Primary chip formation during the micromachining of engineering materials

The advent of nanotechnology has created a demand for precision-machined substrates so that 'bottom-up' nanomanufacturing processes can be used to produce functional products on the nanoscale. However, machining processes must be scaled down by an order of magnitude that requires very stable desktop machine tools to produce precision-machined substrates. Therefore, the mechanics of chip formation at this scale is critical when the effect is considered of chip formation on the generation of surface roughness on the substrate. The tight curl of a machined chip in orthogonal machining appears to be part of the primary shear process. It is also known that transient tight curl occurs before a secondary shear zone develops ahead of the removal of the chip from the cutting zone. However, continuum models predict that curled chips incorporate stresses due to the establishment of a secondary shear zone. A model is presented in terms of the heterogeneous aspects of continuous chip formation, which shows very good agreement with experimental data.