Textile Institute of Pakistan: Looming Process

Questions and Answers

What is the primary difference between a power loom and a handloom?

The motions on power looms are carried out by an external source of power. (correct)

Power looms are slower than handlooms.

Power looms do not use any yarns.

Handlooms use external power sources to perform weaving motions.

Which of the following is NOT a type of picking medium used in looms?

Water-jet

Hand-picking (correct)

Shuttle-less

Air-jet

What does PPM stand for in the context of loom specifications?

Picks per meter

Pieces per membrane

Picks per minute (correct)

Picks per machine

What category of motion includes the primary mechanisms of weaving fabric?

Primary motions Signup and view all the answers

Which type of raw material can be handled by looms?

Cotton, silk, and polyester Signup and view all the answers

Which type of shedding mechanism is NOT mentioned as an option for looms?

Flywheel Signup and view all the answers

What is the maximum number of frames a loom can handle typically related to?

The design capabilities of the loom Signup and view all the answers

Which of the following fabric types is primarily associated with loom capabilities?

Terry Signup and view all the answers

What is the primary function of the shuttle checking mechanism?

To stop the shuttle before it is thrown back. Signup and view all the answers

How fast does the shuttle travel on shuttle-less looms?

40 feet/sec Signup and view all the answers

What ensures a constant and uniform tension on the weft during picking in shuttle-less looms?

Weft accumulators Signup and view all the answers

What amount of weft yarn do weft accumulators typically store on their drum?

2 - 3 pick lengths Signup and view all the answers

Which year was the projectile picking technique introduced commercially?

1952 Signup and view all the answers

What type of yarn can be used with the projectile picking technique?

Any type of yarn including cotton, wool, synthetic, and blended Signup and view all the answers

What happens to the shuttle as it is launched from one side of the loom to the other?

It reaches the opposite shuttle box with a high velocity. Signup and view all the answers

What is the acceleration achieved by the shuttle in shuttle-less looms?

2500 inches/sec^2 Signup and view all the answers

What is the main purpose of the warp stop-motion in weaving?

To stop the loom when any warp yarn breaks Signup and view all the answers

Which motion is responsible for replenishing the weft yarn supply during weaving?

Weft replenishing motion Signup and view all the answers

What action is taken by the weft stop-motion during weaving?

Stopping the loom when the weft yarn breaks Signup and view all the answers

In which scenario would the warp protector motion activate?

When a shuttle gets entrapped in the shed Signup and view all the answers

Which auxiliary motion is specifically designed to stop the loom during a weft yarn issue?

Weft stop-motion Signup and view all the answers

What is the primary function of the warp protector motion?

To stop the loom when a shuttle becomes caught Signup and view all the answers

What is the maximum speed that air-jet weaving can achieve?

2400 metres per minute Signup and view all the answers

What feature is used to maintain the speed of the weft yarn in air-jet weaving?

Sub-nozzles Signup and view all the answers

Which innovation in air-jet looms was introduced to prevent air from spreading?

Confusors (guides) Signup and view all the answers

What is the primary benefit of the reduced number of mechanical parts in air-jet weaving?

Lower maintenance costs Signup and view all the answers

Which component acts as a channel for air and weft yarn to avoid scattering of air pressure?

Profiled reed Signup and view all the answers

In what year was the concept of using multiple sub-nozzles along with main nozzles introduced?

1969 Signup and view all the answers

What was the maximum width of air-jet looms introduced in the early 1980s?

156 inches Signup and view all the answers

Which innovation helped air-jet looms to achieve speeds of up to 600 ppm in 1975?

Profiled reed Signup and view all the answers

What is one of the advantages of projectile picking compared to shuttle picking?

Low power consumption at high speeds Signup and view all the answers

Which type of projectile is preferred for weaving delicate fabrics?

K3 type carbon composite projectile Signup and view all the answers

How does the projectile picking mechanism eject the projectile after use?

It is sent back via a conveyor belt Signup and view all the answers

What materials are projectile types typically made from?

Steel and carbon composite Signup and view all the answers

What is the maximum picking rate achieved with projectile picking?

2000 metres per minute Signup and view all the answers

What is the purpose of the guides during the projectile picking process?

To direct the projectile movement Signup and view all the answers

Which of the following statements is true about the widths available for projectile picking?

Widths can go up to 212 inches Signup and view all the answers

Who commercially introduced air-jet picking?

Max Paabo Signup and view all the answers

Study Notes

Looming Process

Looming process refers to the weaving of warp and weft yarns into fabric on a loom.
Looms are categorized primarily based on their picking medium.

Loom Specifications

Picking methods include shuttle and shuttle-less types such as air-jet, rapier, water-jet, and projectile.
Speed metrics include Picks per Minute (PPM) and picking rate in meters per minute, calculated using:
Metres per minute = PPM x Reed space (meters/mm).
Shedding mechanisms vary, including crank, tappet, dobby, and jacquard.
Looms can process various raw materials: cotton, silk, polyester.
Fabric weights produced range from lightweight to heavyweight, with specific types like terry or velvet.

Loom Motions

Weaving involves primary, secondary, and tertiary motions.
Handlooms operate all motions manually, while power looms use electrical drives.
Shuttle-less looms insert weft yarn from one side only.

Shuttle Movement and Mechanisms

Shuttle speed averages 40 feet/sec, utilizing an acceleration of 2500 inches/sec².
A shuttle checking mechanism is implemented to stop the shuttle to prevent damage.

Picking Techniques

Weft Accumulators: Ensure constant, uniform tension on weft yarn by storing 2-3 pick lengths of yarn.
Projectile Picking: Introduced in 1952, uses a projectile to insert various types of yarn efficiently for both light and heavy fabrics.

Stop-Motions

Weft Stop-motion: Stops loom when the weft yarn breaks or depletes.
Warp Stop-motion: Interrupts the loom when any warp yarn breaks.
Warp Protector Motion: Stops loom if the shuttle becomes entrapped in the shed.
Weft Replenishing Motion: Automatically changes the pirn before exhaustion.

Air-Jet Weaving

Utilizes compressed air to propel weft yarn, achieving speeds up to 2400 meters/min.
Air-jet weaving is noted for low noise, reduced mechanical parts, and low maintenance costs.
Operational Principle: Involves tandem and main nozzles to control air and yarn movement, facilitated by a profiled reed.

Historical Development of Air-Jet Weaving

Initial air-jet looms had limits on width and speed; significant advancements were made in the 1960s.
Multiple sub-nozzles and profiled reeds allowed wider looms and higher PPM.

Advantages of Projectile Picking

Consumes less power at high speeds than shuttle picking.
Facilitates weaving at widths up to 212" and picking rates up to 2000 meters/min.
Allows multi-colour pick insertion for diverse fabric production.

Types of Projectiles

Projectiles are crafted from steel or carbon composites, with distinct classifications for varying fabric types.
K3 projectiles are favored for delicate fabric weaving.

Projectile Picking Mechanism

Projectiles grab weft yarns and navigate over guides for insertion.
After completing a pick, projectiles are recirculated back to the picking unit via conveyer belts.

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Description

Explore the essential components and mechanisms involved in the looming process of fabric technology. This quiz covers the different types of looms and their classifications based on the picking medium. Test your knowledge on the intricate process that transforms yarns into woven fabric.