Podcast
Questions and Answers
What is the primary difference between a power loom and a handloom?
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?
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?
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?
What category of motion includes the primary mechanisms of weaving fabric?
Which type of raw material can be handled by looms?
Which type of raw material can be handled by looms?
Which type of shedding mechanism is NOT mentioned as an option for looms?
Which type of shedding mechanism is NOT mentioned as an option for looms?
What is the maximum number of frames a loom can handle typically related to?
What is the maximum number of frames a loom can handle typically related to?
Which of the following fabric types is primarily associated with loom capabilities?
Which of the following fabric types is primarily associated with loom capabilities?
What is the primary function of the shuttle checking mechanism?
What is the primary function of the shuttle checking mechanism?
How fast does the shuttle travel on shuttle-less looms?
How fast does the shuttle travel on shuttle-less looms?
What ensures a constant and uniform tension on the weft during picking in shuttle-less looms?
What ensures a constant and uniform tension on the weft during picking in shuttle-less looms?
What amount of weft yarn do weft accumulators typically store on their drum?
What amount of weft yarn do weft accumulators typically store on their drum?
Which year was the projectile picking technique introduced commercially?
Which year was the projectile picking technique introduced commercially?
What type of yarn can be used with the projectile picking technique?
What type of yarn can be used with the projectile picking technique?
What happens to the shuttle as it is launched from one side of the loom to the other?
What happens to the shuttle as it is launched from one side of the loom to the other?
What is the acceleration achieved by the shuttle in shuttle-less looms?
What is the acceleration achieved by the shuttle in shuttle-less looms?
What is the main purpose of the warp stop-motion in weaving?
What is the main purpose of the warp stop-motion in weaving?
Which motion is responsible for replenishing the weft yarn supply during weaving?
Which motion is responsible for replenishing the weft yarn supply during weaving?
What action is taken by the weft stop-motion during weaving?
What action is taken by the weft stop-motion during weaving?
In which scenario would the warp protector motion activate?
In which scenario would the warp protector motion activate?
Which auxiliary motion is specifically designed to stop the loom during a weft yarn issue?
Which auxiliary motion is specifically designed to stop the loom during a weft yarn issue?
What is the primary function of the warp protector motion?
What is the primary function of the warp protector motion?
What is the maximum speed that air-jet weaving can achieve?
What is the maximum speed that air-jet weaving can achieve?
What feature is used to maintain the speed of the weft yarn in air-jet weaving?
What feature is used to maintain the speed of the weft yarn in air-jet weaving?
Which innovation in air-jet looms was introduced to prevent air from spreading?
Which innovation in air-jet looms was introduced to prevent air from spreading?
What is the primary benefit of the reduced number of mechanical parts in air-jet weaving?
What is the primary benefit of the reduced number of mechanical parts in air-jet weaving?
Which component acts as a channel for air and weft yarn to avoid scattering of air pressure?
Which component acts as a channel for air and weft yarn to avoid scattering of air pressure?
In what year was the concept of using multiple sub-nozzles along with main nozzles introduced?
In what year was the concept of using multiple sub-nozzles along with main nozzles introduced?
What was the maximum width of air-jet looms introduced in the early 1980s?
What was the maximum width of air-jet looms introduced in the early 1980s?
Which innovation helped air-jet looms to achieve speeds of up to 600 ppm in 1975?
Which innovation helped air-jet looms to achieve speeds of up to 600 ppm in 1975?
What is one of the advantages of projectile picking compared to shuttle picking?
What is one of the advantages of projectile picking compared to shuttle picking?
Which type of projectile is preferred for weaving delicate fabrics?
Which type of projectile is preferred for weaving delicate fabrics?
How does the projectile picking mechanism eject the projectile after use?
How does the projectile picking mechanism eject the projectile after use?
What materials are projectile types typically made from?
What materials are projectile types typically made from?
What is the maximum picking rate achieved with projectile picking?
What is the maximum picking rate achieved with projectile picking?
What is the purpose of the guides during the projectile picking process?
What is the purpose of the guides during the projectile picking process?
Which of the following statements is true about the widths available for projectile picking?
Which of the following statements is true about the widths available for projectile picking?
Who commercially introduced air-jet picking?
Who commercially introduced air-jet picking?
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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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