ASSIGNMENTASSIGNMENT

ON ON COMBING PROCESSCOMBING PROCESS

Course code Tex-205Course title Yarn Manufacturing

Technology-IISubmitted Date 23th December 2008

Submitted by

Name Muhammad Riyaz- ul- IslamID 06313241

Program BSTEBatch 4th

Semester Fall-2008

Submitted ToMD ROKONUZZAMAN KHAN

LECTURER OF BSTECITY UNIVERSITY

Page 1 of 11

THE COMBING PROCESSThe combing process is normally used to produce smoother finer stronger and more uniform yarns Therefore combing is commonly confined to high grade long staple natural fibers In recent years combing has been utilized for upgrading the quality of medium staple fibers In addition a yarn made of combed cotton needs less twist than a carded yarn However these quality improvements are obtained at the cost of additional expenditure on machines floor-space and personnel together with a loss of raw material Yarn production coast is increased by something under 1 US$Kg of yarn (depending on the intensity of combing) To improve the yarn quality the comber must perform the following operations Elimination of precisely pre-determined quantity of short fibers Elimination of the remaining impurities Elimination of a large proportion (not all) of the neps in the fiber material Formation of a sliver having maximum possible evenness Producing of more straight and parallel fibers

Elimination of short fibers produces an improvement mainly in staple length but also affects the fineness of the raw material The micronaire value of combed sliver is slightly higher than that of feedstock (elimination of dead fibers) Also the degree of parallelization might reduce the inter-fiber adhesion in the sliver to such an extent that fibers slide apart while being pulled out of the can ndash ie sliver breaks or false drafts might be caused Types of applicationsThe amount of material combed out varies within the range 5 ndash 25 of the in feed stock Three major groups of spinning mills using combing are as follows

1048766Long staple combing mills Processing first-class expensive cotton of high strength containing a low proportion of short fibers and little dirt The product is a fine to very fine yarn of top quality The demands placed on know-how and skill of operating personnel is correspondingly high as they are on the design and maintenance of the machines Yarn production is low while generation of noil is high

1048766Medium-staple combing mills here medium cotton qualities with a wide spread of quality parameters are spun to medium (to fine) yarns of good quality at economic production costs The process is problematic in that it has to achieve a high strand of quality and at the same time give high production at low cost The maximum demands placed on medium staple combing can only be fulfilled by optimally trained personnel

1048766Short (to medium) staple combing mills raw material used have the same as that for production of carded yarns In comparison with a carded yarn the combed yarn should chiefly exhibit better smoothness and strength In this combination with low level noil level (6 ndash 14) This process is the most widely used in practice it is technologically undemanding and can be operated without problems when good machines are available

Page 2 of 11

Lap preparation system for combingThere are used two systems for lap preparation

1) Old system I Sliver lap machine II Ribbon lap machine

2) Modern system Super lap former machine

Types of comber The major types of combers include

1048766Rectilinear comber (For short staple spinning ie cotton) 1048766Circular combers (For worsted process ie wool) 1048766Rotary comber (Production of Schappe spun yarns ie silk) and 1048766Hackling machines (Bast fibers ie jute)

The short staple spinning mill uses only the rectilinear comber with swinging nippers and stationary detaching rollers as originally developed in 1902 by the Englishman Nasmith and in 1948 by whitin company Machine layouts used in practice comprise single sided machines with eight heads

Effect of change of setting sliver quality If staple length 1-18˝ Roller setting should be for front zone- 41mm back zone-

44 mm If staple length below 1-18˝ Back zone amp front zone should be closed 05-1mm If staple length above 1-18˝ Back zone amp front zone should be wide 05-1mm

Bottom roller setting depends on staple length of fibre If roller setting is not properly as per staple length then good fibre will rupture CV will increase of sliver amp finally CV hairness amp end breakage will increase amp yarn strength will decrease

The Combing Machine The basic elements of the combing machine are shown in figure These are the feeding

element the nipper plate the combing system and the detaching rollers The feeding element consists of a feed plate and feed roll The main function of the feeding element is to feed the comber lap in a series of short lengths The nipper plate grips the fibers as a means of holding long fibers while the short fibers neps and trash are being removed The combing system

Page 3 of 11

consists of two combs The first one is a rotating bottom circular comb that performs the main combing action The second one is a linear top comb that completes the function of the bottom comb through vertical combing movement The detaching rolls are two pairs of gripping rolls that rotate forward and backward in intermittent fashion to hold and move the combed web for a net forward travelThe objectives of combing mentioned earlier are accomplished by a precise sequence and synchronized series of actions performed by the combing elements The following text will review this sequence of actions or the combing cycle in a very simplified manner to demonstrate the function of each comber component

Fig Combing machine

Principle of comber Cylinder comb amp top comb extract short fibres impurities amp neps The comb fleece is compressed to form sliver amp the doubled amp drawn in the

drafting system

Main components of combing machine

1 Feed roller It controls the feed amount

2 Cylinder comb amp Top comb They extract short fibres impurities amp neps

3 Nipper The combing nipper performs forward amp reverses movements with the feed roller amp helps to extract waste

4 Detaching roller It moves to amp fro amp helps to extract waste

5 Index wheel Comber lap feeding nipping combing amp delivery are completed by one full revolution of index wheel This is called combing cycle

Page 4 of 11

The Combing Cycle The following figures illustrate the different actions involved in the combing cycle The principle of combing is to advance a pre-determined portion of the fiber lap to the combing station This portion is then gripped by a pair of nipper plate while a toothed half (bottom comb) is combing the fiber fringe and removing the short fibers neps and trashes This waste (noil) is later removed from the needles of the bottom comb using a revolving brush The detailed actions are illustrated in the figures

Page 5 of 11

Technical data of combing machine

Precomb drawing is essential for combing operation In carded sliver fibres are oriented in different direction variation of weight unit length of sliver more amp amount of hooked fibre also more Fibre parallelization less

So long fibres also remove with short fibres in combing amp waste extraction increases

If precomb drawing uses fibres are more parallel in sliver weightunit length variation also reduces More ever by using precomb drawing less needle damage less fibre breakage amp waste extraction reduces

