Thanks to intensive research into the area of inorganic binder systems, the gap between cold-box technology and the INOTEC system has become ever smaller. Statements that often argue against the use of INOTEC technology have frequently been disputed and/or qualified. By contrast, INOTEC technology offers significant technological advantages for the foundry industry.

Benefits:

• Reduction of sand adhesions and penetrations
• Optimization of shake-out performance, enabling filigree water jacket cores to be removed safely from the casting
• Excellent dimensional accuracy during casting due to improved thermal stability
• Improved structural properties (shorter dendrite arm spacing)
• The use of water-based coatings in iron casting is also possible

New technological potential: central feeding concept

The absence of combustion residue offers new freedom to component developers. One impressive example of this is the new central feeding concept, which is used at BMW’s Landshut plant for crankcases of future engine generations. Inorganic cores are used as central feeders here, thus minimizing the risk of sooting ventilation ducts in the low-pressure permanent mold. This concept is not feasible with organic cores.

The dendrite arm spacing (DAS) of the three feeding concepts is shown in the illustration below. It is apparent that the new central feeder concept leads to DAS advantages in all component areas. The warmest point (thermal center, binding of the feeder) and therefore the point with the highest local DAS is in the area of the lower dead center of the piston, a point that is not subject to excessive thermal or mechanical stress. The tension rod area also solidifies very quickly and can be influenced externally via the permanent mold. The tendency towards leaking after mechanical processing falls dramatically, and the sealing rates are miniscule.

Potential in iron casting

Inorganics have considerable potential in iron casting. In particular, problematic parts that require work with special sands or additives in combination with a coating against veining are predestined for use of inorganic binders, since they show a much lower tendency towards veining – or indeed none at all – compared to organic systems.