The research results of assuring the quality of hollow continuous cast billets from copper alloys are given in the paper. For this purpose, the design of a continuous casting machine mandrel of hollow billets from copper alloys by making cuts on its surface was improved.It allows modifying the contact area in the “mandrel - billet” system and the extraction force of a billet from the mold respectively. Supporting them at a given level has allowed increasing stability of continuous casting.As a result of the studies, dependencies of the influence of the step size and inner diameter of a hollow billet on the extraction force of the hollow billet from the mold were determined, and also limit values of the step size at a cyclical motion of the billet for various values of the internal diameter of the billet.Changing the step size, when using a mandrel with cuts, allows changing extraction forces from the mold. It allows supporting the extraction force of the billet by increasing the step size not more than the critical force of a graphite mandrel fracturing. Thus, the possibility of maintaining stable operation of the continuous casting machine, used for manufacturing hollow billets from copper alloys, emerges