Bobbin

A bobbin is a spindle or cylinder, with or without flanges, on which wire, yarn, thread or film is wound. Bobbins are typically found in sewing machines, cameras, and within electronic equipment. In non-electrical applications the bobbin is used for tidy storage without tangles. In electrical applications a coil of wire carrying a current has important magnetic properties. As used in spinning, weaving, knitting, sewing, or lacemaking, the bobbin provides temporary or permanent storage for yarn and may be made of plastic, metal, bone or wood.

Bobbin lacemaking is a handcraft which requires the winding of yarn onto a temporary storage spindle made of wood, previously bone, often turned on a lathe. Many lace designs use dozens of bobbins at any one time. Exotic woods are extremely popular with contemporary lacemakers. Both traditional and contemporary bobbins may be decorated with designs, inscriptions, or pewter or wire inlays. Often, the bobbins are 'spangled' to provide additional weight to keep the thread in tension. A hole is drilled near the base to enable glass beads and other ornaments to be attached by a loop of wire. Again, in the modern context of the hobby of bobbin lacemaking, these spangles provide a means of self-expression in the decoration of a tool of the craft. Both antique and unique bobbins, sometimes spangled, have become highly sought after by collectors.

In the case of an electrical transformer, inductor or relay, the bobbin is a permanent container for the wire, acting to form the shape of the coil (and ease assembly of the windings into or onto the magnetic core). The bobbin may be made of thermoplastic or thermosetting (for example, phenolic) materials. This plastic often has to have a TÜV, UL or other regulatory agency flammability rating for safety reasons.

...
Wikipedia