In this study, a tip test was carried out under various ram velocities of 0.01 mm/s, 0.1 mm/s, 1.0 mm/s, and 5.0 mm/s to investigate the effect of deformation speed on friction using the commercially available AL6061-O. For experiments, four different lubrication conditions with grease, corn oil, VG100, and VG32 were used to investigate the lubrication characteristics. During the test, temperature was measured in the specimen by a K-type thermocouple to determine the temperature increase induced by heat generation due to plastic deformation. In the present investigation, the linearity between tip distance and experimentally measured maximum load was consistently observed in spite of different orders of ram velocity and types of lubrication. As the ram velocity increased, loads were reduced for liquid lubricants and increased for grease. To better understand such a lubrication phenomenon, white-light interferometer microscopy and laser confocal microscopy were used to observe and compare surface topographies on the bottom and circumferential side of the deformed specimens at various experimental conditions, which formed lubrication pockets incurring hydrodynamic pressure of liquid lubricants. Finally, the effect of deformation speed on the level of shear friction factors at the punch and die interfaces was characterized by the finite element simulations and was determined to be expressed as an exponential function depending on the lubricant. This investigation demonstrates the capability of the tip test to experimentally characterize the effect of deformation speed on the frictional behavior for practical use.

1.
Dowson
,
D.
, 1979,
History of Tribology
,
Longman
,
London, UK
.
2.
Male
,
A. T.
, and
Cockroft
,
M. G.
, 1964, “
A Method for the Determination of the Coefficient of Friction of Metals Under Conditions of Bulk Plastic Deformation
,”
J. Inst. Met.
0020-2975,
93
, pp.
38
46
.
3.
Wang
,
F.
, and
Lenard
,
J. G.
, 1992, “
An Experimental Study of Interfacial Friction-Hot Ring Compression
,”
ASME J. Eng. Mater. Technol.
0094-4289,
114
, pp.
13
18
.
4.
Schey
,
J. A.
, 1979, “
Modelling of the Tool-Workpiece Interface
,”
Metal Forming Plasticity, IUTAM Symposium
,
H.
Lippmann
, ed.,
Springer-Verlag
,
Berlin, Germany
, pp.
336
348
.
5.
Hwu
,
Y. J.
,
Hsu
,
C. T.
, and
Wang
,
F.
, 1993, “
Measurement of Friction and the Flow Stress of Steels at Room and Elevated Temperatures by Ring-Compression Tests
,”
J. Mater. Process. Technol.
0924-0136,
37
, pp.
319
335
.
6.
Buschhausen
,
A.
,
Weinmann
,
K.
,
Lee
,
J. Y.
, and
Altan
,
T.
, 1992, “
Evaluation of Lubrication and Friction in Cold Forging Using a Double Backward-Extrusion Process
,”
J. Mater. Process. Technol.
0924-0136,
33
, pp.
95
108
.
7.
Tan
,
X.
,
Bay
,
N.
, and
Zhang
,
W.
, 1998, “
On Parameters Affecting Metal Flow and Friction in the Double Cup Extrusion Test
,”
Scand. J. Metall.
0371-0459,
27
(
6
), pp.
246
252
.
8.
Schrader
,
T.
,
Shirgaokar
,
M.
, and
Altan
,
T.
, 2007, “
A Critical Evaluation of the Double Cup Extrusion Test for Selection of Cold Forging Lubricants
,”
J. Mater. Process. Technol.
0924-0136,
189
, pp.
36
44
.
9.
Im
,
Y. T.
,
Cheon
,
J. S.
, and
Kang
,
S. H.
, 2002, “
Determination of Friction Condition by Geometrical Measurement of Backward Extruded Aluminum Alloy Specimen
,”
ASME J. Manuf. Sci. Eng.
1087-1357,
124
, pp.
409
415
.
10.
Im
,
Y. T.
,
Cheon
,
J. S.
, and
Kang
,
S. H.
, 2003, “
Finite Element Investigation of Friction Condition in a Backward Extrusion of Aluminum Alloy
,”
ASME J. Manuf. Sci. Eng.
1087-1357,
125
, pp.
378
383
.
11.
Kang
,
S. H.
,
Lee
,
J. H.
,
Cheon
,
J. S.
, and
Im
,
Y. T.
, 2004, “
The Effect of Strain Hardening on Frictional Behavior in Tip Test
,”
Int. J. Mech. Sci.
0020-7403,
46
, pp.
855
869
.
12.
Chauviere
,
P.
,
Jung
,
K. H.
,
Kim
,
D. K.
,
Lee
,
H. C.
,
Kang
,
S. H.
, and
Im
,
Y. T.
, 2008, “
Experimental Study of Miniaturized Tip Test
,”
J. Mech. Sci. Technol.
1738-494X,
22
, pp.
924
930
.
13.
Jung
,
K. H.
,
Lee
,
H. C.
,
Ajiboye
,
J. S.
,
Kang
,
S. H.
, and
Im
,
Y. T.
, 2010, “
The Effect of Surface Conditions on Friction by Tip Test
,”
ASME J. Tribol.
0742-4787,
132
, p.
011601
.
14.
ASM International
, 1979,
Metals Handbook
,
9th ed.
,
American Society for Metals
,
Ohio
, Vol.
2
.
15.
Fox
,
W. R.
, and
McDonald
,
A. T.
, 1994,
Introduction to Fluid Mechanics
,
4th ed.
,
Wiley
,
New York
, Chap. 2.
16.
Jung
,
K. H.
,
Lee
,
H. C.
,
Ajiboye
,
J. S.
, and
Im
,
Y. T.
, 2010, “
Characterization of Frictional Behavior in Cold Forging
,”
Tribol. Lett.
1023-8883,
37
, pp.
353
359
.
17.
Kim
,
S. Y.
, and
Im
,
Y. T.
, 2002, “
Three-Dimensional Finite Element Analysis of Non-Isothermal Shape Rolling
,”
J. Mater. Process. Technol.
0924-0136,
127
, pp.
57
63
.
18.
Kwak
,
D. Y.
,
Cheon
,
J. S.
, and
Im
,
Y. T.
, 2002, “
Remeshing for Metal Forming Simulations—Part I: Two-Dimensional Quadrilateral Remeshing
,”
Int. J. Numer. Methods Eng.
0029-5981,
53
(
11
), pp.
2463
2500
.
19.
Kwak
,
D. Y.
, and
Im
,
Y. T.
, 2002, “
Remeshing for Metal Forming Simulations—Part II: Three-Dimensional Hexahedral Mesh Generation
,”
Int. J. Numer. Methods Eng.
0029-5981,
53
(
11
), pp.
2501
2528
.
20.
Ajiboye
,
J. S.
,
Jung
,
K. H.
, and
Im
,
Y. T.
, 2010, “
Sensitivity Study of Frictional Behavior by Dimensional Analysis in Cold Forging
,”
J. Mech. Sci. Technol.
1738-494X,
24
, pp.
115
118
.
You do not currently have access to this content.