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In the present work, design of experiments (DOE) technique with response surface methodology was used to develop both linear and non-linear models, to establish the input-output relationships in green sand mould system. Grain fineness number (GFN), amount of clay, amount of water and number of strokes (degree of ramming) were considered as the input variables (parameters), which control the outputs (i.e. mould properties). Full factorial DOE was utilised for the linear model, whereas central composite design and Box-Behnken designs were used to develop the non-linear models. Experiments were conducted to measure the green sand mould properties, such as permeability, green compression strength, mould hardness and bulk density. The adequacy of all the developed models was checked through statistical analysis. Twenty random test cases were considered, to validate the models and compare their performances. A model that is statistically adequate and gives minimum percentage of deviation in prediction was adjudged as the best model for a particular response.

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In this paper an attempt has been made for linear and non linear modeling of resin bonded sand mould system using full factorial design of experiments and response surface methodology, respectively. It is important to note that the quality of castings produced using the resin bonded sand mould system depends largely on properties of moulds, which are influenced by the characteristics of sand, like type of sand, grain fineness number, grain size distribution and quantity and type of resin, catalyst, curing time etc. In the present study, percentage of resin, percentage of hardener, number of strokes and curing time are considered as input parameters and the mould properties, such as compression strength, shear strength, tensile strength and permeability are treated as responses. In the present work, phenol formaldehyde is used as the resin whereas tetrahydrophthalic anhydride as the hardener. A two level full factorial and three level central composite designs are utilized to develop input-output relationships. Surface plots and main effects plots are used to study the effects of amount of resign, amount of hardener, number of strokes and curing time on the responses, namely, compression strength, tensile strength, shear strength and permeability. Moreover, the adequacies of the developed models have been tested using analysis of variance. The prediction accuracy of the developed models have been tested with the help of twenty test cases and found reasonably good accuracy.

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