In the field of polymer injection molding, the accuracy of numerical simulations is crucial to minimize manufacturing defects. The accurate simulation of such a complex process is computationally expensive and can greatly benefit from advanced adapting meshing techniques. In this study, we present a macro-scale two-phase flow formulation for polymer injection molding. We use an in-house finite-element solver to simulate the polymer and air flows as an interfacial flow, utilizing the level-set method. In these two-phase flow simulations, where the interface constitutes only a small part of the entire domain, adaptive mesh refinement can significantly improve the simulation’s efficiency. In our work, we explore localized refinement in time, achievable through a time-discontinuous space-time discretization [1]. This methodology can noticeably reduce the computational time while ensuring a high-fidelity resolution around the moving polymer-air interface. We will present our findings on the application of this adaptive meshing technique to a realistic injection molding test case and discuss how adaptive time refinement can lead to improved accuracy and performance in interfacial flow simulations. [1] von Danwitz M, Voulis I, Hosters N, Behr M. Time-continuous and time-discontinuous space-time finite elements for advection-diffusion problems. Int J Numer Methods Eng. 2023; 124(14): 3117-3144. doi:10.1002/nme.7241