How to Understand Friction and Wear in Mechanical Working Processes
For a number of mechanical working processes using a lot of different metals it has
been proven that in dry friction plastic deformation is always observed in the contact zone. It has
been stated that friction is a result of plastic deformation. However the process of wear is not
understood. In the past several investigators tried to interpret it in a thermodynamic way but this
more or less failed. At present it is possible to prove that it is started by diffusion. For a very
stable tool workpiece material combination we can fundamentally prove that diffusion always
takes place. For the tool material it means a change in the chemical composition, leading to a
decrease in hardness. Together with the high process temperatures, which lower the hardness
of the tool material too, it is possible that the cold workpiece material can be smeared out and
taken along with the tool material. The tool thus is worn. From this point of view the influence
of the free enthalpy, the thermal conductivity, the hardness, and the ductility of different tool -
workpiece material combinations on wear can be clarified. A number of practical examples are
given to support this idea.
D.A. TAMINIAU, J.H. DAUTZENBERG
Reçu le 21 mars 2000.
Accepté le 21 mars 2001.
Thermodynamics, Plasticity, Wear.