Primary motions of Loom.

Fabric Manufacturing Engineering-II
Primary Motions
JAHID KHAN
LECTURER,
DEPATMENT OF TEXTILE ENGINEERING,
PORT CITY INTERNATIONAL UNIVERSITY.

Fabric
A manufactured assembly of fiber and/or
yarn produced by interlacing, interloping,
interbonding or intralooping having
substantial surface area which is
thousand times in relation to it’s thickness
and have sufficient cohesion to give the
assembly useful mechanical strength.

Types of Fabric
 Woven Fabric (Produced by Interlacing)
 Plain Weave Fabric
 Twill Weave Fabric
 Satin/sateen Weave Fabric
 Knitted Fabric (Produced by Interlooping)
 Warp Knitted Fabric
 Raschel
 Tricot
 Chrochet
 Milanese
 Weft Knitted Fabric
 Single Jersey
 Rib
 Purl
 Interlock
 Non Woven Fabric (Produced by Interbonding)
 Braid Fabric (Produced by Intralooping/Intertwisting)

LOOM:
 Loom is machine or device which is used to produce woven
fabric. It is the central point of whole process of cloth
production.
It is a device used to weave cloth. The basic purpose of any loom is to
hold the warp threads under tension to facilitate the interweaving of
the weft threads. The precise shape of the loom and its mechanics may
vary, but the basic function is the same.

CHRONOLOGICAL/ HISTORICAL DEVELOPMENT OF LOOM
Damask, Tapestry.1. Vertical loom:
2. Pit loom.
3. Frame loom.
4. Chittarangan/ Semi-automatic loom:Take up automatic but let off manually.
5. Hattersley loom.
6. Natural Source/ Ordinary power loom: a) Water wheel was until 195
b) Steam engine
c) Diesel engine
7. Electric power loom: 1st power loom 1784
1st weaving mill with power loom 1789
a) Large single motor
b) Large group motor
c) Individual motor in 1930
8. Modern loom:
a) Projectile
b) Rapier
c) Air Jet
d) Water Jet
e) Multiphase

PIT LOOM:
Weaving has a long tradition in Egypt going back as far
as 6,000BC during which time methods have changed
enormously. This simple pit loom is the kind that is
frequently found in farms and villages operated by men
and women who make carpets, chair covers, shawls,
blankets and bed covers
The weaver sits with his or her legs in the pit where there
are two pedals which open the warp threads allowing the
weft shuttle to pass through freely. This type of loom
leaves the weavers' hands free to pass the weft shuttle
through from side to side and to compress the weaving as
they go.

FRAME LOOM
 Simple and effective
- wonderful introduction to weaving
- very quick to warp and weave
- strong
- compact
Create wall hangings, cushions, tablemats and
coasters. The loom is ideal for students or any
weaver wanting a simple way to be creative. Made
from solid Silver Beech hard wood the frames are
strong and robust for a variety of warps and tensions.
Small and compact, the weaving frame is ideal for
taking on holiday. The finished piece can be left in the
frame and hung on the wall

 Loom motions: There are three types of loom
motions:-
1. Primary
2. Secondary.
3. Tertiary.
Primary motions are: a) Shedding b) Picking c)
Beating.
Secondary motions are: a) Take-up b) Let-off
Tertiary motions are: a) Warp stop b) Weft stop c) Reed
stop.
Drafting: The process of passing yarn through the drop wire
is called drafting.
Drawing: The process of passing yarn through the heald eye
is called drawing.
Denting: The process of passing yarn through the reed is
called denting.

POWER DEVELOPMENT OF LOOM DRIVE
1. Hand loom: Human power drive
2. Power loom:
1. Water wheel
2. Steam wheel
3. Diesel Wheel
4. Electric wheel
3. Large common motor (200loom/ motor)
4. Group motor ( 200 loom/ motor)
5. Individual motor invented at 1930
1. Direct drive
2. Indirect drive
6. Multiple motor : for each modern loom

What is Primary Motion..?
These are fundamental or essential mechanisms of loom.
Without these mechanisms, it is practically impossible to
produce a fabric. It is for this reason that these mechanisms
are called Primary mechanisms.

