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فارسیFoundry Sand
Foundry sand is a silica-based quartz sand with high refractoriness (heat resistance) and a controlled particle-size distribution, used in the production of moulds and cores in the metal casting industry. It is preferred in iron, steel, aluminium, brass and bronze casting.
Foundry sand is a critical raw material that can withstand the high temperature of molten metal, accurately maintains the mould cavity and directly determines the surface quality of the final cast part. Thanks to its high SiO₂ purity and low impurity levels, it reduces the risk of sintering and sticking on the sand surface during casting.
The AFS (American Foundry Society) grain fineness number is the most important technical criterion for foundry sand. At Seyman Maden, we supply products tailored to iron, steel, aluminium and brass casting applications with 10 different fraction options in the 15-120 AFS range. The particle size determines the surface roughness of the cast part, gas permeability and mould strength.
Used in the production of green sand moulds, resin moulds (no-bake, cold-box, shell) and cores, foundry sand provides homogeneous mould performance thanks to its washed and screened structure. Its low clay and dust content optimises resin and binder consumption and reduces casting defects.
Choosing Sand by Moulding System
Foundry sand is not a single product; the binder system you work with changes what you need from the sand. In green sand the sand is bonded with bentonite and water; the system tolerates a certain amount of fines, and the decisive factors are AFS and grain distribution. In resin systems (cold-box, no-bake, shell) the binder is chemical and its cost depends directly on how clean the sand is: as dust and clay content rise, resin consumption rises with it, because fine grains increase the total surface area and demand more binder. This is why washed, dried and narrowly graded sand is preferred in resin systems.
What Changes in Core Sand?
The core forms the cavities inside the mould and every surface of it is surrounded by molten metal during pouring. Core sand therefore works under harder conditions than moulding sand: it must hold its shape without breaking down, yet break down easily after casting. In practice this means a narrow grain distribution and a low fines content. In a broadly graded sand the fine grains fill the voids, gas permeability drops and gas-related defects appear on the core surface. For core applications our grades in the 50-70 AFS range are generally preferred; finer grades may be used depending on the wall thickness of the part.
Fines, Clay and Moisture: Three Values That Drive Consumption
Even with the right AFS value, the result will not be what you want if these three values are wrong. Fine dust lowers gas permeability and increases binder consumption. Clay is useful in green sand but upsets the catalyst balance in resin systems. Moisture directly affects curing time and bond strength in resin systems, which is why our sand goes through fluid-bed drying and moisture is measured again before shipment. In resin and acid-catalysed systems the acid demand value (ADV) of the sand also becomes decisive — carbonate residue consumes the catalyst. Where this value is critical for you, we share the analysis of the batch to be shipped in advance.
Main Applications
- Iron and steel casting
- Aluminium, brass and bronze casting
- Green sand mould systems
- Resin mould and core production (no-bake, cold-box, shell)
- Fraction options in the 15-120 AFS range
- High refractoriness and low gas emission
- Automotive, machinery and industrial foundries