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Tamil Nadu HSE Second Year Textile Technology study materials
Tamil Nadu HSE Second Year Textile Technology study resources

Tamil Nadu HSE Second Year Textile Technology practice questions

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Question 1Textile Fibres: Classification, Properties and Identification

In the standard classification of textile fibres, which of the following is grouped as a natural cellulosic fibre?

  1. Wool
  2. Silk
  3. Polyester
  4. Cotton Correct answer.

Explanation

Cotton is a seed hair of the cotton plant and consists mainly of cellulose, so it belongs to the natural cellulosic group. Wool and silk are natural protein fibres, while polyester is a manufactured synthetic fibre.

Question 2Textile Fibres: Classification, Properties and Identification

Which property of cotton makes it suitable for absorbent towels and undergarments?

  1. High thermoplasticity
  2. High abrasion resistance
  3. High moisture regain Correct answer.
  4. High elastic recovery

Explanation

Cotton has a high moisture regain because the many hydroxyl groups in cellulose attract water, giving good absorbency and comfort. Elastic recovery, thermoplasticity and abrasion resistance are not strong features of cotton.

Question 3Textile Fibres: Classification, Properties and Identification

A fibre sample burns with a smell of burning hair and leaves a crushable black ash. Which fibre is most likely present?

  1. Acrylic
  2. Wool Correct answer.
  3. Viscose rayon
  4. Cotton

Explanation

Protein fibres such as wool contain nitrogen and sulphur, so they burn slowly with a smell of burning hair and form a crushable black ash. Cellulosic and acrylic fibres do not give this characteristic hair smell.

Question 4Textile Fibres: Classification, Properties and Identification

In the solubility test for fibre identification, which reagent dissolves cotton but leaves polyester unaffected?

  1. Dilute acetic acid
  2. Cold water
  3. Carbon tetrachloride
  4. Concentrated sulphuric acid Correct answer.

Explanation

Concentrated sulphuric acid dissolves cellulosic fibres such as cotton by breaking down the cellulose, while polyester resists it. Water, dilute acetic acid and carbon tetrachloride do not dissolve cellulose under these conditions.

Question 5Textile Fibres: Classification, Properties and Identification

Under a microscope, cotton appears as a flat, twisted ribbon. What does this twist indicate?

  1. Natural convolutions of the fibre Correct answer.
  2. Heat setting of the yarn
  3. Mechanical crimping during spinning
  4. Mercerisation of the fabric

Explanation

Cotton fibres develop natural convolutions or twists along their length as the cellulose layers dry in the boll. These convolutions help fibres interlock during spinning and are not produced by spinning, heat setting or mercerisation.

Question 6Textile Fibres: Classification, Properties and Identification

Which fibre is a regenerated cellulosic fibre produced by dissolving wood pulp and extruding it through a spinneret?

  1. Wool
  2. Nylon
  3. Viscose rayon Correct answer.
  4. Cotton

Explanation

Viscose rayon is made by treating wood pulp cellulose with chemicals and extruding the solution through a spinneret, so it is a regenerated cellulosic fibre. Cotton is natural cellulose, while nylon and wool are not cellulosic.

Question 7Textile Fibres: Classification, Properties and Identification

Which property of silk is mainly responsible for its use in fine, lustrous sarees?

  1. High resistance to sunlight
  2. Smooth triangular cross-section giving high lustre Correct answer.
  3. Low tensile strength allowing fine yarns
  4. High moisture regain giving warmth

Explanation

Silk filaments have a smooth, roughly triangular cross-section that reflects light strongly, producing the characteristic lustre valued in fine fabrics. Silk is not noted for high sunlight resistance or low strength.

Question 8Textile Fibres: Classification, Properties and Identification

A fabric sample shrinks markedly and felts when washed in hot water with agitation. Which fibre is most likely present?

  1. Acetate
  2. Nylon
  3. Polyester
  4. Wool Correct answer.

Explanation

Wool fibres have overlapping scales that interlock under heat, moisture and agitation, causing felting and shrinkage. Synthetic fibres such as polyester, nylon and acetate do not have this scale structure and do not felt.

Question 9Textile Fibres: Classification, Properties and Identification

Which of the following fibres is classified as a synthetic polyamide?