So precomb drawing must be used in combing operation

Effect of temp amp humidity in combingLack of atmospheric moistureStatic electricity resulting in roller lapping split slivers increase in fly waste As a result sliver quality will deteriorate

Too much atmospheric moistureSticky condition between the cotton fibers amp running surfaces resulting in roller lapping sliver irregularity amp low production

So recommended relative humidity amp temp for combing section is RH-(50-52) Tem-(27-29˚C)

Page 6 of 11

1) Number of combing head doubling

8

2) Number of deliveries 13) Nipsmin Maximum 450 npm4) Feedmin Maximum 59 mm5) Noil 10 ndash 256) Efficiency 90 ndash 957) Production Maximum 60 kgshour8) Delivery sliver weight 3 ndash 6 ktex or 3- 6 gmsmetre9) Total draft 912 ndash 2510) Break draft 113 ndash 2011) Bottom roller setting-

Front zone 41 mmBack zone 44 mm

Drafting system of comber machine Drawing amp doubling are the purpose of drafting system The drafting work in drafting system is performed by the break draft amp main

draft In the drafting system the fibre mass is evened by doubling amp the fibres are laid

parallel by drafting The pressure bar guides the fibres in the main draft The total draft includes both break draft amp main draft The main draft ie front zone amp break draft ie back zone is adjustable amp

depends on fibre length The main draft converts the fibre mass to the final count amp parallels the fibre The break draft helps to reduce the irregularity of sliver By using the pressure bar the floating short fibres are guide better

Sliver coiling system It consist of coiler amp calender roller

Coiler Convering the sliver compressing the sliver amp depositing the sliver in the cam

Calender roller The calender roller draws the sliver through the funnel amp compresses it so that it holds together

Neps removal efficiency of combing (NRE) How much neps remove from comber lap by using combing machine is called neps removal efficiency It is expressed on percentage

NRE = (Neps gm in comber lap ndash Nep gm in comber sliver) Neps gm in comber lap

THE TECHNOLOGY OF COMBING Parameters influencing the combing operation

Raw material Fiber type fiber length uniformity of fiber length (cv) fiber stiffness moisture content

Material preparation Parallelization of fibers in sheet sheet thickness sheet evenness orientation of hooks

Factors associated with machine Condition of machine condition of combs speeds operation of combs type of piecing accuracy of setting drafting arrangement

Machine setting Feed distance type of feed detachment setting point density of combs piecing draft and draft arrangement settings Ambient conditions Room temperature humidity

Page 7 of 11

Influence of feed stock on combing Parallelization of fibers in the sheet

1048766Lake of longitudinal orientation ie noticeable fiber disorder leads to elimination of longer fibers and hence overloading the cylindrical comb (Thick sheet)

1048766At same machine settings noil quantity decreases linearly with increasing parallelization of the fibers without any reduction in yarn quality (see figure 17)

1048766It is not always following that more noil is automatically associated with better yarn quality The correct goal is always a predetermined waste elimination level

The self cleaning effect of the sheet will be greater the more random is the disposition of the fibers making up the sheet If the fibers have a very high degree of parallelization the retaining power of the sheet can be so strongly reduced that it is no longer also able to hold back the neps as it usually does Some of the sheet neps also pass through the top comb Neppiness of the web is increased

Figure 01 Dependence of noil elimination on degree of parallelization (draft) of fibers in the feedstock A Noil percentage B draft between card and comber

1048766If the degree of order of fibers is too high the sheet does not hold together well 1048766High degree of parallelization always leads to marked hairiness of the lap 1048766The degree of parallelization depends on the total draft between the card and the

comber

Figure 01 Yarn strength and cleanliness versus the degree of parallelization An improvement or deterioration in B draft between card and comber

Sheet thickness 1048766A thick sheet always exerts a greater retaining power than a thin one

Page 8 of 11

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

THE COMBING PROCESSThe combing process is normally used to produce smoother finer stronger and more uniform yarns Therefore combing is commonly confined to high grade long staple natural fibers In recent years combing has been utilized for upgrading the quality of medium staple fibers In addition a yarn made of combed cotton needs less twist than a carded yarn However these quality improvements are obtained at the cost of additional expenditure on machines floor-space and personnel together with a loss of raw material Yarn production coast is increased by something under 1 US$Kg of yarn (depending on the intensity of combing) To improve the yarn quality the comber must perform the following operations Elimination of precisely pre-determined quantity of short fibers Elimination of the remaining impurities Elimination of a large proportion (not all) of the neps in the fiber material Formation of a sliver having maximum possible evenness Producing of more straight and parallel fibers

Elimination of short fibers produces an improvement mainly in staple length but also affects the fineness of the raw material The micronaire value of combed sliver is slightly higher than that of feedstock (elimination of dead fibers) Also the degree of parallelization might reduce the inter-fiber adhesion in the sliver to such an extent that fibers slide apart while being pulled out of the can ndash ie sliver breaks or false drafts might be caused Types of applicationsThe amount of material combed out varies within the range 5 ndash 25 of the in feed stock Three major groups of spinning mills using combing are as follows

1048766Long staple combing mills Processing first-class expensive cotton of high strength containing a low proportion of short fibers and little dirt The product is a fine to very fine yarn of top quality The demands placed on know-how and skill of operating personnel is correspondingly high as they are on the design and maintenance of the machines Yarn production is low while generation of noil is high

1048766Medium-staple combing mills here medium cotton qualities with a wide spread of quality parameters are spun to medium (to fine) yarns of good quality at economic production costs The process is problematic in that it has to achieve a high strand of quality and at the same time give high production at low cost The maximum demands placed on medium staple combing can only be fulfilled by optimally trained personnel

1048766Short (to medium) staple combing mills raw material used have the same as that for production of carded yarns In comparison with a carded yarn the combed yarn should chiefly exhibit better smoothness and strength In this combination with low level noil level (6 ndash 14) This process is the most widely used in practice it is technologically undemanding and can be operated without problems when good machines are available

