Impact of different cryogenic cooling strategies on the surface integrity of roller bearing steels in hard turning

Due to the increasing global challenges, the demand for sustainable, resource- and energy-efficient manufacturing processes is growing. In particular, functional surfaces need increased performance due to the expected load in later use. This includes adapted surface and subsurface properties such as increased hardness to ensure resistance to given stresses. Heat treatment is typically carried out to adjust the material hardness. This means an additional process step, which is associated with additional costs and energy expenditure. Cryogenic processing offers the advantage of being able to adjust the required subsurface properties locally during the manufacturing of a workpiece. In this study, the influence of different cryogenic manufacturing technologies on the resulting surface and subsurface properties is analyzed, taking into account the importance of dimensional accuracy. A comparison is made between in-process CO₂ cooling and LN₂ pre-cooling.