Statistical process control of in-plane shape deformation for additive manufacturing

Statistical monitoring of additive manufacturing (AM) processes faces major challenge due to the nature of one-of-a-kind manufacturing. In contrast to mass production, AM processes fabricate products with complex shapes and low volumes, which result in disparate training data and small sample sizes. Furthermore, constant changes of product designs demand the capability of monitoring the process of building new products not being tried before. Traditional Statistical Process Control (SPC) therefore can hardly be applied directly. A popular solution is to monitor AM process parameters indicative of process conditions. However, process conditions have to be benchmarked by product quality. This work put forth a prescriptive SPC scheme to monitor shape deformation from shape to shape. Only a limited number of test shapes are required to establish control limits. The strategy is extension of our previous work on the prescriptive modeling and compensation of shape deformation to the field of SPC. Experimental investigation using stereolithography process validates the proposed deformation monitoring approach.