Foundry mold sand for making sand molds.
It consists of a refractory material, usually quartz sand, a binder and water. In most cases, further special additives for mold materials are also added. The structure and composition of foundry mold materials are determined by the requirements to which these materials are subject during the casting process, such as casting range, casting mass, casting material, shape, wall thickness, casting temperature, etc.
Molds based on clay-bonded mold materials can be made by means of different types of mold material systems:
Mold sands found in nature which contain clay as a binder; depending on the clay content, they can be divided into lean, medium-fat and fat sands. These mold sands are generally very fine-grained, their properties can only be varied to a very limited extent.
Semisynthetic mold sands
These materials are prepared by mixing natural mold sands and synthetic mold materials. It is also possible to add or clay to natural mold materials. By doing so, the properties of the natural mold sands can be improved in a targeted manner and improved control can be gained.
Synthetic mold materials
These mold materials are synthetically prepared from the basic component quartz sand or another basic mold material, a binder (bentonite), additives and water. The composition can be varied within a wide range, allowing optimum adjustment of the mold material quality to the specified requirements.
Basically, the quality of the mold material is determined by material-related influencing factors (quality of the basic mold material, bentonite, lustrous carbon formers), quantity-related influencing factors (composition) and technical influencing factors (type and method of conditioning, intensity).
This is how Simpson Technologies states: “As molding lines get larger and faster, modern foundries require larger volumes of high-quality molding sand produced at the lowest total cost. Foundries that use batch mixers experience downtime when they do not have an adequate supply of sand. In addition, these batch mixers produce non-uniformity in the molding sand which negatively impacts the quality of castings. The most advanced sand preparation tool for medium to large foundries is continuous mulling."
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