Types of Primary
Motion….
Shedding
Picking
Beat-up

SHEDDING:
 Dividation of warp threads into two parts for
insertion of weft threads is called shed and
mechanism of shed is called shedding.it is the
first primary motion of weaving.
Types of shed:
 Bottom close shed
 Centre close shed
 Semi open shed
 Open shed

Shedding Mechanism
The shedding mechanism separates the warp threads into two layers or
divisions to form a tunnel known as shed. The shed provides room for passage
of the shuttle.
Types of Shedding Mechanism :
1.Tappet Shedding Mechanism:
a. Positive tappet shedding
b. Negative tappet shedding
2.Dobby shedding Mechanism:
a. Positive dobby shedding
b. Negative dobby shedding
3.JacquardShedding Mechanism:
a. Single lift and single cylinder (SLSC)
b. Double lift and single cylinder (DLSC)
c. Double lift and double cylinder(DLDC)

BOTTOM CLOSE SHED
 This type of
A Bottom line of warp
B Rising and falling line
C An arrow showing the space
passed through
shedding is produced
by giving motion
only to threads that
are to form the upper
line.under this condition,
the warp is level in the
bottom line. Hence in
order to form a top shed
it is necessary to move
some threads through a
space equal to twice the
depth of a shed.
A
B
C

ADVANTAGE:
 Used in hand loom
 Alternate tightening and slacking the warp threads
produce a covered cloth
DISADVANTAGE:
 More stress or tension on top warp line
 Different tension on the warp threads
 Low speed
 Not possible to produce compact fabric
 Poor quality fabric
 More chance of breakage on top warp line
 More power consumption

CENTRE CLOSE SHED
 This type of shed is produced by imparting an upward
movement to those threads which are to form the top line
and a downward movement to the threads which are to form
the bottom line. Then after inserting pick both trhe lines
meet at the centre between the highest and lowest lines of a
divided warp
 A Closed warp line
 B, C Upper and lower lines of
a divided warp
 D Arrow showing the half distance
of a shed in an upward direction
E Arrow showing the half distance
of a shed in a downward direction
A
C
B
D
E A

ADVANTAGE:
 Equal tension on top and bottom warp line
 Less time required, so high production
 Less wear of the machine
 Less power consumption
 Less tear of the threads
DISADVANTAGE:
 Beat up takes place in the closed shed
 Compact fabric can not be produced
 Chance of weft being moved backward

SEMI OPEN SHED
 In this shed, the stationary bottom is retained but threads
for the top line either passes to bottom at one movement
and again carried to the top mid way and again carried to
top. In this shed close and open shed occurred
simultaneously. In it the stationary bottom line is retained,
but threads for the top line either pass to the bottom at
one movement, or are arrested midway and again carried
to the top. Such a shed can be formed as expeditiously as
an open shed, for the upward movement begins and ends
with the downward through movement, and the arrested
downward movement is converted into an upward
movement immediately the falling threads are in the same
plane as the rising ones. They all reach the top together
but the strain upon them is not equally distribut

SEMI-OPENSHED:
A STATIONARY BOTTOM LINE
B TOP POINT
C THE POINT WHERE DOWNWARD MOVEMENT CEASES IN THREADS
D, E SHOWING THE MOVEMENT OF THROUGH HEALDS
F ARROW SHOWING THE THREADS WHICH ARE TO LIFT FOR THE NEXT PICK
C
A
D
B
F
E

SEMI-OPEN SHED:
ADVANTAGE:
 Equal tension on the top and bottom warp line
 Beat up takes place in the close shed
 Speed faster
 For fency fabric
 Less power need
 Less tear of threads
 Possible to produce compact fabric
Disadvantage:
unusual movement

OPEN SHED:
 In open shed, the warp threads form two stationary lines,
the top line and the bottom line and changes are made by
carrying the threads from one fixed line to the other without
any interval.
 A, B Stationary warp line
C, D Arrows which show the movement of rising and
falling warp to equal the distance between A & B
C
A
D
B

OPEN SHED
ADVANTAGE:
 Beat up takes place in cross shed condition
 Equal tension top and bottom warp threads
 Faster speed
 Extensively used in tappet shedding mechanism
 Basic fabric (twill, sateen, plain) can be produced
 Less power consumption
 Less wear of loom
DISADVANTAGE:
 High breakage rate
 If higher no of heald shafts are used then warp in back
healds are more stained than the front ones

BASIC SHEDDING MECHANISMS:
1. Paddle/ treadle loom: hand loom
2. Tappet shedding mechanism
3. Dobby shedding mechanism
4. Jacquard shedding mechanism
5. Combined shedding

TAPPET SHEDDING
 A type of cam which transforms a rotary motion into a
reciprocating motion in rods and levers by sliding
contact is tappet.
When the receives a series of lifts, with intervals of rest
and thus forms a shed called tappet
Scope of tappet shedding:
 Maximum capacity 14 heald shafts
 Normally produce square design
 Only the basic weave and small design are produced

