Core shooting
Core shooting is a mechanical process used in foundry technology ( primary molding ) to produce cores with so-called core shooting machines and core boxes suitable for this.
Pouring liquid metal into a mold (e.g. a sand mold) results in a solid casting without the use of cores. However, if the casting is intended for the sake of an intricate geometric construction, e.g. B. be hollow as weight savings or the passage of media (for example a liquid), there are various methods to achieve this by means of cores produced by the core shooting process. Here, the shape of the cavity to be created is made with specially prepared molding material. This sand core is then placed within the mold at the point where the cavity or an undercut is to be created. If necessary, this core is reinforced with core iron so that it is not destroyed during the casting process.
In the core shooting machine, basic mold material mixed with binding agent is introduced into a core mold (the “ core box ”) at a specific shooting pressure (2–6 bar) and possibly a defined working temperature . After the casting core produced in this way has hardened , it is installed in the casting mold . After the casting has taken place , the molding material from which the core was made is removed through the openings provided in the cast construction.
So-called coldbox or hotbox core shooters are used, depending on the binding agent added for the hardening of the molding material .
Core shooting simulation
In order to optimize the core shooting, the process (all process steps including shooting and venting, gassing and curing) can be simulated, virtually predicted and mapped over time using an animation ( core shooting simulation ). The different flows of sand and air, their interactions with each other and with the environment of the core box are dynamically modeled.
A core simulation can be used for both organic and inorganic binders and for cold (coldbox) manufacturing processes as well as temperature-controlled core cans (hotbox, croning, inorganic cores). From the simulation results it can be seen how process parameters - shooting pressure, number and positions of shooting and ventilation nozzles or sand-binder mixture - have to be selected in order to obtain the required sand density everywhere and to economically manufacture cores with which cast parts are in the desired Have quality produced.