Abstract

The surface finish and dimensional accuracy in extrusion-based additive manufacturing processes are typically poor. Despite the use of a small nozzle size and layer thickness, postprocessing is often required to reach desired finish and tolerance on top of the already-long printing time. Hybrid manufacturing combines additive and subtractive methods to produce near-net-shape parts with improved quality. However, more research needs to be done to examine the hybrid process on polymers and its potential to reduce the total manufacturing time through rapid printing followed by detailed contour machining. To demonstrate this concept, a custom-built 3-axis machine with separate heads for printing and machining was developed. This study alters the parameters of nozzle diameter (0.4 and 0.8 mm) and the printing speed (3600 and 9000 mm/min) to print two generic parts with drastically different times and quality and then conduct an in-situ finishing process to produce the final parts. The finished and as-printed parts are then compared based on surface finish, dimensional accuracy, and manufacturing time. The results show that the hybrid process can greatly improve the form errors in rapid printing. The study also discusses a feature-size case study that can help implement the results and develop general strategies for hybrid manufacturing.

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