Cutting performance and effectiveness evaluation on organic monolayer embrittlement in ductile metal precision machining

In the traditional machining field, the addition of cutting fluid can appropriately reduce cutting forces, dissipate cutting heat, and facilitate the machining process. However, the use of cutting fluids has environmental implications. Recently, a phenomenon known as organic monolayer embrittlement (OME) has been proposed, which could address this issue. OME can reduce cutting forces, enhance surface quality, and improve machining performance without the need for cutting fluids, particularly noticeable in ductile metals like pure copper. This study conducted micro-cutting experiments on pure copper to investigate the microstructural features, cutting performance, chip flow patterns, and the effectiveness of OME. The results indicate that OME alters chip flow patterns from sinuous flow to segmented quasi-periodic micro-fracture flow, resulting in a 42% and 63% reduction in cutting forces for copper materials with different initial hardness. This phenomenon significantly improves surface quality, diminishes surface defects caused by adhesion, and effectively reduces work hardening layers. The study also demonstrates that OME is a physical phenomenon closely related to the adsorption properties of organic catalytic agents and van der Waals interactions. Materials with higher initial hardness exhibit less pronounced OME due to a sufficiently high grain boundary density, impeding dislocation movement during shear deformation and causing a local stress increase at the free surface of the chip. This leads to a change in chip flow patterns, improving machining performance, analogous to the adsorption effect of organic catalytic agents.