• Journal of Korea Foundry Society
• /
• v.25 no.4
• /
• pp.173-178
• /
• 2005

The vacuum molding process is one of the clean-foundry molding-processes that can recycle molding sands repeatedly, because molding can be accomplished by introducing vacuum only among dry molding sands in flask. The effects of molding conditions such as sand grain fineness, vacuum pressure and coating thickness on the fluidity of A356 Al alloy were studied and the results was obtained that the fluidity length was decreased as the sand grain fineness number and coating thikness were decreased and the vacuum pressure was increased. A large amount of heat removal from the molten metal resulting from the vacuum suction during the vacuum molding process was the principal cause of this decrease in fluidity.

• Journal of Korea Foundry Society
• /
• v.1 no.3
• /
• pp.19-29
• /
• 1981

An emphasis has been placed on the importance of selecting a sand for furan sand process, which ie affected by the properties of sand. Investigations have been carried out to use the domestic artificial sands for the furan sand process. For laboratory investigations, the sands have been prepared and tested for chemical analysis, loss on ignition, sieve analysis, AFS grain fineness number, grain shape, PH value, acid demand, surface shape, theoretical surface area, moisture absorption, crushing durability and compressive strength and S. S. I. of molding sands. Most commercial sands have been found to be able to be used. The main requirement of the sands has been shown to be that 3 or 4 screen sands, AFS no.40-70 (or 100), of low acid demand, good surface area and good grain shape require less resin and catalyst to give an adequate strength.

• Journal of Korea Foundry Society
• /
• v.34 no.3
• /
• pp.107-111
• /
• 2014

Permeability is the ability of a material to transmit fluid/gases. It is an important material property and it depends on mould parameters such as grain fineness number, clay, moisture, mulling time, and hardness. Modeling the relationships among these variable and interactions by mathematical models is complex. Hence a biologically inspired artificial neural-network technique with a back-propagation-learning algorithm was developed to estimate the permeability of green sand. The developed model was used to perform a sensitivity analysis to estimate permeability. The individual as well as the combined influence of mould parameters on permeability were simulated. The model was able to describe the complex relationships in the system. The optimum process window for maximum permeability was obtained as 8.75-10.5% clay and 3.9-9.5% moisture. The developed model is very useful in understanding various interactions between inputs and their effects on permeability.

• Journal of the Korea Convergence Society
• /
• v.12 no.2
• /
• pp.185-191
• /
• 2021

The characteristics of the foundry sand were analyzed for water jacket core required to prevent structural deformation from the heat generated in the cylinder bore during the casting of the cylinder block of an automobile. The sand core tensile strength tester, AFS-GFN, and optical microscope were used to evaluate the its properties. If the SiO2 content is high in the foundry sand, the dimensional defects and veining defects occur due to high temperature expansion. Also, if it is too low, the core breakage, porosities, chemical burn-on defects occur. The particle size index and grain shape influenced the core strength and resin consumption, resulting in fluctuations in defect types. The higher the alkalinity of the dried sand, the lower the core strength. And the more basic, the lower the core strength. At the resin content of 1.6~1.8%, the increase in core strength after 1 hour curing was approximately at its maximum.

• Korean Journal of Agricultural Science
• /
• v.10 no.2
• /
• pp.334-344
• /
• 1983

This study was conducted to investigate the variables affecting the performance of hammer mills by the theoretical and dimensional analysis, and evaluate the power requirements of hammer mills for farm use in Korea. From the theoretical analysis, 16 variables affecting the performance of hammer mills were defined. In order to develop the mathematical relationships among the variables, the dimensional analysis was made for power requirements and $12{\pi}$ parameters were obtained. For the evaluation of the power requirements of hammer mills, approximate rates of grinding for 1HP, 3HP, 5HP, 6HP, 8HP, and 10HP were analyzed. Then, the fineness of grinding recommendation and average feeding rate of grain for livestock which is native cattle, dairy cattle, beef cattle, swine, broilers, and layers, were estimated. Finally number of livestock feeding shelled corn and barley were estimated from the above for one hour's hammer mill operation having the various power requirements. From this study it is known that 5HP is considered as an enough power for feed grinding of any kinds of livestock of Korean farm, as far as the grinding capacity is concerned.