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ITI/NCVT Sewing Technology (AITT Theory) study materials
ITI/NCVT Sewing Technology (AITT Theory) study resources

ITI/NCVT Sewing Technology (AITT Theory) practice questions

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Question 1Trade Safety, Occupational Health and Environment

In a sewing workshop, which fire extinguisher class is specifically suitable for a fire involving the electric motor of an industrial stitching machine?

  1. Class C carbon dioxide extinguisher Correct answer.
  2. Class B foam extinguisher
  3. Class A water extinguisher
  4. Class D dry powder extinguisher

Explanation

Energised electrical equipment fires are Class C (or E in some standards), and carbon dioxide extinguishers are preferred because the gas is non-conductive and leaves no residue on the machine. Water and foam conduct electricity and risk electrocution of the operator. Class D agents are formulated for burning metals only.

Question 2Trade Safety, Occupational Health and Environment

Before threading a needle on an industrial lockstitch machine, which practice best protects the operator's fingers from needle puncture?

  1. Thread the needle with the presser foot raised and the motor engaged
  2. Switch off the motor and wait for the needle to stop completely Correct answer.
  3. Hold the handwheel with the left hand while threading
  4. Keep the machine running at low speed while threading

Explanation

The needle should never be threaded while the machine can start; isolating the power and letting all motion stop removes the risk of accidental starts. A clutch motor can creep or a servo can be triggered by a knee lifter, so isolation is the reliable safeguard. Handwheel holding does not remove stored kinetic energy or prevent a foot-pedal start.

Question 3Trade Safety, Occupational Health and Environment

What is the main reason for fitting a needle guard on an industrial sewing machine?

  1. To keep the bobbin case free of lint
  2. To shield the operator's fingers from the needle path Correct answer.
  3. To prevent the needle from bending during heavy fabric sewing
  4. To guide the thread into the needle eye automatically

Explanation

The needle guard is a physical barrier positioned around the needle so that a finger entering the stitching area is deflected rather than pierced. It is an engineering control that works even when the operator's attention lapses. It has no thread-guiding, lint-control or needle-stiffening function.

Question 4Trade Safety, Occupational Health and Environment

In an apparel production floor, which housekeeping practice most directly reduces the risk of slips and falls?

  1. Placing cutting waste in open bins beside the machine
  2. Clearing thread clippings and fabric scraps from the walkway at regular intervals Correct answer.
  3. Sweeping the floor only at the end of the shift
  4. Storing fabric rolls vertically against the wall

Explanation

Loose thread, fabric scraps and trim on a smooth floor act like skids and are a leading cause of slips in sewing rooms. Frequent clearing of walkways removes the hazard at source. End-of-shift sweeping leaves the hazard present for the whole working period.

Question 5Trade Safety, Occupational Health and Environment

Which personal protective equipment is essential when handling a hot iron or steam press in a finishing section?

  1. Cotton gloves and eye protection Correct answer.
  2. Apron and rubber gum boots
  3. Ear plugs and a face shield
  4. Steel-toe boots and a dust mask

Explanation

Heat-resistant or thick cotton gloves protect the hands from contact burns and steam, and eye protection guards against steam bursts and spitting. The other combinations address impact, noise, dust or wet floors rather than thermal hazards. PPE should be selected to match the specific hazard of the task.

Question 6Trade Safety, Occupational Health and Environment

A tailor develops wrist pain and tingling in the fingers after long shifts of hand sewing. Which work-related condition is most consistent with these symptoms?

  1. Carpal tunnel syndrome Correct answer.
  2. Contact dermatitis
  3. Occupational asthma
  4. Noise-induced hearing loss

Explanation

Repetitive flexion of the wrist combined with sustained gripping is a recognised cause of carpal tunnel syndrome, which produces tingling and numbness in the median nerve distribution. Asthma, hearing loss and dermatitis relate to airborne, noise and skin exposures respectively. Early reporting allows workstation and tool changes to reduce the strain.

