Showing posts with label Yarn. Show all posts
Showing posts with label Yarn. Show all posts
21 March 2013
Twist Mechanism
Twist:
Twist
is the number of turns about its axis per unit of length of a yarn or
other textile strand. Twist is expressed as turns per inch (tpi), turns
per meter (tpm), or turns per centimeter (tpcm). It is a very essential
process in the production of staple yarn, twine, cord and ropes. Twist
is inserted to the staple yarn to hold the constituent fibres together,
thus giving enough strength to the yarn, and also producing a continuous
length of yarn. The mechanism of twist insertion to the strand during
ring spinning has been studied. The twisting of the strand occurs not
only due to the rotation of twisting elements, but also due to the
winding of yarn on the package. When the yarn is wound on a stationary
cop by gripping and winding the yarn by hand, for every coil of yarn
wind one turn of twist to the yarn is inserted. Now we will discuss
about way of twist insertion to the yarn.
 |
| Twist direction |
Twist Insertion to the Yarn When the Spindle is Stationary:
We assume that the spindle is stationary and the traveller
rotates in the ring frame. Each revolution of the traveller winds one
coil of yarn onto the cop. This is similar to gripping and winding the
yarn on a cop by hand. The yarn will rotate 3600 per coil wind while
winding the yarn onto a stationary cop by hand; hence the winding causes
yarn twisting.
- Length of yarn wound per revolution of traveller = πd
- Turns/cm due to winding = 1/Ï€d
If
the yarn is unwound in parallel from the cop, the yarn will retain all
the twists present in the yarn, whereas if the yarn is over-end unwound,
unwinding a coil removes one turn of twist. The unwinding causes
twisting. So, the twists inserted into the yarn during winding are
removed during over-end unwinding. The over-end withdrawal may be from
any side of the cop. If the traveller rotates in a clockwise direction
to wind the yarn onto the cop, each coil of wind inserts one turn of ‘Z’
twist to the yarn. When the same is over-end unwound, every unwinding
coil inserts one turn of twist in an ‘S’ direction, and so the resultant
yarn will not have any twist.
Twist Insertion into the Yarn when the Traveller is Stationary:
Twist Insertion into the Yarn when the Traveller is Stationary:
We
assume that the traveller is fixed on a stationary ring and that the
spindle is rotating at a constant speed. Every revolution of spindle
winds one coil of yarn onto the cop. Here winding does not cause
twisting, and hence the yarn in the cop will not have any twist. But if
the yarn is over-end unwound, every unwinding of a coil of yarn inserts
one turn of twist into the yarn.
- Turns/cm due to over-end unwinding = 1/Ï€d
Twist Insertion onto the Yarn when both Spindle and Traveller rotate in Opposite Direction:
It may be wondered why it should be necessary to rotate the traveller and spindle in the opposite direction, and also how to rotate the traveller in the opposite direction. This is only to enable the reader to clearly understand the mechanism of twisting. When both the spindle and traveller rotate in the opposite direction, each revolution of the spindle and traveller winds one coil each. The length of yarn wound per min and twist/cm can be calculated.
- Length of yarn wound per min = π d (NS+NT)
- Twist/cm due to winding = - NT/ π d (NS+NT) where
- NS – spindle speed in rpm,
- NT – traveller speed in rpm.
- Twist/cm due to over-end unwinding = (NT/ π d (NS+NT)) + (NS/ π d (NS+NT))
- Twist/cm in the yarn after over-end withdrawal = (NS/ π d (NS+NT)
In ring spinning, both the spindle and traveller rotate in the same direction. However, the spindle rotates at a higher speed than the traveller. If both rotate at the same speed, only the twisting of yarn takes place without winding. Due to the difference in their rotational speeds, the winding of the yarn takes place on the cop.
- Length of yarn wound on the cop per min = Ï€d (NS –NT)
- Turns/cm in the yarn = NT/Ï€d (NS –NT)
- The winding rate should be equal to the delivery rate.
- Length of yarn delivered (cm/min) = Ï€d (NS –NT)
- Turns/cm for unwinding = 1/Ï€d
- Total twist present in the yarn after over-end unwound = NT/Ï€d(NS –NT) + 1/Ï€d = NS/Ï€d(NS-NT)
Twist Insertion onto the Strand when Flyer leads Bobbin:
Due to the difference in the speeds of the flyer and the bobbin, the winding of roving takes place on the bobbin.
- Twist/cm due to twisting = NB / πd(NF-NB)
- Twist/cm due to winding = (NF-NB)/ πd(NF-NB)
- Twist/cm in the roving = NF / πd(NF-NB) where
- NF - flyer speed in rpm,
- NB - bobbin speed in rpm.
- Turns/cm due to over-end withdrawal = - (NF-NB)/ πd(NF-NB)
- Turns/cm in the roving after over-end withdrawal = NB/Ï€d (NF-NB)
2 December 2012
Warp and Weft Yarn Preparation | Necessity of Warp/Weft Yarn Preparation
Warp Preparation
Drawing-In
Provides each warp yam with its drop wire, heddle, and reed dent.
Tying- In
When mass producing the same fabric by simply typing each end of a new beam to its corresponding end of the old beam
Necessity of Warp Yarn Preparation
We need to prepare the warp yarn because of:
- Imperfection of yarn.
- Requirement to transfer the spun yarns in a conventional package.
- Extra treatment to make the yarn ready for weaving.
- Warp yarn must be able to withstand destructive forces to which it is subjected during the weaving process.
- Yarn hairiness must be decreases.
- Yarn must be aligned properly.
- Yarn elongation & flexibility must be sustained.
On conventional loom the filling yarn is inserted by means of a shuttle carrying a bobbin. This bobbin should be tapered at the end so that the yarn may be pulled without interruption through the eye of the shuttle as the shuttle travels from one side of the loom to the other.
Necessity of Weft Yarn Preparation
- Removal of slubs & weak places during processing which otherwise would impair the running of the loom.
- The production of the tighter packages having more yards per pirn. This reduces the number of pirn changes in the loom. This, in turn, reduces the possibilities of flaws & wastage.
