The paper presents the test results of molding compounds, sand casting molds and their analysis. The subject of testing was compound containing furan resins prepared according to the following recipe: matrix – regenerate 90% + fresh sand – 10%, furan resin – 1.10% by weight, hardener – 0.40% by weight. The impact of adhesive type and its quantity (Quan = 0.90, 1.1 and 1.5%) on the strength indexes of molding compound subject to densification was analyzed. The publication presents the test results: tensile strength Rm, compressive strength Rc and flexural strength Rg, as well as compound permeability as function of its density. The analysis also covers the impact of density level on mold strength and the distribution of density level along the mold height.

Based on the test results, it was found that the best method to obtain high strength molds made from compounds with chemical adhesives was to densify it by vibrating the system: match plate – molding flask – compound filling the mold. The effectiveness of this densification method depends on the amplitude and frequency of vibrations.

Contribution gives an overview of knowledge about the method of centrifugal casting with orientate on Tekcast system. Company Tekcast

Industries has developed a device for centrifugal casting, extending the area of production of castings or prototyping of metal or plastic.

Materials suitable for the centrifugal casting with flexible operating parameters may include non-ferrous metal alloy based on zinc or

aluminum or non-metallic materials such as polyester resins, polyurethane resins, epoxy resins, waxes and the like. The casting process is

particularly suitable for a wide range of commercial castings and decorative objects.

Production of defect free castings requires good understanding of casting characteristics like mold filling ability and volume deficit characteristic. Pin test piece with cylindrical cores proposed by Engler and Ellerbrok was used to study the mold filling ability. Volume deficit characteristics experiments were conducted using the method designed by Engler. Alloy composition, Mold coat and Pouring temperature were considered as process parameters for the present study and experimental plan has been taken up through design of experiments. The alloy composition is most significant in influencing the mold filling ability, where as pouring temperature is for volume deficit. The Correlation Co-efficient value obtained is -0.98901 indicating strong a negative relation between mold filling ability and volume deficit characteristics. Negative values indicate a relationship between mold filling ability and volume deficit such that as values for mold filling ability increase, for volume deficit decrease.

This article presents measurements of the thickness of alcohol-based coatings on sand foundry cores and moulds. These coatings were applied using two methods, the dipping method and the painting method. For the purposes of the study, a zircon alcohol-based coating was prepared with three different levels of nominal viscosity; very thin at 10s, average at 20s, and thick at 30s. The coating was applied to a core made of quartz sand and furan resin. The cores were made of sand with three different grain sizes; dL = 0.22 mm – fine sand, dL = 0.33 mm medium sand, and dL = 0.47 mm coarse sand. In the study, the thickness of the coating obtained to the core was measured immediately after application as well as after drying. Additionally, the extent of penetration into the intergranular spaces of the core matrix was measured. On the basis of this study, the impact of the grain size of the core matrix on the thickness of the coating and its penetration into the core was assessed. The thickness of coatings obtained using different application methods was also assessed.

Relatively cold die material comes into contact with the substantially higher temperature melt during the casting cycle, causing high thermal fluctuations resulting into the cyclic change of thermal field. The presented contribution is devoted to the assessment of the impact of temperature distribution on individual zones in the die volume. The evaluated parameter is the die temperature. It was monitored at two selected locations with the 1 mm, 2 mm, 5 mm, 10 mm and 20 mm spacing from the die cavity surface to the volume of cover die and ejector die. As a comparative parameter, the melt temperature in the middle of the runner above the measuring point and the melt temperature close to the die face were monitored. Overall, the temperature was monitored in 26 evaluation points. The measurement was performed using the Magmasoft simulation software. The input settings of the casting cycle in the simulation were identical to those in real operation. It was found, that the most heavily stressed die zones by temperature were within the 20 mm from the die face. Above this distance, the heat supplied by the melt passes gradually into the entire die mass without significant temperature fluctuations. To verify the impact of the die cooling on the thermal field, a tempering system was designed to ensure different heat dissipation conditions in individual locations. At the end of the contribution, the measures proposals to reduce the high change of thermal field of dies resulting from the design of the tempering channel are presented. These proposals will be experimentally verified in the following research work.

The article presents the results of permeability measurements of a zirconium alcohol coating applied on moulds and cores. The introduction extensively discusses the reasons for the application of protective coatings, as well as their advantages and disadvantages. Also, the problems related to the application of protective coatings are presented i.e. limited permeability and thus the possibility of the presence of gas-originated defects in the casts. Next, the paper discusses the methods of measuring the permeability of protective coating proposed by Falęcki and Pacyniak. The study also presents an indirect permeability measurement method. For the investigations, zirconium alcohol coatings with the three conventional viscosities 10, 20 and 30s were used. The viscosity was determined by means of the Ford cup with the clearance of 4mm. The coatings were applied onto profiles of Φ 50 x 50 mm, made of moulding sand consisting of a sand matrix with the mean grain size of dL = 0,11, 17, 24, 31 and 34 mm and phenol-formaldehyde resin. The effect of the matrix grain size on the permeability of the sand with and without a coating was determined.

The method of determining the accuracy of polymer molds in plaster forms has been discussed. Distortion of the surface of molds and

plaster molds has been assessed. It has been found that the presence of monolithic and porous structure in the samples does not change the

accuracy of the surfaces when forms are prepared for removing the material of the model. It has been found that in case of full-mold

casting it is more expedient to form the mold cavity with cellular adjustable structures of molding prototypes.

