Analytical and experimental study on micro-grinding surface-generated mechanism of DD5 single-crystal superalloy using micro-diamond pencil grinding tool

Abstract

Single-crystal superalloy is characterized by no grain boundary and widely used in the aviation and aerospace industry due to its high creep strength and high thermal fatigue resistance, especially applications in aero engine necessitate numerous micro-scale structures made of single-crystal superalloy material with high-dimensional accuracy and surface quality. Micro-grinding as one of micro-precision machining technology is capable to fabricate micro-parts and structures with high machining precision and quality. In this work, a series of diamond micro-pencil grinding tool (MPGT) with diameter ranged from about 100 to 800 μm are firstly prepared by hybrid processes. The surface-generated mechanism of micro-grinding process associated with effects of length ratio of rubbing, ploughing and chip forming were explored based on analytical and experimental investigations. In addition, a novel analytical force model for the DD5 material machined by MPGT is developed considering variable size effect under different length proportion, protrusion height distribution of MPGT and material mechanical properties, which can more accurately agree well with the measured results compared with the traditional micro-grinding force model. This study enabled an in-depth understanding of mechanical behaviour characteristics, surface formation and material removal mechanism under microscopic scale of single-crystal superalloy involved in micro-grinding.