0
Research Papers

Effect of Thermal Deformation on Part Errors in Metal Powder Based Additive Manufacturing Processes

[+] Author and Article Information
Ratnadeep Paul

Center for Global Design and Manufacturing,
School of Dynamic Systems,
Mechanical Engineering Program,
University of Cincinnati,
Cincinnati, OH 45221
e-mail: paulrp@ucmail.uc.edu

Sam Anand

Center for Global Design and Manufacturing,
School of Dynamic Systems,
Mechanical Engineering Program,
University of Cincinnati,
Cincinnati, OH 45221
e-mail: sam.anand@uc.edu

Frank Gerner

Microscale Heat Transfer Lab,
School of Dynamic Systems,
Mechanical Engineering Program,
University of Cincinnati,
Cincinnati, OH 45221
e-mail: frank.gerner@uc.edu

1Corresponding author.

Manuscript received May 1, 2013; final manuscript received January 16, 2014; published online March 26, 2014. Assoc. Editor: Yung Shin.

J. Manuf. Sci. Eng 136(3), 031009 (Mar 26, 2014) (12 pages) Paper No: MANU-13-1211; doi: 10.1115/1.4026524 History: Received May 01, 2013; Revised January 16, 2014

In metal additive manufacturing (AM) processes, parts are manufactured in layers by sintering or melting metal or metal alloy powder under the effect of a powerful laser or an electron beam. As the laser/electron beam scans the powder bed, it melts the powder in successive tracks which overlap each other. This overlap, called the hatch overlap, results in a continuous cycle of rapid melting and resolidification of the metal. The melting of the metal from powder to liquid and subsequent solidification causes anisotropic shrinkage in the layers. The thermal strains caused by the thermal gradients existing between the different layers and between the layers and the substrate leads to considerable thermal stresses in the part. As a result, stress gradients develop in the different directions of the part which lead to distortion and warpage in AM parts. The deformations due to shrinkage and thermal stresses have a significant effect on the dimensional inaccuracies of the final part. A three-dimensional thermomechanical finite element (FE) model has been developed in this paper which calculates the thermal deformation in AM parts based on slice thickness, part orientation, scanning speed, and material properties. The FE model has been validated and benchmarked with results already available in literature. The thermal deformation model is then superimposed with a geometric virtual manufacturing model of the AM process to calculate the form and runout errors in AM parts. Finally, the errors in the critical features of the AM parts calculated using the combined thermal deformation and geometric model are correlated with part orientation and slice thickness.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Overall methodology for thermal distortion based error modeling

Grahic Jump Location
Fig. 3

3D Schematic of the thermomechanical model

Grahic Jump Location
Fig. 5

Thermal boundary condition

Grahic Jump Location
Fig. 6

(a) Structural boundary condition during deposition of layers, (b) structural boundary condition after deposition of all layers: first case and (c) structural boundary condition after deposition of all layers: second case

Grahic Jump Location
Fig. 7

Schematic for validating FEA model

Grahic Jump Location
Fig. 8

Geometric virtual manufacturing model

Grahic Jump Location
Fig. 9

Error in surface point location due to thermal deformation

Grahic Jump Location
Fig. 11

Cylindricity error

Grahic Jump Location
Fig. 12

Circularity error evaluation

Grahic Jump Location
Fig. 13

Total runout error evaluation

Grahic Jump Location
Fig. 14

Circular runout error evaluation

Grahic Jump Location
Fig. 17

FEA result: deformed shape of (a) test part 1 and (b) test part 2

Grahic Jump Location
Fig. 18

Vertical nodal displacement (mm) map for test part 1, (a) 0 deg part orientation, (b) 30 deg orientation, and (c) 45 deg orientation

Grahic Jump Location
Fig. 19

Vertical nodal displacement (mm) map for test part 2, (a) 0 deg part orientation, (b) 45 deg orientation, and (c) 60 deg orientation

Grahic Jump Location
Fig. 20

(a) Virtually manufactured geometry of test part 1 at 45 deg orientation, (b) points sampled from cylindrical feature, C2, and (c) points sampled from planar feature, F2

Grahic Jump Location
Fig. 21

(a) Virtually manufactured geometry of test part 2 at 45 deg orientation, (b) points sampled from cylindrical feature, C2, and (c) points sampled from planar feature, F2

Grahic Jump Location
Fig. 22

Flatness error for test part 1

Grahic Jump Location
Fig. 23

Flatness error for test part 2

Grahic Jump Location
Fig. 24

Cylindricity error for test part 1

Grahic Jump Location
Fig. 25

Cylindricity error for test part 2

Grahic Jump Location
Fig. 26

Circularity error at different locations from the base of the feature, test part 1

Grahic Jump Location
Fig. 27

Circularity error at different locations from the base of the feature, test part 2

Grahic Jump Location
Fig. 28

Circular runout error at different locations from the base of the feature, test part 1

Grahic Jump Location
Fig. 29

Circular runout error at different locations from the base of the feature, test part 2

Grahic Jump Location
Fig. 30

Runout error for test parts 1 and 2

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In