Hot plate welding is one of the most popular techniques for joining power and conveyor belts made of thermoplastic elastomers. A crucial technological operation within this process is the plasticization of the belt material on the hot plate surface, as a consequence of the elevated temperature and the axial compressive force. Due to the multiplication of the technological parameters involved in this operation, there are many possibilities for optimisation, mainly focussing on energy efficiency, which can positively impact the energy consumption of the entire welding process. The energy efficiency of the belt plasticization on the hot plate depends mainly on two factors, firstly the thermal energy required to heat and maintain a constant temperature of the heating plate and, for the second, the energy consumption of the electromechanical drive system, which is responsible for applying pressure to the belt ends against the heating element during plasticization. This work presents an analysis of experimental and numerical research results aimed at understanding the fundamental phenomena occurring during belt plasticization, with a focus on estimating effective plasticization parameters for belts of circular cross-section and varying diameters.