Stamped Collar (Dimple)

Stamped collar is a precision stamping process that cold-flares a hole into a shallow cone, creating a stiffened pocket without adding weight or hardware. Offered in nine standard diameters (from 1/2" to 3"), the operation reinforces thin sheet metal while maintaining a clean opening. The laser makes the pilot hole and hydraulic press forms the collar, ensuring perfect concentricity, smooth edges and no added insert. Our software automatically filters available sizes based on material, thickness and required clearances, so each feature increases rigidity and looks purpose-built right off the machine.

Dimensional Constraints

Part size and collar positioning must meet minimum dimensions according to dimple size used. Each size requires sufficient working surface to avoid edge deformation and ensure clean stamping. Minimum distances between collars, between a collar and part edge, and between a collar and other features (holes, bends) are automatically calculated by our application. In your CAD files, indicate only the minor hole (desired inner diameter); the system automatically resizes to accommodate the stamping tool.

Distance to Bend Lines

Sufficient spacing between collars and bend lines is essential to avoid interference. Minimum distance from collar center to bend center is calculated by adding half the bend allowance to minimum distance to other features. Bend allowance varies according to material thickness and bend angle. Use our bend calculator to determine this value before positioning your collars in the design.

Deformation and Rigidity

Stamping can occasionally cause slight sheet bowing, due to the combination of material properties, its elasticity, sheet orientation and thickness variations. The most effective solution to counter this deformation is to add a stiffening bend. A bent flange creates a reinforced edge that generates a stiffening effect, preventing material from flexing or deforming. If your design allows, position bends strategically to maximize structural rigidity.

Design Considerations

When adding stamped collars, consider other planned operations. Holes too close to a collar will deform during stamping. Depending on design, material and collar proximity to edge, bending may be affected (slight bowing or flange length variations). Tooling marks will be visible on all stamped parts. Collars can be combined with finishes (powder coating, plating, anodizing), but tool marks may show through, particularly with plating and anodizing.

A collar can be formed on either face of sheet; choose desired face and confirm it in 3D preview. Stamping is done after deburring, after tapping and countersinking, but before bending, hardware insertion and surface finishes.