Research Papers

Experimental Study of Failure Modes and Scaling Effects in Micro-Incremental Forming

[+] Author and Article Information
A. J. Nelson

Department of Mechanical Engineering,
Northwestern University,
Evanston, IL 60201

N. V. Reddy

Department of Mechanical Engineering,
Indian Institute of Technology,
Kanpur 208016, India

Jian Cao

Department of Mechanical Engineering,
Northwestern University,
Evanston, IL 60201
e-mail: jcao@northwestern.edu

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF Micro- AND Nano-Manufacturing. Manuscript received November 20, 2012; final manuscript received July 24, 2013; published online xx xx, xxxx. Assoc. Editor: Shiv G. Kapoor.

J. Micro Nano-Manuf 1(3), 031005 (Aug 13, 2013) (15 pages) Paper No: JMNM-12-1075; doi: 10.1115/1.4025098 History: Received November 20, 2012; Revised July 24, 2013

Incremental forming (IF) is a relatively new technique that uses a simple hemispherical ended tool moving along a predefined three-dimensional toolpath to deform a sheet of metal into the desired shape. The greater process flexibility and higher formability in IF have resulted in greater academic and industrial interest in this process as it can successfully produce ultrathin parts beyond the forming limit seen in conventional stamping and the process does not require any geometry-specific tooling. Another emerging paradigm in manufacturing has been the increasing application of forming in micromanufacturing. The above stated process characteristics of IF make it an ideal candidate for being incorporated into the micromanufacturing paradigm. This work investigates micro-IF to examine how forces and occurrence of sheet failure change when the geometric dimensions of incremental forming are scaled down. The development of a highly repeatable micro-IF experimental setup is described and experiments are performed to show that a previously unknown buckling mode of deformation exists in micro-incremental forming, that is linked to the material microstructure. The analysis provides guidelines for the design and understanding of the micro-incremental forming process.

Copyright © 2013 by ASME
Topics: Buckling , Failure , Shapes
Your Session has timed out. Please sign back in to continue.


Qin, Y., 2010, Micromanufacturing Engineering and Technology, Elsevier, Inc., Burlington, MA.
Qin, Y., Ma, Y., Harrison, C., Brockett, A., Zhou, M., Zhao, J., Law, F., Razali, A., Smith, R., and Egiua, J., 2008, “Development of a New Machine System for the Forming of Micro-Sheet-Products,” Int. J. Mater. Form., 1(1), pp. 475–478. [CrossRef]
DeVor, R. E., and Ehmann, K. F., 2005, Introduction, WTEC Study on Micromanufacturing, National Science Foundation, Arlington, VA.
Malhotra, R., Xue, L., Belytschko, T., and Cao, J., 2012, “Mechanics of Fracture in Single Point Incremental Forming,” J. Mater. Process. Technol., 212(7), pp. 1573–1590. [CrossRef]
Jeswiet, J., Micari, F., Hirt, G., Bramley, A., Duflou, J., and Allwood, J., 2005, “Asymmetric Single Point Incremental Forming of Sheet Metal,” CIRP Ann., 54(2), pp. 88–114. [CrossRef]
Filice, L., and Ambrogio, G., 2006, “On-Line Control of Single Point Incremental Forming Operations Through Punch Force Monitoring,” CIRP Ann., 55(1), pp. 245–248. [CrossRef]
Szekeres, A., Ham, M., and Jeswiet, J., 2007, “Force Measurement in Pyramid Shaped Parts With a Spindle Mounted Force Sensor,” Key Eng. Mater., 344, pp. 551–558. [CrossRef]
Filice, L., Fratini, L., and Micari, F., 2002, “Analysis of Material Formability in Incremental Forming,” CIRP Ann., 51(1), pp. 199–202. [CrossRef]
Emmens, W. C, and vandenBoogard, A. H., 2009, “An Overview of Stabilizing Deformation Mechanisms in Incremental Sheet Forming,” J. Mater. Process. Technol., 209, pp. 3688–3695. [CrossRef]
Yao, H., and Cao, J., 2002, “Prediction of Forming Limit Curves Using an Anisotropic Yield Function With Prestrain Induced Backstress,” Int. J. Plast., 18(8), pp. 1013–1038. [CrossRef]
Smith, L. M., Averill, R. C., Lucas, J. P., Stoughton, T. B., and Matin, P. H., 2003, “Influence of Transverse Normal Stress on Sheet Metal Formability,” J. Plast., 19, pp. 1567–1583. [CrossRef]
Van Bael, A., Eyckens, P., He, S., Bouffioux, C., Henrard, C., Habraken, A. M., Dulfou, J., and van Houtte, P., 2007, “Forming Limit Predictions for Single Point Incremental Sheet Metal Forming,” Proceedings of the 10th ESAFORM Conference on Material Forming, AIP Conference Proceedings, American Institute of Physics, College Park, Maryland, Vol. 907, pp. 309–314.
Huang, Y., Cao, J., Smith, S., Woody, B., Ziegert, J., and Li, M., 2008, “Experimental and Numerical Investigation of Forming Limits in Incremental Forming of a Conical Cup,” Trans. North Am. Manuf. Res. Inst. SME, 36, pp. 389–396.
Silva, M. B., Skjoedt, M., Bay, N., and Martins, P. A. F., 2009, “Revisiting Single-Point Incremental Forming and Formability/Failure Diagrams by Means of Finite Elements and Experimentation,” J. Strain Anal., 44, pp. 221–234. [CrossRef]
Xue, L., 2007, “Damage Accumulation and Fracture Initiation in Uncracked Ductile Solids Subjected to Triaxial Loading,” Int. J. Solids Struct., 44(16), pp. 5163–5181. [CrossRef]
Jackson, K., and Allwood, J., 2009, “The Mechanics of Incremental Sheet Forming,” J. Mater. Process. Technol., 209, pp. 1158–1174. [CrossRef]
Allwood, J. M., Shouler, D. R., and Tekkaya, A. E., 2007, “The Increased Forming Limits of Incremental Sheet Forming Processes,” Key Eng. Mater., 344, pp. 621–628. [CrossRef]
Allwood, J. M., and Shouler, D. R., 2009, “Generalized Forming Limit Diagrams Showing Increased Forming Limits With Non-Planar Stress States,” Int. J. Plasticity, 25, pp. 1207–1230. [CrossRef]
Obikawa, T., Satou, S., and Hakutani, T., 2009, “Dieless Incremental Micro-Forming of Miniature Shell Objects of Aluminum Foils,” Int. J. Mach. Tools Manuf., 49, pp. 906–915. [CrossRef]
Saotome, Y., and Okamoto, T., 2011, “An In-Situ Incremental Microforming System for Three-Dimensional Shell Structures of Foil Materials,” J. Mater. Process. Technol., 113, pp. 636–640. [CrossRef]
Sekine, T., and Obikawa, T., 2010, “Single Point Micro Incremental Forming of Miniature Shell Structures,” J. Adv. Mech. Des. Syst. Manuf., 4(2), pp. 543–557. [CrossRef]
Hussain, G., Gao, L., Hayat, N., and Qijia, L., 2007, “The Effect of Variation in the Curvature of Part on the Formability in Incremental Forming, An Experimental Investigation,” Int. J. Mach. Tools Manuf., 47, pp. 2177–2181. [CrossRef]
Cao, J., Wang, X., and Mills, F. A., 2002, “Characterization of Sheet Buckling Phenomenon Subjected to Controlled Boundary Constraints,” ASME J. Manuf. Sci. Eng., 124, pp. 493–501. [CrossRef]
Cao, J., 1999, “Prediction of Plastic Wrinkling Using Energy Method,” ASME J. Appl. Mech., 66, pp. 646–652. [CrossRef]


