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Rotor or open-end spinning came into widespread use in the late '70s and early '80s.

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It is still in use today and comprises a large percentage

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of the 100% cotton yarn spun in the United States.

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It is very fast when compared to ring spinning,

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up to 10 times the production per spindle.

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From a cost standpoint,

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it doesn't require the roving process step and

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it does not require an extra winding step.

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Yarn is ready for use directly from the machine.

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The process today is highly automated and includes automatic piecing,

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restarting of broken ends,

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and doffing,

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removal of full packages.

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For these important economic reasons,

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rotor spinning became the yarn making system of

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choice through the early '90s in the US.

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Yarn count range is somewhat limited when compared to ring spinning.

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Rotor spinning doesn't perform well at much above number 40 singles and

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is really most productive in the yarn counts below number 20 singles.

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More than 95% of denim yarn produced in the US is made using rotor spinning.

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The rotor spinning process is difficult to conceptualize.

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A sliver is used as the input and is fed into

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a small carting device called a combing roll or opening roll.

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This individualizes the fibers and performs the drafting.

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The loose fibers are sucked into a rotating rotor cup where they

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are attached to the rolling open end of yarn found there—

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thus the name open-end spinning.

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The yarn is withdrawn and the process becomes continuous.