Difficulty: Medium
Finer fibres in ring spinning can improve which yarn property?
A Package taper
B Spindle balance
C Yarn evenness
D Fibre length
Answer: C. Yarn evenness. Fine fibres can produce finer and more even yarns, although they may raise nep formation during carding.
Shorter fibres usually require what yarn adjustment?
A More twist
B Lower spindle speed
C Less roller pressure
D Larger rotor
Answer: A. More twist. Shorter fibres tend to need more twist for cohesion and can increase yarn hairiness.
Around the spinning balloon, a control ring mainly limits what?
A Yarn count
B Balloon expansion
C Roving twist
D Rotor speed
Answer: B. Balloon expansion. A balloon-control ring restrains the yarn balloon and can help manage balloon tension.
Why monitor traveller temperature at high spindle speeds?
A It changes fibre length
B It removes twist
C Heat can damage parts
D It makes sliver thicker
Answer: C. Heat can damage parts. Friction at the ring and traveller generates heat, which can accelerate wear or cause damage.
Greater fibre crimp raises which spinning interaction?
A Package lift
B Inter-fibre friction
C Rotor speed
D Ring diameter
Answer: B. Inter-fibre friction. Crimp increases friction between fibres, which can assist spinning and add yarn bulk.
Roller-rotation-matched thick-thin faults suggest which source?
A Weak package flange
B Eccentric roller motion
C Low dye uptake
D Excessive winding angle
Answer: B. Eccentric roller motion. Eccentric rollers can cause a repeating drafting variation linked to roller rotation.
Traversing the fibre strand during roller drafting can improve what?
A Twist direction
B Drafting behaviour
C Rotor speed
D Cop taper
Answer: B. Drafting behaviour. Lateral strand traversal can improve fibre drafting behaviour in roller drafting.
Excessive roller gauge for the fibre length can allow what?
A More package layers
B Floating fibres
C Lower rotor speed
D Higher fibre maturity
Answer: B. Floating fibres. A wide setting may leave fibres uncontrolled between roller nips, increasing drafting irregularity.
For 38 mm staple, a ring-yarn cross-section should contain about how many fibres?
A 38 fibres
B 85 fibres
C 51 fibres
D 68 fibres
Answer: B. 85 fibres. NPTEL ring-spinning guidance gives about 85 fibres for a 38 mm fibre length for better spinning performance.
With the same count system, twist multiplier relates twist to what?
A Package colour
B Spindle length
C Moisture regain
D Yarn linear density
Answer: D. Yarn linear density. Twist multiplier expresses twist in relation to yarn count or linear density under a chosen system.
What task occurs when a full ring-frame cop is removed?
A Doffing the package
B Setting the comber
C Changing fibre grade
D Opening the rotor
Answer: A. Doffing the package. Doffing removes full packages and prepares the frame for the next winding cycle.
Why can excessive spindle speed raise end-break risk?
A It shortens the staple
B It removes the traveller
C It lowers all friction
D It raises dynamic tension
Answer: D. It raises dynamic tension. Higher speed can increase balloon and traveller forces, making the yarn more vulnerable to breaks.
Which ring-frame rail covers the greatest travel distance?
A Ring rail
B Spindle rail
C BCR rail
D Lappet rail
Answer: A. Ring rail. Among the listed ring-frame rails, the ring rail traverses through the greatest distance.
At fixed spindle speed, reducing yarn delivery changes twist how?
A It becomes zero
B It falls
C It stays fixed
D It increases
Answer: D. It increases. With fewer delivered metres per spindle turn, turns per unit length increase.
What distinguishes Z twist from S twist?
A Visible helix direction
B Package density
C Yarn count system
D Fibre maturity
Answer: A. Visible helix direction. Z and S describe the apparent direction of the yarn helix, like the centre stroke of each letter.
Convert 25 tex to approximately which Nm count?
A 100 Nm
B 25 Nm
C 50 Nm
D 40 Nm
Answer: D. 40 Nm. Nm is metres per gram; 1000 divided by 25 tex gives 40 metres per gram.
Why can a sudden balloon-tension rise cause breaks?
A It lowers twist always
B It removes package layers
C It overloads the yarn
D It raises fibre length
Answer: C. It overloads the yarn. A tension spike may exceed the yarn’s strength, especially at weak places or during unstable running.
What may a worn ring surface cause?
A Unstable traveller friction
B Lower sliver count
C More fibre maturity
D A longer staple
Answer: A. Unstable traveller friction. Ring wear changes contact conditions and can make traveller motion and tension less stable.
How can cot hardness affect drafting control?
A It sets rotor diameter
B It fixes package colour
C It adds fibre length
D It changes nip behaviour
Answer: D. It changes nip behaviour. Top-roller cot hardness influences deformation and contact at the nip, affecting fibre control.
Roving twist is mainly chosen to provide what before drafting?
A A rotor groove
B A woven structure
C Final yarn strength
D Enough cohesion for handling
Answer: D. Enough cohesion for handling. Roving needs enough cohesion to withstand transport and unwinding while still drafting readily.
What does the roving-frame tension-change wheel adjust?
A Roving count
B Flyer speed
C Apron tension
D Cop taper
Answer: C. Apron tension. The tension-change wheel is used to adjust apron tension in the roving-frame drafting system.
As yarn twist increases, yarn strength usually does what?
A Falls immediately
B Stays unchanged
C Rises, then falls
D Rises without limit
Answer: C. Rises, then falls. More twist improves fibre cohesion only up to an optimum; excessive twist reduces tensile strength.
What is needed to reconnect a broken end in rotor spinning?
A Replacing all sliver
B Adding a traveler
C Piecing the yarn end
D Changing the ring rail
Answer: C. Piecing the yarn end. Rotor machines use a piecing operation to re-establish yarn formation after an end break.
How many air jets does MJS air-jet spinning use?
A Two air jets
B One air jet
C Three air jets
D Four air jets
Answer: A. Two air jets. The MJS air-jet system uses two air jets to form the yarn structure.
Why is direct sliver feeding useful in rotor spinning?
A It adds ring twist
B It needs a cop
C It requires a traveler
D It removes roving preparation
Answer: D. It removes roving preparation. Rotor spinning can feed drawn sliver directly, avoiding a separate roving stage.