Compensation of distortion in the bottom exposure of stereolithography process

The rapid prototyping (RP) process is the fastest and most feasible method for prototype construction. However, with the use of any material or build method the phenomenon of volume shrinkage is unavoidable. It is known that volume shrinkage and curl distortion are the major causes that lead to poor accuracy of the built prototype. Subsequently, in order to improve the precision of dimension and volume shrinkage, more expensive equipment is used on the market. Also, it is expensive and inefficient to obtain better process parameters through trail and error in the RP process. In order to improve the precision of dimension, reduce the processing cost and the frequency of trail and error, this study first induces the concept of computer-aided engineering (CAE) into the processing of RP, which uses a dynamic finite element simulation code to simulate the photopolymerization process, so as to reduce the time for selecting the processing parameters and obtain the distortion data. Second, by means of reverse distortion compensation to obtain a new CAD model, then it is sent to a RP machine for the actual prototyping processes, so as to obtain a more accurate precision. Finally, in order to confirm this method and restriction in experimental equipment, the stereolithography process and simple laser scanning path are chosen as examples. The results of the simulation and experiment prove that the method proposed herein is effective. It not only can reduce the cost of equipment but also obtain a better precision of dimension on final-parts at the same time. Besides, it is believed that this research method can be promoted to other materials or build methods in RP fabrication .