STL-based Finish Machining of Rapid Manufacturing Parts and Tools

Accuracy and surface quality problems when utilizing layered manufacturing technologies have limited its use in tooling areas. Therefore, in some situations a CNC machine is still necessary for finish machining of rapid manufactured parts and tools. This paper presents a STL-based CNC machining technique for automating the finishing of RP tools and parts to obtain CNC accuracies and surface finishes. Preprocess operations, such as rotate and scale, are used to change the part orientation and compensate for shrinkage in the whole process. An offset algorithm is developed to add “skin” to the original STL file to make sure enough material is left for finish machining after the rapid manufacturing process. The machining strategy of adaptive raster milling of the surface, plus hole drilling and sharp edge contour machining, is proposed to finish the RP parts and tools. Corresponding algorithms of adaptive tool path generation for raster milling, automatic hole recognition and drilling tool path generation, and automatic sharp edge detection and tool path generation are developed. Finally, a designed benchmark is machined successfully by using the above mentioned machining strategies and tool paths generated by developed software.Mechanical Engineerin