Optimising Tool Positioning for End-Mill Machining of Free-Form Surfaces on 5-Axis Machines for both Semi-Finishing and Finishing

End-milling of free-form surfaces on 5-axis NC machine tools is a complex problem which has been studied by a large number of research scientists. When end-milling non-convex surfaces there is a risk of interference between the tool and the surface. Using a 5-axis NC machine tool enables the tool to be oriented in any spatial direction to access a given point. This means interference can be avoided and the position of the tool can be optimised so as to minimise residual material. Here, a new method is presented for tool positioning in end-milling of free-form surfaces based on evaluating the interference for a set of test points distributed around the circumference of the tip of the tool. Distinction is made between the cases of semi-finishing and finishing which can be performed using a large diameter flat-end tool and a toroidal tool, respectively. Further, all developments are implemented for interactive use in a CAD/CAM software environment.