  1. Acrylic
  2. Nylon Correct answer.
  3. Polyester
  4. Viscose rayon

Explanation

Nylon is a polyamide formed by condensation of a diamine and a dicarboxylic acid, so it belongs to the synthetic polyamide group. Polyester, acrylic and viscose belong to different chemical groups.

Question 10Textile Fibres: Classification, Properties and Identification

Why does polyester fabric dry quickly after washing?

  1. It has high moisture regain
  2. It has a scaly surface
  3. It has low moisture regain Correct answer.
  4. It contains many hydroxyl groups

Explanation

Polyester is hydrophobic, with few water-attracting groups, so it holds little moisture and dries quickly. High moisture regain, scaly surfaces and many hydroxyl groups would all increase water retention.

Question 11Textile Fibres: Classification, Properties and Identification

Which test would you use to distinguish cotton from viscose rayon, both of which are cellulosic?

  1. Burning test for burning-hair smell
  2. Microscopic examination for convolutions Correct answer.
  3. Solubility in cold water
  4. Solubility in concentrated sulphuric acid

Explanation

Cotton shows natural convolutions and a ribbon shape under the microscope, while viscose rayon appears as a smooth, striated cylinder. Both are cellulosic, so burning and acid solubility tests give similar results.

Question 12Textile Fibres: Classification, Properties and Identification

Which fibre property is measured by the length-to-breadth ratio of a fibre?

  1. Fibre lustre
  2. Fibre crimp
  3. Fibre maturity
  4. Fibre fineness ratio Correct answer.

Explanation

The length-to-breadth ratio, sometimes called the fibre's aspect ratio, describes how slender the fibre is and is related to fineness. Crimp, maturity and lustre are separate properties measured in other ways.

Question 13Textile Fibres: Classification, Properties and Identification

A cotton fibre that is immature will most likely show which characteristic?

  1. Thick wall and high strength
  2. Thin wall and low strength Correct answer.
  3. High lustre and high maturity
  4. High elongation and high strength

Explanation

Immature cotton has a thin cell wall and little cellulose deposition, so it is weak, poorly dyeable and appears thin under the microscope. Thick walls and high strength indicate mature cotton.

Question 14Textile Fibres: Classification, Properties and Identification

Which fibre is obtained from the stem of a plant and is therefore classified as a bast fibre?

  1. Silk
  2. Coir
  3. Cotton
  4. Jute Correct answer.

Explanation

Jute is obtained from the stem of the jute plant, so it is a bast or stem fibre. Cotton is a seed fibre, coir is a fruit-husk fibre and silk is an animal filament.

Question 15Textile Fibres: Classification, Properties and Identification

Which of these fibres is most suitable for making ropes that must resist water and rot?

  1. Cotton
  2. Jute
  3. Wool
  4. Nylon Correct answer.

Explanation

Nylon is strong, hydrophobic and resistant to microbial attack, so it performs well in wet rope applications. Cotton, jute and wool absorb water and are prone to rotting when wet.

Question 16Textile Fibres: Classification, Properties and Identification

What does the term 'regenerated fibre' mean in textile classification?

  1. A fibre produced by drawing a molten metal
  2. A fibre made by dissolving natural polymer and reforming it Correct answer.
  3. A fibre produced directly by a plant or animal
  4. A fibre made entirely from petrochemical monomers

Explanation

Regenerated fibres are made by dissolving a naturally occurring polymer such as cellulose and extruding it into fibre form, as in viscose rayon. Natural fibres grow directly, while synthetic fibres are built from simple chemical monomers.

Question 17Textile Fibres: Classification, Properties and Identification

Which fibre property explains why woollen garments feel warm in winter?

  1. Smooth, glassy surface
  2. High thermal conductivity
  3. Low moisture regain
  4. Trapped air in crimped, scaly structure Correct answer.

Explanation

Wool is highly crimped and has a scaly surface, so it traps air and provides insulation, making garments feel warm. High thermal conductivity and a smooth glassy surface would conduct heat away rather than retain it.

Question 18Textile Fibres: Classification, Properties and Identification

Which fibre is most likely to develop static electricity and cling to the body in dry weather?

