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J. Beňo, F. Mikšovský, P. Jelínek, K. Konečná and P. Smysl

Abstract

For the evaluation of silica sands, which belongs to the most employed sands of foundry molding mixtures, there are a number of methods and techniques to characterize their quality. This implies good knowledge of their strengths and weaknesses. However, a small proportion of published results are dedicated to the impact of transport on transport routes in the foundry and the processes of dry reclamation on the properties of the silica sands, in particular on changes to the granulometry and the formation of undesirable dust sands shares, which significantly affect the properties of the sand mixture.

The aim of this contribution is the evaluation of inclination of the silica sand to crush (the formation of dust, change the granulometry) according to the newly developed methodology with regard to its nature of sand (genesis, the shape of the grains, the character of the surface).

Open access

P. Jelínek, J. Duda, F. Mikšovský and J. Beňo

Reclamation of Self-Setting Mixtures with Olivine Bound with Alkaline Resols

For the reason of environmental problems connected with the use of furan binders, attention is increasingly being paid to self-setting mixtures using alkali resols. A resol binder stabilized with KOH, NaOH is hardened by liquid esters with the formation of alkaline salts. The increase of their concentration affects the shortening of the mixture bench life, it also decreases strength, increases abrasive wear to moulds and cores, and results in uneconomical dilution of the reclaim with expensive new base sand. The length of life (bench life) of mixtures plays an important role in the manufacture of huge and voluminous moulds and cores in self-setting mixtures. This study aims at analyzing the function of reactive alkaline salts in the reclaim, monitors the consequences of its thermal exposure on the properties of self-setting mixtures, and deals with development of methods evaluating its qualities.

Open access

P. Jelínek, E. Adámková, F. Mikšovský and J. Beňo

Abstract

A number of technologies is developed that substitute simple metal cores in the high-pressure casting technology. Soluble cores, namely on the salt basis, represent the highest prospect. The contribution gives the results of the production of salt cores by high-pressure squeezing and shooting with using a binder. Special attention is paid to the shape of NaCl salt crystals with additives and the influence on strength properties of cores. A technology of bonding the salt cores is developing. Salinity of circulating water is studied and it is checked with the aid of electrical conductance.