Effect of layer thickness and orientation angle on surface roughness in laminated object manufacturing

Abstract

The laminated object manufacturing (LOM) process is a freeform fabrication process used to produce wood-like prototypes and patterns for manufacturing processes such as sand casting. Therefore, surface roughness is an important factor in the utility of LOM prototypes. This study investigated the source of surface roughness in the LOM process to offer insight into the in-process control of surface roughness. A full-factorial experiment was performed to investigate the effect of layer thickness and orientation angle on the centerline average surface roughness of LOM prototypes. Results show orientation angle and paper thickness to be statistically significant. Further, the nature of surface roughness in LOM was found to be different than the nature of surface roughness in other freeform fabrication processes such as stereolithography. Overall, this study indicates that the inprocess control of prototype surface roughness may be possible in LOM by gaining greater control of the working distance during processing.

Introduction

Conclusions

A theoretical model for predicting surface roughness on LOM prototypes was developed and verified experimentally. Results show that the model provided generally good agreement for surfaces with moderate surface roughness (>13 (mu)m;

Orientation angle and paper thickness were both found to be statistically significant with respect to centerline average surface roughness of LOM prototypes. Further, the findings of this experiment have provided some new insights into the control of surface roughness in LOM prototypes. Overall, it was found that the voxel geometry does have a significant effect on the surface roughness of LOM prototypes. Further, the nature of surface roughness in LOM was found to be different than the nature of surface roughness in stereolithography. The smallest surface roughness was found on the upfacing surfaces of LOM prototypes, which is in contrast with surface roughness studies performed on stereolithography prototypes where the smoothest surfaces were generally found on downfacing surfaces. Finally, this study indicates that the in-process control of prototype surface roughness may be possible in LOM by gaining greater control of the working distance during processing.

Some experimental evidence was provided indicating that surface roughness in LOM prototypes is minimized at smaller orientation angles. In addition, it is suggested that shorter cycle times may be had in LOM processing by processing with thicker layers without proportional increases in surface roughness.

References

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Brian K. Paul and Vinay Voorakarnam, Oregon State University, Corvallis, Oregon, USA

Authors' Biographies

Brian K. Paul is an associate professor in the Dept. of Industrial and Manufacturing Engineering at Oregon State University. He received his BS, MS, and PhD in industrial engineering from Wichita State University, Arizona State University, and The Pennsylvania State University, respectively. He has seven years industrial experience with Boeing Military Airplane Co., Honeywell Industrial Automation Systems Div., and Battelle Pacific Northwest National Laboratory. His current research interests are related to the application of layered manufacturing techniques to microtechnology.

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