Rubber molding processes in heated-plate hydraulic presses (HHPs) demand substantial energy input, making them a critical target for sustainable manufacturing improvements. This study evaluates the application of a PLC-controlled preheating furnace in mold preparation and quantifies its impact on energy use, production efficiency, and heat transfer performance. The optimized preheating reduced energy consumption by 68% and shortened the preheating time by 83%, resulting in a decrease of over 70% in press downtime and an increase in weekly mold changes from 40 to 70. These operational gains translated into annual energy savings exceeding 135 million kJ and avoided more than 20,000 kg of CO₂ emissions, with the potential to surpass 35,000 kg under intensified production scenarios. Heat transfer analysis revealed that surface resistance heating generated significant internal gradients (high Bi number), whereas forced convection heating (Bi <1) enabled faster and more uniform heat penetration. These findings demonstrate that integrating a preheating furnace into the production line not only enhances sustainability but also provides valuable insights into industrial heat transfer mechanisms, offering a cost-effective alternative to investing in new hydraulic presses.