Spinning Systems

Step 1: Analyze the mechanism described. The key elements are: 1. Yarn rotation (twist insertion) is caused by rotary movement. 2. The movement comes from "two drums". 3. The force is generated by "frictional contact" with the drum surfaces.

Step 2: Evaluate the spinning systems.
- Airjet spinning: Twist (or rather, a wrapping of fibers) is inserted by a vortex of compressed air. No drums are involved in twisting.
- Ring spinning: Twist is inserted by a traveler rotating around a ring, driven by the rotating spindle. No drums are involved.
- Open end (Rotor) spinning: Twist is inserted by the rotation of a single, solid rotor. Not two drums.
- Friction spinning (e.g., DREF): In this system, opened fibers are fed into the nip point between two rotating, perforated drums (or rollers). The surfaces of the drums rotate in the same direction, causing the fibers collected at the nip to be rolled and twisted into a yarn. The twisting force is purely from the friction between the fibers and the moving drum surfaces. This perfectly matches the description.

Conclusion: The system that uses two friction drums to roll fibers into a twisted yarn is friction spinning.