Safety points while switching of the weaving machine

 Safety points while  switching  of the weaving machine     

Safety points while Running of Weaving Machines

Before starting the weaving machine, a weaver should know about the safety points and operations of running a weaving machine as follows:

1. Checking the weaving machines.



a. Switches: Red switches generally used should be on, during weaving machine in OFF position, Green switch should be on, during weaving machine in ON (working) position.

b. Starting handle: Red switch should be on, during weaving machine in OFF position, Green switch should be on, during weaving machine in ON (working) position.

c. Let off mechanism

d. Take up mechanism

e. Crank & crankshaft

f. Sley, race board and reed

g. Shuttle boxes & shuttles

h. Starting handle and brake

i. Emery & cloth roller

j. Top rollers (for heald shaft movement from top)

k. Tie rods (for heald shaft movements from the underside)

l. Loom crown



2. Running the looms, replacing the pins in the shuttle, attending breaks and unweave and correct the damages in the fabric



a) Loom to be at a correct position before the start.

b) Two shuttles on each loom should be in good condition.

c) Shuttle in the box should have groove and eye in the front.

d) Shuttle box spring should grip the shuttle properly, neither too tight nor too loose.

e) Yarn of the pirn should be properly passed through the shuttle guide/eye so as to be released smoothly, without obstruction.

f) If there are nylon loop tensioners provided in the shuttle, the same should be in good condition.

g) The loose end of yarn from a fresh shuttle should be attached to the temple before inserting shuttle in the shuttle box.

h) Fresh pirn in the empty (extra) shuttle should be fixed immediately after starting loom with a new pirn.

i) There should be a sufficient number of weft pirns available on each loom.

j) Empty pirns should be kept in a separate box and not mixed with full pirns.

k) At the start, 1-2 picks should be inserted holding starting handle with hand, out of its notch. If there is no problem, starting handle should be pressed into its notch.

l) Warp shed should be clearly open such that shuttle does not fly out.

m) Brakes should stop loom in the right position.

n) Loom should always be rotated in the right direction for any operation.

o) The fresh pick should be inserted in a new warp shed and two picks should not be inserted in one shed.

p) If there is a double pick at fell of the cloth, it should be removed, the fabric should be loosened slightly by take-up release and reed at the front centre.

q) There should not be any starting mark when the loom is started after a stop.

r) There should not be any thick & thin weft bars (Jhiri& Patti) in the fabric during weaving.    

s) In the event of a warp break, loom should be immediately stopped and broken warp should be tied with extra ends with a weaver’s knot and then drawn in the right heald wire and right dent of the reed.

t) If a slub, thick yarn, big knot or long tail end is observed in warp sheet, loom should be stopped and a fresh yarn should be tied in place of defective yarn.

u) If there is a patch of floating warp & weft (Jala), it should be removed by stopping the loom and unweaving the defective part of the fabric and then loom should be restarted properly.

v) If warp has a colour pattern, it must be ensured that the pattern is maintained as it is while attending warp breaks.

w) The operator should keep on patrolling around the running looms and see whether there is any problem which may lead to stoppage of the loom or may create a defect in the fabric. In such an event, precautionary action must be taken immediately.

1. To maintain optimum possible production with good quality in respect of patterns, proper picks, thick & thin places, broken threads, clear selvedge, cloth cover, starting marks etc.



2. basic functions performed by a pirn, shuttle and its major parts:
method of fabric production in which two sets of yarns namely warp and weft are interlaced at right angles to form a fabric. The warp yarns (or ends) run lengthwise in the fabric, and the weft yarns (or picks) run from side to side. The machine which is used to produce the fabric is called weaving machine or loom.

Basic Mechanisms of a Plain Powerloom

In order to interlace warp and weft threads to produce a fabric, the following mechanisms are necessary on any type of loom:

1. Primary mechanisms

2. Secondary mechanisms

3.Auxiliary mechanisms

1. Primary Mechanisms

These are fundamental or essential mechanisms. Without these mechanisms, it is practically impossible to produce a fabric. It is for this reason that these mechanisms are called ‘primary’ mechanisms. The primary mechanisms are three in number.

a. Shedding mechanism

b.Picking mechanism

c.Beat-up mechanism

1a. Shedding mechanism: The shedding mechanism separates the warp threads into two layers or divisions to form a tunnel known as ‘shed’.

Shed: space created when selected warp threads are raised and lowered through which the weft is passed.

1b. Picking mechanism: The picking mechanism passes weft thread from one selvedge of the fabric to the other through the shed by means of a shuttle, a projectile, a rapier, a needle, an air-jet or a water-jet. The inserted weft thread is known as “pick”.

1c. Beat-up mechanism: The beat-up mechanism beats or pushes the newly inserted length of weft thread (pick) into the already woven fabric at a point known as “fell of the cloth”.


These three mechanisms namely shedding, picking and then beat-up is done in sequence.

2. Secondary Mechanisms

These mechanisms are next in importance to the primary mechanisms. If weaving is to be continuous, these mechanisms are essential. So they are called the ‘secondary’ mechanisms. They are:

a. Take-up motion

b.Let-off motion

2a. Take-up motion: The take-up motion withdraws the cloth from the weaving area at a constant rate, so as to give the required pick-spacing (in picks/inch or picks/cm) and then winds it on to a cloth roller.

2b. Let-off motion: The let-off motion delivers the warp to the weaving area at the required rate and at constant tension by unwinding it from the weaver’s beam.