Page 2 of 11

Lap preparation system for combingThere are used two systems for lap preparation

1) Old system I Sliver lap machine II Ribbon lap machine

2) Modern system Super lap former machine

Types of comber The major types of combers include

1048766Rectilinear comber (For short staple spinning ie cotton) 1048766Circular combers (For worsted process ie wool) 1048766Rotary comber (Production of Schappe spun yarns ie silk) and 1048766Hackling machines (Bast fibers ie jute)

The short staple spinning mill uses only the rectilinear comber with swinging nippers and stationary detaching rollers as originally developed in 1902 by the Englishman Nasmith and in 1948 by whitin company Machine layouts used in practice comprise single sided machines with eight heads

Effect of change of setting sliver quality If staple length 1-18˝ Roller setting should be for front zone- 41mm back zone-

44 mm If staple length below 1-18˝ Back zone amp front zone should be closed 05-1mm If staple length above 1-18˝ Back zone amp front zone should be wide 05-1mm

Bottom roller setting depends on staple length of fibre If roller setting is not properly as per staple length then good fibre will rupture CV will increase of sliver amp finally CV hairness amp end breakage will increase amp yarn strength will decrease

The Combing Machine The basic elements of the combing machine are shown in figure These are the feeding

element the nipper plate the combing system and the detaching rollers The feeding element consists of a feed plate and feed roll The main function of the feeding element is to feed the comber lap in a series of short lengths The nipper plate grips the fibers as a means of holding long fibers while the short fibers neps and trash are being removed The combing system

Page 3 of 11

consists of two combs The first one is a rotating bottom circular comb that performs the main combing action The second one is a linear top comb that completes the function of the bottom comb through vertical combing movement The detaching rolls are two pairs of gripping rolls that rotate forward and backward in intermittent fashion to hold and move the combed web for a net forward travelThe objectives of combing mentioned earlier are accomplished by a precise sequence and synchronized series of actions performed by the combing elements The following text will review this sequence of actions or the combing cycle in a very simplified manner to demonstrate the function of each comber component

Fig Combing machine

Principle of comber Cylinder comb amp top comb extract short fibres impurities amp neps The comb fleece is compressed to form sliver amp the doubled amp drawn in the

drafting system

Main components of combing machine

1 Feed roller It controls the feed amount

2 Cylinder comb amp Top comb They extract short fibres impurities amp neps

3 Nipper The combing nipper performs forward amp reverses movements with the feed roller amp helps to extract waste

4 Detaching roller It moves to amp fro amp helps to extract waste

5 Index wheel Comber lap feeding nipping combing amp delivery are completed by one full revolution of index wheel This is called combing cycle

Page 4 of 11

The Combing Cycle The following figures illustrate the different actions involved in the combing cycle The principle of combing is to advance a pre-determined portion of the fiber lap to the combing station This portion is then gripped by a pair of nipper plate while a toothed half (bottom comb) is combing the fiber fringe and removing the short fibers neps and trashes This waste (noil) is later removed from the needles of the bottom comb using a revolving brush The detailed actions are illustrated in the figures

Page 5 of 11

Technical data of combing machine

Precomb drawing is essential for combing operation In carded sliver fibres are oriented in different direction variation of weight unit length of sliver more amp amount of hooked fibre also more Fibre parallelization less

So long fibres also remove with short fibres in combing amp waste extraction increases

If precomb drawing uses fibres are more parallel in sliver weightunit length variation also reduces More ever by using precomb drawing less needle damage less fibre breakage amp waste extraction reduces

So precomb drawing must be used in combing operation

Effect of temp amp humidity in combingLack of atmospheric moistureStatic electricity resulting in roller lapping split slivers increase in fly waste As a result sliver quality will deteriorate

Too much atmospheric moistureSticky condition between the cotton fibers amp running surfaces resulting in roller lapping sliver irregularity amp low production

So recommended relative humidity amp temp for combing section is RH-(50-52) Tem-(27-29˚C)

Page 6 of 11

1) Number of combing head doubling

8

2) Number of deliveries 13) Nipsmin Maximum 450 npm4) Feedmin Maximum 59 mm5) Noil 10 ndash 256) Efficiency 90 ndash 957) Production Maximum 60 kgshour8) Delivery sliver weight 3 ndash 6 ktex or 3- 6 gmsmetre9) Total draft 912 ndash 2510) Break draft 113 ndash 2011) Bottom roller setting-

Front zone 41 mmBack zone 44 mm

Drafting system of comber machine Drawing amp doubling are the purpose of drafting system The drafting work in drafting system is performed by the break draft amp main

draft In the drafting system the fibre mass is evened by doubling amp the fibres are laid

parallel by drafting The pressure bar guides the fibres in the main draft The total draft includes both break draft amp main draft The main draft ie front zone amp break draft ie back zone is adjustable amp

depends on fibre length The main draft converts the fibre mass to the final count amp parallels the fibre The break draft helps to reduce the irregularity of sliver By using the pressure bar the floating short fibres are guide better

Sliver coiling system It consist of coiler amp calender roller

Coiler Convering the sliver compressing the sliver amp depositing the sliver in the cam

Calender roller The calender roller draws the sliver through the funnel amp compresses it so that it holds together

Neps removal efficiency of combing (NRE) How much neps remove from comber lap by using combing machine is called neps removal efficiency It is expressed on percentage

NRE = (Neps gm in comber lap ndash Nep gm in comber sliver) Neps gm in comber lap

THE TECHNOLOGY OF COMBING Parameters influencing the combing operation

Raw material Fiber type fiber length uniformity of fiber length (cv) fiber stiffness moisture content

Material preparation Parallelization of fibers in sheet sheet thickness sheet evenness orientation of hooks

Factors associated with machine Condition of machine condition of combs speeds operation of combs type of piecing accuracy of setting drafting arrangement

Machine setting Feed distance type of feed detachment setting point density of combs piecing draft and draft arrangement settings Ambient conditions Room temperature humidity

Page 7 of 11

Influence of feed stock on combing Parallelization of fibers in the sheet

1048766Lake of longitudinal orientation ie noticeable fiber disorder leads to elimination of longer fibers and hence overloading the cylindrical comb (Thick sheet)