Question 7Trade Safety, Occupational Health and Environment

Which control measure ranks highest in the hierarchy of controls for reducing needle-prick injuries in a sewing unit?

  1. Elimination of the hazard through guarded, automated needle systems Correct answer.
  2. Retraining operators every month
  3. Posting a warning sign at each machine
  4. Issuing gloves to every operator

Explanation

The hierarchy of controls places elimination and engineering controls above administrative measures and PPE. A guarded or automated system that removes hand access to the needle eliminates the hazard rather than relying on behaviour. Signs and retraining are administrative, and gloves are the least reliable layer.

Question 8Trade Safety, Occupational Health and Environment

A worker in a fabric store feels dizzy and develops a headache in an area where solvent-based spot removers are used. What is the first correct emergency action?

  1. Move the worker to fresh air and seek medical advice Correct answer.
  2. Apply a cold cloth and resume the task after ten minutes
  3. Open a window and let the worker rest inside the room
  4. Give the worker strong coffee and continue work

Explanation

Dizziness and headache after solvent exposure suggest inhalation of volatile organic compounds, so the affected person must be removed from the contaminated atmosphere and assessed medically. Ventilating the room while the person remains inside does not stop continued absorption. Stimulants such as coffee do not treat chemical exposure.

Question 9Trade Safety, Occupational Health and Environment

Which statement correctly describes the purpose of a Material Safety Data Sheet (SDS) for a spotting chemical used in a garment unit?

  1. It certifies that the chemical has been approved by the factory manager
  2. It communicates hazard, handling, first-aid and storage information for the substance Correct answer.
  3. It lists the retail price and supplier discount for the product
  4. It records the daily consumption of the chemical in the store

Explanation

A safety data sheet is a hazard communication document covering identification, hazards, safe handling, first aid, firefighting, storage and disposal. It does not certify approval, track consumption or carry commercial pricing. Workers must be able to access it and understand it before using the substance.

Question 10Trade Safety, Occupational Health and Environment

Why is it unsafe to clean an industrial sewing machine with compressed air while other operators are working nearby?

  1. Air jets blow lint and oil particles into eyes and lungs of people nearby Correct answer.
  2. Compressed air damages the machine's painted surface
  3. Compressed air cools the machine too quickly
  4. Air cleaning increases the electrical load on the motor

Explanation

Compressed air converts settled lint, dust and oil mist into an airborne cloud that can enter eyes and the respiratory tract of everyone in the area. It also drives debris deeper into bearings and shuttle raceways. Vacuum extraction or a brush is the safer cleaning method.

Question 11Trade Safety, Occupational Health and Environment

An operator stands for eight hours at a straight-bar machine with the table height fixed. Which change best reduces lower-back and leg fatigue?

  1. Replacing the chair with a rigid wooden bench
  2. Adding a second task light above the machine
  3. Providing an anti-fatigue mat and a height-adjustable stool Correct answer.
  4. Increasing sewing speed to finish work sooner

Explanation

Prolonged static standing loads the lumbar spine and legs; a compliant mat and the option to sit or perch reduce that load and allow posture change. Faster running does not address posture and may raise strain. Rigid seating without adjustment worsens the mismatch between worker and workstation.

Question 12Trade Safety, Occupational Health and Environment

Which of the following is the correct way to lift a heavy fabric roll from the floor in a cutting room?

  1. Bend at the waist with straight legs and twist to place the roll
  2. Bend the knees, keep the back straight, hold the load close and lift smoothly Correct answer.
  3. Hold the roll at arm's length and lean backwards
  4. Keep the legs straight and lift with a jerking motion

Explanation

Safe manual handling keeps the load close to the body, uses the leg muscles with knees bent and the back kept in its natural alignment, and avoids twisting. Twisting under load and jerking motions concentrate force on the lumbar discs. Holding a load at arm's length multiplies the moment on the spine.

Question 13Trade Safety, Occupational Health and Environment

A workshop has an electrical socket with a cracked casing near a pressing table. What is the most appropriate immediate action?

