Compute the ring-frame draft from its roller speeds.
A Front/back roller speeds
B Cop/rail speed ratio
C Rotor/withdrawal ratio
D Ring/traveller speed ratio
Answer: A. Front/back roller speeds. Draft is the ratio of front-roller surface speed to back-roller surface speed.
For long-staple fibres, which input guides roller-gauge selection?
A Rotor groove depth
B Fibre colour alone
C Package flange width
D Staple-length distribution
Answer: D. Staple-length distribution. Roller gauge must suit fibre length and its distribution so fibres remain controlled between nips.
Before the main drafting zone, break draft primarily helps to do what?
A Wind the cop
B Loosen incoming roving
C Apply final twist
D Form a rotor groove
Answer: B. Loosen incoming roving. Break draft gently opens and loosens the roving before the main drafting action.
Concentrating excessive draft in one zone can increase what?
A Extra twist direction
B Drafting irregularity
C Lower yarn count
D More fibre maturity
Answer: B. Drafting irregularity. An unsuitable draft distribution can disturb fibre control and create yarn unevenness.
Using sliver linear densities, total draft equals which ratio?
A Spindle/ring speed ratio
B Output/feed linear density
C Twist/diameter ratio
D Feed/output linear density
Answer: D. Feed/output linear density. Draft is feed material linear density divided by delivered linear density, with units kept consistent.
At fixed speed and ring size, an excessively heavy traveller tends to raise what?
A Higher yarn tension
B Lower staple length
C Lower fibre maturity
D Less roller speed
Answer: A. Higher yarn tension. A heavier traveller increases centrifugal loading and frictional tension, risking heat and end breaks.
If yarn delivery slows but spindle speed stays constant, twist per length does what?
A Greater twist per length
B No fibre migration
C No spindle rotation
D Less package density
Answer: A. Greater twist per length. The spindle makes more turns for each unit length delivered, so twist per length rises.
The ring traveller trails the spindle mainly because of what?
A Yarn winding drag
B Roving twist
C Rotor suction
D Air-jet pressure
Answer: A. Yarn winding drag. Yarn winding and contact forces make the traveller rotate slightly slower than the spindle.
As a cop builds, package rotation is controlled to do what?
A Maintain package winding
B Increase staple length
C Remove roller gauge
D Set fibre maturity
Answer: A. Maintain package winding. Changing package rotation accommodates the growing package diameter during cop formation.
What does ring-rail traverse build over successive lifts?
A Yarn count conversion
B Sliver doubling
C Cop layer formation
D Rotor fibre collection
Answer: C. Cop layer formation. The ring rail moves vertically to lay successive yarn layers and form the cop.
Rotor speed rises while withdrawal stays fixed. Rotor twist does what?
A More fly formation
B Less fibre tension
C Lower package density
D Higher twist per length
Answer: C. Lower package density. Rotor turns per unit length increase when withdrawal speed is unchanged.
At fixed rotor speed, faster yarn withdrawal gives what result?
A Lower twist per length
B Higher twist factor
C More rotor ends
D No yarn delivery
Answer: B. Higher twist factor. Faster withdrawal yields fewer rotor revolutions per unit length and therefore less twist.
Why can rotor-spun yarn have lower tenacity than comparable ring yarn?
A Reduced fibre migration
B More twist direction
C Greater fibre maturity
D Increased staple length
Answer: A. Reduced fibre migration. Rotor yarn structure has less fibre migration and can consequently have lower strength than ring yarn.
Back doubling in rotor spinning can primarily do what?
A Increase ring friction
B Remove every wrapper
C Raise hairiness only
D Improve yarn evenness
Answer: C. Raise hairiness only. Back doubling brings fibres together repeatedly and can improve yarn evenness.
Electrostatic staple spinning aligns fibres through what?
A Electrostatic attraction
B Rotor groove friction
C Traveller drag
D Pneumatic drafting
Answer: A. Electrostatic attraction. An electric field attracts and aligns charged fibres toward the twisting or collection element.
If a compact-spinning suction system fails, the yarn may show what?
A Increased yarn hairiness
B Automatic twist loss
C Lower yarn hairiness
D Better fibre maturity
Answer: C. Lower yarn hairiness. Without suction condensing, the strand becomes less compact and more fibre ends can protrude.
Which structure is characteristic of vortex-spun yarn?
A Wrapper fibres around core
B Parallel fibres only
C Friction-drummed core
D Ring travellers around cop
Answer: D. Ring travellers around cop. Vortex spinning forms wrapper fibres around a largely parallel fibre core.
Air-jet spinning creates wrapper fibres using what?
A Swirling compressed air
B Traveler-rim contact
C Centrifugal force
D Card clothing teeth
Answer: B. Traveler-rim contact. Air jets generate swirling flow that wraps surface fibres around the yarn core.
DREF friction spinning twists fibres through what action?
A Friction between drums
B Air vortex alone
C Rotor suction alone
D Ring traveller contact
Answer: C. Rotor suction alone. In common friction-spinning arrangements, rotating drums impart twist to the fibre assembly.
When a ring-frame end break is detected, the spindle brake does what?
A Stops spindle rotation
B Adds roving twist
C Restarts the traveler
D Raises package speed
Answer: D. Raises package speed. A spindle brake stops rotation after an end break to prevent loose yarn from wrapping nearby parts.
Calculate ideal twist at 9,000 rpm and 0.3 m/s delivery.
A 300 turns per metre
B 500 turns per metre
C 900 turns per metre
D 30 turns per metre
Answer: B. 500 turns per metre. At 9,000 rpm the spindle makes 150 turns each second; divided by 0.3 m/s gives 500 turns per metre.
At fixed twist multiplier, changing Ne from 20 to 40 makes turns per inch do what?
A Fall by about half
B Double precisely
C Rise by about 1.41×
D Stay exactly constant
Answer: C. Rise by about 1.41×. For the same twist multiplier, turns per inch scale with the square root of English cotton count; √(40/20) is about 1.41.
DREF core-sheath yarn can combine which functions?
A Twist-free filament only
B Rotor-groove collection
C Carded web formation
D Core strength, sheath cover
Answer: D. Core strength, sheath cover. A core and surrounding sheath can be selected to provide different functional properties in one yarn.
In friction spinning, perforated drums help do what?
A Twist the yarn directly
B Hold fibres on drum
C Shorten the staple
D Build ring cops
Answer: B. Hold fibres on drum. Airflow through perforations helps hold fibres against the drum surface while frictional motion contributes to twisting.
At a compact-spinning unit, suction acts to do what?
A Add ring friction
B Open the sliver
C Increase fibre length
D Condense fibres before twist
Answer: D. Condense fibres before twist. The compacting zone condenses the drafted strand before twist insertion, reducing protruding fibre ends.