The Analysis of Molding and Modification of the Ceramic Surfaces and Its Impact on the Roughness of Castings

The article presents an analysis of changes in the outer surface of the casting made in a modified ceramic form. The introduction of the modification in the inner surface of the form, as a metallic coating was intended to produce a high quality of the casting surface. To describe the results, the three parameters have been chosen to characterize the surface roughness, i.e. Ra, Rz and Rq. In implementing the popular method of casting was used, so – called the lost polymer models. The models made from different plastic materials are chemically and electrochemically coated with a layer of nickel. The next step was to remove the model from the form and pouring the liquid metal over it. The observation of the casting surface was performed by using the scanning electron microscope and a profilometer. As a result of these attempts a number of castings have been obtained with an outside layer generated of lower roughness than the casting made in the normal gypsum form. The proposed method can be called an innovative one because it reduces the technological cycle by one processing operation of investment casting. During the process of casting both the cast and the outer layer improving the properties of the manufactured product is being produced.