Theoretical problems concerning the determination of work parameters of the two-phase sand-air stream in the cores making process by blowing methods as well as experimental methods of determination of the main and auxiliary parameters of this process decisive on the cores quality assessed by the value and distribution of their apparent density are presented in the paper. In addition the results of visualisations of the core-box filling with the sand-air stream, from the blowing chamber, obtained by the process filming by means of the quick-action camera are presented in the paper and compared with the results of simulation calculations with the application of the ProCast software.
The effects of filling the core box cavity and sand compaction in processes of core production by blowing methods (blowing, shooting) depend on several main factors. The most important are: geometrical parameters of cavity and complexity of its shape, number, distribution and shape of blowing holes feeding sands as well as the venting of a technological cavity. Values of individual parameters are selected according to various criteria, but mostly they should be adjusted to properties of the applied core sand. Various methods developed by several researchers, including the authors own attempts, allow to assess core sands properties on the basis of special technological tests projecting the process into a laboratory scale. The developed criteria defining a degree or a filling ability factor provide a better possibility of assessing the core sand behavior during flowing and core box filling, which indicate the value and structure of the obtained compacting decisive – after hardening – for strength and permeability. The mentioned above aspects are analyzed – on the basis of authors’ own examinations - in the hereby paper.
Development of salt cores prepared by high-pressure squeezing and shooting with inorganic binders has shown a high potential of the given technology even for high-pressure casting of castings. Strength, surface quality of achieved castings, and solubility in water become a decisive criterion. The shape and quality of grain surface particularly of NaCl – cooking salts that can be well applied without anticaking additives has shown to be an important criterion. Thus the salt cores technology can cover increasingly growing demands for casting complexity especially for the automobile industry.