The secondary motions are carried out simultaneously.

3. Auxiliary Mechanisms

To get high productivity and good quality of fabric, additional mechanisms, called auxiliary mechanisms, are added to a plain power loom. The auxiliary mechanisms are useful, but not absolutely essential. This is why they are called the ‘auxiliary’ mechanisms. These are listed below.

a. Warp protector mechanism

b.Weft stop motion

c.Temples

d.Brake

e.Warp and weft stop motion

3a. Warp protector mechanism: The warp protector mechanism will stop the loom if the shuttle gets trapped between the top and bottom layers of the shed. It thus prevents excessive damage to the warp threads, reed wires and shuttle.

3b. Weft stop motion: The object of the weft stop motion is to stop the loom when a weft thread breaks or gets exhausted. This motion helps to avoid cracks in a fabric.

3c. Temples: The function of the temples is to grip the cloth and hold it at the same width as the warp in the reed before it is taken up.

3d. Brake: The brake stops the loom immediately whenever required. The weaver uses it to stop the loom to repair broken ends and picks.

3e. Warp stop motion: The object of the warp stop motion is to stop the loom immediately when a warp thread breaks during the weaving process.

Warp protector mechanism

4. Weaving Process

The sequence of operation in the weaving process for warp threads and

the sequence of operation in the weaving process for weft threads are as follows:

Weaving Process

Weaving Machine

Weaving Machine

5. Basic loom parts

5.1. Weavers beam: It is a wooden or metal cylinder on the back of the loom on which the warp sheet is wound.

5.2. Warp sheet: It contains the warp threads extend in parallel order from the weaver's beam.

5.3. Backrest: It provides the support to the warp sheet which is coming out of the weaver's beam.

5.4. Drop pins: It is supported by the warp thread and whenever a thread breaks or loosens, the drop pin - is no longer supported - drops and gives a signal for warp stop motion.

5.5. Reed: It is a metallic comb which is used to push the weft yarn securely in the fell of the cloth, separates the threads and keeps them in their position.

5.6. Shed: It is the triangular space, made by the upward and downward motion of the selected warp threads, through which the weft is passed in a straight motion.

5.7. Shuttle: It is a wooden tool which is used to carry the weft thread through the shed.

5.8. Front rest: It provides support to the cloth.



5.9. Cloth guide roll:It guides the cloth being wound on to the cloth roller.





5.10. Emery roller: It is a roller which provides tension to the cloth before its winding on the cloth roll.

5.11. Cloth roll: It is the roller on which the woven cloth is wound.

5.12. Rocking shaft: It is an axle which provides support to the sley.

5.13. Sley: It is responsible for pushing up the weft thread to the fell of the cloth and hence does the beat-up motion.

5.14. Heald frame: It is a wooden/metallic frame containing heads through which the warp threads pass and it separates the warp threads into two or more groups.

5.15. Heald eye: It is the opening (or eye) of the head wire through which each thread or group of thread passes.

5.16. Sley race: It is made up of wood and provides support to the shuttle

5.17. Temple: The temples are used to hold fast the width of the woven cloth as equal to as possible to the width of the warp.

5.18. Tension rod: The tension rod is used to hold fast the width of the woven cloth under a tensioned condition in the cloth roller.

5.19. Passage of the warp yarns: The warp yarns passes from the weaver's beam which is generally placed at the back side of the weaving machine. The passage of warp through a loom is shown in figure 2. The warp after leaving the weaver’s beam 1 pass over two bars 2 and 3 connected by a bracket at each end. One half of the warp end now passes under the back lease rod 4, and the other half passes over this rod. Those warp ends which pass under the back lease rod pass over the front lease rod 5, and ends from over the back lease rod pass under the front lease rod. Therefore, the warp is completely divided as it passes through the lease rods, and facilitates the straightening of any warp ends which may break and become entangled before they reach the heads 6 and 7. The lease rods also assist in forming an even shed.

Leaving the lease rods, the warp ends next pass through the heads. Odd numbered pass through the front heald7, and the even numbered ends pass through the back heald 6. The heads consist of heald wires with eyes at the centre through which the warp ends are passed, the warp ends being thus controlled in their upward and downward movement. The warp ends next pass through the reed 8, this being comprised of a flat wire comb with the teeth secured at both ends. Usually, two ends pass between one tooth and the next—this space being termed “dent”. In the figure, two warp ends are represented as being in the same dent.

At point 9 is what is known as the ‘Cloth fell’. It may be considered as the point where the warp and weft become cloth because it is at this point where the last pick of weft, which was left by the shuttle, becomes beaten up. Passing forward, the cloth is held at each side by a temple 10 which holds the cloth fell out to the width of the warp yarn, in the reed. From the temples, the cloth passes over the breast beam/front rest 11, partly around the sand or emery roller K, over the steel roller, or tension rod L, and then on to the cloth roller M.

6. Machine types, side and passage of warp through weaving machine parts
6.1. Machine type: The weaving machine can be tappet loom, dobby loom or jacquard loom. Mostly plain power looms that are run by a weaver for 4 looms are Tappet looms.

6.2. The side of the Machine: The weaving machines are also termed as Left hand or Right hand loom depending on the position of the starting handle of the loom.

6.3. Size of the Machine: The weaving machines are also categorised according to the size of the loom depending on the width of the machine, like 48”, 72” or 108” loom.