A crimp ferrule – also known as a wire ferrule and electrical ferrule – is a soft metal tube that is crimped onto the end of a stripped wire to protect the strands inside a terminal from fraying. Most ferrules are made of copper. A crimp ferrule is typically plated with tin and the size of a ferrule – both its diameter and length – is determined by a specific wire gauge. An electrical ferrule has a flare on one end; this flare collects and bundles individual wire strands as these are placed into the ferrule. The flare is typically covered with a conical plastic cable entry sleeve, which means the flare is not immediately apparent when looking at the ferrule. This plastic sleeve provides a transition between the wire insulation and the ferrule. The plastic sleeve stays intact around the insulation, and unlike a traditional crimp connection, it is not pressed during installation. Most ferrules are color-coded for wire size.
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