In the situation of serious tool-workpiece contact when a smooth surface is desired in metal forming, the lubricant is either enclosed within the micro pits or infiltrates the contact plateaus region. The evolution of surface topography and the interfacial shear stress is accordingly altered. A quantitative analysis has been developed based on a series of compression-sliding tests and three-dimensional measurements of work-piece surface. It is found that the lubricant in the oil pits seeps into the contact region under the present experimental conditions. The fractional area of oil pit is a linear function of the average surface separation. The deformation of the oil pits is in the mode of “centripetal flow” where the opening of the pit is diminished while the depth of the oil pit is basically kept constant during the deformation. The specific permeation flux, which is defined as the nondimensional permeation flux per unit relative sliding speed and width of oil pit is an important index for the tendency of permeation. The variation of the specific permeation flux reveals that the lubricant permeation increases with sliding speed and average surface separation. After adopting the permeation model, it is found that the slipping between tool surface and permeating lubricant might exist. The average film thickness of the infiltrating oil increases with increasing sliding velocity and less serious asperity contact.

1.
Azushima
A.
,
Tsubouchi
M.
,
Kudo
H.
,
Furuta
N.
, and
Minemura
K.
,
1989
, “
Experimental Confirmation of the Micro-Plasto-Hydrodynamic Lubrication Mechanism at the Interface between Workpiece and Forming Die
,”
J. Japan Soc. Technol. of Plasticity
(in Japanese), Vol.
30
, No.
347
, pp.
1631
1638
.
2.
Azushima, A., et al., 1990, “Direct Observation of Lubricant Behavior under the Micro-PHL at the Interface between Workpiece and Die,” Proc. 3rd Int. Conf. on Adv. Technol. of Plasticity, Kyoto, Japan, pp. 551–556.
3.
Azushima
A.
et al.,
1991
, “
An Interpretation on the Speed Dependence of the Coefficient of Friction under the Micro-PHL Condition in Sheet Drawing
,”
Annals of CIRP
, Vol.
40
, pp.
227
230
.
4.
Azushima
A.
,
1995
, “
Direct Observation of Contact Behavior to Interpret the Pressure Dependence of the Coefficient of Friction in Sheet metal Forming
,”
Annals of CIRP
, Vol.
44
, pp.
209
212
.
5.
Chung, K. J., Lo, S. W., and Horng, T. C., 1997, “Experimental Investigation of Low Speed Lubrication in Bulk Metal Forming Processes,” CSME, Proc. 14th National Conf on Meek Eng. (in Chinese), Chungli, Taiwan.
6.
Kataoka, S., Kanno, K., and Kihara, J., 1988, “Experimental Investigation of Lubrication Mechanism in Low Speed Plastic Deformation I, II and III,” JSTP, Ann., Rep., 56.
7.
Kudo
H.
,
1965
, “
A Note on the Role on Microscopically Trapped Lubricant at the Tool-Workpiece Interface
,”
Int. J. Mech. Sci.
, Vol.
7
, pp.
383
388
.
8.
Kudo
H.
et al.,
1982
, “
An Investigation into Plasto-Hydrodynamic Lubrication with a Sheet Drawing Test
,”
Annals of the CIRP
,
31
, pp.
175
180
.
9.
Kudo, H., and Azushima, A., 1987, “Interaction of Surface Microstrticture and Lubricant in Metal Forming Tribology,” Proc. 2nd. Int. Conf. on Adv. Technol. of Plasticity, Stuttgart, pp. 373.
10.
Lo
S. W.
,
1994
, “
A Study on the Flow Phenomena in the Mixed Lubrication Regime by Porous Medium Model
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
116
, No.
3
, pp.
640
647
.
11.
Lo, S. W., and Horng, T. C, 1997, “Surface Roughening and Contact Behavior in Forming of Aluminum Sheet,” Proc. of the 1st Int. Conf. on Tribology in Manufacturing Processes (ICTMP’97), Gifu, Japan, pp. 158–163. Also to appear in ASME JOURNAL OF TRIBOLOGY, Oct. 1998.
12.
Lo, S. W., and Wilson, W. R. D., 1997, “A Theoretical Model of Micro-Pool Lubrication in Metal Forming,” Proc. of the 1st Int. Conf. on Tribology in Manufacturing Processes (ICTMP’97), Gifu, Japan, pp. 83–90. Also accepted by ASME JOURNAL OF TRIBOLOGY.
13.
Mizuno
T.
, and
Okamoto
M.
,
1982
, “
Effects of Lubricant Viscosity at Pressure and Sliding Velocity on Lubricating Conditions in the Compression-Fricdon Test on Sheet Metals
,”
ASME JOURNAL OF LUBRICATION TECHNOLOGY
, Vol.
104
, pp.
53
59
.
14.
Riu
D.
,
Azushima
A.
, and
Shima
T.
,
1993
, “
Behavior of Hydrostatic Pressure of Lubricant Trapped in Surface Pocket on Workpiece at Upsetting Process
,”
J. Japan Soc. Technol. of Plasticity
, Vol.
34
, pp.
1240
1245
.
15.
Ruan
F.
,
Kudo
H.
,
Tsubouch
M.
, and
Hori
T.
,
1988
, “
Experimental Evidence of the Micro-Plasto Hydrodynamic Lubrication Mechanism
,”
J. Japan Soc. Technol. of Plasticity
, Vol.
28
, pp.
41
48
.
16.
Wang
Z.
,
Kondo
K.
, and
Mori
T.
,
1995
a, “
Surface Smoothing Mechanism by Replication in Ironing Process
,”
ASME Journal of Engineering for Industry
, Vol.
117
, No.
2
, pp.
259
265
.
17.
Wang
Z.
,
Kondo
K.
, and
Mori
T.
,
1995
b, “
A Consideration of Optimum Conditions for Surface Smoothing Based on Lubricating Mechanisms in Ironing Process
,”
ASME Journal of Engineering for Industry
, Vol.
117
, No.
3
, pp.
351
356
.
18.
Wang, Z., Dhoda, K., Nobuyasu, Y., and Haruyama, Y., 1997, “Outflow Behavior of Lubricant in Micro Pits in Metal Forming,” Proc. of the 1st Int. Conf. on Tribology in Manufacturing Processes (ICTMP’97), Gifu, Japan, pp. 77–82.
19.
Wilson
W. R. D.
,
1971
, “
The Temporary Breakdown of Hydrodynamic Lubrication During the Initiation of Extrusion
,”
Int. J. Mech. Sci.
, Vol.
13
, pp.
17
28
.
20.
Wilson
W. R. D.
, and
Sheu
S.
,
1988
, “
Real Area of Contact and Boundary Friction in Metal Forming
,”
Int. J. Mech. Sci.
, Vol.
30
, No.
7
, pp.
475
489
.
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