  1. Isolate the circuit, tag it and report it for repair by a competent person Correct answer.
  2. Place a rubber mat in front of the socket and keep using it
  3. Wrap the socket with insulating tape and continue using it
  4. Ask any operator to replace the socket during the lunch break

Explanation

Damaged electrical fittings must be taken out of service, isolated and repaired by a qualified electrician; tagging prevents accidental re-energisation. Tape and mats are improvisations that leave the defect in place. Repair by untrained staff creates a serious shock and fire risk.

Question 14Trade Safety, Occupational Health and Environment

A factory wishes to reduce noise from a bank of overlock machines. Which measure is an engineering control rather than an administrative one?

  1. Shortening each operator's exposure time to four hours
  2. Rotating operators between noisy and quiet sections
  3. Fitting anti-vibration mounts and acoustic enclosures to the machines Correct answer.
  4. Displaying a noise hazard sign at the entrance

Explanation

Engineering controls modify the source or the transmission path, for example by damping vibration or enclosing the machine. Rotation, exposure reduction and signage are administrative controls that rely on people and schedules. Engineering controls protect every worker in the area without depending on compliance.

Question 15Trade Safety, Occupational Health and Environment

During a risk assessment of a sewing line, a supervisor evaluates a task using the formula risk = likelihood x severity. A task has low likelihood of contact with a running needle but the consequence would be severe. What is the correct interpretation?

  1. The risk can be ignored if no injury occurred last year
  2. The risk is acceptable provided workers wear gloves
  3. The risk still requires controls because severity is high Correct answer.
  4. The risk is negligible because the likelihood is low

Explanation

Risk combines probability with the seriousness of the outcome, so a low-probability event with severe consequences can still produce an unacceptable risk level. Controls should be proportionate to that combined score, usually engineering measures first. Past absence of injury is not evidence that the risk is controlled.

Question 16Trade Safety, Occupational Health and Environment

An operator reports burning eyes and a strong smell after a spot-cleaning solvent is decanted into an unlabelled bottle. Which combination of failures is most directly involved?

  1. Incorrect thread tension and blunt scissors
  2. Poor lighting and high machine speed
  3. Missing hazard labelling and inadequate local exhaust ventilation Correct answer.
  4. Worn needle plate and incorrect stitch length

Explanation

Decanting into an unlabelled container removes the hazard communication that warns users, while the eye irritation and odour point to vapour accumulation from insufficient extraction at source. Together these are labelling and ventilation failures. The other pairs concern sewing quality or lighting, not chemical exposure.

Question 17Sewing Tools, Equipment and Machine Maintenance

Which part of an industrial lockstitch machine controls the amount of thread delivered to the needle so that a balanced stitch is formed?

  1. The bobbin winder
  2. The feed dog
  3. The tension disc assembly Correct answer.
  4. The presser foot

Explanation

The tension disc assembly grips the needle thread and regulates how much thread passes to the needle, which directly determines stitch balance and appearance. Adjusting the discs changes the upper thread tension relative to the bobbin thread.

Question 18Sewing Tools, Equipment and Machine Maintenance

A sewing machine needle is specified as DBx1 size 90/14. What does the number 90 refer to?

  1. The needle blade diameter in hundredths of a millimetre Correct answer.
  2. The length of the needle in millimetres
  3. The size of the needle eye in microns
  4. The recommended thread count

Explanation

In the metric needle sizing system the number indicates the blade diameter in hundredths of a millimetre, so a size 90 needle has a blade about 0.90 mm thick. The imperial equivalent (14) is shown alongside for reference.

Question 19Sewing Tools, Equipment and Machine Maintenance

Which needle point type is most suitable for sewing knitted cotton jersey fabric?

  1. Ball point Correct answer.
  2. Chisel point
  3. Leather point
  4. Sharp point

Explanation

A ball point needle has a rounded tip that pushes between the loops of a knit instead of cutting them, preventing ladders and dropped stitches. Sharp or cutting points can sever knit yarns and cause holes.

