The future capital intensive manufacturing industry will demand efficient utilization of machine tools. Thus, a modular real-time adaptive control (AC) system for turning is being developed. Different real-time monitoring and control tasks are assigned to integral subsystems respectively, organized in a distributed computer system and supervised by a master computer in accordance with a main AC strategy. The subsystem for quasi-static cutting force control adapts the feedrate to the present machining situation in order to keep the tangential cutting force constant at a maximum level, given by the machine tool and the tool constraints. Since the cutting process is nonlinear and time-varying, it is difficult to control Therefore, a linearized process model has been introduced and a constant-gain, incremental Pi-controller has been designed and tested with good results. In this paper we will present the AC turning system, focusing on the subsystem for quasi-static cutting force control.