1048766At same machine settings noil quantity decreases linearly with increasing parallelization of the fibers without any reduction in yarn quality (see figure 17)

1048766It is not always following that more noil is automatically associated with better yarn quality The correct goal is always a predetermined waste elimination level

The self cleaning effect of the sheet will be greater the more random is the disposition of the fibers making up the sheet If the fibers have a very high degree of parallelization the retaining power of the sheet can be so strongly reduced that it is no longer also able to hold back the neps as it usually does Some of the sheet neps also pass through the top comb Neppiness of the web is increased

Figure 01 Dependence of noil elimination on degree of parallelization (draft) of fibers in the feedstock A Noil percentage B draft between card and comber

1048766If the degree of order of fibers is too high the sheet does not hold together well 1048766High degree of parallelization always leads to marked hairiness of the lap 1048766The degree of parallelization depends on the total draft between the card and the

comber

Figure 01 Yarn strength and cleanliness versus the degree of parallelization An improvement or deterioration in B draft between card and comber

Sheet thickness 1048766A thick sheet always exerts a greater retaining power than a thin one

Page 8 of 11

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

Lap preparation system for combingThere are used two systems for lap preparation

1) Old system I Sliver lap machine II Ribbon lap machine

2) Modern system Super lap former machine

Types of comber The major types of combers include

1048766Rectilinear comber (For short staple spinning ie cotton) 1048766Circular combers (For worsted process ie wool) 1048766Rotary comber (Production of Schappe spun yarns ie silk) and 1048766Hackling machines (Bast fibers ie jute)

The short staple spinning mill uses only the rectilinear comber with swinging nippers and stationary detaching rollers as originally developed in 1902 by the Englishman Nasmith and in 1948 by whitin company Machine layouts used in practice comprise single sided machines with eight heads

Effect of change of setting sliver quality If staple length 1-18˝ Roller setting should be for front zone- 41mm back zone-

44 mm If staple length below 1-18˝ Back zone amp front zone should be closed 05-1mm If staple length above 1-18˝ Back zone amp front zone should be wide 05-1mm

Bottom roller setting depends on staple length of fibre If roller setting is not properly as per staple length then good fibre will rupture CV will increase of sliver amp finally CV hairness amp end breakage will increase amp yarn strength will decrease

The Combing Machine The basic elements of the combing machine are shown in figure These are the feeding

element the nipper plate the combing system and the detaching rollers The feeding element consists of a feed plate and feed roll The main function of the feeding element is to feed the comber lap in a series of short lengths The nipper plate grips the fibers as a means of holding long fibers while the short fibers neps and trash are being removed The combing system

Page 3 of 11

consists of two combs The first one is a rotating bottom circular comb that performs the main combing action The second one is a linear top comb that completes the function of the bottom comb through vertical combing movement The detaching rolls are two pairs of gripping rolls that rotate forward and backward in intermittent fashion to hold and move the combed web for a net forward travelThe objectives of combing mentioned earlier are accomplished by a precise sequence and synchronized series of actions performed by the combing elements The following text will review this sequence of actions or the combing cycle in a very simplified manner to demonstrate the function of each comber component

Fig Combing machine

Principle of comber Cylinder comb amp top comb extract short fibres impurities amp neps The comb fleece is compressed to form sliver amp the doubled amp drawn in the

drafting system

Main components of combing machine

1 Feed roller It controls the feed amount

2 Cylinder comb amp Top comb They extract short fibres impurities amp neps

3 Nipper The combing nipper performs forward amp reverses movements with the feed roller amp helps to extract waste

4 Detaching roller It moves to amp fro amp helps to extract waste

5 Index wheel Comber lap feeding nipping combing amp delivery are completed by one full revolution of index wheel This is called combing cycle

Page 4 of 11

The Combing Cycle The following figures illustrate the different actions involved in the combing cycle The principle of combing is to advance a pre-determined portion of the fiber lap to the combing station This portion is then gripped by a pair of nipper plate while a toothed half (bottom comb) is combing the fiber fringe and removing the short fibers neps and trashes This waste (noil) is later removed from the needles of the bottom comb using a revolving brush The detailed actions are illustrated in the figures

Page 5 of 11

Technical data of combing machine

Precomb drawing is essential for combing operation In carded sliver fibres are oriented in different direction variation of weight unit length of sliver more amp amount of hooked fibre also more Fibre parallelization less

So long fibres also remove with short fibres in combing amp waste extraction increases

If precomb drawing uses fibres are more parallel in sliver weightunit length variation also reduces More ever by using precomb drawing less needle damage less fibre breakage amp waste extraction reduces

So precomb drawing must be used in combing operation

Effect of temp amp humidity in combingLack of atmospheric moistureStatic electricity resulting in roller lapping split slivers increase in fly waste As a result sliver quality will deteriorate

Too much atmospheric moistureSticky condition between the cotton fibers amp running surfaces resulting in roller lapping sliver irregularity amp low production

So recommended relative humidity amp temp for combing section is RH-(50-52) Tem-(27-29˚C)

Page 6 of 11

1) Number of combing head doubling

8

2) Number of deliveries 13) Nipsmin Maximum 450 npm4) Feedmin Maximum 59 mm5) Noil 10 ndash 256) Efficiency 90 ndash 957) Production Maximum 60 kgshour8) Delivery sliver weight 3 ndash 6 ktex or 3- 6 gmsmetre9) Total draft 912 ndash 2510) Break draft 113 ndash 2011) Bottom roller setting-

Front zone 41 mmBack zone 44 mm

Drafting system of comber machine Drawing amp doubling are the purpose of drafting system The drafting work in drafting system is performed by the break draft amp main

draft In the drafting system the fibre mass is evened by doubling amp the fibres are laid

parallel by drafting The pressure bar guides the fibres in the main draft The total draft includes both break draft amp main draft The main draft ie front zone amp break draft ie back zone is adjustable amp

depends on fibre length The main draft converts the fibre mass to the final count amp parallels the fibre The break draft helps to reduce the irregularity of sliver By using the pressure bar the floating short fibres are guide better