Question 20Sewing Tools, Equipment and Machine Maintenance

What is the main purpose of the feed dog on a lockstitch machine?

  1. To grip and advance the fabric by a set stitch length Correct answer.
  2. To cut the thread after sewing
  3. To guide the needle into the fabric
  4. To hold the bobbin case in position

Explanation

The feed dog rises through the needle plate slots and moves the fabric forward by the amount set on the stitch regulator. Its height, alignment and tooth condition directly affect stitch length consistency and fabric feeding.

Question 21Sewing Tools, Equipment and Machine Maintenance

Which tool is used to measure the stitch length produced by a machine over a marked distance?

  1. A stitch length gauge Correct answer.
  2. A hem gauge
  3. A needle gauge
  4. A seam gauge

Explanation

A stitch length gauge measures how many stitches fall within a set distance, allowing the operator to verify the machine's actual stitch length. This is useful when checking that the stitch regulator matches the dial setting.

Question 22Sewing Tools, Equipment and Machine Maintenance

During routine maintenance, which action best protects the hook and bobbin area of a lockstitch machine?

  1. Running the machine at full speed without fabric
  2. Loosening the needle plate screws permanently
  3. Oiling the hook once a month only
  4. Removing lint and thread waste daily with a brush and air Correct answer.

Explanation

Lint and thread waste accumulate around the hook and can cause skipped stitches, noise and overheating. Daily cleaning with a brush and low-pressure air keeps the mechanism free and extends component life.

Question 23Sewing Tools, Equipment and Machine Maintenance

Which safety practice is required before changing a needle on an industrial sewing machine?

  1. Increasing the presser foot pressure
  2. Removing the bobbin case
  3. Switching off the machine and disconnecting the power Correct answer.
  4. Lowering the needle bar to its lowest point

Explanation

The machine must be isolated from power before any hand work near the needle, because a foot pedal knock or accidental start can cause a serious puncture injury. Locking off also prevents the motor from restarting during the change.

Question 24Sewing Tools, Equipment and Machine Maintenance

A lockstitch machine produces skipped stitches only on thick denim. Which cause should be checked first?

  1. Machine running at reduced speed
  2. Presser foot pressure set too high
  3. Bobbin wound too tightly
  4. Needle too fine for the fabric, causing deflection Correct answer.

Explanation

A needle that is too fine bends or deflects in dense fabric, so the hook fails to pick up the loop and a stitch is skipped. Increasing needle size and matching thread to the fabric usually corrects the fault.

Question 25Sewing Tools, Equipment and Machine Maintenance

What is the function of the take-up lever in a lockstitch machine?

  1. To lift the presser foot during sewing
  2. To move the fabric forward
  3. To pull thread from the supply and set the final stitch tension Correct answer.
  4. To wind thread onto the bobbin

Explanation

The take-up lever draws thread from the spool and tightens it around the bobbin case to lock the stitch. Its timing with the needle and hook determines whether the stitch is properly set.

Question 26Sewing Tools, Equipment and Machine Maintenance

Which lubricant is normally recommended for the high-speed rotating parts of an industrial sewing machine?

  1. White sewing machine oil of the grade specified by the maker Correct answer.
  2. General purpose grease
  3. Cooking oil
  4. Silicone spray

Explanation

Manufacturers specify a light, non-gumming white oil for high-speed bearings and hooks so that it penetrates and drains without leaving residue. Using the wrong lubricant can gum the mechanism or stain fabric.

Question 27Sewing Tools, Equipment and Machine Maintenance

The upper thread tension is correct but the lower thread lies straight along the top of the seam. What adjustment is needed?

  1. Decrease the needle thread tension
  2. Increase the presser foot pressure
  3. Decrease the bobbin thread tension
  4. Increase the bobbin thread tension Correct answer.

Explanation

When the bobbin thread shows straight on the top surface, the upper tension is pulling it through, meaning the bobbin tension is too loose relative to the needle thread. Slightly increasing bobbin case tension pulls the knot back into the fabric.

