Question

In the draw frame, the number of sliver ends to be fed to the machine are limited due to __________ in the mass variation of sliver coming out from the draw frame.

• A. decrease
• B. increase
• C. unchanged
• D. none of the options given

Hint:

In spinning, there is a "sweet spot" for doubling. Too little doubling gives poor blending, but too much leads to high drafts that ruin sliver evenness.

Answer 1

The Correct Option is B

Concept: The primary functions of a draw frame are doubling and drafting. Doubling involves feeding multiple slivers (usually 6 to 8) together to improve uniformity through averaging.

Step 1: Understanding Doubling and Drafting.
While doubling reduces periodic variations, the drafting process itself introduces new irregularities known as "drafting waves." These waves are caused by the uncontrolled movement of short fibers between the drafting rollers.

Step 2: The Limitation of Feeding Ends.
If too many sliver ends are fed, the total draft required to maintain the desired output hank becomes excessively high. High drafts lead to an increase in the mass variation (CV%) of the outgoing sliver because the drafting waves become more pronounced and difficult to control. Therefore, the number of ends is limited to balance the benefits of doubling against the irregularities caused by high drafting.