In this study, corrugated variations in part thickness designed to match the various mold temperature differences between the mold core and mold cavity sides, along with their effects on part warpage, were investigated. Part thickness was varied in a pitched manner and thickness reductions of 10%, 20%, 30%, and 40% of the original part thickness were implemented. The results show that when there is a mold temperature difference between core and cavity, using a corrugated thickness reduction design can greatly reduce or even eliminate part warpage. For a uniform thickness part molded under unbalanced cooling, the thermal neutral axis (where the maximum melt temperature is located) will deviate from the gap center toward the mold wall side with the higher temperature. Variation in thickness will pull the deviated thermal neutral axis back to the center line leading to a reduction in part warpage.