneSystems SH 6025 steel wire rope hoist without hook travel. A calibratable weighing device on the crane's trolley frame is used to determine the exact weight picked up. Some of this crane technology was developed and built by Stahl CraneSystems. The exact position of the crane and trolley must be determined for automatic operation. The position is therefore recorded redundantly via several safe absolute encoders for monitoring the crane travel, trolley travel and rope drum and an additional laser-based distance measurement between the crane bridge and the hall wall.

Safety requirements in automatic mode

Powerful technology in a small space: the SH wire rope hoist in the red paint finish typical of Austrian CraneSystems is designed for high loads.

For safety reasons, no persons are allowed in the hall during automatic operation. This must be confirmed at ground level using a switch before the automatic system is activated. The doors are secured electrically. Automatic operation is started at the height of the crane driver's entrance, around eight meters above the hall floor. The bunkers can only be refilled in manual mode, but filling the circulation boxes with a forklift is also possible to a limited extent in automatic mode.

Strong partner in Austria

Less than twelve months passed between the order being placed at the end of November 2014 and the successful final acceptance, including automatic operation, on November 7, 2015. Austrian CraneSystems only had two weeks during Georg Fischer Automobilguss's summer break to dismantle the old system and assemble the new crane - no problem for the Austrian crane manufacturer thanks to careful planning and expert execution. The partnership between GF and Austrian CraneSystems, which has existed since 2007, was further strengthened by this project. With its special crane, Austrian CraneSystems has shown that it is also capable of handling tricky, challenging projects in Austria and can implement demanding special solutions in line with standards and deadlines.

Contact:Georg Fischer Druckguss GmbH & Co KG 3130 Herzogenburg, Austria Tel.: 00 43 / 27 82 / 8 00-0 E-Mail:[email protected] www.gfau.com

Stahl CraneSystems GmbH 74653 Künzelsau Phone: 0 79 40 / 1 28-0 E-mail:[email protected] www.stahlcranes.com