  1. Jute
  2. Polyester Correct answer.
  3. Cotton
  4. Viscose rayon

Explanation

Polyester is hydrophobic and a poor conductor of electricity, so static charge builds up and causes clinging in dry conditions. Cellulosic fibres such as cotton, viscose and jute absorb moisture and dissipate static more readily.

Question 19Textile Fibres: Classification, Properties and Identification

Which microscopic feature is characteristic of wool fibres?

  1. Triangular cross-section
  2. Natural convolutions
  3. Overlapping surface scales Correct answer.
  4. Smooth striated cylinder

Explanation

Wool fibres have an outer layer of overlapping scales, which is responsible for felting and shrinkage. Convolutions are typical of cotton, triangular cross-sections of silk, and smooth striated cylinders of viscose rayon.

Question 20Textile Fibres: Classification, Properties and Identification

A fabric is suspected to contain a blend of cotton and polyester. Which simple laboratory approach would best confirm the polyester component?

  1. Burn the sample and look for a burning-hair smell
  2. Dissolve the cotton in concentrated sulphuric acid and examine the residue Correct answer.
  3. Examine the sample under the microscope for scales
  4. Soak the sample in cold water and measure shrinkage

Explanation

Concentrated sulphuric acid dissolves the cotton component while polyester remains as a residue, allowing the polyester to be identified. The other tests do not selectively isolate polyester from a cotton blend.

Question 21Textile Fibres: Classification, Properties and Identification

Which fibre is produced from the protein fibroin?

  1. Viscose rayon
  2. Nylon
  3. Silk Correct answer.
  4. Cotton

Explanation

Silk is composed mainly of fibroin, a protein secreted by the silkworm, so it is a natural protein fibre. Cotton and viscose rayon are cellulosic, and nylon is a synthetic polyamide.

Question 22Textile Fibres: Classification, Properties and Identification

Why is viscose rayon often blended with polyester in suiting fabrics?

  1. Rayon adds flame resistance while polyester adds elasticity
  2. Rayon adds thermoplasticity while polyester adds lustre
  3. Rayon adds strength while polyester adds absorbency
  4. Rayon adds absorbency and drape while polyester adds strength and wrinkle resistance Correct answer.

Explanation

Viscose rayon contributes absorbency, softness and drape, while polyester contributes strength, durability and wrinkle resistance, so the blend combines complementary properties. The other pairings misstate the properties of each fibre.

Question 23Textile Fibres: Classification, Properties and Identification

Which property of acrylic fibres makes them a common substitute for wool in knitwear?

  1. High moisture regain and easy dyeing
  2. High resistance to heat and flame
  3. Soft, bulky handle with good warmth retention Correct answer.
  4. High density and heavy weight

Explanation

Acrylic fibres are soft, light and bulky, trapping air to give warmth similar to wool, which makes them popular in knitwear. They do not have high moisture regain, high heat resistance or high density.

Question 24Textile Fibres: Classification, Properties and Identification

A fibre burns rapidly with a smell of burning paper and leaves a soft grey ash. Which group does it belong to?

  1. Polyester fibres
  2. Polyamide fibres
  3. Cellulosic fibres Correct answer.
  4. Protein fibres

Explanation

Cellulosic fibres such as cotton, viscose and jute burn like paper and leave a soft grey ash. Protein fibres smell of burning hair, while polyamide and polyester fibres melt and form hard beads.

Question 25Textile Fibres: Classification, Properties and Identification

Which of these is a key difference between natural and manufactured fibres in terms of length?

  1. Natural fibres are always uniform in length, while manufactured fibres vary widely
  2. Natural fibres have variable staple length, while manufactured fibres can be cut to uniform staple Correct answer.
  3. Natural fibres have no measurable length, while manufactured fibres do
  4. Natural fibres are always continuous filaments, while manufactured fibres are always short

Explanation

Natural fibres such as cotton and wool grow to variable staple lengths, whereas manufactured fibres are extruded as continuous filaments and can be cut to a chosen uniform staple length. The other statements reverse or misstate these facts.

Question 26Textile Fibres: Classification, Properties and Identification

Which fibre is obtained from the cocoon of a moth larva and is therefore classified as an animal fibre?