Sliver coiling system It consist of coiler amp calender roller

Coiler Convering the sliver compressing the sliver amp depositing the sliver in the cam

Calender roller The calender roller draws the sliver through the funnel amp compresses it so that it holds together

Neps removal efficiency of combing (NRE) How much neps remove from comber lap by using combing machine is called neps removal efficiency It is expressed on percentage

NRE = (Neps gm in comber lap ndash Nep gm in comber sliver) Neps gm in comber lap

THE TECHNOLOGY OF COMBING Parameters influencing the combing operation

Raw material Fiber type fiber length uniformity of fiber length (cv) fiber stiffness moisture content

Material preparation Parallelization of fibers in sheet sheet thickness sheet evenness orientation of hooks

Factors associated with machine Condition of machine condition of combs speeds operation of combs type of piecing accuracy of setting drafting arrangement

Machine setting Feed distance type of feed detachment setting point density of combs piecing draft and draft arrangement settings Ambient conditions Room temperature humidity

Page 7 of 11

Influence of feed stock on combing Parallelization of fibers in the sheet

1048766Lake of longitudinal orientation ie noticeable fiber disorder leads to elimination of longer fibers and hence overloading the cylindrical comb (Thick sheet)

1048766At same machine settings noil quantity decreases linearly with increasing parallelization of the fibers without any reduction in yarn quality (see figure 17)

1048766It is not always following that more noil is automatically associated with better yarn quality The correct goal is always a predetermined waste elimination level

The self cleaning effect of the sheet will be greater the more random is the disposition of the fibers making up the sheet If the fibers have a very high degree of parallelization the retaining power of the sheet can be so strongly reduced that it is no longer also able to hold back the neps as it usually does Some of the sheet neps also pass through the top comb Neppiness of the web is increased

Figure 01 Dependence of noil elimination on degree of parallelization (draft) of fibers in the feedstock A Noil percentage B draft between card and comber

1048766If the degree of order of fibers is too high the sheet does not hold together well 1048766High degree of parallelization always leads to marked hairiness of the lap 1048766The degree of parallelization depends on the total draft between the card and the

comber

Figure 01 Yarn strength and cleanliness versus the degree of parallelization An improvement or deterioration in B draft between card and comber

Sheet thickness 1048766A thick sheet always exerts a greater retaining power than a thin one

Page 8 of 11

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

consists of two combs The first one is a rotating bottom circular comb that performs the main combing action The second one is a linear top comb that completes the function of the bottom comb through vertical combing movement The detaching rolls are two pairs of gripping rolls that rotate forward and backward in intermittent fashion to hold and move the combed web for a net forward travelThe objectives of combing mentioned earlier are accomplished by a precise sequence and synchronized series of actions performed by the combing elements The following text will review this sequence of actions or the combing cycle in a very simplified manner to demonstrate the function of each comber component

Fig Combing machine

Principle of comber Cylinder comb amp top comb extract short fibres impurities amp neps The comb fleece is compressed to form sliver amp the doubled amp drawn in the

drafting system

Main components of combing machine

1 Feed roller It controls the feed amount

2 Cylinder comb amp Top comb They extract short fibres impurities amp neps

3 Nipper The combing nipper performs forward amp reverses movements with the feed roller amp helps to extract waste

4 Detaching roller It moves to amp fro amp helps to extract waste

5 Index wheel Comber lap feeding nipping combing amp delivery are completed by one full revolution of index wheel This is called combing cycle

Page 4 of 11

The Combing Cycle The following figures illustrate the different actions involved in the combing cycle The principle of combing is to advance a pre-determined portion of the fiber lap to the combing station This portion is then gripped by a pair of nipper plate while a toothed half (bottom comb) is combing the fiber fringe and removing the short fibers neps and trashes This waste (noil) is later removed from the needles of the bottom comb using a revolving brush The detailed actions are illustrated in the figures

Page 5 of 11

Technical data of combing machine

Precomb drawing is essential for combing operation In carded sliver fibres are oriented in different direction variation of weight unit length of sliver more amp amount of hooked fibre also more Fibre parallelization less

So long fibres also remove with short fibres in combing amp waste extraction increases

If precomb drawing uses fibres are more parallel in sliver weightunit length variation also reduces More ever by using precomb drawing less needle damage less fibre breakage amp waste extraction reduces

So precomb drawing must be used in combing operation

Effect of temp amp humidity in combingLack of atmospheric moistureStatic electricity resulting in roller lapping split slivers increase in fly waste As a result sliver quality will deteriorate

Too much atmospheric moistureSticky condition between the cotton fibers amp running surfaces resulting in roller lapping sliver irregularity amp low production

So recommended relative humidity amp temp for combing section is RH-(50-52) Tem-(27-29˚C)

Page 6 of 11

1) Number of combing head doubling

8

2) Number of deliveries 13) Nipsmin Maximum 450 npm4) Feedmin Maximum 59 mm5) Noil 10 ndash 256) Efficiency 90 ndash 957) Production Maximum 60 kgshour8) Delivery sliver weight 3 ndash 6 ktex or 3- 6 gmsmetre9) Total draft 912 ndash 2510) Break draft 113 ndash 2011) Bottom roller setting-

Front zone 41 mmBack zone 44 mm

Drafting system of comber machine Drawing amp doubling are the purpose of drafting system The drafting work in drafting system is performed by the break draft amp main

draft In the drafting system the fibre mass is evened by doubling amp the fibres are laid

parallel by drafting The pressure bar guides the fibres in the main draft The total draft includes both break draft amp main draft The main draft ie front zone amp break draft ie back zone is adjustable amp

depends on fibre length The main draft converts the fibre mass to the final count amp parallels the fibre The break draft helps to reduce the irregularity of sliver By using the pressure bar the floating short fibres are guide better

Sliver coiling system It consist of coiler amp calender roller

Coiler Convering the sliver compressing the sliver amp depositing the sliver in the cam

Calender roller The calender roller draws the sliver through the funnel amp compresses it so that it holds together

