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Study on shrinkage and deformation of injection molded plastic optical pick-up lens was conducted. Numerical and experimental studies based on Taugchi Methods were performed. The process conditions are including mold temperature, melt temperature, packing pressure, packing time and cooling time, were investigated in the design. The dimension accuracy at inlet, center and end of the lens was used as the measure for qualifying the molded lens. In order to achieve high precision at the lens, two designs of molded inserts the aligning systems were used in the experimental mold. The first system was aligned by the draft angle on the insert edge and the second was aligned by installing two sets of angle position pins. The packing pressure was found to be the main factor affecting the shrinkage of the lens from both the numerical design and molded products. For design of the alignment system, the second aligning system with angle position pin inserts was found to have better precision. The optimal molded lens using second aligning system could achieve an accuracy about 1~3μm at the center thickness of the lens.
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