- Greater uniformity of pirns used on the loom. This improves the uniformity of the fabric.
- The easy handling of small lots.
13 October 2012
Yarn Clearer in Winding | Types of Yarn Clearer | Comprise Between Mechanical and Electronic Clearer
Yarn Clearer
Yarn
clearer is the device which is used to remove the following faults of
yarn in order to increase the yarn quality and weaving efficiency.
Faults of yarn are as follows
Types of Yarn Clearer
There are two types of yarn clearer
1. Mechanical Type
a. Conventional blunt type
b. Serrated blade type
2. Electronic type
a. Capacitance type
b. Photo electric type
Comprise between mechanical and electronic clearer
• Electronic clearer are more sensitive than mechanical clearers
•
In case of mechanical clearers there is abrasion between yarn
and clearer parts but in case of electronic clearers there is no such
abrasion
• Mechanical
clearers do not prevent soft slab from escaping through clearer where as
electronic type does not allow passing of any types of faults
• Mechanical type does not break the thin places and the length of the fault is not considered
•
Mechanical clearer are simple and easy to maintain while the
electronic clearers are costly and requires high standard of maintenance.
http://textilelearner.blogspot.com/search/label/Winding
http://textilelearner.blogspot.com/search/label/Winding
17 August 2012
Yarn Twist | Relationship Between Yarn Count and Twist | Principles of Twist Measuring Methods
Yarn Twist:
Relationship Between Yarn Count and Twist:
From figure, we get,
(Where ɵ= twist angle, d= yarn diameter and L= yarn length)
Also from figure, the height (pitch) of one turn of twist is L. Since the twist level is normally specified as the number of turns per metre, the twist level in one metre of the yarn would be:
We also know from experience that yarn diameter is also very hard to measure, because textile yarns by their very nature are soft and squashy. On the other hand, yarn count is normally used as we have discussed in the first topic of this module. But we can relate yarn diameter to yarn count using the expression below:
Thus, K is a factor relating twist level
to yarn count. The derivation shows that if two yarns have the same
twist factor, they will have the same surface twist angle, regardless of
count. Since surface twist angle is the main factor determining yarn
character, then twist factor can be used to define the character of a
yarn.
It is worth noting though there are minor errors associated with the use of twist factor for the following reasons:
For the tex system:
Please
note the unit for twist is also different in the above expressions of
twist factor. In addition, twist factor is also known as twist
multiplier, twist alpha, or twist coefficient.
Angle of Twist:
The yarn twist angle is the angle between a tangent to the helix formed by a fibre on the yarn surface and the yarn axis. If the twist multiplier of a cotton yarn is known, the twist angle can be easily calculated.
Factors Affecting Twist:
The twist introduced in the yarn during spinning depends upon a number of factors, such as follows:
If someone twists your head, it is your neck that suffers most. That is because the neck is a ‘thin’ place and offers little resistance to being twisted. By analogy, if a yarn of varying thickness is twisted, it is usually the thin spot in the yarn that gets twisted the most. Invariably, yarns spun from staple fibres (eg. wool, cotton) are not perfectly uniform, and there are thick and thin spots along the yarn length. This variation in yarn thickness will lead to variation in the twist level along the yarn length, because twist tends to accumulate in the thin place.
The fact that twist tends to accumulate in the thin spot along the yarn has several important implications:
1. It exacerbates the variation in yarn linear density
While variation in yarn linear density is the fundamental cause of twist variation, concentration of twist in the thin places will make those places even thinner, exacerbating the problem of yarn unevenness.
2. It improves the evenness of a fibre assembly during “drafting against twist”
In the drafting stage of woollen ring spinning, the woollen slubbing is drafted while twist is inserted into the slubbing (drafting against twist) to control fibres during drafting. Because twist tends to accumulate in the thin spots, the fibres in thin regions in the slubbing are more difficult to draft than those in the thick places, which have less twist. As a result, the thick places are drafted more than the thin places, thus improving the evenness of the drafted material. This is depicted in following figure.
3. It has implication for twist measurements
Because the twist level varies along the yarn length, the twist measured at a short length of yarn may not reflect the true average twist of the yarn. Standard test procedures should be followed to measure the yarn twist accurately.
The relationship between twist and yarn count may be expressed by the following formula:
Where,
In the manufacture of staple fibre
yarns, twist is inserted into the fine strand of fibres to hold the
fibres together and impart the desired properties to the twisted yarns.
Without twist, the fine strand of fibres would be very weak and of
little practical use. A change in the level of twist also changes many
yarn properties, such as strength and softness.
Definition:
Twist may be defined as the spiral disposition of the components of a thread which is usually the result of relative rotation of the two ends. Twist is generally expressed as the number of turns per unit length of yarn, e.g. turns per inch (tpi), turns per metre (tpm), etc.
What exactly does twist to a yarn?
Types of Twist:
There are two types of twist: real twist and false twist.
Real twist:
To insert a real twist into a length of yarn, one end of the yarn should be rotated relative to the other end, as indicated in figure (a).
Spun yarns usually have real twist, which holds the fibres together in the yarn.
False twist:
When inserting false twist into a length of yarn, both ends of the yarn are clamped, usually by rollers, and twist is inserted with a false twister between the clamping points, as indicated in figure (b).
If the yarn is not traversing along its axis, the twist will be in opposite directions above and below the false twister. If the false twister is removed, the opposite twists will cancel out one another, leaving no real twist in the length of yarn. If the yarn is traversing along its axis, then the section of the yarn moving away from the false twister would have no net twist, as indicated in figure (b).
False twisting is a very important phenomenon, which has considerable practical implications in yarn technology.
Twist Direction:
A twist can be either in Z direction or S direction as indicated in the following figure, depending on the orientation of the surface fibre in relation to yarn axis.
It is worth noting that twist direction
affects fabric properties. For example, following Figure shows two
identical twill-weave fabrics with the warp yarn of different twist
direction. Fabric A will be more lustrous than fabric B, because light
reflected by fibres in the warp and weft is in the same direction.
