Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology, semiconductor devices, aviation, strategic defense, ultraprecision manufacturing, medical treatment, and power generation. In all these applications, the equipment must deliver extreme working performances such as ultraprecise movement, ultrahigh rotation speed, ultraheavy bearing loads, ultrahigh environmental temperatures, strong radiation resistance, and high vacuum operation, which have challenged the design and optimization of reliable fluid lubricated bearings. Breakthrough of any related bottlenecks will promote the development course of high-end equipment. To promote the advancement of high-end equipment, this paper reviews the design and optimization of fluid lubricated bearings operated at typical extreme working performances, targeting the realization of extreme working performances, current challenges and solutions, underlying deficiencies, and promising developmental directions. This paper can guide the selection of suitable fluid lubricated bearings and optimize their structures to meet their required working performances.

The importance to industry of non-contact bearings is growing rapidly as the demand for high-speed and high-precision manufacturing equipment increases. As a recently developed non-contact technology, near-field acoustic levitation (NFAL) has drawn much attention for the advantages it offers, including no requirement for an external pressurized air supply, its compact structure, and its ability to adapt to its environment. In this paper, the working mechanism of NFAL is introduced in detail and compared to all existing non-contact technologies to demonstrate its versatility and potential for practical applications in industry. The fundamental theory of NFAL, including gas film lubrication theory and acoustic radiation pressure theory is presented. Then, the current state-of-the-art of the design and development of squeeze film air bearings based on NFAL is reviewed. Finally, future trends and obstacles to more widespread use are discussed.