Plasto-hydrodynamic lubrication (PHD) – application of lubrication theory to metal forming processes

The theory of lubrication of plastically deformed surfaces (plasto-hydrodynamics or PHD) was derived in the 60s using the advances in elasto-hydrodynamics (EHD). The transposition is described together with some applications to metal forming processes. PHD was later extended to the mixed regime, so important in metal forming. These models are surveyed. Finally, it is suggested that mixed PHD models could considerably benefit from newer algorithms and numerical techniques used in EHD and more recently in mixed-EHD.