Fabric A will be softer while fabric B firmer, because in Fabric B, the
surface fibres on the warp and weft in the region of contact are aligned
in the same direction and they may ‘get stuck’ inside each other and
reduce the mobility of the intersection. Whereas for fabric A, the
surface fibres on the warp and weft in the region of contact are crossed
over, and they can move about easily. The freedom of movement at the
yarn intersections is the key for fabric softness.
Self-locking Effect:
Because of twist in a yarn, the fibres on yarn surface take a roughly helical configuration around the yarn. When the yarn is under tension, these surface fibres are also under tension. However, because of the helical configuration, part of the tension is diverted radially, which creates a radial pressure. This is illustrated in the following figure.
The radial pressure tends to pack the fibres together, increasing the normal force between them, and so increasing their frictional resistance to slipping past each other. The more tension is applied to the yarn, the more it locks together, hence 'self-locking'. An analogy is, when you wind a string around your arm, as you pull the string along the arm and away from each other, the string bites deeper into the flesh.
Without twist, there won’t be any self-locking effect to prevent fibre slippage. Consequently the yarn would have no strength.
Definition:
Twist may be defined as the spiral disposition of the components of a thread which is usually the result of relative rotation of the two ends. Twist is generally expressed as the number of turns per unit length of yarn, e.g. turns per inch (tpi), turns per metre (tpm), etc.
What exactly does twist to a yarn?
- The twist in a yarn binds the fibres together and helps to keep them in the respective positions. It thus gives coherence to yarn.
- Twist gives sufficient strength to the yarn.
- Twist is also used to bring about novel effects that are prominently visible when the yarn is converted to fabric. This is achieved primarily by having a combination of yarns with different twist levels and twist directions in the fabric.
Types of Twist:
There are two types of twist: real twist and false twist.
Real twist:
To insert a real twist into a length of yarn, one end of the yarn should be rotated relative to the other end, as indicated in figure (a).
Spun yarns usually have real twist, which holds the fibres together in the yarn.
False twist:
When inserting false twist into a length of yarn, both ends of the yarn are clamped, usually by rollers, and twist is inserted with a false twister between the clamping points, as indicated in figure (b).
If the yarn is not traversing along its axis, the twist will be in opposite directions above and below the false twister. If the false twister is removed, the opposite twists will cancel out one another, leaving no real twist in the length of yarn. If the yarn is traversing along its axis, then the section of the yarn moving away from the false twister would have no net twist, as indicated in figure (b).
False twisting is a very important phenomenon, which has considerable practical implications in yarn technology.
 |
| Figure: Real twisting and false twisting |
A twist can be either in Z direction or S direction as indicated in the following figure, depending on the orientation of the surface fibre in relation to yarn axis.
 |
| Fig. : Twist direction |
 |
| Fig. : Effect of twist direction on fabric properties |
Because of twist in a yarn, the fibres on yarn surface take a roughly helical configuration around the yarn. When the yarn is under tension, these surface fibres are also under tension. However, because of the helical configuration, part of the tension is diverted radially, which creates a radial pressure. This is illustrated in the following figure.
The radial pressure tends to pack the fibres together, increasing the normal force between them, and so increasing their frictional resistance to slipping past each other. The more tension is applied to the yarn, the more it locks together, hence 'self-locking'. An analogy is, when you wind a string around your arm, as you pull the string along the arm and away from each other, the string bites deeper into the flesh.
Without twist, there won’t be any self-locking effect to prevent fibre slippage. Consequently the yarn would have no strength.
 |
 |
(Where ɵ= twist angle, d= yarn diameter and L= yarn length)
Also from figure, the height (pitch) of one turn of twist is L. Since the twist level is normally specified as the number of turns per metre, the twist level in one metre of the yarn would be:
We also know from experience that yarn diameter is also very hard to measure, because textile yarns by their very nature are soft and squashy. On the other hand, yarn count is normally used as we have discussed in the first topic of this module. But we can relate yarn diameter to yarn count using the expression below:
 |
It is worth noting though there are minor errors associated with the use of twist factor for the following reasons:
- The cubic density may be different for different yarns. It is assumed in the above calculation that this will not change for yarns of the same surface twist angle.
- Different fibres with different frictional and other properties will create different yarn character.
For the tex system:
 |
Angle of Twist:
The yarn twist angle is the angle between a tangent to the helix formed by a fibre on the yarn surface and the yarn axis. If the twist multiplier of a cotton yarn is known, the twist angle can be easily calculated.
Factors Affecting Twist:
The twist introduced in the yarn during spinning depends upon a number of factors, such as follows:
- The count of yarn to be spun
- The quality of cotton used
- The use to which the yarn is put- is the yarn meant to be used as warp yarn or weft yarn, knitting yarn or any other yarn?
- The fineness of the fibre being spun
- The softness of the fabric into which the yarn is to be converted
If someone twists your head, it is your neck that suffers most. That is because the neck is a ‘thin’ place and offers little resistance to being twisted. By analogy, if a yarn of varying thickness is twisted, it is usually the thin spot in the yarn that gets twisted the most. Invariably, yarns spun from staple fibres (eg. wool, cotton) are not perfectly uniform, and there are thick and thin spots along the yarn length. This variation in yarn thickness will lead to variation in the twist level along the yarn length, because twist tends to accumulate in the thin place.
The fact that twist tends to accumulate in the thin spot along the yarn has several important implications:
1. It exacerbates the variation in yarn linear density
While variation in yarn linear density is the fundamental cause of twist variation, concentration of twist in the thin places will make those places even thinner, exacerbating the problem of yarn unevenness.
2. It improves the evenness of a fibre assembly during “drafting against twist”
In the drafting stage of woollen ring spinning, the woollen slubbing is drafted while twist is inserted into the slubbing (drafting against twist) to control fibres during drafting. Because twist tends to accumulate in the thin spots, the fibres in thin regions in the slubbing are more difficult to draft than those in the thick places, which have less twist. As a result, the thick places are drafted more than the thin places, thus improving the evenness of the drafted material. This is depicted in following figure.
 |
| Figure: 'Drafting against twist' improves evenness |
Because the twist level varies along the yarn length, the twist measured at a short length of yarn may not reflect the true average twist of the yarn. Standard test procedures should be followed to measure the yarn twist accurately.
