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

It is still in use today and comprises a large percentage

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

It is very fast when compared to ring spinning,

up to 10 times the production per spindle.

From a cost standpoint,

it doesn't require the roving process step and

it does not require an extra winding step.

Yarn is ready for use directly from the machine.

The process today is highly automated and includes automatic piecing,

restarting of broken ends,

and doffing,

removal of full packages.

For these important economic reasons,

rotor spinning became the yarn making system of

choice through the early '90s in the US.

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

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

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

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

The rotor spinning process is difficult to conceptualize.

A sliver is used as the input and is fed into

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

This individualizes the fibers and performs the drafting.

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

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

thus the name open-end spinning.

The yarn is withdrawn and the process becomes continuous.