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Research Papers

Experimental and Simulation of Friction Effects in an Open-Die Microforging/Extrusion Process

[+] Author and Article Information
Ehsan Ghassemali

School of Mechanical and
Aerospace Engineering,
Nanyang Technological University,
Singapore 639798, Singapore
Singapore Institute of Manufacturing Technology (SIMTech),
71 Nanyang Dr,
Singapore 638075, Singapore
e-mail: ehsa0005@ntu.edu.sg

Ming-Jen Tan

School of Mechanical and
Aerospace Engineering,
Nanyang Technological University,
Singapore 639798, Singapore
e-mail: MMJTAN@ntu.edu.sg

Samuel Chao Voon Lim

Materials Engineering,
Monash University,
Wellington Road, Clayton,
Victoria, 3800, Australia
e-mail: Samuel.Lim@monash.edu

Chua Beng Wah

Singapore Institute of Manufacturing Technology (SIMTech),
71 Nanyang Dr,
Singapore 638075, Singapore
e-mail: bwchua@simtech.a-star.edu.sg

Anders Eric Wollmar Jarfors

School of Engineering,
Jönköping University,
P.O. Box 1026,
Jönköping SE-551 11, Sweden
e-mail: Anders.Jarfors@jth.hj.se

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MICRO- AND NANO-MANUFACTURING. Manuscript received January 9, 2013; final manuscript received January 13, 2014; published online February 12, 2014. Assoc. Editor: Ulf Engel.

J. Micro Nano-Manuf 2(1), 011005 (Feb 12, 2014) (12 pages) Paper No: JMNM-13-1003; doi: 10.1115/1.4026518 History: Received January 09, 2013; Revised January 13, 2014

Friction effects during a progressive microforming process for production of micropins of various diameters were experimentally investigated and were analytically modeled, using a hybrid friction model. The response surface method and ANOVA analysis were used to generalize the findings for various pin diameters. Besides, it was shown that to get an accurate result in simulation, the friction model must be considered locally instead of a global friction model for the whole process. The effect of friction factor on the final micropart dimensions (the effect on the instantaneous location of the neutral plane) and the forming pressure were investigated. The results showed a reduction in the friction factor as die diameter increased. Following that, the optimum frictional condition to obtain the highest micropart aspect ratio was defined as the maximum friction on the interface between the die upper surface and the punch surface, together with a minimum friction inside the die orifice.

Copyright © 2014 by ASME
Topics: Friction , Simulation
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References

Figures

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Fig. 1

Schematic of the progressive microforming process

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Fig. 2

Measurement method used for measuring the pin height after Sstage I

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Fig. 3

Die set design used in simulation

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Fig. 4

True stress-–strain of the C11000 copper alloy obtained from upsetting test

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Fig. 5

Schematic of (a) the cross-sectional laser marking, and (b) welding of the copper strip

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Fig. 6

Schematic of the manufactured micro-pin. The pin was segmented from the separation line to see the laser marks after forming.

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Fig. 7

Two-dimensional deformation of a material element

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Fig. 8

Simulation results of the pin height versus. punch stroke for different global friction factors. Pin diameter of 0.3 mm manufactured by 1.2 mm punch.

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Fig. 9

Pin height during the progressive microforming process for different die diameters. “m" in the curves represents the hybrid friction factor values used in the simulation

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Fig. 10

Evolution of the required forming load during the progressive microforming process for different die diameters. “m" in the curves represents the hybrid friction coefficient values used in the simulation.

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Fig. 11

Grid-line distortion and shear strain validation in simulation and experiments in the 0.8 mm pin manufactured by 3.2 mm punch in different punch strokes of: (a) 1.5, (b) 2, and (c) 2.3 mm

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Fig. 12

Influence of the geometry on the hybrid friction factor

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Fig. 13

Schematic half-cross-section of the forming process showing the material flow by velocity vectors via simulation. Neutral plane separates the material flow in two opposite directions under the punch.

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Fig. 14

The effect of friction on the location of the neutral plane during the process for different process geometries. (a) in the zone I for various values of m1, and (b) in the zone II for various values of m2.

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Fig. 15

The effect of friction on the pin aspect ratio during the process for different process geometries. (a) in the zone I for various values of m1, and (b) in the zone II for various values of m2.

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Fig. 16

The effect of friction on the required forming pressure during the process for different process geometries. (a) in the zone I for various values of m1, and (b) in the zone II for various values of m2.

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