The relationship between twist and yarn count may be expressed by the following formula:
p is usually greater than 1 but less than 2 for most yarns.
Twist Contraction:
When a bundle of parallel fibres is twisted, the distance between the two ends of a fibre will decrease, particularly for fibres near the surface of the twisted bundle. As a result, the overall length of the twisted bundle is shorter than its length before twist insertion. The reduction in length due to twist insertion is known as twist contraction.
The following formula is used to calculate the amount of twist contraction:
Where,
Twist Contraction:
When a bundle of parallel fibres is twisted, the distance between the two ends of a fibre will decrease, particularly for fibres near the surface of the twisted bundle. As a result, the overall length of the twisted bundle is shorter than its length before twist insertion. The reduction in length due to twist insertion is known as twist contraction.
The following formula is used to calculate the amount of twist contraction:
Lo = original length before twisting
Lf = final length after twisting
It should be noted that because of twist contraction and the associated change in length, the count of a yarn will change slightly when twist in the yarn is changed. Twist contraction increases yarn count (tex), because the weight of the yarn is distributed over a shorter length. The following formula can be used
Where,
No = count (tex) before twisting
Nf = count (tex) after twisting
C = %contraction
Measurement of Twist:
Twist measurement is a routine test for yarns. Because of the variation in twist along yarn length, care should be taken in measuring the twist of staple spun yarns. Some basic principles are discussed here.
Sampling Rules:
The following rules should be observed when measuring yarn twist:
The two common methods used in twist measurement are straightened fibre method and untwist/retwist method.
(1) Straightened Fibre Method:
This method involves counting of the number of turns required to untwist the yarns until the surface fibres appear to be straight and parallel to yarn axis. This method is mainly used for ply and continuous filament yarns.
(2) Untwist / Retwist Method:
This is the common method used for staple fibre yarns. It is based on twist contraction (hence also known as twist contraction method).
For this method, it is assumed that the contraction in length, due to insertion of twist, is the same for both direction of twist (S and Z). Suppose we want to measure the twist level in a yarn with Z twist, the yarn is first untwisted (by a twist tester), and a counter on the twist tester will record the number of turns. During untwisting, the yarn would increase in length from its original length L to a new length L’. If the operation is continued, the yarn would have its twist completely removed first and then twisted up again in S direction. As the yarn gets twisted, its length will decrease (twist contraction) from L’ towards its original length L. When its original length is reached, the total number of turns received by the yarn, as recorded by the counter on the twist tester, would be equal to twice the twist in the original yarn (with a length of L).
Automatic twist testers are now available, such as the Zweigle automatic twist tester.
http://textilelearner.blogspot.com/2013/03/yarn-twist-relationship-between-yarn.html
Lf = final length after twisting
It should be noted that because of twist contraction and the associated change in length, the count of a yarn will change slightly when twist in the yarn is changed. Twist contraction increases yarn count (tex), because the weight of the yarn is distributed over a shorter length. The following formula can be used
No = count (tex) before twisting
Nf = count (tex) after twisting
C = %contraction
Measurement of Twist:
Twist measurement is a routine test for yarns. Because of the variation in twist along yarn length, care should be taken in measuring the twist of staple spun yarns. Some basic principles are discussed here.
Sampling Rules:
The following rules should be observed when measuring yarn twist:
- Tests should not be limited to a short length of the yarn package.
- Beware of "operator bias" - tendency to select either thicker or thinner regions. Taking samples at fixed intervals along the yarn length will reduce the bias.
- Discard first few metres from package. Being a free end, it could have lost twist.
- Remove yarn from side of package, not over end. Removing yarn over end will change the twist level in the yarn.
- Tension in Yarn during test e.g. For single worsted yarns: 5 + 1 mN/tex
The two common methods used in twist measurement are straightened fibre method and untwist/retwist method.
(1) Straightened Fibre Method:
This method involves counting of the number of turns required to untwist the yarns until the surface fibres appear to be straight and parallel to yarn axis. This method is mainly used for ply and continuous filament yarns.
(2) Untwist / Retwist Method:
This is the common method used for staple fibre yarns. It is based on twist contraction (hence also known as twist contraction method).
For this method, it is assumed that the contraction in length, due to insertion of twist, is the same for both direction of twist (S and Z). Suppose we want to measure the twist level in a yarn with Z twist, the yarn is first untwisted (by a twist tester), and a counter on the twist tester will record the number of turns. During untwisting, the yarn would increase in length from its original length L to a new length L’. If the operation is continued, the yarn would have its twist completely removed first and then twisted up again in S direction. As the yarn gets twisted, its length will decrease (twist contraction) from L’ towards its original length L. When its original length is reached, the total number of turns received by the yarn, as recorded by the counter on the twist tester, would be equal to twice the twist in the original yarn (with a length of L).
Automatic twist testers are now available, such as the Zweigle automatic twist tester.
http://textilelearner.blogspot.com/2013/03/yarn-twist-relationship-between-yarn.html
2 August 2012
Count conversion
Count conversion
Denier to Tex:
Denier means,
weight of 9000m of yarn= Dx1 gm
Tex means ,
weight of 1000m of yarn= Tx1 gm
Mathematically,
Wt. of 9000m yarn= 1x D gm
Wt. of 1m yarn = (1xD) / 9000gm
Wt. of 1000m yarn= (1x1000xD) / 9000 gm
= D/9
From definition we can write, T(tex)= D/9
D (denier) = 9xT (tex)
Denier means,
weight of 9000m of yarn= Dx1 gm
Tex means ,
weight of 1000m of yarn= Tx1 gm
Mathematically,
Wt. of 9000m yarn= 1x D gm
Wt. of 1m yarn = (1xD) / 9000gm
Wt. of 1000m yarn= (1x1000xD) / 9000 gm
= D/9
From definition we can write, T(tex)= D/9
D (denier) = 9xT (tex)
Den = 9xTex
This is the relation.