  1. Nylon
  2. Ramie
  3. Jute
  4. Silk Correct answer.

Explanation

Silk is secreted as a continuous filament by the silkworm larva to build its cocoon, so it is an animal (protein) fibre. Jute and ramie are plant fibres, while nylon is a manufactured synthetic fibre.

Question 27Textile Fibres: Classification, Properties and Identification

A fibre sample is held in a flame and gives off a smell of burning hair while forming a dark, crushable bead. To which fibre group does the sample most probably belong?

  1. Mineral
  2. Synthetic polyamide
  3. Protein (animal) Correct answer.
  4. Regenerated cellulosic

Explanation

Burning hair smell and a crushable dark bead are typical of protein fibres such as wool and silk, because they contain nitrogen and sulphur. Cellulosic fibres smell of burning paper, while synthetic fibres usually melt and give hard beads.

Question 28Textile Fibres: Classification, Properties and Identification

Why is the moisture regain of viscose rayon higher than that of polyester?

  1. Viscose has a higher degree of polymerisation than polyester
  2. Polyester has a higher crystallinity than viscose, so it absorbs more water
  3. Polyester has a longer fibre length than viscose
  4. Viscose contains many hydroxyl groups that attract water molecules Correct answer.

Explanation

Cellulose chains in viscose carry many free hydroxyl (-OH) groups that form hydrogen bonds with water, giving high moisture regain. Polyester has few such groups and is largely hydrophobic, so it absorbs very little moisture.

Question 29Textile Fibres: Classification, Properties and Identification

In a blend analysis, a yarn is treated with concentrated sulphuric acid; one component dissolves completely while the other remains. Which pair best fits this observation?

  1. Cotton and polyester Correct answer.
  2. Silk and wool
  3. Cotton and wool
  4. Polyester and nylon

Explanation

Concentrated sulphuric acid dissolves cellulosic fibres such as cotton but leaves polyester largely intact, so this pair can be separated and estimated. The other pairs are both soluble or both resistant in the same reagent, so they cannot be separated this way.

Question 30Textile Fibres: Classification, Properties and Identification

Two manufactured fibres are compared: fibre P is made by dissolving cellulose and regenerating it, while fibre Q is made by polymerising a monomer. Which statement correctly describes their classification?

  1. P is a regenerated fibre and Q is a synthetic fibre Correct answer.
  2. P is a natural fibre and Q is a regenerated fibre
  3. Both P and Q are regenerated fibres
  4. P is a synthetic fibre and Q is a regenerated fibre

Explanation

Regenerated fibres start from a naturally occurring polymer such as cellulose, which is dissolved and re-formed, as in viscose. Synthetic fibres are built up from simple monomers by polymerisation, as in polyester or nylon.

Question 31Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

In a roller ginning machine, the function of the leather roller is to:

  1. Compress the ginned lint into a uniform batt
  2. Grip the seed cotton fibres and pull them past the fixed knife Correct answer.
  3. Clean the lint of leaf trash before baling
  4. Separate the lint from the seed by saw-tooth action

Explanation

Roller ginning works on the principle that a rough leather roller grips the fibres while a fixed knife holds back the seed, so the lint is pulled away from the seed. The saw-tooth action belongs to the saw gin, and cleaning and batt formation are later operations, not the roller's job.

Question 32Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The main purpose of the beater in an opening machine of the blow room is to:

  1. Remove short fibres below a set length
  2. Twist the fibre strand into a coherent yarn
  3. Strike the tufted cotton and open it into smaller flocks while releasing trash Correct answer.
  4. Parallelise the fibres so they lie along one direction

Explanation

Beaters such as the porcupine or Kirschner beater strike the cotton at high speed, breaking large tufts into small flocks and liberating loose trash through the grid bars. Fibre parallelisation is done in carding and drawing, short fibre removal in combing, and twisting at spinning.

