Cycle time affects the overall economics of plastic and composite molding processes. The choice of mold materials greatly influences the temperatures in the cavity, the cycle time and part quality. This paper summarizes and highlights two investigations of the influence of mold materials on the productivity of injection molding and resin transfer molding.The investigation of injection molding compared the performance of molds made from six copper alloys with P20 steel. The results showed that high thermal conductivity copper-alloy molds reduced the cycle time compared to steel and showed a significantly lower cavity-surface temperature and more uniform cooling.The investigation of resin transfer molding (RTM) showed how the thermal diffusivity of copper alloys enables the mold to reach steady state quickly, to maintain a more uniform temperature, to dissipate reaction exotherm, to improve temperature control, and to provide more uniform curing of the part.These advantages can be translated into economic advantages by reducing cycle time, improving production efficiencies, and lowering capital costs. The thermal and economic benefits are available from a wide range of copper alloys that eliminate the need to compromise hardness or strength.