Repeated conditioning, i.e. addition of components and water in accordance with the thermal load acting on the recirculating mold material in a sand foundry.
Since used sand makes up for the major proportion of the mold material mixture to be conditioned, it is the quality and homogeneity of the sand that determine the achievable mold material properties. To ensure the required homogeneity, the sand must be appropriately pretreated during the process stages of mold material recovery.
Mold material recovery includes the following process steps:
- Demolding the castings from the mold. In this step best possible separation of the sand from the casting must be ensured. This reduces output losses and facilitates cleaning. It is also beneficial to realize separation of mold sand and coresand.
- Removal of metal components, core residues and used sand nodules.
- Crushing of used sand nodules and controlled introduction into mold material circulation.
- Cooling of used sand to temperatures of < 40 °C.
- Homogenization of used sand (recirculating mold material). Homogenization must include a number of several used molds. Homogenization can be profitably implemented through the principle of “hopper strategies”.
- Adjustment of the required mixing ratios between used sand, quartz sand, binder, additives, and water.
- Visual inspection, dedusting, and removal of wear products in the molding material circulation.