factors affecting production in spinning mill

8/10/2019 Factors Affecting Production in Spinning Mill

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Factors affectingProduction in Spinning

Mill


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Raw material

Labour

Machinery


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Raw material

FIBER LENGTH

STAPLE LENGTH, SPAN LENGTH AND

EFFECTIVE LENGTH


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1.If fibershave good staple length it results in

the form of high production, because less TPI

is required to give enough strength.

2.Higher percentage of short fibers will result in

the form of production losses due to more

end breakage and higher twist per inch.
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3.Fiber maturity, in case of immature fibers it

results in the form of production loss.

Because the yarn made from these types of

fibers have poor strength and also it producesbreakage in spinningdepartment.
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4.Fiber strength is the dominating feature offiber.

When fiber strength is higher it outcomes inthe form of high production due to less twistmultiplier.


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Labour

Labourplays a very crucial role becausewithout their participation nothing could be

done.

The proper way to improve productivity intextile mills is first to take those workers


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Machinery

Machinery is the back bone of every industry.

In the textile industry machineare working 24hours so it is important that its efficiencywould be excellent.
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While analyzing in Ring Department, during working

stoppages may occur due to the following reasons.

Ends down

Doffs

Creeling Bobbin size

These factors affect the productivity to a great extent.

If we control these stoppages then production can beincreased and it also has an impact on yarn qualitywhich is improved under the same conditions of costand labour charges.


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Ends Down

The end down is due to the less strength of yarn andgreater spindle speed.

Adding to stops, no. of spindles per frame, lift of bobbin railand cleanliness of the department also affects the

production.

More number of spindles on a frame increases itsefficiency.

Cleanliness means no fibrous mass is floating inatmosphere of ring otherwise ends down rate will beincreased.


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Doffs

Doffing means removal of full size package and replacing itwith the empty one.

During doffing, the machine is stopped and it is carried out

by skilled workers.

For coarse count like 7s, 10s etc, doff time is less and forfiner count like 30s, 40s etc, time is more. For 20S it takes90-110 min for complete doff.

During doffing, it should be kept in mind that it should becarried out in the shortest possible time.


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Creeling

The changing of the roving bobbin when it isempty and to replace it by a new full roving

bobbin is called creeling.

Creeling time should be as small as possible.


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Bobbin Size

The production can be increased by increasing the bobbinsize because with a bigger bobbin less doff is required per

shift.

The Bobbin size depends on ring dia, but as we increase thering dia, ends down rate also increases so it also has a limit.

Usually 42 mm ring dia is available on which 40 mm diabobbin can be prepared.


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Maintenance

Proper maintenance of machine is necessary otherwiseit results in the form of many problems like sudden

shut downs and big production loss.

Proper maintenance results in the form of efficientworking of machine and good outputs.

For example by proper maintenance and by properpreparation of roving it results in the form ofminimizing the end breakage rate.


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Improving productivity of ring

frames

Functions of ring frame:

1.To draft the roving until the required fineness

is achieved,

2.To impart strength to the fibre, by inserting

twist

3.To wind up the twisted strand (yarn) in a form

suitable for storage, transportation and

further processing


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Drafting zone

Drafting type

Design of drafting system

Drafting settingsSelection of drafting elements like cots,

aprons, travelers, etc

Choice of appropriate draftService and maintenance


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Drafting arrangement influences the economics of themachine -- directly by affecting the end-break rate andindirectly by the maximum draft possible.

If higher drafts can be used with a draftingarrangement, then coarser roving can be used as afeeding material.

This results in higher production rate at the rovingframe and thus reducing the number of rovingmachines required, space, personnel and so on.


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In fact increase in draft affects the yarn quality

beyond certain limit.

Within the limit some studies show that

increase in draft improves yarn quality


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Twisting zone

Traveler imparts twist to the yarn. Traveler and

spindle together help to wind the yarn on the bobbin

Length wound up on the bobbin corresponds to thedifference in peripheral speeds of the spindle and

traveler.

The difference in speed should correspond to lengthdelivered at the front rollers. Since traveler does not

have a drive on its own, it is dragged along behind by

the spindle.


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High contact pressure (up to 35 N/square mm)

is generated between the ring and the travelerduring winding, mainly due to centrifugalforce.

This pressure leads to generation of heat. Lowmass of the traveler does not permitdissipation of the generated heat in the shorttime available.

As a result the operating speed of the traveleris limited.