English Count to Tex:
Cotton count means,
length of 1 pound yarn=Ne x 840 yards
Tex means,
weight of 1000 m of yarn = T x 1gm
Mathematically,
length of 1 pound yarn=Ne x 840 yards
length of 1 = 1 x 453.6gm yarn = Ne x 840 x 0.9144 m
wt. of Ne x 840 x 0.9144 m yarn = 1 x 453.6 gm
wt. of 1m yarn = (1 x 453.6) / (Ne x 840 x 0.9144) gm
wt. of 1000m yarn = (1 x 1000 x 453.6) / (Ne x 840 x 0.9144)gm
From definition we can write,
T(tex)= (1 x 1000 x 453.6) / (Ne x 840 x 0.9144)
Tex x Ne = 590.5
This is the relation.
English count to Denier:
Cotton count means,
length of 1 pound yarn=Ne x 840 yards
Denier means,
weight of 9000m of yarn= Dx1 gm
Mathematically,
This is the relation.
English Count to Tex:
Cotton count means,
length of 1 pound yarn=Ne x 840 yards
Tex means,
weight of 1000 m of yarn = T x 1gm
Mathematically,
length of 1 pound yarn=Ne x 840 yards
length of 1 = 1 x 453.6gm yarn = Ne x 840 x 0.9144 m
wt. of Ne x 840 x 0.9144 m yarn = 1 x 453.6 gm
wt. of 1m yarn = (1 x 453.6) / (Ne x 840 x 0.9144) gm
wt. of 1000m yarn = (1 x 1000 x 453.6) / (Ne x 840 x 0.9144)gm
From definition we can write,
T(tex)= (1 x 1000 x 453.6) / (Ne x 840 x 0.9144)
Tex x Ne = 590.5
This is the relation.
English count to Denier:
Cotton count means,
length of 1 pound yarn=Ne x 840 yards
Denier means,
weight of 9000m of yarn= Dx1 gm
Mathematically,
length of 1 pound yarn=Ne x 840 m
length of 1 = 1 x 453.6gm yarn = Ne x 840 x 0.9144 m
Now,
length of 1 = 1 x 453.6gm yarn = Ne x 840 x 0.9144 m
Now,
wt. of Ne x 840 x 0.9144 m yarn = 1 x 453.6 gm
wt. of 1m yarn = (1 x 453.6) / (Ne x 840 x 0.9144) gm
wt. of 9000m yarn = (1 x 9000 x 453.6) / (Ne x 840 x 0.9144)gm
From definition we can write,
Denier = (1 x 9000 x 453.6) / (Ne x 840 x 0.9144)
Denier x Ne ≈ 5315
This is the desired relation.
Denier & Metric:
Denier means ,
weight of 9000m yarn = 1 x D gm
Metric means,
length of 1000 m yarn = Nm x1000 m.
Mathematically,
wt. of 9000 m yarn = 1 x D gm
wt. of 1 m yarn = (1 x D) / 9000 gm
length of (1 x D) / 9000 gm yarn = 1 m
length of 1000 gm yarn = (1 x 9000 x 1000) / (1 x D) m
From definition we can write,
wt. of 1m yarn = (1 x 453.6) / (Ne x 840 x 0.9144) gm
wt. of 9000m yarn = (1 x 9000 x 453.6) / (Ne x 840 x 0.9144)gm
From definition we can write,
Denier = (1 x 9000 x 453.6) / (Ne x 840 x 0.9144)
Denier x Ne ≈ 5315
This is the desired relation.
Denier & Metric:
Denier means ,
weight of 9000m yarn = 1 x D gm
Metric means,
length of 1000 m yarn = Nm x1000 m.
Mathematically,
wt. of 9000 m yarn = 1 x D gm
wt. of 1 m yarn = (1 x D) / 9000 gm
length of (1 x D) / 9000 gm yarn = 1 m
length of 1000 gm yarn = (1 x 9000 x 1000) / (1 x D) m
From definition we can write,
Nm= (1 x 9000 x 1000) / (1 x D)
Nm x Den= 9000000
This is the relation.
English count to Metric:
Cotton count means,
length of 1 pound yarn=Ne x 840 yards
Metric means,
length of 1000 gm yarn = Nm x1000 m
Since,
length of 1 pound yarn=Ne x 840 yards
length of 1x453.6gm yarn=Ne x 840x0.9144 m
Again,
wt. of Ne x 840 x 0.9144 m yarn = 1 x 453.6 gm
wt. of 1m yarn = (1 x 453.6) / (Ne x 840 x 0.9144) gm
wt. of 1000m yarn = (1 x 1000 x 453.6) / (Ne x 840 x 0.9144)gm
Mathematically,
(Ne x 840 x 0.9144) / 453.6 = (Metric) Nm x 1000
or,
Nm x Den= 9000000
This is the relation.
English count to Metric:
Cotton count means,
length of 1 pound yarn=Ne x 840 yards
Metric means,
length of 1000 gm yarn = Nm x1000 m
Since,
length of 1 pound yarn=Ne x 840 yards
length of 1x453.6gm yarn=Ne x 840x0.9144 m
Again,
wt. of Ne x 840 x 0.9144 m yarn = 1 x 453.6 gm
wt. of 1m yarn = (1 x 453.6) / (Ne x 840 x 0.9144) gm
wt. of 1000m yarn = (1 x 1000 x 453.6) / (Ne x 840 x 0.9144)gm
Mathematically,
(Ne x 840 x 0.9144) / 453.6 = (Metric) Nm x 1000
or,
Ne = Nm x ( 453.6) / (840 x 0.9144)
or,
28 July 2012
Yarn Numbering System (Yarn Count) | Direct Count System | Indirect Count System
Yarn Count:
Count is a numerical value, which express the coarseness or fineness (diameter) of the yarn and also indicate the relationship between length and weight(the mass per unit length or the length per unit mass)of that yarn. Therefore, the concept of yarn count has been introduced which specifies a certain ratio of length to weight.