CONSTRUCTION OF TAPPET SHEDDING:
 The figure shows a negative tappet shedding mechanism. A pair
of tappets A and B are fixed to the bottom shaft C at 180 degrees
to each other. Two treadle levers D and E are connected to the
loom back-rail by a bracket F.
The bracket acts as a fulcrum for the levers. The two treadles
have teeth to carry the lamb rods G and H respectively. Two
heald shafts J and K are connected to the lamb rods. A top
reversing roller shaft Q carries two rollers of different diameters.
The roller of small diameter N is connected to a leather strap L to
which the front heald shaft J is connected. The roller P of large
diameter is connected to a leather strap M to which the back
heald shaft K is connected. The tappets A and B touch the anti-
friction bowls or followers R and S respectively, which are fixed to
the treadle levers. The heald shafts have heald eyes T and U
through which the war p threads pass X is the war p sheet and Y
is the cloth. The odd ends are passed through one heald shaft
while the even ends are passed through the other heald shaft.

WORKING PRINCIPLE OF TAPPET:
 When the bottom shaft is rotate as shown in the figure, the
tappets also rotate. The tappet will depress the anti-friction bowl
and the treadle. Being fulcrumed at one end, the front portion of
the treadle moves down. This action is transferred to the lamb
rod, the heald shaft and the leather strap. So one heald shaft is
lowered and the threads connected to this heald shaft are
lowered and form the bottom layer of the shed.
 The leather straps attached to the reversing rollers are
connected in opposite directions, i.e. when leather strap is pulled
down, it is unwound from its roller. The shaft therefore rotates in
the clockwise direction and the other leather strap is wound on to
its roller. The heald shaft is raised and therefore the lamb rod and
treadle lever are also raised. The threads connected to the heald
shaft are also raised and form the top layer of the shed.
 For the next shed, the other tappet works with the other set of
bowl, treadle, lamb rod, heald shaft, strap and roller and the other
heald shaft is lowered.

TYPES OF TAPPET:
 Negative tappet: in a tappet shedding
mechanism if the tappet controls only one
movement either an upward or downward
movement of heald shaft, then the shedding is
known as negative tappet shedding.
 Positive tappet: : in a tappet shedding
mechanism if the tappet controls both the
upward and downward movement of heald
shaft,then the shedding is known as positive
tappet shedding.

ADVANTAGES OF TAPPET SHEDDING:
 Simplest
 Cheapest
 If properly used, it gives the best results within
its capasity
 Action is certain
 It is capable of lifting heavy weights with less
wear and tear than other shedding mechanisms
 Less wear and tear
 Consumes less power and give greater output

DEFECTS OF TAPPET SHEDDING:
 Over shedding strains and breaks the warp
threads
 Under shedding does not permit the space to
pass the shuttle through the shed.
 Sometimes unequal shedding by lifting one end
of the shaft more than the other
 Missed shedding
 May impart jerky motion
 Capacity is only 14 healdshaft

Picking
• Picking: Picking is the second primary motion in the weaving. It is
the action of filling insertion the weft through the shed from one
edge of fabric to the other edge.
• The object of picking is to insert the weft yarn through the warp sheet
during
weaving.
• Types of picking:
1. Conventional picking mechanism or negative picking
mechanism
2. Unconventional picking mechanism or positive picking
mechanism
• Conventional Picking mechanism – types
1. Overpick mechanism – Cone overpick mechanism
2. Underpick mechanism
a) Side- lever underpick mechanism
b) Side- shaft underpick mechanism
c) Cone underpick mechanism

Over Pick Under Pick
1. Arm position is above the shuttle box. 1. Arm position is below the shuttle box.
2. Higher loom speed. 2. Lower loom speed.
3. Less power required. 3. More power required.
4. Works more smoothly. 4. Works less smoothly.
5. Less clean mechanism. 5. More clean mechanism.
6. Less direct action. 6. More direct action.
7. Comparatively gentle in picking
action.
7. Comparatively harsh in picking action.
8. Less wear and tear. 8. More wear and tear.
Over Pick: When picking arm position is situated above the shuttle box then it is
called over pick.
Under Pick: When picking arm position is situated under the shuttle box then it
is called under pick.
Difference between over pick and under pick:

Cone overpick mechanism
.
Working flowchart of tappet cone over picking mechanism:
With the rotation of loom/bottom shaft, picking tappet or cam
rotates
↓
In revolving, picking tappet nose strikes the cone shaped
antifriction roller on the stud and partly rotates the picking shaft
and the picking lever/stitch
↓
The picking arm/lever moves from right side to left side of the
loom. It will give angular movement which causes the picker to
move inward with sufficient velocity to drive the shuttle across the
loom
↓
When the picker strikes the shuttle, the shuttle moves into the
open shed through race board
↓
Picking is done
↓
The spring causes the picking arm and picker to move back after
the delivery of a pick.

