Civil Engineering Reference
In-Depth Information
Chapter 9
Tribological and Contact Area Effects
In order for the electroplastic effect to take place, the applied electricity must be
able to flow from the dies and through the workpiece. Because of this, the inter-
faces between the dies/workpiece are critical. The contact area effects and the
tribological effects on EAF will be examined in this chapter. Contact area varies
depending on the surface roughness of the specimen contact faces and the magni-
tude of the applied force, which will then vary the resistance of the system, hence
the temperature of the system [
1
-
4
]. Even at high forming loads, there will still be
some level of differences between the apparent contact area and the actual con-
tact area [
5
], and it must be determined at which point the differences in the con-
tact areas have a noticeable effect on the effectiveness of the EAF technique. In
addition to contact area, the tribological effects study investigates several common
metal forming lubricants and compares how well they perform when used with the
EAF technique.
9.1 Contact Area Effect on EAF Effectiveness
Within this chapter, the examination explores several aspects of the impact contact
area has on EAM effectiveness. In addition, unique compression test specimens
were fabricated to experimentally prove the impacts of contact area. The subsec-
tions on this work include: (a) an explanation of how the surface ground speci-
mens and enhanced asperity specimens were produced, (b) a post-forming EAF
roughness profile examination, (c) a description of the experimental setup and pro-
cedures, (d) a thermal analysis, (e) an explanation of the voltage-contact resistance
contact area model, (f) a mechanical analysis of EAF based on contact area, and
(g) conclusions on contact area effects.
