The cut jump ring is the standard production form of the jump ring. It is manufactured by winding wire tightly around a mandrel of the desired inside diameter to produce a long coil, then cutting the coil along its length so that each turn of the coil falls free as an individual ring with a single seam.

Production sequence

The wire is first hardened to the temper required for spring-back. It is then wound under tension onto a steel or brass mandrel, with each turn touching the previous one tightly. Once the coil is complete the mandrel is removed and the coil is cut along a line parallel to the mandrel axis. Cutting can be done with a jeweller's saw, a fine slitting saw, a laser, or in industrial production a machine cutter. The cut produces two flat parallel end faces on each ring, which is the finding's identifying feature.

Quality variables

The quality of a cut jump ring depends on three variables. The squareness of the cut faces determines whether the ring will close flush. The smoothness of the inside diameter determines whether it will rotate freely on a chain link. And the temper of the wire determines whether the ring will spring back to its original round shape after being twisted open and closed. Industrial production grades typically run from soft jewellery temper for hand assembly to spring temper for production use. Saw-cut rings are higher quality than guillotine-cut or shear-cut rings because they leave less burr and a flatter face.

Alternatives

The principal alternative to the cut jump ring is the welded or soldered jump ring, in which the seam is permanently closed at the time of manufacture. Welded rings are stronger and are used in chain manufacture, but cannot be opened and reclosed by hand. The cut jump ring's commercial niche is therefore the assembly market, where the ring's openability is the point.

Trade significance

Cut jump rings are sold in vast quantities in production findings catalogues. They are the workhorse finding for chain repair, charm attachment, clasp connection and any application in which a temporarily openable connection is required. Their quality, expressed in cut squareness and metal temper, is one of the simplest indicators of a findings supplier's general production standard.