Neps removal efficiency of combing (NRE) How much neps remove from comber lap by using combing machine is called neps removal efficiency It is expressed on percentage

NRE = (Neps gm in comber lap ndash Nep gm in comber sliver) Neps gm in comber lap

THE TECHNOLOGY OF COMBING Parameters influencing the combing operation

Raw material Fiber type fiber length uniformity of fiber length (cv) fiber stiffness moisture content

Material preparation Parallelization of fibers in sheet sheet thickness sheet evenness orientation of hooks

Factors associated with machine Condition of machine condition of combs speeds operation of combs type of piecing accuracy of setting drafting arrangement

Machine setting Feed distance type of feed detachment setting point density of combs piecing draft and draft arrangement settings Ambient conditions Room temperature humidity

Page 7 of 11

Influence of feed stock on combing Parallelization of fibers in the sheet

1048766Lake of longitudinal orientation ie noticeable fiber disorder leads to elimination of longer fibers and hence overloading the cylindrical comb (Thick sheet)

1048766At same machine settings noil quantity decreases linearly with increasing parallelization of the fibers without any reduction in yarn quality (see figure 17)

1048766It is not always following that more noil is automatically associated with better yarn quality The correct goal is always a predetermined waste elimination level

The self cleaning effect of the sheet will be greater the more random is the disposition of the fibers making up the sheet If the fibers have a very high degree of parallelization the retaining power of the sheet can be so strongly reduced that it is no longer also able to hold back the neps as it usually does Some of the sheet neps also pass through the top comb Neppiness of the web is increased

Figure 01 Dependence of noil elimination on degree of parallelization (draft) of fibers in the feedstock A Noil percentage B draft between card and comber

1048766If the degree of order of fibers is too high the sheet does not hold together well 1048766High degree of parallelization always leads to marked hairiness of the lap 1048766The degree of parallelization depends on the total draft between the card and the

comber

Figure 01 Yarn strength and cleanliness versus the degree of parallelization An improvement or deterioration in B draft between card and comber

Sheet thickness 1048766A thick sheet always exerts a greater retaining power than a thin one

Page 8 of 11

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

The Combing Cycle The following figures illustrate the different actions involved in the combing cycle The principle of combing is to advance a pre-determined portion of the fiber lap to the combing station This portion is then gripped by a pair of nipper plate while a toothed half (bottom comb) is combing the fiber fringe and removing the short fibers neps and trashes This waste (noil) is later removed from the needles of the bottom comb using a revolving brush The detailed actions are illustrated in the figures

Page 5 of 11

Technical data of combing machine

Precomb drawing is essential for combing operation In carded sliver fibres are oriented in different direction variation of weight unit length of sliver more amp amount of hooked fibre also more Fibre parallelization less

So long fibres also remove with short fibres in combing amp waste extraction increases

If precomb drawing uses fibres are more parallel in sliver weightunit length variation also reduces More ever by using precomb drawing less needle damage less fibre breakage amp waste extraction reduces

So precomb drawing must be used in combing operation

Effect of temp amp humidity in combingLack of atmospheric moistureStatic electricity resulting in roller lapping split slivers increase in fly waste As a result sliver quality will deteriorate

Too much atmospheric moistureSticky condition between the cotton fibers amp running surfaces resulting in roller lapping sliver irregularity amp low production

So recommended relative humidity amp temp for combing section is RH-(50-52) Tem-(27-29˚C)

Page 6 of 11

1) Number of combing head doubling

8

2) Number of deliveries 13) Nipsmin Maximum 450 npm4) Feedmin Maximum 59 mm5) Noil 10 ndash 256) Efficiency 90 ndash 957) Production Maximum 60 kgshour8) Delivery sliver weight 3 ndash 6 ktex or 3- 6 gmsmetre9) Total draft 912 ndash 2510) Break draft 113 ndash 2011) Bottom roller setting-

Front zone 41 mmBack zone 44 mm

Drafting system of comber machine Drawing amp doubling are the purpose of drafting system The drafting work in drafting system is performed by the break draft amp main

draft In the drafting system the fibre mass is evened by doubling amp the fibres are laid

parallel by drafting The pressure bar guides the fibres in the main draft The total draft includes both break draft amp main draft The main draft ie front zone amp break draft ie back zone is adjustable amp

depends on fibre length The main draft converts the fibre mass to the final count amp parallels the fibre The break draft helps to reduce the irregularity of sliver By using the pressure bar the floating short fibres are guide better

Sliver coiling system It consist of coiler amp calender roller

Coiler Convering the sliver compressing the sliver amp depositing the sliver in the cam

Calender roller The calender roller draws the sliver through the funnel amp compresses it so that it holds together

Neps removal efficiency of combing (NRE) How much neps remove from comber lap by using combing machine is called neps removal efficiency It is expressed on percentage

NRE = (Neps gm in comber lap ndash Nep gm in comber sliver) Neps gm in comber lap

THE TECHNOLOGY OF COMBING Parameters influencing the combing operation

Raw material Fiber type fiber length uniformity of fiber length (cv) fiber stiffness moisture content

Material preparation Parallelization of fibers in sheet sheet thickness sheet evenness orientation of hooks

Factors associated with machine Condition of machine condition of combs speeds operation of combs type of piecing accuracy of setting drafting arrangement

Machine setting Feed distance type of feed detachment setting point density of combs piecing draft and draft arrangement settings Ambient conditions Room temperature humidity

Page 7 of 11

Influence of feed stock on combing Parallelization of fibers in the sheet

1048766Lake of longitudinal orientation ie noticeable fiber disorder leads to elimination of longer fibers and hence overloading the cylindrical comb (Thick sheet)

1048766At same machine settings noil quantity decreases linearly with increasing parallelization of the fibers without any reduction in yarn quality (see figure 17)

1048766It is not always following that more noil is automatically associated with better yarn quality The correct goal is always a predetermined waste elimination level

The self cleaning effect of the sheet will be greater the more random is the disposition of the fibers making up the sheet If the fibers have a very high degree of parallelization the retaining power of the sheet can be so strongly reduced that it is no longer also able to hold back the neps as it usually does Some of the sheet neps also pass through the top comb Neppiness of the web is increased