Question 33Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The wire points on the cylinder and flats of a carding machine are set so that the fibre is:

  1. Thrown off the cylinder by centrifugal force into the grid
  2. Held by the cylinder wire and combed by the flats, then transferred to the doffer Correct answer.
  3. Carried round the cylinder and returned to the doffer
  4. Deposited directly into a sliver can from the flats

Explanation

The cylinder wire is inclined to hold the fibres while the flats, moving slowly, comb and separate them; the doffer then lifts the web off the cylinder. This relative movement is what individualises the fibres and removes trash and neps.

Question 34Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The draft in a drawing frame is calculated as:

  1. Delivery count divided by feed count
  2. Feed hank or count multiplied by delivery count
  3. Delivery hank or count divided by feed hank or count Correct answer.
  4. Feed hank minus delivery hank

Explanation

Draft is the ratio of the mass per unit length delivered to that fed, so when expressed in hank or count it equals delivery count divided by feed count. Using the feed count in the numerator would invert the ratio and give the reciprocal of the true draft.

Question 35Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

A draw frame with a feed sliver of 4 ktex and a delivery sliver of 1 ktex is running at a draft of:

  1. 3
  2. 4 Correct answer.
  3. 0.25
  4. 5

Explanation

Draft equals feed mass per unit length divided by delivery mass per unit length, so 4 ktex divided by 1 ktex gives a draft of 4. The value 0.25 is the reciprocal and the others are arithmetic differences.

Question 36Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

In a comber, the function of the nipper is to:

  1. Detach the combed tuft and lay it as a piecing
  2. Hold the lap fringe firmly while the cylinder comb passes through it Correct answer.
  3. Draw the combed ribbon into a sliver at the delivery end
  4. Separate the noils from the lap by air suction

Explanation

The nipper jaws clamp the fringe of the lap so that the combing cylinder can comb the projecting fibres without pulling the whole lap forward. Detachment and piecing are done by the detaching rollers, and sliver formation by the coiler.

Question 37Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

Combing is normally applied to cotton yarns that require:

  1. Greater yarn irregularity for fancy effects
  2. Lower cost by skipping the card
  3. Finer, smoother yarns with fewer short fibres and neps Correct answer.
  4. Higher production with coarser counts

Explanation

Combing removes short fibres, neps and remaining trash, giving a cleaner, stronger and more even yarn suited to fine counts and premium fabrics. Coarse yarns are generally carded, not combed, and combing never replaces the card.

Question 38Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The main objective of the drafting operation in a speed frame is to:

  1. Remove all short fibres from the sliver
  2. Set the final twist in the yarn
  3. Double the number of fibres in the strand
  4. Reduce the sliver mass to roving count and insert a small protective twist Correct answer.

Explanation

The speed frame drafts the draw-frame sliver down to a fine roving and adds a low level of twist so the roving can be wound and handled without breaking. It does not remove short fibres or set final yarn twist.

Question 39Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

In ring spinning, the traveller rotates around the ring at a speed:

  1. Slightly less than the spindle speed Correct answer.
  2. Equal to the spindle speed
  3. Independent of the spindle speed
  4. Slightly more than the spindle speed

Explanation

The traveller is dragged round by the yarn and lags slightly behind the spindle because of friction on the ring, so it revolves a little slower than the spindle. This speed difference is what winds the yarn onto the cop.

Question 40Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The function of the condenser in a card is to:

  1. Apply draft to the sliver before coiling
  2. Remove neps by cutting them out
  3. Gather the web into a loose rope for the calender and coiler Correct answer.
  4. Comb the fibres on the cylinder

Explanation

After doffing, the thin web passes through a condenser trumpet or tape condenser that gathers it into a loose rope so it can be calendered and coiled into a sliver. Combing and nep removal happen earlier on the cylinder and flats.

Question 41Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

In a modern draw frame, autolevelling is used to:

  1. Correct long and short term mass variations by adjusting the draft continuously Correct answer.
  2. Increase the production rate by removing the coiler
  3. Clean the drafting rollers during running
  4. Add twist to the sliver for strength

Explanation

Autolevelling senses sliver thickness and adjusts the draft in the drafting zone so that mass variation is reduced, improving the evenness of the delivered sliver. It does not add twist, remove the coiler, or clean rollers.