Cone over picking mechanism
Cone overpick mechanism

Cone under picking mechanism:
Working Flow Chart of Cone Under Picking:
The tappet is driven by the bottom shaft
↓
When the picking tappet strikes the picking cone, it displaced and the side shaft is
turned
↓
The turning action of side shaft pulls the picking stick which is connected to side shaft
by picking strap
↓
The lower end of picking stick is pivoted. So that is pulled with the pulling of side shaft
↓
Then the picker connected to picking arm strikes the shuttle and causes it to pass
through the warp shed
↓
Picking is done

Loom Timing diagram
• All events on the loom are to be properly synchronised which can be demonstrated
on a loom timing diagram.
• However, all the basic motions of a loom have to be completed in 360°
• The shuttle starts moving at around 80° following the beatup.
• The contact between the shuttle and the picker lasts around 30° which corresponds
to approximately 20 cm.
• At this position, the shuttle reaches a speed of around 15 m/sec, the picker stops
pushing the shuttle and the shuttle flies across the loom byitself.
• Once at the other side of the loom, the shuttle is brought to a stop by thechecking
mechanism which is similar to picking.
• Insertion with shuttle is an inefficient process in the sense, that the shuttle weighs
0.5 kg while the weight of the inserted weft is less than 1/1000 of the shuttle weight

• If the picking mechanism behaves as a simple elastic system, it can be
represented by a mass in series with a spring. In fig, the mass M, which
rests on a smooth, horizontal surface, represents the shuttle, and the spring
represents the elasticity of the picking mechanism.
PICKING MECHANISM AS ASIMPLE
ELASTIC MATERIAL
An elastic model of the picking mechanism

Beat-up
• Beating up is the third and final primary motion in weaving; it performs driving
the last pick of weft to the fell of the cloth.
• The object of the beatup mechanism is to push the last laid weft thread into
the fell of the cloth by means of a reed.
Types of Beating Up:
1.According to number of beat-up:
1.Single beat-up.
2.Double beat-up.
2.According to beat-up mechanism:
1.Conventional beat-up.
2.Cam beat-up.
3.According to movement of reed:
1.Real beat-up.
2.False beat-up.
4.According to Fell of the cloth:
1.Fixed fell beat-up.
2.Moving fell beat-up.

Single beat mechanism
The lower end of sley sword is pivoted to the rocking shaft and the sley race
is connected to the sley-sword and reed.
The connecting rod or crank arm is connected to the back of sley-race by a
pin called sword pin and its other end fastens round the bend in the crank
shaft, known as cranks.
Working principle: For beating up process, the sley sword must reciprocate;
the sley sword is connected to the rocking shaft for this purpose.
When the crank of the crank shaft rotates and comes in forward position (at
90°), then it pushes the crank arm forward. Thus crank arm gives to purpose.
and fro movement.
As the crank arm is connected to the sley race and reed is situated above
the, reed race, reed also moves for vard as the crank arm move forwards.
The reed pushes the weft in the fell of the cloth. In this mechanism, one beat
up is done for every picking.

Double beat up sley:
Construction: Construction by a sley sword, a crank, a connecting arm, two
arms one of them is hinged to the framing & other is attached to sley by
usual connecting pin.
Working principle: In one drawing the arms E & F are straight but when the
crank moves to the top centre it is pushed up & E,F are bent.
When the crank moves & there comes a stage when the arm become s
traight & a beat-up is done by the system. When the crank again moves up,
the knuckle joint moves up & again the arms become straight & cause beat-
up. Hence the two beat up is done for a pick.
The time, that elapses between the first & second straightening, can be
increased either by moving the crank centre up or by lengthening the crank
arm
Lowering the crank or shortening connecting arm can reduce time
Lengthening the size of the crank the force of beat up may also be
increased

Motion of sley
The sley is wooden frame accommodating two shutte boxes, a
sley race, a reed, a reed cap and two sley- swords. It swings
forward and backward. At its forward and two sley- motion, the
last pick of weft is beaten up to the fell of the cloth and at its
backward motion the shuttle is allowed to pass over the sley-
race through the open shed. So its forward centre position is
known as beating up position and the back centre position is
called shedding and picking position
The sley gets motion from the rotation of crank via a erank
arm. When the crank shaft rotates it pushes and pulls the sley
with the help of it pushes and pulls the sley with the help of the
crank arm in forward and backward direction.

Primary motions of Loom.

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