EINFLUSS DER SCHLICHTE AUF FORMFUELLUNGSMECHANISMEN UND GUSSTEILMERKMALE BEIM VOLLFORMGIESSEN

摘要

The growing interest of foundries in the lost foam technology as a manufacturing method for the production of high quality and complex building components explains the supreme efforts in the area of research and development to open the problem fields of this technology and further the development in the procedure for a stable use in serial production. The quality of lost foam manufactured aluminium castings depends mainly upon the adjusted cavity filling procedures. The exhaust of the developed gaseous and liquid products of decomposition is an essentiel factor during the casting process. The development and draw off of the products of decomposition is determined by the EPS-modell charasteristics, the modell geometry as well as the casting temperature. With constant EPS-modell and casting conditions the casting quality is highly influenced by the permeability and characteristics of the used moulding system. In addition the forming system is defined by the characteristics of the binder-free moulding material, the compressing parameters and the coating-characteristics. Research results of coating analyses together with cavity filling studies show a correlation between the permeability of different coat thicknesses and the casting results. Suitable coatings for the aluminium lost foam procedure have a good absorbing effect facing to the liquid and gaseous products of the modell decomposition products by means of a rapid draw off. By selection suitable coatings, that have to be balanced to the geometry of the casting, the cavity filling time can be influenced and consequently also the casting characteristics. With the knowledge of te shown cavity filling procedures, the coatings can be used as an instrument to find the optimum cavity filling time and thus to procedure high quality and complex castings.