Civil Engineering Reference
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be around 18 A/mm
2
. Hence, with the current densities and deformation speeds
used in this work, the threshold will be met and exceeded.
For the tests where electricity is present, current is applied at the start of defor-
mation and is ceased when the desired stroke is displaced. Note that the current
densities mentioned here are initial values. A constant current (variable voltage)
power supply was used to produce the electricity and maintain a constant current
throughout the duration of each test. Specifically, as the specimen deformed, the
resistance decreased and therefore the voltage was decreased to maintain the spec-
ified current. However, while the current is constant, the specimen area increases,
thus the current density decreases during a test. For each combination of lubricant,
stroke, and current density, a number of three-to-five replicates were run to ensure
repeatability.
9.2.5 Candidate Metal Forming Lubricants
There are four groups of lubricants used in metal forming processes: water-based,
oil-based, synthetic, and solid film. The choice of the lubricant for one specific
process takes into consideration a multitude of process variables that may influ-
ence the effectiveness of the lubricant, such as: interface pressure and tempera-
ture, sliding velocity, surface expansion, tool and workpiece material properties
and geometries, and surface topography [
17
]. For EAF, there are two more aspects
to consider: dielectric permittivity and higher temperatures at the interface, which
may require the presence of pressure additives (EP). For this study, three lubri-
cants were selected: (i) Renoform OL569NE (oil-based lubricant), (ii) TufDraw
1919 (water-based lubricant), and (iii) SynDraw 1310D (synthetic lubricant).
Table
9.8
summarizes some characteristics of the lubricants.
Table 9.8
Metal formi
ng lubricants analyzed with EAF [
13
,
14
]
Lubricant
Lubricant characteristics
Petroleum-based
Light duty
Exhibits high lubricity from a lard oil additive
Viscosity at 40 °C: 11.5 cSt
Renoform
OL569NE
Water dilutable petroleum-based
Heavy duty
Has chlorinated paraffin extreme pressure additives and a proprietary
binder/lubricity additive, used 1: 1 with water
Viscosity at 40 °C: 400 cSt
TufDraw 1919
Water-based synthetic, non-petroleum
Medium duty
Has phosphate ester extreme pressure agent and fatty ester lubricity
additives
Viscosity at 40 °C: 110 cSt
SynDraw 1310D
