The paper presents results of measuring heat diffusivity and thermal conductivity coefficients of used green foundry sand in temperature
range ambient – 600 o
C. During the experiments a technical purity Cu plate was cast into the green-sand moulds. Basing on measurements
of the mould temperature field during the solidification of the casting, the temperature relationships of the measured properties were
evaluated. It was confirmed that the obtained relationships are complex and that water vaporization strongly influences thermal
conductivity of the moulding sand in the first period of the mould heating by the poured and solidified casting
A determination of the heating degree of the moulding sand with bentonite on the grounds of simulating investigations with the application of the MAGMA program, constitutes the contents of the paper. To this end the numerical simulation of the temperature distribution in the virtual casting mould was performed. It was assumed that the mould cavity was filled with a moulding sand with bentonite of a moisture content 3,2 % and bentonite content 8 %. A computer simulation can be used for predicting the heating degree of moulding sands with bentonite. Thus, prediction of the active bentonite (montmorillonite) content in individual layers of the overheated moulding sand can be done by means of the simulation. An overheating degree of a moulding sand with bentonite, and thus the bentonite deactivation depends on a temperature of a casting alloy, casting mass, ratio of: masssand : masscasting, moulding sand amount in the mould and contact area: metal – mould (geometry of the casting shape). Generally it can be stated, that the bentonite deactivation degree depends on two main factors: temperature of moulding sand heating and time of its operation.
The paper undertakes an important topic of evaluation of effectiveness of SCADA (Supervisory Control and Data Acquisition) systems,
used for monitoring and control of selected processing parameters of classic green sands used in foundry. Main focus was put on process
studies of properties of so-called 1st generation molding sands in the respect of their preparation process. Possible methods of control of
this processing are presented, with consideration of application of fresh raw materials, return sand (regenerate) and water. The studies
conducted in one of European foundries were aimed at pointing out how much application of new, automated plant of sand processing
incorporating the SCADA systems allows stabilizing results of measurement of selected sand parameters after its mixing. The studies
concerned two comparative periods of time, before an implementation of the automated devices for green sands processing (ASMS -
Automatic Sand Measurement System and MCM – Main Control Module) and after the implementation. Results of measurement of
selected sand properties after implementation of the ASMS were also evaluated and compared with testing studies conducted periodically
in laboratory.
Today, about two thirds of iron alloys casting (especially for graphitizing alloys of iron) are produced into green sand systems with usually organically bonded cores. Separation of core sands from the green sand mixture is very difficult, after pouring. The core sand concentration increase due to circulation of green sand mixture in a closed circulation system. Furthermore in some foundries, core sands have been adding to green sand systems as a replacement for new sands. The goal of this contribution is: “How the green sand systems are influenced by core sands?” This effect is considered by determination of selected technological properties and degree of green sand system re-bonding. From the studies, which have been published yet, there is not consistent opinion on influence of core sand dilution on green sand system properties. In order to simulation of the effect of core sands on the technological properties of green sands, there were applied the most common used technologies of cores production, which are based on bonding with phenolic resin. Core sand concentration added to green sand system, was up to 50 %. Influence of core sand dilution on basic properties of green sand systems was determined by evaluation of basic industrial properties: moisture, green compression strength and splitting strength, wet tensile strength, mixture stability against staling and physical-chemistry properties (pH, conductivity, and loss of ignition). Ratio of active bentonite by Methylene blue test was also determined.