The diaphragm is the smallest component unit that makes up an edge welded bellows. A diaphragm is a metal ring stamped from thin‑walled metal material. Resembling the vinyl records commonly seen in daily life, it features a large hollow central area and a relatively thin wall thickness. Multiple individual metal diaphragms are connected in series to form the corrugation of the edge welded bellows.
Unlike formed bellows, which are manufactured by plastic deformation of metal tubes, edge welded bellows are fabricated by welding metal diaphragms. Commonly used raw materials include 316L stainless steel, Inconel, AM350, and other special alloys. As seen from the diaphragm cross-section drawing, it does not need to experience severe deformation like formed bellows. The low residual stress in edge welded bellows is one of the key reasons behind their exceptionally long fatigue life.
Metal diaphragms with identical geometric dimensions are first welded in pairs at their inner diameters, then stacked and welded at their outer diameters to produce precision edge welded bellows. When edge welded bellows are subjected to axial, lateral or angular displacement under external force, the diaphragms develop uniform elastic deformation. Edge welded bellows can absorb displacement and maintain overall structural stability through the constraints of the welds.
The performance of edge welded bellows is affected by the thickness and geometric dimensions of metal diaphragms. Thinner diaphragms deliver better elasticity, while thicker diaphragms offer superior pressure resistance and strength. Therefore, strict controls are imposed on the inner diameter, outer diameter, thickness and welding quality of metal diaphragms during manufacturing.
Diaphragm design is an important part of edge welded bellows design. Optimized inner diameter, outer diameter and thickness of the diaphragm help achieve improved stroke, fatigue life and sealing performance. Metal diaphragms form the foundation of edge welded bellows. Through ingenious design and precise joining, metal diaphragms deliver high‑quality flexible connection solutions for high‑technology and extreme condition applications.