The fineness of the yarn is usually expressed in terms of its linear density or count. There are a number of systems and units for expressing yarn fineness. But they are classified as follows .
Types of Yarn Count:
1. Direct Count System
Count is a numerical value, which express the coarseness or fineness (diameter) of the yarn and also indicate the relationship between length and weight(the mass per unit length or the length per unit mass)of that yarn. Therefore, the concept of yarn count has been introduced which specifies a certain ratio of length to weight.
The fineness of the yarn is usually expressed in terms of its linear density or count. There are a number of systems and units for expressing yarn fineness. But they are classified as follows .
Types of Yarn Count:
1. Direct Count System
2. Indirect Count System
1. Direct Count System:
The weight of a fixed length of yarn is determined. The weight per unit length is the yarn count! The common features of aII direct count systems are the length of yarn is fixed and the weight of yarn varies according to its fineness.
The following formula is used to calculate the yarn count:
N= (W×l) / L
Where,
1. Direct Count System:
The weight of a fixed length of yarn is determined. The weight per unit length is the yarn count! The common features of aII direct count systems are the length of yarn is fixed and the weight of yarn varies according to its fineness.
The following formula is used to calculate the yarn count:
N= (W×l) / L
Where,
N =Yarn count or numbering system
W =Weight of the sample at the official regain in the unit of the system
L=Length of the sample
l=Unit of length of the sample
W =Weight of the sample at the official regain in the unit of the system
L=Length of the sample
l=Unit of length of the sample
- Tex system ..........................NO. of grams per 1000 meters
- Denier .................................No. of Grams per 9000 meters
- Deci Tex ..............................No. of grams per 10,000 metres
- Millitex ................................No. of milligrams per 1000 metres
- Kilotex............................... .No. of kilograms per 1000 metres.
- Jute count........................No. of lb per 14,400 yds
From above discussion it is concluded that, higher the yarn number(count) coarser the yarn and lower the number finer the yarn.
2. Indirect Count System:
The length of a fixed weight of yarn is measured. The length per unit weight is the yarn count. The common features of all indirect count systems are the weight of yarn is fixed and the Length of yarn varies according to its fineness.
The following formula is used to calculate they are count:
N = (L×w) / W×l
Where,
N =Yarn count or numbering system
W =Weight of the sample at the official regain in the unit of the system
L=Length of the sample
l=Unit of length of the sample
w = Unit of weight of the sample.
W =Weight of the sample at the official regain in the unit of the system
L=Length of the sample
l=Unit of length of the sample
w = Unit of weight of the sample.
2. Nm: No of one kilometer yarn weighing in One Kilogram
The Ne indicate show many hanks of 840 yards length weigh one English pound. So that 32 Ne Means 32 hanks of 840yards i.e.32x840 yards length weigh one pound.
For the determination of the count of yarn, it is necessary to determine the weight of a known length of the yarn. For taking out known lengths of yarns, a wrap-reel is used. The length of yarn reeled off depends upon the count system used. One of the most important requirements for a spinner is to maintain the average count and count variation within control.
Yarn Count Variation:
The term count variation is generally used to express variation in the weight of a lea and this is expressed as C.V.%. The number of samples and the length being considered for count checking affects this. While assessing count variation, it is very important to test adequate number of leas. After reeling the appropriate length of yarn, the yarn is conditioned in the standard atmosphere for testing before it's weight is determined.
http://textilelearner.blogspot.com/
6 June 2012
Calculation of twist, twist constant of the ring frame.
Name of the experiment: Calculation of twist, twist constant of the ring frame.
Objects:
i) To find out twist per inch of the ring frame.
ii) To find out twist constant of the ring frame.
Objects:
i) To find out twist per inch of the ring frame.
ii) To find out twist constant of the ring frame.
Specification:
Front roller diameter = 1"
Tin cylinder diameter = 10"
Whrave diameter = 1.125"
Twist change pinion = 48T
Gearing diagram:
Calculation:
Result:
1) TPI= 21
2) Twist constant= 1008
Conclusion:
Ring frame is the final and very important machine for build the yarn onto bobbin in a form suitable for storage, transportation and processing. It is used to twist the drafted strand to form yarn of required count and strength. In this practical we calculate twist, twist constant of the ring frame. By this practical we come to know about the gearing diagram of ring frame. Special thanks to our teacher and his assistance for helping us.
http://textilelearner.blogspot.com/
Front roller diameter = 1"
Tin cylinder diameter = 10"
Whrave diameter = 1.125"
Twist change pinion = 48T
Gearing diagram:
 |
| Figure: gearing diagram for calculating twist and twist constant of ring frame. |
Result:
1) TPI= 21
2) Twist constant= 1008
Conclusion:
Ring frame is the final and very important machine for build the yarn onto bobbin in a form suitable for storage, transportation and processing. It is used to twist the drafted strand to form yarn of required count and strength. In this practical we calculate twist, twist constant of the ring frame. By this practical we come to know about the gearing diagram of ring frame. Special thanks to our teacher and his assistance for helping us.
http://textilelearner.blogspot.com/
15 March 2012
Study on ring doubling frame
Experiment Name: Study on ring doubling frame
1.Spindle speed, front roller delivery.
2.Twist, twist Constant.
Objects:
1) To combine two or more single threads into one.
2) To insert sufficient amount of twist for holding the yarns.
3) To increase strength, smoothness and luster.
4) To reduce hairiness.
5) To make sewing thread.
6) To wind a suitable bobbin.
Main parts:
1.Spindle speed, front roller delivery.
2.Twist, twist Constant.
Objects:
1) To combine two or more single threads into one.
2) To insert sufficient amount of twist for holding the yarns.
3) To increase strength, smoothness and luster.
4) To reduce hairiness.
5) To make sewing thread.
6) To wind a suitable bobbin.
Main parts:
- Creel stand and creel.
- Front roller.
- Yarn guide.
- Ring and ring rail
- Tin cylinder.
- Traveller.
- Thread weight or slip roller.
