Basic Textiles II Weaving
Reader 1: Weaving fundamentals and design
Structure of woven fabric
Interlacing two sets of yarns
Length → warp yarns/ warp ends/ ends.
Width → weft yarns/ filling yarns/ picks.
Fabric count (thread count/ fabric construction)” how dense is the fabric according to the
yarns inserted per square inch of fabric. Warp / weft
A 300 count sheeting fabric → 150 warp and 150 filling yarns per inch.
16x12 → 16 warp and 12 weft
Over-construction → too many yarns → stiff fabric, poor drape or flexibility.
Often more warp than weft yarns.
Cross-over points present stress points, affect the stiffness and flexibility. Fewer interlacing
points → more flexible, softer.
More meters of yarn are inserted into the fabric than meters of fabric produced. Often
more warp crimp than weft crimp.
Weaving machine parts
, 1. Warps yarns are unwound from loom beam in sheet form.
2. Warp yarns are passed over a whip roll to guide the yarns forward (whip roll is
adjusted for warp yarn tension).
3. Warp yarn is threaded through metal drop wire → stop motion device. When yarn
breaks, wire drops, weaving machine stops.
4. Warp yarn goes through heddle.
5. Harnesses move up and down.
6. Warp yarns pass through reed → spreads warp yarn sheet out to width-in-reed
(WIR). Beats filling yarn into cloth fell.
Harnesses = metal frames that contain thin metal wired called heddles. In each heddle goes
a warp yarn. The harnesses move up and down, creating a design in the fabric.
Cloth fell= line across fabric width where yarns become woven fabric).
Large filling packages are placed at one side of the machine. Weft yarn comes off these
packages, pass through filling feeder (= winding device so weft is inserted).
Five primary motions:
1. Shedding (separation). By up and down movement of harness frames.
2. Weft insertion. Through open shed of warp yarns, weft yarn is inserted.
3. Beat-up. Reed moves forward beating the weft yarn into the fabric.
4. Unwinding of the warp yarns as the produced fabric passes.
5. Take-up to form a cloth roll.
The speed of unwinding the warp yarns must be higher than the speed of taking up the
fabric. Difference in speed → crimping of warp yarns as they are interlaced.
Only 24 to 28 heddles per inch can occupy a given harness. When the number of warp yarns
becomes larger, the number of harnesses must be increased so that the heddles will not be
too close together impeding the shedding process.
Primary weaving motions
Shedding
Separation of the warp yarns which provide an opening to insert the weft yarn.
, 1. Cam shedding
Very simple shedding. Utilizes rotating cams to lift and lower the harnesses. 6 to 8
harnesses. Only simple designs. Nowadays, some cam shedding machines can also have 14
harnesses. Plain, simple twill and satin weaves. Cams in oil bath.
each cam has a low and high profile. Rotates
on cam shaft so high and low profile come in contact with cam follower → connected to
lever/ jack → linked to given harness.
To change design → replace cams with cams of different shape/ profile.
Often, two harnesses contain warp yarns for forming the fabric edges/ selvages. The other
harnesses weave the rest of the fabric. Tucked-in selvage: tucks the end of each cut filling
yarn into the fabric edge.
2. Dobby shedding
Chains of wooden bars with pegs inserted, plastic paper with holes inserted, or computer
controlled (to dictate the design). Number of harnesses range from 8 to 28+. More complex
designs can be woven.
Electronic dobby controls raising and lowering the harnesses. Warp yarns are controlled by
harnesses.
Reader 1: Weaving fundamentals and design
Structure of woven fabric
Interlacing two sets of yarns
Length → warp yarns/ warp ends/ ends.
Width → weft yarns/ filling yarns/ picks.
Fabric count (thread count/ fabric construction)” how dense is the fabric according to the
yarns inserted per square inch of fabric. Warp / weft
A 300 count sheeting fabric → 150 warp and 150 filling yarns per inch.
16x12 → 16 warp and 12 weft
Over-construction → too many yarns → stiff fabric, poor drape or flexibility.
Often more warp than weft yarns.
Cross-over points present stress points, affect the stiffness and flexibility. Fewer interlacing
points → more flexible, softer.
More meters of yarn are inserted into the fabric than meters of fabric produced. Often
more warp crimp than weft crimp.
Weaving machine parts
, 1. Warps yarns are unwound from loom beam in sheet form.
2. Warp yarns are passed over a whip roll to guide the yarns forward (whip roll is
adjusted for warp yarn tension).
3. Warp yarn is threaded through metal drop wire → stop motion device. When yarn
breaks, wire drops, weaving machine stops.
4. Warp yarn goes through heddle.
5. Harnesses move up and down.
6. Warp yarns pass through reed → spreads warp yarn sheet out to width-in-reed
(WIR). Beats filling yarn into cloth fell.
Harnesses = metal frames that contain thin metal wired called heddles. In each heddle goes
a warp yarn. The harnesses move up and down, creating a design in the fabric.
Cloth fell= line across fabric width where yarns become woven fabric).
Large filling packages are placed at one side of the machine. Weft yarn comes off these
packages, pass through filling feeder (= winding device so weft is inserted).
Five primary motions:
1. Shedding (separation). By up and down movement of harness frames.
2. Weft insertion. Through open shed of warp yarns, weft yarn is inserted.
3. Beat-up. Reed moves forward beating the weft yarn into the fabric.
4. Unwinding of the warp yarns as the produced fabric passes.
5. Take-up to form a cloth roll.
The speed of unwinding the warp yarns must be higher than the speed of taking up the
fabric. Difference in speed → crimping of warp yarns as they are interlaced.
Only 24 to 28 heddles per inch can occupy a given harness. When the number of warp yarns
becomes larger, the number of harnesses must be increased so that the heddles will not be
too close together impeding the shedding process.
Primary weaving motions
Shedding
Separation of the warp yarns which provide an opening to insert the weft yarn.
, 1. Cam shedding
Very simple shedding. Utilizes rotating cams to lift and lower the harnesses. 6 to 8
harnesses. Only simple designs. Nowadays, some cam shedding machines can also have 14
harnesses. Plain, simple twill and satin weaves. Cams in oil bath.
each cam has a low and high profile. Rotates
on cam shaft so high and low profile come in contact with cam follower → connected to
lever/ jack → linked to given harness.
To change design → replace cams with cams of different shape/ profile.
Often, two harnesses contain warp yarns for forming the fabric edges/ selvages. The other
harnesses weave the rest of the fabric. Tucked-in selvage: tucks the end of each cut filling
yarn into the fabric edge.
2. Dobby shedding
Chains of wooden bars with pegs inserted, plastic paper with holes inserted, or computer
controlled (to dictate the design). Number of harnesses range from 8 to 28+. More complex
designs can be woven.
Electronic dobby controls raising and lowering the harnesses. Warp yarns are controlled by
harnesses.
