Ring Spinning

Step 1: Understand the scenario. The question describes a situation in the twisting zone of a ring frame. A fiber's front end is held by the delivery rollers, but its rear end is free because it's shorter than the drafting distance. This free, trailing end is not under tension or control.

Step 2: Analyze the effect of the rotating yarn. As the yarn balloon rotates at high speed to insert twist, this uncontrolled, trailing fiber end is subject to centrifugal force.

Step 3: Determine the outcome. The centrifugal force will throw the trailing end of the fiber outwards, away from the body of the yarn. This protruding fiber end becomes part of the yarn's "hairy" surface. This phenomenon is a primary cause of yarn hairiness, especially from shorter fibers in the blend.

Conclusion: An uncontrolled fiber end in the twisting zone is thrown outwards by rotation, causing yarn hairiness.

Step 1: Understand a ring frame drafting system. A modern ring frame uses a 3-over-3 drafting system with aprons. It has three pairs of rollers: back, middle, and front. The rollers rotate at progressively faster surface speeds from back to front to attenuate (draft) the roving.

Step 2: Define the drafting zones. The total draft is divided into two zones:

- Main Draft Zone: This is between the middle rollers and the fast-moving front rollers. This is where the majority of the drafting takes place, controlled by aprons.

- Break Draft Zone (or Back Zone Draft): This is between the slow-moving back rollers and the slightly faster middle rollers. A small amount of draft, called the break draft, is applied here.

Step 3: Analyze the purpose of the break draft. The break draft's purpose is to prepare the roving for the main draft. It slightly straightens the fibers and breaks any weak points or remaining cohesion from the roving twist, allowing the main draft to proceed smoothly and evenly.

Conclusion: The break draft is applied in the back zone, which is the zone between the back and middle rollers.