Metal closure for a container, method for making the same and method for capping a container with the same

A method for making a metal closure for a container having a circular opening which has a swelling, comprising the following steps:

• making a capsule defining a body of the metal closure, configured to be applied to cover the opening of the container for closing the container, the capsule comprising a circular part, configured to rest over the opening, and a perimeter edge extending from the circular part and configured to wrap circumferentially around the opening, to form a seal of the capsule relative to the container;
• making a rounding or folding of the perimeter edge by curling the perimeter edge, the rounding or folding having a double layer of material of the perimeter edge at an end portion of the perimeter edge distal from the circular part;
• providing that the perimeter edge extends at right angles or substantially right angles to the circular part and includes a series of deformations made in a radial direction towards a center of the capsule and configured to engage the container and apply a pressure to the container below a swelling of the opening to obtain a pulling action of the circular part against the opening and form a seal, the deformations being made in predetermined areas of the perimeter edge spaced apart from the rounding or folding toward the circular part;
• providing that a distance between a start of the rounding or folding, which constitutes the end portion of the perimeter edge, and an inner surface of the circular part, is greater than 4 mm;
• providing that the capsule is made of a metallic material having a thickness between 0.12 mm and 0.16 mm;
• providing that a quantity of the deformations is between 6 and 14;
• providing that:
• an entirety of the circular part is smooth and flat;
• the perimeter edge has a smooth and continuous cylindrical profile extending 360° around the circular part;
• the smooth and continuous cylindrical profile merges with the circular part in a smooth radius extending 360° around the circular part;
• the smooth and continuous cylindrical profile entirely extends from the smooth radius to a position matching a lower portion of the swelling of the opening.