This paper considers the problem of modelling the thermal cutting process of sheet material, which occurs when cutting using equipment, such as laser, gas, etc. The aim of the study is to solve the problem of optimizing the toolpath while considering the thermal effects that occur in the material being cut. A problem statement is given in this paper. An approach to modelling the change in temperature of the material during cutting is proposed, based on a discrete representation of information. The results of the computational experiment are also given.