Grahic Jump Location
Fig. 1

Schematic of SPIF process

Grahic Jump Location
Fig. 7

Example of drift in force measurement

Grahic Jump Location
Fig. 6

Schematic showing incorrectly shaped tool and ideal cross section of tool

Grahic Jump Location
Fig. 5

Schematic of error resulting from inaccurate fabrication of sheet clamping setup. Bottom face of the top constraint plate is highlighted in red. The angled dashed line is an exaggeration of the nonparallelism that may have existed.

Grahic Jump Location
Fig. 4

(a) Procedure for making bolt clearance holes and (b) 250 μm tool used for μ-SPIF

Grahic Jump Location
Fig. 2

(a) Overall design of blank holding fixture, (b) sectional view of blank holding fixture, and (c) fabricated sheet holding fixture

Grahic Jump Location
Fig. 8

(a) Etched strain grid on sheet and (b) prefabricated strain grid adhered to sheet surface

Grahic Jump Location
Fig. 9

(a) Strain circle grid created with laser ablation and (b) picosecond laser system used to create the strain grid

Grahic Jump Location
Fig. 10

(a) Schematic of toolpaths used, (b) channels formed on sheet, and (c) close up view of failure location

Grahic Jump Location
Fig. 11

(a) 55 deg cone, (b) freeform component, and (c) triangular pyramids, formed using μ-SPIF

Grahic Jump Location
Fig. 12

Illustration of the cone component and variables listed in DOE factors

Grahic Jump Location
Fig. 15

A formed sample showing the phenomenon of sheet buckling. When buckling was observed, no tearing of the part had yet occurred.

Grahic Jump Location
Fig. 16

Surface roughness measurements for SS304 sheets (a) before and (b) after polishing

Grahic Jump Location
Fig. 17

Forming forces for μ-SPIF of a 65 deg cone with an unpolished sheet

Grahic Jump Location
Fig. 18

Forming forces for μ-SPIF of a 65 deg cone with a polished sheet

Grahic Jump Location
Fig. 19

CAD model of fixture designed to ensure planarity of clamped sheet

Grahic Jump Location
Fig. 20

Cone formed with new fixture

Grahic Jump Location
Fig. 13

Forming forces for failure by tearing in μ-SPIF of the cone

Grahic Jump Location
Fig. 14

Forming forces for failure by buckling in μ-SPIF of the cone

Grahic Jump Location
Fig. 23

Illustration of the profile of the funnel shape

Grahic Jump Location
Fig. 24

Fracture locations for μ-SPIF of funnel shapes. The lighter lines represent visible tearing. Note the absence of “x” marks indicating an absence of buckling.

Grahic Jump Location
Fig. 25

Typical force curves for μ-SPIF of the funnel shape

Grahic Jump Location
Fig. 26

Experimental setup for macro-SPIF

Grahic Jump Location
Fig. 27

Comparison for failure depths for macro-SPIF and μ-SPIF

Grahic Jump Location
Fig. 28

Schematic of the FEA model

Grahic Jump Location
Fig. 21

Failure locations and observable types for cone tests run with the tensioned sample constraint plate. The lighter lines represent visible tearing, while the “x” marks indicate the appearance of sheet buckling. The lines inside the circles indicate the rolling direction in which the grains are more elongated.

Grahic Jump Location
Fig. 22

(a) Geometry of formed 55 deg wall angle cone, (b) normal contact between tool and sheet in SPIF, (c) buckling of sheet in the plane, and (d) eventual failure of the sheet due to buckling (the section indicates the part of the sheet in contact with the tool and section indicates the buckled zone of the sheet)

Grahic Jump Location
Fig. 29

(a) Undeformed and (b) deformed strain grids for the cone shape corresponding to case 15 in Table 2



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