International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Contemporary production of castings is inevitably associated with improvement of foundry mixtures, and in particular with quartz sands as a basic moulding material. The interest is motivated by opportunity of reaching mixture’s appropriate parameters at different combinations between sands and binding compositions. One option of particular importance in obtaining mixtures’ physical and mechanical, and technological properties is to get a greater number of contact points among individual grains of quartz sands.

The report examines the impact of dispersive mineral particles for increasing contact points of interaction between individual sand particles in the process of solidification. A theoretical basis for the possibility of applying such reinforcement in the preparation of mixtures is presented. An attempt for optimization has been done by some criteria – porosity, morphology, gas permeability and other properties.

Results and conclusions from the conducted tests have been graphically presented.

As a whole, the contemporary self-hardening foundry moulds and cores represent a result of chemical reactions between quartz sands and binders at mould formation after good homogenization in mixers. Mixtures are hardened, obtaing the necessary physico-chemical characteristics; thus they realize the geometry of the future cast. One of the most important characteristics is the strength of mixtures, especially the adhesion strength that is formed on the border between sand and binding composition.

In this report, an improved method on adhesive strength determination of foundry mixtures is presented. Some theoretical protection aspects of the shown method are considered. A technological sequence of the method work and way of measurement are given. In figures, practical results from measurements of adhesion strength according to “No Bake”are shown.

At the contemporary conditions of cast production there has been a permanent interest in economically more profitable technologies for obtaining moulds and cores of controlled properties. A part of this interest is related to quartz sands as a basic and the most common component in the practice of foundry mixture productions. State of sand surface and its influence in formation of foundry mould and core physico-chemical properties are of particular importance.
In this report, various conditions of mechanical activation on the surface of quartz sand in “a fluidized bed” are discussed. The theory of such activation necessity has been partly explained. The “time” factor in preserving the activated layer potential is noticed. The efficiency of the activated layer in producing foundry mixtures strength by the method “No Bake is shown.