The BMW foundry at Landshut, Germany, has been the object of much attention in recent years, attention that centers around the automaker’s determination to establish the world's first emission-free casting plant for engine blocks. That project succeeded on the basis of several process innovations, including the Inotec inorganic sand binder developed by ASK Chemicals and adopted by BMW.
Inotec allows foundries to achieve odorless core production and odor-reduced casting, but it also significantly lowers cleaning requirements for machines and tools, and contributes to
stronger cast components with improved surface quality, and improved shakeout operations.
On this last point, the BMW foundry also benefits from a customized vibrating conveyor system developed by Cyrus GmbH Schwingtechnik, including vibrating conveyors, vibrating screens, and lump breakers that stretch over 140 meters of space in the foundry, which produces around 5 million nonferrous alloy castings/year: cylinder heads, crankcases, structural components, and numerous chassis parts.
As noted by Cyrus GmbH’s Frank Will and Sven Borghoff in their own report, the Landshut foundry consumes about 120 metric tons every day. So, in the course of establishing the inorganic sand coremaking operation, the sand processing system was modernized and equipped with the new vibratory conveyor technology from Cyrus, as well as vibrating screens and lump breakers.
In regard to the foundry’s emission-free objectives, handling and treating sand is as important pouring and processing castings. When BMW devised a new coremaking operation in 2012, the plans included an integrated system for sustainable sand regeneration. The system developed by Cyrus offers maximum availability, easy access for maintenance, process-safe sand handling, and automatic removal for foreign elements.
In the coremaking process, defective cores are separated and redirected for sand processing through a shakeout grid and downstream vibration conveyor. The shake-out grid is subjected to vertical vibration movements via unbalanced motors, and crushes the sand cores down to a maximum of 200 x 200 mm. Then, sand is then taken to the main conveyor lines through a chute distributor.
At that point, sand that has been separated from cooled castings and the defective cores pre-crushed in the shakeout grid are brought together. While the sand is still hot, it is fed to three vibrating lump crushers over vibrating conveyors with a total length of around 140 m.
The total mass flow of core sand is 12 metric tons/hour. With a maximum output of 7 metric tons/hour per vibrating lump crusher, the conveyed material is pulverized to grain size. Any metals, slag residue, and other foreign elements still present are removed automatically. Any impurities still adhering are removed in the subsequent, linearly vibrating screen.
A stationary 'control screen' monitors the maximum permitted grain size of < 3 mm. This ensures that no larger particles can reach the processing stage through the sand conveyor and damage the system.
According to Will and Borghoff, after this process the material achieves the quality of “new sand.” Their overall design included a comprehensive testing phase for the working components prior to installation and commissioning, including measurement of the vibration data.
BMW required a system design that met the highest fail-safe status, resulting in a redundant arrangement with two parallel sand-transport lines. Even so, the vibratory conveying technology has demonstrated consistent operational reliability, meaning redundancy has not been required for fail-safe operation. The systems now run in regular alternation, and will have a considerably longer service life due to the parallel operation.
The technology and efficiency of the Cyrus design support the overall system availability, which is somewhat more impressive due the customized nature of all such installations.
"Every sand processing system has its own requirements and needs different concepts which are analyzed, planned and implemented with the highest levels of accuracy by Cyrus as a supplier of vibration conveying technology all the way through to complete systems,” reflected Borghoff, who heads sales and marketing for the developer. “In addition to professional engineering, objectives are always selecting ideal components for the product-friendly conveying of sensitive castings, a high degree of operational safety, and low-maintenance operation of the system.”