Question 42Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The noil percentage in combing is best described as the:

  1. Percentage of short fibres and waste removed during combing Correct answer.
  2. Draft applied by the detaching rollers
  3. Twist inserted in the combed sliver
  4. Ratio of combed sliver mass to lap mass

Explanation

Noil is the short fibre and waste fraction removed by the comber, and the noil percentage expresses it as a proportion of the feed lap. It is a measure of the cleaning and short-fibre extraction achieved, not of draft or twist.

Question 43Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

Which machine in the short-staple spinning sequence converts sliver into a fine, twisted yarn ready for winding?

  1. Carding machine
  2. Ring spinning frame Correct answer.
  3. Draw frame
  4. Speed frame

Explanation

The ring spinning frame drafts the roving to the required yarn count and inserts twist with the traveller and spindle, producing yarn for winding. Earlier machines only prepare or reduce the strand without producing the final twisted yarn.

Question 44Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

In an opening and cleaning line, the purpose of the grid bars under a beater is to:

  1. Moisten the cotton for better cleaning
  2. Allow trash and dust to fall through while retaining the fibre Correct answer.
  3. Increase the draft on the material
  4. Support the beater blades

Explanation

Grid bars form a curved surface beneath the beater; opened trash and dust pass between the bars while the fibre flocks are carried forward by air. They do not support the blades, apply draft, or add moisture.

Question 45Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The main reason for doubling slivers at the draw frame is to:

  1. Reduce the fibre length of the sliver
  2. Add twist so that the sliver holds together
  3. Increase production by feeding more material
  4. Improve evenness by averaging out irregularities of individual slivers Correct answer.

Explanation

When several slivers are combined, random thick and thin places tend to cancel, so the delivered sliver is more regular than any single feed sliver. Doubling is not a production-raising measure and does not alter fibre length or add twist.

Question 46Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

Which of the following best explains why the card is called the heart of the spinning mill?

  1. It is the largest machine in the mill
  2. It is the only machine that adds twist
  3. It individualises fibres and removes most trash and neps, determining sliver quality for later processes Correct answer.
  4. It produces the final yarn directly

Explanation

The card opens tufts into individual fibres, removes a large share of trash and neps, and forms the sliver whose quality strongly influences all downstream yarn properties. Its importance lies in this fibre-opening and cleaning role, not in size, yarn production, or twist.

Question 47Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The setting between the feed plate and the licker-in in a card is kept small in order to:

  1. Increase the draft in the card
  2. Reduce the power consumption of the cylinder
  3. Allow the fibre to be combed by the flats
  4. Prevent the cotton from being carried round the licker-in without being opened Correct answer.

Explanation

A close feed-plate-to-licker-in setting grips the tuft so that the licker-in teeth can tear fibres from it rather than carrying the whole tuft round. This setting does not govern cylinder power, card draft, or flat combing.

Question 48Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

In ring spinning, the spinning triangle is formed between the:

  1. Back rollers and the middle rollers
  2. Roving bobbin and the top roller
  3. Spindle and the ring rail
  4. Front drafting rollers and the traveller Correct answer.

Explanation

The triangle of fibres appears where the drafted ribbon leaves the front roller nip and converges to the point where twist is inserted at the traveller. Its shape controls hairiness and end breakage, so it is a key spinning condition.

Question 49Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

A comber lap of 60 ktex is combed to give a noil of 12 percent. The combed sliver mass per unit length, ignoring other losses, is approximately:

  1. 72.0 ktex
  2. 67.2 ktex
  3. 48.0 ktex
  4. 52.8 ktex Correct answer.

Explanation

If 12 percent of the mass is removed as noil, 88 percent remains, so 60 ktex multiplied by 0.88 gives about 52.8 ktex. The other values come from adding the noil instead of subtracting it or from using the wrong fraction.

Question 50Yarn Manufacture: Ginning, Opening, Carding, Drawing, Combing, Roving and Spinning

The function of the top and bottom aprons in the drafting zone of a speed frame is to:

  1. Apply the final twist to the roving
  2. Guide the fibre strand and control floating fibres for better evenness Correct answer.
  3. Wind the roving onto the bobbin
  4. Clean the drafting rollers

Explanation

Aprons in the double-apron drafting system support and guide the fibres, especially short ones, so they remain under control and the roving is more even. Winding and twisting of the roving happen after drafting, at the flyer and bobbin.