Abstract: A physically accurate and computationally effective implicit algorithm for injection mold process simulations is presented. The governing equations involving the pressure field and fill factor which tracks the location of the front surface are developed in terms of mass conservation for each control volume. The transient equations are solved in an iterative manner for both pressure field and fill factor for tracking the progression of the resin front in the mold cavity. The present formulations accurately account for and capture the physical transient nature of the mold filling process while maintaining improved numerical and computational attributes. The selection of time steps is based on accuracy considerations and resolution of flow front locations, which is free from the restrictions that exist in the traditional explicit finite element control volume based formulations. The time increments of the traditional explicit methodology are restricted so that no more than one complete control volume region is updated and filled at each time increment. In certain cases, more than one control volume may be simultaneously filled. The present methodology does not have such a restriction and computes the position of the flow front at each of the selected discrete time intervals. The computed position of the flow front at the end of a certain time interval is independent of the time step size used to reach that time interval.In the end,the methodology is used successfully in two examples.