- Lappet Spindle.
Specification:
- Motor rpm = 1430
- Motor pulley diameter = 6.25²
- Machine pulley diameter = 10.25²
- Tin cylinder diameter = 10²
- Wharve diameter = 1.37²
- Cylinder carrier wheel = 24T
- TCP carrier wheel = 62T
- TCP = 63T
- Front roller diameter = 2’’
Gearing diagram of doubling frame:
 |
| Figure: gearing diagram of doubling frame. |
1) Spindle speed = 6461.59 rpm
2) Twist constant = 1235.25
3) Front roller delivery = 319.143 inch/min.
4) Existing TPI = 20
5) Production = 14.37 lb/shift/frame.
6) Required TPI = 16.266
7) Required TCP =76.25T
Conclusion:
By
this experiment we come to know about various parts and working
principle of ring doubling frame. This machine is important for
producing double yarn on sewing thread.
http://textilelearner.blogspot.com/
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1 February 2012
Determination of crimp percentage
Experiment name: Determination of crimp percentage in warp and weft of a given fabric.
Introduction:
When warp and weft yarns interlace in fabric they follow a wavy or corrugated path. Crimp percentage is a measure of this waviness in yarns. Warp and weft crimp percentages are two of the eleven structural elements in fabric construction discussed by Peirce. The relationships between the geometry of a cloth structure and its physical behavior in use are complex. Although much pioneer work has been done there are many unresolved problems still to be investigated.
Objective:
To measure the crimp percentage in warp and weft of a given fabric.
Theory:
Percentage crimp is defined as the mean difference between the straightened thread length and the distance between the ends of the thread while in the cloth, expressed as a percentage. From the definition of crimp two values must be known, the cloth length from which the yarns is removed and the straightened length of the thread. In order to straighten the thread, tension must be applied, just sufficient to remove all the kinks without stretching the yarn. In practice it is seldom possible to remove all the crimp before the yarn itself begins to stretch. The standardized tensions recommended in the B.S. Handbook are given below:
Calculation:
Result:
Average warp crimp percentage 6.7%
and average weft crimp percentage 10.5%.
Remark:
We found that crimp percentage for warp is less than weft. It is because the warp yarns are kept in tension during weaving. Besides they are stronger and better yarn than weft. So they do not extend more. On the other hand weft yarns are kept in low tension and low in quality. So they can extend more. As a result their crimp percentage is more. We should notice that variation in crimp can give rise to faults in fabrics, e.g. reduction in strength, bright picks and diamond barring in rayons, strips in yarn dyed cloths and so on. So we should control it which is also necessary for design fabric to give required extensibility. Since crimp is related to length, it affects the amount of cloth as well as cost of production.
http://textilelearner.blogspot.com/
Introduction:
When warp and weft yarns interlace in fabric they follow a wavy or corrugated path. Crimp percentage is a measure of this waviness in yarns. Warp and weft crimp percentages are two of the eleven structural elements in fabric construction discussed by Peirce. The relationships between the geometry of a cloth structure and its physical behavior in use are complex. Although much pioneer work has been done there are many unresolved problems still to be investigated.
Objective:
To measure the crimp percentage in warp and weft of a given fabric.
Theory:
Percentage crimp is defined as the mean difference between the straightened thread length and the distance between the ends of the thread while in the cloth, expressed as a percentage. From the definition of crimp two values must be known, the cloth length from which the yarns is removed and the straightened length of the thread. In order to straighten the thread, tension must be applied, just sufficient to remove all the kinks without stretching the yarn. In practice it is seldom possible to remove all the crimp before the yarn itself begins to stretch. The standardized tensions recommended in the B.S. Handbook are given below:
From those two values we can calculate the crimp percentage with the following formula:
C=(l-p)/p*100%
where, c = crimp, l = uncrimped length and p = crimped length.
Five groups of threads selected for test are two warp way and three weft way groups. The mean crimp percentage is calculated warp way and weft way. Rectangular strips are carefully marked on the cloth and each strip cut into the form of a flap. From each strip ten threads will be removed. Removal of threads is as follows: the central part of the first thread is separated from the flap fringe by means of a dissecting needle, but the two extreme ends are left secured. One end is then removed and place in the grip of the tester, and the other end is removed and placed in the second grip. In this way the thread is transferred from the cloth to the crimp tester without loss of twist and with a minimum handling. Several crimp testers are available, Shirley crimp tester is one of them.
Atmosphere:
Temperature – 25oC and relative humidity – 67%
Standard atmosphere: temperature – 20oC and relative humidity - 65%.
Apparatus:
1. Crimp tester
2. Fabric sample
3. Scissor
4. Scale
Sample:
Cotton woven fabric. Length = 10².
Procedure:
1. At first we have to select the warp or weft way of the fabric. Then we should select the test length of the yarn. Here it is 10².
2. According to test length we will cut the flap of fabric.
3. Now a single yarn is to remove from the flap of fabric carefully as discussed in theory.
4. One end of the yarn is gripped in the fixed gripper of the m/c and the other end is gripped in the other setting the test length.
5. Now the tension for the sample is found out from its count and it is set in the m/c.
6. After that we will apply tension along the yarn length with hand by taking away the other end of yarn far from the first end.
7. As soon as the white marl on the tension bar is on the same line of its both sides white mark, we will stop far away the other end.
8. The length of the yarn after applying tension is taken from the scale.
9. Now from this two lengths crimp percentage is calculated from the given formula.
10. In this way at least 10 crimp percentage for warp and 10 for weft is taken and average crimp percentage is calculated from them.
where, c = crimp, l = uncrimped length and p = crimped length.
Five groups of threads selected for test are two warp way and three weft way groups. The mean crimp percentage is calculated warp way and weft way. Rectangular strips are carefully marked on the cloth and each strip cut into the form of a flap. From each strip ten threads will be removed. Removal of threads is as follows: the central part of the first thread is separated from the flap fringe by means of a dissecting needle, but the two extreme ends are left secured. One end is then removed and place in the grip of the tester, and the other end is removed and placed in the second grip. In this way the thread is transferred from the cloth to the crimp tester without loss of twist and with a minimum handling. Several crimp testers are available, Shirley crimp tester is one of them.