Question 28Sewing Tools, Equipment and Machine Maintenance

What happens if the needle is installed with its long groove facing the wrong way on a standard lockstitch machine?

  1. The bobbin will overfill
  2. The machine will sew backwards
  3. The feed dog will stop moving
  4. The thread will not form a proper loop and stitches will skip or break Correct answer.

Explanation

The long groove and scarf must face the hook so the thread is protected and a loop can be formed at the scarf. Reversing the needle prevents loop formation and causes skipped or broken stitches.

Question 29Sewing Tools, Equipment and Machine Maintenance

Which component of an overlock machine prevents the fabric edge from curling before it is sewn?

  1. The needle cooler
  2. The chain cutter
  3. The differential feed Correct answer.
  4. The upper and lower loopers

Explanation

Differential feed uses two feed dogs moving at different rates; setting them to stretch or gather controls the fabric edge so it does not curl or wave. This is a key adjustment unique to overlock machines.

Question 30Sewing Tools, Equipment and Machine Maintenance

A machine is noisy and vibrates strongly after a new motor was fitted. What is the most likely cause?

  1. The motor pulley is misaligned with the machine pulley Correct answer.
  2. The bobbin is empty
  3. The needle is new
  4. The stitch length is set too short

Explanation

Misalignment between motor and machine pulleys causes belt whip, vibration and noise, and can wear bearings. The belt should run true and be tensioned to the maker's specification.

Question 31Sewing Tools, Equipment and Machine Maintenance

Which needle system is generally used on an industrial overlock machine?

  1. HAx1 domestic needle
  2. DBx1 lockstitch needle
  3. DPx5 lockstitch needle
  4. DCx1 or similar overlock needle Correct answer.

Explanation

Overlock machines use their own needle systems, such as DCx1 or DCx27, which have a shorter shank and different scarf suited to the looper geometry. Fitting a lockstitch needle can cause skipped stitches or damage.

Question 32Sewing Tools, Equipment and Machine Maintenance

A seam shows puckering along its length on a lightweight woven fabric. Which combination is the most likely cause?

  1. Too heavy a needle and too tight a thread tension Correct answer.
  2. Correct needle with balanced tension
  3. A new bobbin case
  4. Too fine a needle and too loose a thread tension

Explanation

On lightweight fabric, an oversized needle punches a large hole and pushes fabric into the seam, while excessive thread tension draws the seam up. Reducing needle size and tension usually removes the puckering.

Question 33Sewing Tools, Equipment and Machine Maintenance

What is the purpose of the needle plate on a lockstitch machine?

  1. To hold the needle in the bar
  2. To support the fabric and provide slots for the feed dog Correct answer.
  3. To tension the bobbin thread
  4. To guide the thread from the spool

Explanation

The needle plate gives the fabric a flat surface and has slots through which the feed dog rises to move the fabric. Its hole size must suit the needle to avoid needle deflection or fabric being pulled down.

Question 34Sewing Tools, Equipment and Machine Maintenance

Which routine check is most important for the belt driving an industrial sewing machine?

  1. Correct tension and alignment without fraying Correct answer.
  2. Length longer than the maker specifies
  3. Colour match with the machine
  4. Presence of oil on the belt surface

Explanation

A belt that is too tight overloads bearings while a slack belt slips and causes uneven speed; alignment prevents edge wear. Inspecting for fraying allows replacement before sudden failure mid-production.

Question 35Sewing Tools, Equipment and Machine Maintenance

What does the term 'hook timing' refer to on a lockstitch machine?

  1. The time taken to wind a full bobbin
  2. The interval between two oil changes
  3. The order in which the tension discs are threaded
  4. The synchronisation of the hook point with the needle scarf as the loop forms Correct answer.

Explanation

Hook timing is the precise relationship in which the hook point meets the needle scarf just as the thread loop forms. If it is late or early, the hook misses the loop and stitches skip.

