The original method of investigation of efficiency of quasi-cutting of thermoplastic pipes materials (especially recycled materials from opto-telecommunication pipes) is presented. Investigations of mechanical properties, simulations of powers and sections of quasi-cutting as well as investigations of grinding process in the machine conditions have been done. General models of the process efficiency based on application of the grinding product processability are presented. An assumption has been made that input energy of the process (including grinding) is the sum of the energies present in plastic material and delivered to it. In the case of assumptions made and factors taken, the solution of this constructional task was to obtain the value of energy-effectiveness factor of plastics grinding, going to maximum (equation [11]). The model was verified experimentally in strength machine, as a simulation of powers and sections, physical investigations of 3-disc milling sizes. Analysis of results obtained made selection of construction features of quasi-cutting set, with the aim to maximize the efficiency, possible. The 3-disc set let break up the pipe pieces (from recycling process) of diameter above 50 mm and to 6 mm thick; power installed is 7.5 kW. Double increase of energy efficiency of the grinding process of recycled pipes material has been reached (from 4.2% to 8.5%) as well as high - up to 120 - degree of grinding (as an average dimensions - before and after - ratio) and significant (more than 80%) part of the product has been suitable for the next processing (average dimension of particles: 4.60 mm).