Figure 01 Dependence of noil elimination on degree of parallelization (draft) of fibers in the feedstock A Noil percentage B draft between card and comber

1048766If the degree of order of fibers is too high the sheet does not hold together well 1048766High degree of parallelization always leads to marked hairiness of the lap 1048766The degree of parallelization depends on the total draft between the card and the

comber

Figure 01 Yarn strength and cleanliness versus the degree of parallelization An improvement or deterioration in B draft between card and comber

Sheet thickness 1048766A thick sheet always exerts a greater retaining power than a thin one

Page 8 of 11

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

Technical data of combing machine

Precomb drawing is essential for combing operation In carded sliver fibres are oriented in different direction variation of weight unit length of sliver more amp amount of hooked fibre also more Fibre parallelization less

So long fibres also remove with short fibres in combing amp waste extraction increases

If precomb drawing uses fibres are more parallel in sliver weightunit length variation also reduces More ever by using precomb drawing less needle damage less fibre breakage amp waste extraction reduces

So precomb drawing must be used in combing operation

Effect of temp amp humidity in combingLack of atmospheric moistureStatic electricity resulting in roller lapping split slivers increase in fly waste As a result sliver quality will deteriorate

Too much atmospheric moistureSticky condition between the cotton fibers amp running surfaces resulting in roller lapping sliver irregularity amp low production

So recommended relative humidity amp temp for combing section is RH-(50-52) Tem-(27-29˚C)

Page 6 of 11

1) Number of combing head doubling

8

2) Number of deliveries 13) Nipsmin Maximum 450 npm4) Feedmin Maximum 59 mm5) Noil 10 ndash 256) Efficiency 90 ndash 957) Production Maximum 60 kgshour8) Delivery sliver weight 3 ndash 6 ktex or 3- 6 gmsmetre9) Total draft 912 ndash 2510) Break draft 113 ndash 2011) Bottom roller setting-

Front zone 41 mmBack zone 44 mm

Drafting system of comber machine Drawing amp doubling are the purpose of drafting system The drafting work in drafting system is performed by the break draft amp main

draft In the drafting system the fibre mass is evened by doubling amp the fibres are laid

parallel by drafting The pressure bar guides the fibres in the main draft The total draft includes both break draft amp main draft The main draft ie front zone amp break draft ie back zone is adjustable amp

depends on fibre length The main draft converts the fibre mass to the final count amp parallels the fibre The break draft helps to reduce the irregularity of sliver By using the pressure bar the floating short fibres are guide better

Sliver coiling system It consist of coiler amp calender roller

Coiler Convering the sliver compressing the sliver amp depositing the sliver in the cam

Calender roller The calender roller draws the sliver through the funnel amp compresses it so that it holds together

Neps removal efficiency of combing (NRE) How much neps remove from comber lap by using combing machine is called neps removal efficiency It is expressed on percentage

NRE = (Neps gm in comber lap ndash Nep gm in comber sliver) Neps gm in comber lap

THE TECHNOLOGY OF COMBING Parameters influencing the combing operation

Raw material Fiber type fiber length uniformity of fiber length (cv) fiber stiffness moisture content

Material preparation Parallelization of fibers in sheet sheet thickness sheet evenness orientation of hooks

Factors associated with machine Condition of machine condition of combs speeds operation of combs type of piecing accuracy of setting drafting arrangement

Machine setting Feed distance type of feed detachment setting point density of combs piecing draft and draft arrangement settings Ambient conditions Room temperature humidity

Page 7 of 11

Influence of feed stock on combing Parallelization of fibers in the sheet

1048766Lake of longitudinal orientation ie noticeable fiber disorder leads to elimination of longer fibers and hence overloading the cylindrical comb (Thick sheet)

1048766At same machine settings noil quantity decreases linearly with increasing parallelization of the fibers without any reduction in yarn quality (see figure 17)

1048766It is not always following that more noil is automatically associated with better yarn quality The correct goal is always a predetermined waste elimination level

The self cleaning effect of the sheet will be greater the more random is the disposition of the fibers making up the sheet If the fibers have a very high degree of parallelization the retaining power of the sheet can be so strongly reduced that it is no longer also able to hold back the neps as it usually does Some of the sheet neps also pass through the top comb Neppiness of the web is increased

Figure 01 Dependence of noil elimination on degree of parallelization (draft) of fibers in the feedstock A Noil percentage B draft between card and comber

1048766If the degree of order of fibers is too high the sheet does not hold together well 1048766High degree of parallelization always leads to marked hairiness of the lap 1048766The degree of parallelization depends on the total draft between the card and the

comber

Figure 01 Yarn strength and cleanliness versus the degree of parallelization An improvement or deterioration in B draft between card and comber

Sheet thickness 1048766A thick sheet always exerts a greater retaining power than a thin one

Page 8 of 11

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

Drafting system of comber machine Drawing amp doubling are the purpose of drafting system The drafting work in drafting system is performed by the break draft amp main

draft In the drafting system the fibre mass is evened by doubling amp the fibres are laid

parallel by drafting The pressure bar guides the fibres in the main draft The total draft includes both break draft amp main draft The main draft ie front zone amp break draft ie back zone is adjustable amp

depends on fibre length The main draft converts the fibre mass to the final count amp parallels the fibre The break draft helps to reduce the irregularity of sliver By using the pressure bar the floating short fibres are guide better

Sliver coiling system It consist of coiler amp calender roller

Coiler Convering the sliver compressing the sliver amp depositing the sliver in the cam

Calender roller The calender roller draws the sliver through the funnel amp compresses it so that it holds together

Neps removal efficiency of combing (NRE) How much neps remove from comber lap by using combing machine is called neps removal efficiency It is expressed on percentage

NRE = (Neps gm in comber lap ndash Nep gm in comber sliver) Neps gm in comber lap

THE TECHNOLOGY OF COMBING Parameters influencing the combing operation

Raw material Fiber type fiber length uniformity of fiber length (cv) fiber stiffness moisture content

