D. Fedorishin, A. Stone, N. Eadie, L. Christie, P. Schneider, K. Oh
University at Buffalo,
Keywords: post processing, 3d printing, additive manufacturing, automated, surface roughness, thermal imaging, postprocess, finishing, surface finishing, fused deposition modeling
Summary:This paper reports the analysis of the effects of post processing on a 3D printed dynamic model engine (Figure 1) in collaboration with PostProcess Technologies. Prior Work: Advancements in 3D printing have made it a viable option for rapid and cost effective modeling of dynamic systems. However, the rough finish of raw 3D printed parts can cause dynamic models to stick and bind due to surface roughness causing excess friction, leading to heat buildup. Traditional methods of finishing printed parts involve manual use of abrasives  or an acetone vapor smoothing process  to surface finish parts. Using patented automated PostProcessTM techniques, 3D printed parts were processed, removing rough edges with minimal change in the dimensions of the parts. An automated post processing system allows for rapid finishing of 3D printed parts to increase productivity, allowing the full potential of additive manufacturing to be realized. Methods: The proprietary post processing technology offered by PostProcess™: Submerged Vortex Cavitation, Suspended Rotational Force, Thermal Atomized Fusillade and Volumetric Velocity Dispersion allows for 3D printed parts to undergo automated support removal and surface finishing procedures. PostProcess’ NITOR machine (Figure 2) allows for intelligent surface finishing, controlling temperature, frequency, vibration and lubricity parameters. Utilizing fused deposition modeling technology, dynamic models including a Toyota 22RE engine model and a 2:1 ratio gearbox were printed with a FolgerTech FT-5 in PLA for a comparison study of post processing effects. Experimental Results: The surface roughness of the unfinished and post processed engine models were measured using a Tencor profilometer (Figure 3). A 38% reduction in surface roughness, from 0.2815μm to 0.1092μm was experienced after post processing via the NITOR. Changes in heat generation due to friction before and after post processing were captured using a FLIR Pro thermal imaging camera. After spinning the gearboxes at 300 rpm for 120 seconds, the post processed gearbox showed a smaller average temperature and a reduction in heat concentrations at high friction points (Figure 4B). Peak static input torque and average moving torque were measured using a torque gauge. After post processing, a 23.9% reduction in peak static resistance and a 58.6% drop in average moving resistance was measured (Figure 4C). Post-processing techniques have proven their usefulness for improving the operation and longevity of dynamic models. Further analyses on the effects of post processing on different printing materials (ABS, Nylon, Resin) and printing technologies (FDM, SLA, SLS) could be conducted. In addition a stress/strain analysis will be done to quantify the internal and structural changes 3D printed parts experience after post processing occurs.