Bellow Couplings

Bellow Couplings

Flexible couplings are generally two hubs connected by a compliant member. The compliant member can be an elastomer and even some soft or springy metal. Bellow couplings represent one type of flexible metal coupling. They come in three types: formed, electroplated, and edge-welded.

Bellow couplings resist axial, parallel, and angular misalignment. Their design can be costly, though, and not necessarily be able to handle greater misalignments than elastomeric or other flexible couplings. Such couplings can account for misalignment while adding little to no residual stress on the connecting shaft.

Bellows can be designed for a theoretically infinite life. Edge-welded bellows differ from their electroplated counterparts in their ability to handle larger outer diameters of shafts and greater lengths between shafts. In addition, edge-welded bellows offer a wider range in materials, and can be cheaper in startup tool cost. However, depending on the volume, both formed and electroplated bellows can be competitive price-wise despite startup tool cost.           

Other differences between electroplated and formed bellows include tolerance in wall thicknesses and material selection. Electroplating can offer more consistent wall thicknesses at 25 µm or less. This allows electroformed bellows to be used for sensitive precise applications that require an exacting coupling. The different processes will inherently lend themselves to different materials. For example, metals with a high modulus of elasticity may not form easily and might better lend themselves to electroplating.

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