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Kinetics of Gases Emission from Surface Layers of Sand Moulds

Zych J., Mocek J., Kaźnica N.

Archives of Foundry Engineering

2018

Vol. 18, iss. 1

222--226

Gas emission from casting moulds, cores and coatings applied for sand and permanent moulds is one of the fundamental reasons of casting defects occurrence. In the previous studies, gas emission was measured in two ways: normalized, in which the evolving gas volume was measured during heating of the moulding sand sample in a sealed flask, or by measuring the amount of gas from sand core (sample) which is produced during the pouring of liquid metal. After the pouring process the sand mould is heated very unequally, the most heated areas are layers adjacent to the liquid metal. The emission of gas is significantly larger from the surface layer than from the remaining ones. New, original method of measuring kinetics of gas emission from very thin layers of sand moulds heated by liquid metal developed by the authors is presented in the hereby paper. Description of this new method and the investigation results of kinetics of gas emission from moulding sand with furan and alkyd resin are shown. Liquid grey cast iron and Al-Si alloy were used as a heat source in the sand moulds. Comparison of the kinetics of gas emission of these two kinds of moulding sands filled with two different alloys was made. The momentary metal temperature in sand mould was assigned to the kinetics of gas emission, what creates a full view of the possibility of formation of casting defects of the gaseous origin. Moulding sand with alkyd resin is characterized by larger gas emission; however gases are emitted slower than in the case of moulding sands with furan resin. This new investigation method has a high repeatability and is the only one which gives a full view of phenomenon’s in the surface layer which determines quality of the casings. The obtained results are presented on several graphs and analyzed in detail. They have a great application value and can be used in the production of iron as well as light metal alloy castings.

Prognozowanie jakości odlewów wykonywanych w formach z mas ze spoiwami oparte o badania nieniszczące

Zych J.

Archiwum Odlewnictwa

2004

R. 4, nr 13

253--260

W pracy, na przykładach z własnych badań, przedstawiono obszary, w których może być wykorzystana technika ultradźwiękowa do monitowania procesów utwardzania (przy wiązaniu) i destrukcji (po zalaniu metalem) masy w formie. Ponadto opisano sposób pomiaru zagęszczenia masy w formie. W oparciu o tak zebrane dane o procesach zachodzących w masie formierskiej w całym okresie technologicznym można przewidywać jakość wykonywanych odlewów, ich stan powierzchni oraz skłonność do tworzenia grupy wad odlewniczych związanych z jakością formy.

In the work there were shown, using original results, areas in which an ultrasound technique can be applied to monitor processes of hardening (binding stage) and destruction (after pouring with metal) of moulding sand in a mould. Furthermore, a method of estimation of the density of moulding sand in a mould was developed. On the base of the obtained data about processes taking place in moulding sand during the whole technological cycle, it is possible to forecast the quality of produced castings, state of their surface, and tendency to creation of a group of casting defects related to mould quality.