The paper presents a detailed description of one of the newest methods of vacuum saturation of reinforcing preforms in gypsum molds. As an appropriate selection of the infiltration time is a crucial problem during realization of this process, aim of the analysis shown in the paper is to present methods of selection of subatmospheric pressure application time, a sequence of lowering and increasing pressure, as well as examining influence of structure of reinforcing preforms on efficiency of this process. To realize the aim, studies on infiltration of reinforcing preforms made of a corundum sinter of various granulation of sintered particles with a model alloy were conducted. The infiltration process analysis was carried out in two stages. The first stage consisted in investigation of influence of lengthening of sucking off air from the reinforcing preforms on efficiency of this process. In the second stage, an analysis of influence of a two-staged infiltration process on saturation of the studied materials was conducted. Because the studied preforms were of similar porosity, the obtained differences of the saturation level of particular preforms have shown, that the saturation process is influenced mostly by size of pores present in the reinforcement. Because of these differences, each reinforcement type requires individual selection of time and sequence of the saturation process. For reinforcements of higher pore diameter, it is sufficient to simply increase air sucking off time to improve the saturation, while for reinforcement of smaller pore diameter, it is a better solution to apply the two-staged process of sucking off air. Application of the proposed analysis method allows not only obtaining composite castings of higher quality, but also economical optimization of the whole process.

The paper presents the use of rapid prototyping technology of three dimensional printing (3DP) to make a prototype shell casting mold. In

the first step, for identification purposes, a mold was prepared to enable different alloys to be cast. All molds being cast were designed in a

universal CAD environment and printed with the zp151 composite material (Calcium sulfate hemihydrate) with a zb63 binder (2-

pyrrolidone). It is designated to be used to prepare colourful models presenting prototypes or casting models and molds. The usefulness of

3DP technology for use with copper alloys, aluminum and zinc was analyzed. The strength of the mold during casting was assumed as a

characteristic comparative feature in the material resistance to high temperature, the quality of the resulting casting and its surface

roughness. Casting tests were carried out in vacuum – pressure casting. The casting programs applied, significantly increased the quality of

castings and enabled precise mold submergence. Significant improvement was noted in the quality compared to the same castings obtained

by gravity casting.

Some metallographic studies performed on the basis of the massive forging steel static ingot, on its cross-section, allowed to reveal the

following morphological zones: a/ columnar grains (treated as the austenite single crystals), b/ columnar into equiaxed grains

transformation, c/ equiaxed grains at the ingot axis. These zones are reproduced theoretically by the numerical simulation. The simulation

was based on the calculation of both temperature field in the solidifying large steel ingot and thermal gradient field obtained for the same

boundary conditions. The detailed analysis of the velocity of the liquidus isotherm movement shows that the zone of columnar grains

begins to disappear at the first point of inflection and the equiaxed grains are formed exclusively at the second point of inflection of the

analyzed curve. In the case of the continuously cast brass ingots three different morphologies are revealed: a/ columnar structure, b/

columnar and equiaxed structure with the CET, and c/ columnar structure with the single crystal formation at the ingot axis. Some

forecasts of the temperature field are proposed for these three revealed morphologies. An analysis / forecast of the behavior of the

operating point in the mold is delivered for the continuously cast ingot. A characteristic delay between some points of breakage of the

temperature profile recorded at the operating point and analogous phenomena in the solidifying alloy is postulated.

The techniques of micro and nano structurization of surfaces of various materials are utilized in electronics and medicine. Such procedure as wet and dry etching allows to fabricate protruded or recessed micro and nanostructures on the surface. In the paper some examples of utilization of a surface structurization, known from literature, are described. Some structurization methods and experimental results for fabrication of the arrays of sharp microtips are presented. Wet and/or dry etching, and thermal oxidation process were used to form the arrays of sharp gated and non-gated, protruded or recessed silicon microtips on silicon wafer. For the first time, the arrays of silicon carbide (SiC) microtips on glass wafer have been produced by use of the transfer mold technique. Arrays of sharp microtips are used as field electron emission cathodes for vacuum microelectronics devices. Some electron emission measurements for these cathodes have been carried out. New application of silicon microtips array in biochemistry has been tested with satisfactory results.

The shipment of cut flowers from Colombia and Ecuador to the United States, the biggest importer of this product in the world, has doubled in the last 20 years. One of the main constraints in cut roses production is the gray mold disease caused by the fungus Botrytis cinerea, which can destroy the flowers, in the crop, during storage and/or shipping. Since the resistance of the fungus to conventional fungicides has been increasing, as well as the health effects in rose growers, alternative approaches for controlling the disease are needed. The effect of UV-C light on the gray mold development in cut roses was studied. Irradiation with 2,160; 1,080 and 540 J ⋅ m–2 UV-C, every 24 h for 5 days in a humid chamber, did not harm the roses. Instead, as seen by image analysis, a highly significant reduction of the area of the lesions by the disease and of the fungus germination was obtained at 1,080 J ⋅ m–2. The addition of a 4-h dark period to the irradiation did not improve the effect of UV-C on the disease. The results of this work potentiate the use of UV-C light in the agro-industry as a low-cost and non-invasive alternative method to control diseases. They also reflect the application of optical approaches as image analysis in the evaluation of important agricultural features.