SCHOOL: SCHOOL OF ENGINEERING
DEPARTMENT: MANUFACTURING, INDUSTRIAL AND TEXTILE
NAME: JOHN WAITI
REG NO: MTI/4721/22
COURSE: FABRIC FORMATION III
CODE: MTI 426
DATE: 12TH JUNE, 2025
1. compare the evolution of shuttleless weaving machines with regard to:
a. productivity
Shuttleless weaving machines dramatically increased productivity compared to traditional
shuttle looms by enabling much higher weaving speeds. They operate at speeds 4 to 8 times
faster than shuttle looms, with some air jet looms reaching weft insertion rates up to 2850
meters per minute.
Reduced downtime and faster weft insertion methods (rapier, air jet, water jet, projectile)
contribute to continuous, high-volume fabric production.
The elimination of the heavy shuttle reduces vibration and mechanical stress, allowing
smoother and faster operation.
b. Flexibility
Shuttleless looms offer greater flexibility in fabric production. Rapier looms, for example,
can insert multiple weft yarns simultaneously, enabling complex multi-color patterns and
diverse fabric designs.
Different types of shuttleless looms (rapier, air jet, water jet, projectile) cater to a wide range
of yarn types and fabric weights, from delicate textiles to heavy fabrics.
The capability to produce wider fabrics and incorporate multiple colors in the weft direction
enhances design versatility.
c. Market Share
Since their commercial introduction in the mid-20th century, shuttleless looms have rapidly
gained market share and now constitute about 80% of looms in developed textile markets,
largely replacing shuttle looms.
The shift is driven by their superior speed, efficiency, and adaptability to modern textile
manufacturing demands.
d. Automation
Shuttleless weaving machines have progressively integrated computerized controls,
microprocessors, and automatic monitoring systems, improving precision and reducing
human intervention.
Features such as automatic pick finding, weft replenishment without stopping, and automatic
loom stopping on faults originated in early power looms and have been enhanced in
shuttleless looms.
Modern shuttleless looms support digital customization, enabling automated pattern control
and quality management
e. Cost of Production
Shuttleless looms reduce production costs by lowering labor requirements, energy
consumption, and maintenance downtime compared to shuttle looms
Although initial investment costs for shuttleless looms can be higher due to advanced
technology, the overall cost per unit of fabric decreases because of higher productivity and
less waste
The improved efficiency and reduced defect rates contribute to approximately 10% cost
savings in fabric production
2. for a weft prewinder (weft accumulator):
b. Discuss its operation (4mks)
a. Discuss the objectives (5mks)
a. Discuss its operation (4mks)
Ensure Continuous Weft Supply:
The primary objective is to maintain a continuous supply of weft yarn to the loom during the
weaving process, preventing stoppages caused by weft yarn replacement or tension
fluctuations.
Maintain Constant Weft Tension:
It helps in maintaining consistent tension in the weft yarn, which is crucial for producing
defect-free fabric and avoiding yarn breakage or slackness.
Prevent Loom Stoppage During Pirn Change:
The accumulator stores a certain length of weft yarn so that when the weft package (pirn or
bobbin) is exhausted and needs replacement, the loom can continue weaving without
stopping.
Compensate for Weft Insertion Speed Variations:
It balances the difference between the constant speed of the weft insertion system and the
variable speed of the weft package, allowing smooth operation.
Improve Weaving Efficiency and Productivity:
By reducing the frequency of loom stoppages and ensuring smooth weft feeding, the
accumulator increases overall weaving efficiency and fabric production rates.
b. Operation of a Weft Prewinder (Weft Accumulator) (4 marks)
Yarn Storage Mechanism:
The weft yarn is wound onto a small rotating drum or stored in a looped form in the
accumulator, creating a reserve of yarn that can be quickly supplied to the loom.
Automatic Yarn Feeding:
As the loom inserts weft yarn, the accumulator releases the stored yarn to maintain
continuous supply. When the yarn in the accumulator runs low, it triggers the prewinder to
rewind more yarn from the main package.
Synchronization with Loom Speed:
The accumulator’s operation is synchronized with the loom’s weft insertion rate to ensure
that yarn tension remains constant and the supply matches the demand without causing slack
or breakage.
Control System:
Sensors or mechanical devices detect the yarn level in the accumulator and control the
prewinder motor to rewind yarn as needed, ensuring the accumulator is always sufficiently
stocked.
3. with regard to modern weaving machines(shuttleless looms):
a. discuss the need for selvedge motion (5mks)
b. describe the selvedge mechanisms available (5mks)
c. for each selvedge mechanism, describe the structure of selvedge attained (5mks)
a. discuss the need for selvedge motion (5mks)
Prevent Fraying and Unraveling:
Shuttleless looms cut the weft yarn after each insertion, leaving fringe edges. Without
selvedge motion, these edges would unravel during handling or downstream processing
Ensure Fabric Integrity:
Selvedges bind warp and weft threads at the edges, preventing warp yarns from slipping out
and maintaining structural stability during weaving
Facilitate Safe Handling:
Strong selvedges allow fabrics to withstand tension during dyeing, finishing, and cutting
without damage
Aesthetic Requirements:
Selvedges provide a neat, finished appearance, which is critical for textiles used in apparel or
home furnishings
Compatibility with Automation:
Modern high-speed shuttleless looms require automated selvedge mechanisms to maintain
efficiency and reduce manual intervention
b. Selvedge Mechanisms Available (5 marks)
Tucked-In Selvedge:
Uses a hooked needle or cam-driven device to tuck the cut weft ends back into the fabric.
Leno Selvedge:
Binds weft yarns using additional warp threads woven in a gauze (crossed) pattern, often with
specialized needles.
Chain Stitch Selvedge:
Forms a sewn edge using a chain stitch, typically in narrow fabric looms.
Fused Selvedge:
Melts thermoplastic yarns at the fabric edges using heat, sealing the weft ends.
Stitched/Bound Selvedge: .
Secures edges with a monofilament thread, followed by cutting to create a fringe
c. Structure of Selvedge Attained (5 marks)
Mechanism Structure of Selvedge
Tucked-In - Double weft density at edges; weft ends woven back into the fabric in a hairpin
shape
Leno - Twisted warp threads encase weft yarns, forming a reinforced, fray-resistant edge
Chain Stitch - Decorative sewn edge with a chain-like stitch; may include a fringe after
cutting
Fused - Sealed, non-raveling edge created by melting thermoplastic yarns
Stitched/Bound - Neat fringe secured by a dummy list and monofilament stitching, later
trimmed