Atmosphere:
Temperature – 25oC and relative humidity – 67%
Standard atmosphere: temperature – 20oC and relative humidity - 65%.
Apparatus:
1. Crimp tester
2. Fabric sample
3. Scissor
4. Scale
Sample:
Cotton woven fabric. Length = 10².
Procedure:
1. At first we have to select the warp or weft way of the fabric. Then we should select the test length of the yarn. Here it is 10².
2. According to test length we will cut the flap of fabric.
3. Now a single yarn is to remove from the flap of fabric carefully as discussed in theory.
4. One end of the yarn is gripped in the fixed gripper of the m/c and the other end is gripped in the other setting the test length.
5. Now the tension for the sample is found out from its count and it is set in the m/c.
6. After that we will apply tension along the yarn length with hand by taking away the other end of yarn far from the first end.
7. As soon as the white marl on the tension bar is on the same line of its both sides white mark, we will stop far away the other end.
8. The length of the yarn after applying tension is taken from the scale.
9. Now from this two lengths crimp percentage is calculated from the given formula.
10. In this way at least 10 crimp percentage for warp and 10 for weft is taken and average crimp percentage is calculated from them.
Data:
S/n
|
Warp Yarn
|
Weft yarn
| ||||||
Crimped length p
|
Uncrimped length l
|
Crimp percentage c
|
Mean
|
Crimped length p
|
Uncrimped length l
|
Crimp percentage c
|
Mean
| |
1
|
10²
|
10.7²
|
7%
|
6.7%
|
10²
|
11.1²
|
11%
|
10.5%
|
2
|
10.9²
|
9%
|
11²
|
10%
| ||||
3
|
10.8²
|
8%
|
11.2²
|
12%
| ||||
4
|
10.4²
|
4%
|
11.1²
|
11%
| ||||
5
|
10.6²
|
6%
|
10.9²
|
9%
| ||||
Average warp crimp percentage 6.7%
and average weft crimp percentage 10.5%.
Remark:
We found that crimp percentage for warp is less than weft. It is because the warp yarns are kept in tension during weaving. Besides they are stronger and better yarn than weft. So they do not extend more. On the other hand weft yarns are kept in low tension and low in quality. So they can extend more. As a result their crimp percentage is more. We should notice that variation in crimp can give rise to faults in fabrics, e.g. reduction in strength, bright picks and diamond barring in rayons, strips in yarn dyed cloths and so on. So we should control it which is also necessary for design fabric to give required extensibility. Since crimp is related to length, it affects the amount of cloth as well as cost of production.
http://textilelearner.blogspot.com/
1 January 2012
What is Yarn Withdrawal? | Types of Yarn Withdrawal | Advantages/Disadvantages of Yarn Withdrawal
Yarn Withdrawal
Removal or unwinding of yarn from the package during weaving is called withdrawal of yarn.
Types of Yarn Withdrawal
There are 2 types of yarn withdrawal:
Removal or unwinding of yarn from the package during weaving is called withdrawal of yarn.
Types of Yarn Withdrawal
There are 2 types of yarn withdrawal:
- Side withdrawal.
- Over-end withdrawal.
Side Withdrawal:
In
side withdrawal, the spool must rotate in order for the yarn to be
removed. Typical uses of side withdrawal are to be found in the various
operations on a warp; in view of the multiplicity of ends in a warp it
is virtually impossible to use anything but side withdrawal.Advantages:
- The yarn does not rotate upon withdrawal.
- The yarn twists remain constant.
- At high winding speeds, due to inertia, the rotation of the spool may lead to tension variations in the yarn.
- This process is costlier for practical use.
- High speed impairs the stability of the package.
This method is simplest & most common method of yarn withdrawal. The yarn is to take away along a line which roughly coincides with the axis of the package. Using this technique it is not necessary to rotate the package. It is used in circumstances where high winding speeds are required, such as in high speed beaming & the removal of yarn from weft packages.
Advantages:
- Very high rates of yarn withdrawal.
- Not so expensive.
- Not necessary to rotate the package.
- Flanged is not required.
- Balloon formation.
- There is a chance of one turn twist in the yarn.
21 December 2011
Introduction of Lycra | Properties of Lycra Yarn | Application/Uses of Lycra Yarn
LYCRA®
is a man-made elastic fibre invented and produced only by DuPont . It
is INVISTA's trademark for a synthetic fabric material with elastic
properties of the sort known generically as "spandex".
Lycra is commonly used in athletic or active clothing. Lycra as a
clothing material is fetishized by some people, perhaps on the basis
that the garment forms a "second skin" that acts as a fetishistic
surrogate for the wearer's own skin. This is known as lycra fetishism.
Lycra is normally one of the fabrics in leggings.
 |
| Lycra Yarn |
LYCRA
can be stretched four to seven times its initial length, yet springs
back to it’s original length once tension is released. While Lycra
appears to be a single continuous thread, it is in reality a bundle of
tiny filaments.
Properties of Lycra Yarn:
- Heat : Sticks at 350-390F. Melts above 500F.
- Bleaches &Solvents : Good resistance to oxidizing agents. Poor resistance to bleaches.
- Acids & Alkalis : Good
- Abrasion : Good in diluted (weak), but degrades in strong acids & bases.
- Mildew, Aging &Sunlight : Excellent aging and mildew resistance. Good resistance to sunlight.
- Made from premium quality materials
- Long life and strong structure
- Unique weave pattern
- Ideally suited for industrial as well as household applications
Lycra is never used alone; it is always combined with another fiber (or fibers), natural or man-made. Fabrics enhanced with lycra retain the appearance of the majority fibre.
 |
Application/Uses of Lycra Yarn:
Widely used for weaving items like
- Apparels
- Socks & stockings
- Seamless garments
- Gloves
- Sweaters
- Swimwear
- Narrow fabrics
- Smocking
- Medical bandages
- Head bandages
- Wrist bands
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