This paper deals with machine tools characterized by a periodic behaviour and high-power peaks that require an oversized electrical network and cause high costs because electrical utilities charge greatly each power peak. To solve this issue, a new peak-shaving methodology is proposed based on polynomial models and optimization, to reduce the power-consumption peaks height in machine tools with periodic behaviour. A test-bench that emulates the electrical behaviour of a machine tool is used in order to test the proposed method with real data. In the scenarios simulated, the peak height has been reduced between 35% and 15%.