A novel bio-inspired compound restrictor for high-precision aerostatic bearings: design and evaluation

Compound restrictors are widely adopted in aerostatic bearings due to their good static performance and ease of fabrication. However, further enhancement of their performance using surfaces with groove structures designed is still rarely researched. Inspired by the unique fluid controllability of the biomimetic hexagonal micro-pattern, this paper proposes a novel bio-inspired aerostatic bearing design to realize high stability without compromising load capacity and static stiffness. Air mass flow rate, another key factor affecting its static performance, is also considered. Computational fluid dynamics (CFD) simulation study reveals that setting suitable divergence angle enables better pressurized airflow controllability. The key structural parameters were calculated using the resistance network method (RNM). The results were further verified through experimental measurements. Performance tests of the prototyped aerostatic linear motion stage verified the theoretical modelling accuracy. A positioning accuracy (perpendicular to the stage feed direction) of less than 15 nm/10 mm was achieved, which was almost half of that of the conventional linear bearing stage under the same conditions (8 μm bearing clearance, 0.2 MPa supply pressure).