LEAKLAB · TECHNICAL INSIGHTS
A Japanese patent application separates radial and circumferential impact absorption in a turbomolecular-pump inlet flange.
JP2026009478A · Edwards Japan Limited · published 21 January 2026 · patent application.
Why the mounting matters
A high-speed rotor stores mechanical energy. If it contacts a stationary part, torque and radial loads can reach the casing, fasteners and vacuum chamber. The application addresses the behaviour of the casing and mounting during such an event.
Two energy-absorption mechanisms
A recess beside the bolt hole is shallower than the flange thickness, leaving a thin section and room for the bolt to bend under a radial load. A separate through-hole is positioned opposite the rotor’s rotation direction and separated from the bolt hole by another thin section. Plastic deformation of this ligament absorbs circumferential movement.
The geometry is functional and tied to the rotor axis, rotation and fastener position. It is not simply a set of holes for reducing weight.
Engineering implications
Rotor inertia and speed, flange material, bolt strength and chamber stiffness determine the actual loads. The patent drawings explain a principle; they do not provide a universally safe retrofit. Drilling or thinning an existing flange without the manufacturer’s design review can weaken the mounting.
After an incident, a deformed energy-absorbing region requires technical evaluation and replacement of damaged parts. Remaining vacuum tightness alone does not prove that the mounting is mechanically sound. The publication is an application, not evidence of certification of a production pump.