Development of Feature Recognition and Feature Based Machining Algorithm for Three Axis CNC Lathe Mill

Abstract

Over the past few years, manufacturing companies have had to deal with an increasing demand for feature-rich products. There is also a lot of work done on sculptured parts using lathe-mill CNC machines. The present state of the art generates scallops on the part surface. There is a need to finish these scallops using feature recognition and contoured machining of these scallops. A CAD package provides the information about the part geometry saved as stereo lithography (STL) file, which is taken as an input to the tool path generation algorithm. The algorithm calculates the cutter location (CL) points based on various parameters given as input like depth of cut for roughing pass, side step for roughing and finishing operation. Various checks have been applied in the algorithm to find the best suitable point at particular tool position. The tool path for a lathe mill CNC machine follows a helical path to machine the surface, with cutter profile as ball nose end mill with varying radius for roughing and finishing passes, which can be changed by the user. In this work features like cavities, grooves, and protrusions of any shape are recognized based on the roughing and finishing files generated by the computer algorithm. The tool path planning algorithm is developed for skipping the features in the first go and then these features are separately approached for machining them in the last. The testing of tool path is carried out on a Custom Simulator ‘Tool Sim’ and has been validated by comparing the actual part geometry saved as STL file with the final machined geometry output taken as obj file from ‘Tool Sim’ into a CAD package like CREO.