The quality of surfaces machined by lapping depends on numerous variables, some of them controllable and others not. Their existence renders the task of selecting adequate working parameters and their values (set points) such as to obtain the desired response difficult. For this reason, this paper discusses the robust parameter design as an optimisation method for plane lapping. The paper presents the working equipment, the utilized methodology as well as the obtained experimental results. The output quantities selected for describing the lapped surface quality and the machining productivity, respectively, were roughness Ra and the height of the cut layer h.