Complex molds and dies often need grinding to achieve the required surface finishes and tolerances. Due to complex part geometry and multiple-axis motion, the wheel–workpiece engagement conditions may vary drastically during grinding, which imposes challenges to choose the appropriate workspeeds. This paper presents a modeling approach to optimize mold and die grinding to reduce cycle time while maintaining process parameters such as grinding force and specific removal rate below critical limits. The wheel–workpiece engagement conditions are calculated for each grinding step by processing the NC program, part and wheel geometries. Grinding forces, power, and temperature are calculated and used as decision variables to optimize workspeed to reduce cycle time. Results for grinding a half bottle shaped mold show that the grinding process parameters vary significantly along the wheel axis at any instant and along the grinding path. The grinding process is far from optimum if a constant workspeed is used. Model-based optimization has been shown to reduce cycle time by 50% while achieving much lower grinding forces and power.