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When the spindle speed is increased, the friction

work between ring and traveler (hence the build-up) increases as the 3rd power of the spindle rpm

Consequently if the spindle speed is too high, thetraveler sustains thermal damage and fails.

This speed restriction is felt particularly whenspinning cotton yarns of relatively high strength.


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If the traveler speed is raised beyond normal

levels, the thermal stress limit of the traveler

is exceeded; a drastic change in the wear

behaviour of the ring and traveler ensures.


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Winding zone

The bobbin is formed in three parts:

1.The curved base2.The cylindrical body and

3.The conical top


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The winding procedure is:

The ring rail is raised slowly to wind the yarnand is then moved downward at a higher

speed to lay coils at an increased helix angle

to lock-in the previous layer.


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The combination of the two layers havingdifferent winding angles is beneficial in thestability of the build in the re-winding process.

Occasionally the spinning ends down will behigher during the faster downward movementand should be considered in setting up thespeeds and conditions of the machine.

The stroke is short at the beginning of the buildand is increased throughout the formation of thecurved base. After the base formation the strokelength remains constant.


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The upward and downward movement is referred to asthe stroke.

The height of the stroke is normally about 15 to 20%greater than the diameter of the ring.

The downward movement of the ring rail is 2 to 3 timesfaster than the upward movement.

The combination of the two layers having differentwinding angles is beneficial in the stability of the build inthe re-winding process.


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Occasionally the spinning ends down will be

higher during the faster downward movementand should be considered in setting up the

speeds and conditions of the machine.

The stroke is short at the beginning of the

build and is increased throughout the

formation of the curved base. After the base

formation the stroke length remains constant.


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End Breakage in Spinning

One basic way to increase the profit andquality in ring spinning process is to keep theend breakage rate to a minimum level.

The end breakage is a critical spinningparameter that not only affects the maximum

spindle speed but may also indicate thequality of yarn, the mechanical condition ofthe machines and the quality of raw material.


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End breaks is an important parameter which

determines the overall working of a spinning

mill.

Any attempt to explain the end breakage

mechanism in terms of qualitative approach

will provide an aid to understanding the

problem and to tackling it to any possibledegree.


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To reduce end breaks, the following

few aspects should be taken into

consideration.

1. The width of the drafted ribbon at the front

roller nip should be reduced.

2. Measures to be taken to reduce mass

irregularity of yarn straight after carding.


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3.A reduction in friction between ring and travelercould reduce the peak tension during the rotationof the traveler.

4. Since the end breakage in ring spinning is relatedto slippage of fibers at the spinning triangle as aresult of peaks occurring in the spinning tension

fiber, the grip at the front drafting rollers shouldbe increased by having a higher top rollerpressure.


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The use of softer cots also enhances the gripat the front roller. If the total pressure on therollers can not be increased.

The grip at the front rollers nip can beimproved by reducing the width of cots.

5. The permutation and combination of speedsat different stages of cop build in ring framescan help a lot in reduction of breaks.


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6. In case of spring loading top arms in ring

frames, when you restart the ring frame after

a mill holiday, the breakages are very high.

7. In case of pneumatic loading top arms ring

frames, when you restart the ring frame after

a mill holiday, the breakages are very high.


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The practice of tightening the material in

drafting zone by reversing the back & middle

rollers with the help of back roller wheel

before starting the machine helps in reductionof end breaks during starting of the ring

frames.


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1. The lowering of spindle speed by 5 to 6%

just after putting new travelers for 2 hours forrunning-in of travelers helps in reduction of

end breaks to large extent.

2. The use higher twist multipliers willreduce breaks even at higher spindle speeds

than at lower spindle speeds with low twist

multipliers.


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3.The higher twist than required in roving reduces thecreel breaks in ring frames.

4. The delay in change of travelers will increase end

breaks in spinning. Hence timely change of travelers isa must.

5. The use of common tube suction system improves

suction of pneumafil system further without increasingpower consumption compared to individual suctiontube system in ring frame and reduces end breakagesto a large extent.


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6. Any compromise in right selection of fibre

properties may lead to higher end breakages

in spinning ring frames.

7. The frequent stoppage of Over Head

Travelling Cleaners accumulates fly and results

into higher breaks due to loading of traveler

with fly.


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The end breakage in spinning not only

increases physical exercise of workmen, but

also increases waste.

Hence ultimate effect is on productivity of

spinning mill.

factors affecting production in spinning mill

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