Characteristic value for permeability properties of a mold material or a compacted mold material (s. Compaction and Mold sand testing).
Sufficient degree of permeability to gas is a mandatory prerequisite for production of fault-free castings using moist, compacted sand molds and is predominantly determined by the overall grain characteristics of the basic mold material, composition of the molding material, and intensity of compaction. The development of gasses mainly depends on the quantity of volatile components (coal dust, residual organic binder contents) and the water content present in the molding material. Moreover, the gas development capacity of cores must not be neglected.
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