Tribological contacts are responsible for approximately 23% of world's total energy
consumption with the majority of energy consumption involved in manufacturing
operations. Manufacturing is one of the main energy consuming sectors and the
optimizing of its friction and wear performance can significantly increase the lifetime
and reduce the maintenance work of equipment. In cold stamping, friction
and wear that are generated between the tool and work-piece are important tribological
responses infuencing the material
ow, surface quality and tool-life. It has
been found that these responses are not material properties but highly nonlinear
phenomena, which vary spatially and historically with operation parameters, such
as contact pressure, sliding speed and sliding distance of forming processes.
It has been widely observed that galling and lubricant breakdown phenomena
that occur during cold stamping cause evolutionary surface morphology changes
and thus involve the simultaneous interaction between friction and wear: the galling
generated on a tool surface during forming can cause coefficient of friction (COF) to
increase and wear rate to decrease; the lubricant lm breakdown with time during
single path sliding leads to a rapid increase in the COF and wear at the contact.
In this thesis, interactive friction models were developed to predict the evolution
of COF with the effect of galling and lubricant breakdown. In these models, the
historical and pressure dependencies of these phenomena combining the effects of
operation parameters were addressed. These interactive friction models could be
applied to situations involving galling and lubricant breakdown in a dynamic environment
such as the metal forming industry, where the use of traditional constant
COF values present limits in predictive accuracy.