Question 36Sewing Tools, Equipment and Machine Maintenance

A candidate is selecting a needle for a heavy canvas bag sewn with a size 40 ticket thread. Which choice is most appropriate?

  1. Size 60/8 with a ball point
  2. Size 70/10 with a leather point
  3. Size 110/18 with a sharp point Correct answer.
  4. Size 75/11 with a ball point

Explanation

Heavy canvas needs a large needle that can penetrate dense weave without bending, and the needle should be matched to the thread so the thread fills the eye and groove. A size 110/18 sharp point suits both the fabric and the heavier thread.

Question 37Sewing Tools, Equipment and Machine Maintenance

After servicing the hook, the machine sews but the stitch is loose and the bobbin thread pulls freely with almost no resistance. What is the most probable fault?

  1. The bobbin case tension spring screw was left too loose Correct answer.
  2. The needle is fitted backwards
  3. The presser foot pressure is too low
  4. The feed dog is set too high

Explanation

If the bobbin case tension spring screw is not reset after servicing, the bobbin thread has almost no drag and the stitch cannot interlock. Resetting the screw to a normal drop-test tension restores balance.

Question 38Sewing Tools, Equipment and Machine Maintenance

Which statement best explains why the needle should be changed after a long production run even if it appears straight?

  1. The eye closes gradually during sewing
  2. The point and scarf wear and burrs form, causing damage and skipped stitches Correct answer.
  3. The needle becomes magnetised and stops forming loops
  4. The needle shank grows and no longer fits the clamp

Explanation

Repeated impact work-hardens and dulls the point and can raise burrs at the scarf or eye, which snag thread and pierce fabric roughly. A worn needle causes skipped stitches, thread breakage and fabric pulls even when it looks straight.

Question 39Sewing Tools, Equipment and Machine Maintenance

An overlocker produces a seam where the fabric edge rolls and the stitch width appears narrow. Which adjustment set is most appropriate?

  1. Loosen both looper tensions fully
  2. Increase differential feed ratio and widen the cutting width Correct answer.
  3. Fit a finer needle and increase stitch length
  4. Reduce differential feed ratio and narrow the cutting width

Explanation

Rolled edges on an overlocker are corrected by increasing differential feed so the front feed dog gathers slightly, and by adjusting the upper knife so a wider edge is cut and covered by the loops. Both adjustments act together on edge appearance.

Question 40Sewing Tools, Equipment and Machine Maintenance

Why must the machine be re-timed after replacing a worn hook assembly?

  1. The hook controls the upper thread tension setting
  2. The hook drives the feed dog and must be aligned to it
  3. The hook determines the stitch length and must match the dial
  4. A new hook must be set so its point meets the needle scarf at the specified position Correct answer.

Explanation

The hook point must pass the needle scarf at a defined height and rotational position to catch the loop; a new hook may sit slightly differently on its shaft. Retiming ensures the loop is picked up reliably at all speeds.

Question 41Textile Fibres, Yarns and Fabric Construction

Which natural fibre is obtained from the seed hair of a plant and is composed mainly of cellulose?

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

Explanation

Cotton is a seed fibre harvested from the boll of the cotton plant and is about 90 percent cellulose, making it the classic natural cellulosic staple fibre. Jute is a bast fibre from the stem, silk is an animal filament, and wool is a protein fibre from sheep.

Question 42Textile Fibres, Yarns and Fabric Construction

A sewing room needs a fibre that gives high tenacity with low moisture regain for industrial sewing threads. Which fibre property pair best matches this requirement?

  1. Wool: elastic and moisture absorbing
  2. Viscose: soft and highly absorbent
  3. Polyester: strong and hydrophobic Correct answer.
  4. Cotton: strong when wet and absorbent

Explanation

Polyester filament gives high specific tenacity and very low moisture regain (around 0.4 percent), so it retains strength and resists rot in industrial thread. The absorbent fibres listed lose strength or swell when wet and are less suitable where low regain is required.

