The effects of cryogenic cooling on surface integrity in hard machining

This paper presents the results of an experimental investigation to determine the effects of cryogenic coolant on surface integrity in orthogonal machining of hardened AISI 52100 bearing steel. Experiments were performed under dry and cryogenic conditions using chamfered CBN tool inserts. Several experimental techniques were used in the analyzing of the machined surface and subsurface: optical and scanning electron microscopes (SEM) were utilized for the surface topography characterization; chemical characterization (phase study) was carried out by means of Energydispersive spectroscopy (EDS) techniques; and X-ray diffraction (XRD) technique was used to determine residual stresses and phase changes induced by dry and cryogenic machining. The results show the benefits and the future potential of cryogenic cooling for surface integrity enhancement to achieve improved product's functional performance in hard machining.