Decoring of castings

The shaping for metallic castings is determined by molds and cores made of bonded sand. Cores are used to be able to create internal structures such as integrated pipes in castings. After casting, the sand cores must be removed from the casting without leaving any residue. A two-stage process typically carries out this coring. First, targeted hammer blows to the light metal component are used to create fractures in the core, and these fractures are then removed from the component with the aid of a vibrating system. The design of the coring process has been based purely on experience due to a lack of forecasting possibilities.

In close cooperation with FILL GmbH from Gurten (Austria), we could model the process virtually for the first time and describe it exactly. With the phenomenological material model developed at our company, it is now possible to predict the formation and expression of the core fracture in a virtual test laboratory.

The simulation model includes position, intensity, number, and frequency of hammer blows. Thanks to a user-friendly graphical interface, it is possible to ensure the basic coring capability for filigree internal structures as early as the component design stage and design the coring process and optimize it in terms of efficiency.

Our approach ensures a key knowledge gain in the use of inorganic sand-binder systems. The validation of the developed methodology is carried out using reference structures close to the industry. In future projects, the model will be further developed and validated with series components.

Selected Publications:

2020

• Ettemeyer, F.; Lechner, P.; Hofmann, T.; Andrä, H.; Schneider, M.; Grund, D.; ... & Günther, D. (2020). Digital sand core physics: Predicting physical properties of sand cores by simulations on digital microstructures. International Journal of Solids and Structures, 188, 155-168.
• Ettemeyer, F.; Schweinefuß, M.; Lustig, C.; Reinold, L. M; Lechner, P.; Volk, W. & Günther, D.: Charakterisierung des Entkernverhaltens von anorganischen Sand-Binder-Systemen für das Leichtmetallgießen. Formstoff-Forum, 2020
• Lechner, P.; Ettemeyer, F. & Volk, W.: Ein mechanisches Bruchmodell für wasserglasgebundene Formstoffe. Formstoff-Forum, 2020
• Ettemeyer, F.: Simulation und Optimierung des Entkernprozesses von anorganischen Sand-Binder-Systemen für das Leichtmetallgießen, Annual Report 2019/2020 Fraunhofer IGCV, 2020

2019

• Ettemeyer, F.; Sehrschön, H.; Lechner, P.; Volk, W. & Günther, D.: Simulation und Optimierung des Entkernprozesses von anorganischen Sand-Binder-Systemen für das Leichtmetallgießen, Leichtbau in Guss, Nürtingen, 2019
• Sehrschön, H.; Rathner, T.; Günther, D. & Ettemeyer, F. (2019): Simulation und Optimierung des Entkernprozesses von anorganischen Sand- Binder-Systemen für das Leichtmetallgießen, GIFA-Forum 2019, Düsseldorf
• Ettemeyer, F.: Erzeugung von Sollbruchstellen für das Entkernen von Gussbauteilen mit additiven Fertigungsmethoden, Annual Report 2018 Fraunhofer IGCV, 2019

2018

• Ettemeyer, F.; Steinlehner, F.; Lechner, P.; Volk, W. & Günther, D. (2018, November). Detection of Core Fracture in Inorganically Bound Cast-in Sand Cores by Acoustic Microphony. In Congress of the German Academic Association for Production Technology (pp. 34-43). Springer, Cham.
• Günther, D.; Ettemeyer, F.: Entkernung anorganisch gebundener Kerne beim Aluminiumgießen durch konsequentes Kerndrucken, GIESSEREI, 105, 06/2018
• Günther, D.; Ettemeyer, F.: Vergleich der Entkernung von 3D-gedruckten und geschossenen, anorganisch gebundenen Kernen im Aluminiumguss, Formstoff-Forum 2018
• Schneider, M.; Hofmann, T.; Andrä, H.; Lechner, P.; Ettemeyer, F.; Volk, W. & Steeb, H.: Modelling the microstructure and computing effective elastic properties of sand core materials. International Journal of Solids and Structures, 2018