Grid method for improving the accuracy of layer based RP parts

The paper proposes a new method for strain investigation in layer based Rapid Prototyping (RP) technologies. This method is based on building test plates with a predefined square grid on them, positioned in different places and with different orientations within the build envelope. The differences between nominal and measured coordinates of the grid points are used for strain calculation following the approach utilised in sheet metal forming analysis. Pilot implementations of the method are illustrated and discussed – determination and visualisation of deformation distribution within the build volume in the case of polystyrene SLS (selective laser sintering), calculation of nonlinear scaling factors and detecting technical problems of equipment. Other possible applications of the method in RP practice are suggested, proposing the method as a generic approach for accuracy investigation and improvement.