Material preparation Parallelization of fibers in sheet sheet thickness sheet evenness orientation of hooks

Factors associated with machine Condition of machine condition of combs speeds operation of combs type of piecing accuracy of setting drafting arrangement

Machine setting Feed distance type of feed detachment setting point density of combs piecing draft and draft arrangement settings Ambient conditions Room temperature humidity

Page 7 of 11

Influence of feed stock on combing Parallelization of fibers in the sheet

1048766Lake of longitudinal orientation ie noticeable fiber disorder leads to elimination of longer fibers and hence overloading the cylindrical comb (Thick sheet)

1048766At same machine settings noil quantity decreases linearly with increasing parallelization of the fibers without any reduction in yarn quality (see figure 17)

1048766It is not always following that more noil is automatically associated with better yarn quality The correct goal is always a predetermined waste elimination level

The self cleaning effect of the sheet will be greater the more random is the disposition of the fibers making up the sheet If the fibers have a very high degree of parallelization the retaining power of the sheet can be so strongly reduced that it is no longer also able to hold back the neps as it usually does Some of the sheet neps also pass through the top comb Neppiness of the web is increased

Figure 01 Dependence of noil elimination on degree of parallelization (draft) of fibers in the feedstock A Noil percentage B draft between card and comber

1048766If the degree of order of fibers is too high the sheet does not hold together well 1048766High degree of parallelization always leads to marked hairiness of the lap 1048766The degree of parallelization depends on the total draft between the card and the

comber

Figure 01 Yarn strength and cleanliness versus the degree of parallelization An improvement or deterioration in B draft between card and comber

Sheet thickness 1048766A thick sheet always exerts a greater retaining power than a thin one

Page 8 of 11

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

Influence of feed stock on combing Parallelization of fibers in the sheet

1048766Lake of longitudinal orientation ie noticeable fiber disorder leads to elimination of longer fibers and hence overloading the cylindrical comb (Thick sheet)

1048766At same machine settings noil quantity decreases linearly with increasing parallelization of the fibers without any reduction in yarn quality (see figure 17)

1048766It is not always following that more noil is automatically associated with better yarn quality The correct goal is always a predetermined waste elimination level

The self cleaning effect of the sheet will be greater the more random is the disposition of the fibers making up the sheet If the fibers have a very high degree of parallelization the retaining power of the sheet can be so strongly reduced that it is no longer also able to hold back the neps as it usually does Some of the sheet neps also pass through the top comb Neppiness of the web is increased

Figure 01 Dependence of noil elimination on degree of parallelization (draft) of fibers in the feedstock A Noil percentage B draft between card and comber

1048766If the degree of order of fibers is too high the sheet does not hold together well 1048766High degree of parallelization always leads to marked hairiness of the lap 1048766The degree of parallelization depends on the total draft between the card and the

comber

Figure 01 Yarn strength and cleanliness versus the degree of parallelization An improvement or deterioration in B draft between card and comber

Sheet thickness 1048766A thick sheet always exerts a greater retaining power than a thin one

Page 8 of 11

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

1048766Also a thick sheet always applies a strong load on the comb and this can lead to uncontrolled combing

1048766In case of very thick sheet the fibers farthest from the cylinder comb may escape the combing operation because the combs are no longer able to pass through the whole layer

1048766Optimal sheet fineness now normally lies between 55 and 75 ktex Typical values can be derived from figure 8

Figure 18 Typical values for the fineness of the feed sheet A sheet fineness and B Staple length I Comber from previous generation II combers from current generation

Evenness of the lap sheet 1048766Evening of the lap is of considerable significance ldquobetter clampingrdquo 1048766High degree of evenness is due to higher doubling 1048766This explains the effect of doubling on the ribbon lab machine

The disposition of the hooks 1048766Fibers should be presented to the comber so that leading hooks predominate in the

feedstock 1048766If the sheet is fed in the wrong direction the number of neps rises markedly 1048766Quantity and form of fiber hooks depend mainly upon the stiffness of the fibers

this rises to the second or third power with increasing the coarseness of the fibers 1048766Fine and long fibers will always exhibit more and longer hooks (horseshoe shape)

than short fibers coarse fibers (hokey stick form) 1048766Accordingly the role of fiber hooks in spinning process becomes more significant

as fibers become finer

Influence of combing operation on quality Combing can be applied to a wide range of spinning processes Following is the classification of quality of combed yarns

Page 9 of 11

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

1048766Semi-combed (upgrading to higher grade) with noil percentage of 5 -10 (- 12) 1048766Normally combed with a noil percentage between 10 and 20 1048766Super combed with noil percentage over 20

The following characteristics of combing process have to be controlled To control loss of fibre larger than the preselected length To control presence of fibre shorter than the preselected length in comber sliver To control fibre breakage To control periodic irregularities due to piecing To control disturbance of fibre parallelization due to bad piecing

Faults of combing1) Cutting across

Causes Due to incorrect roller setting more draft amp roller slippage If stop motion does not work properly

2) CurlingCauses Due to improper atmospheric condition ie moisture becomes more dry or

more wet Due to bent of cylinder amp top comb needle

3) Head to head variationCauses Due to variation in comber lap Due to un-uniformity in suction Due to incorrect setting of cylinder height amp incorrect setting of nipper to

Detaching roller

4) Detaching roller lappingCauses Due to remain oil in the roller Due to higher relative humidity Due to sticky dirt in the roller

5) Long fibres in the wasteCauses Due to more hooked fibre in comber lap Due to broken amp bent needle of cylinder amp top comb

6) Short fibres in the wasteCauses Due to poorly oriented fibres amp hooked fibres

Page 10 of 11

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement

Due to damage needle

Reference Class lecture

Reference links wwwyahoocom wwwgooglecom

AcknowledgementI am thanks to our honorable teacher (MD Rokonuzzaman Khan) for his cordial assist to make my assignment successfully due to his provided lecture amp advice

THE END

Page 11 of 11

• THE COMBING PROCESS
• Types of applications
• Lap preparation system for combing
• Types of comber
• Effect of change of setting sliver quality
• Acknowledgement