Question 43Textile Fibres, Yarns and Fabric Construction

In the standard worsted system of yarn manufacture, which operation immediately follows carding?

  1. Roving
  2. Winding
  3. Combing Correct answer.
  4. Doubling

Explanation

In the worsted route the carded sliver is combed to remove short fibres and align the long fibres parallel before drafting. Roving and winding come later in the sequence, and doubling is a separate process used to build plied yarns.

Question 44Textile Fibres, Yarns and Fabric Construction

A yarn is described as 40s count in the English cotton system. What does this indicate?

  1. 40 hanks of 840 yards weigh one pound Correct answer.
  2. 40 metres of yarn weigh one gram
  3. 40 plies are twisted together
  4. 40 grams of yarn measure one kilometre

Explanation

The English cotton count is an indirect system in which the count equals the number of 840-yard hanks per pound. A 40s cotton yarn therefore has 40 such hanks in one pound, so a higher count means a finer yarn.

Question 45Textile Fibres, Yarns and Fabric Construction

Which weave produces the maximum possible number of interlacements per unit area and therefore the firmest, smoothest plain surface?

  1. 2/2 twill
  2. 5-end satin
  3. 8-end satin
  4. Plain weave Correct answer.

Explanation

In plain weave each warp end interlaces with each weft pick alternately, so the number of intersections is the highest of any simple weave. Twill and satin float yarns over several threads, reducing interlacements and giving a looser, more lustrous surface.

Question 46Textile Fibres, Yarns and Fabric Construction

A trouser fabric must drape well and resist abrasion in wear. Which weave structure is most commonly selected for its diagonal rib and balanced durability?

  1. Twill weave Correct answer.
  2. Leno weave
  3. Pile weave
  4. Dobby spot weave

Explanation

Twill weave produces diagonal lines and floats that give good abrasion resistance and drape, which is why it dominates trouser and denim fabrics. Leno, pile and spot structures serve very different purposes such as open gauze, raised surface or small figured effects.

Question 47Textile Fibres, Yarns and Fabric Construction

Which spinning system drafts the fibre strand between a roller pair and adds twist with a ring and traveller?

  1. Rotor spinning
  2. Ring spinning Correct answer.
  3. Wrap spinning
  4. Air-jet spinning

Explanation

Ring spinning drafts the roving in a roller drafting zone and inserts twist by means of a traveller circulating on a ring around the spindle. Rotor, air-jet and wrap systems form yarn by different means without a ring and traveller.

Question 48Textile Fibres, Yarns and Fabric Construction

A single yarn of 20 tex is twofold. What is the resultant linear density of the plied yarn, ignoring twist contraction?

  1. 400 tex
  2. 20 tex
  3. 40 tex Correct answer.
  4. 10 tex

Explanation

In the direct tex system the linear densities of identical plied components are added, so two 20 tex yarns give 40 tex. Doubling adds mass per unit length rather than halving it or multiplying it.

Question 49Textile Fibres, Yarns and Fabric Construction

Why is combing included in the production of fine worsted yarns?

  1. To remove short fibres and neps and align long fibres Correct answer.
  2. To set the twist permanently in the yarn
  3. To increase the twist level of the roving
  4. To blend two different fibre types uniformly

Explanation

Combing removes short fibres, neps and impurities and lays the remaining long fibres parallel, which allows finer, smoother, stronger worsted yarns. Twist setting, blending and roving twist are handled by other processes.

Question 50Textile Fibres, Yarns and Fabric Construction

Which fibre is a regenerated cellulosic filament made by dissolving cellulose pulp and extruding it through spinnerets?

  1. Viscose rayon Correct answer.
  2. Polypropylene
  3. Nylon 6,6
  4. Acetate

Explanation

Viscose rayon is regenerated cellulose: pulp is converted to a soluble xanthate, extruded into a spin bath and regenerated as filament. Nylon and polypropylene are melt-spun synthetic polymers, and acetate is a cellulose ester rather than regenerated cellulose.