: Injection molding is one of the most flexible and important operation for mass production of plastic parts. In injection molding process, cooling system design is very important as it largely affects the cycle time. A good quality cooling system design can reduce cycle time and attain dimensional stability of the part. In this study used heat transfer analysis during polymer processing, the equation for calculating the cooling time inside the injection mold was derived, and the same empirical equation that was obtained through experiments was reached