Comparative Study between Open Line & Tube Line Finishing Process

Comparative Study between Open Line & Tube Line Finishing Process

Md. Israil Hossain & Md. Shah Alam
Department of Textile Engineering
Dhaka University of Engineering & Technology (DUET)
Gazipur -1700, Bangladesh

ABSTRACT
After dyeing the weft knitted fabrics, the dyed fabrics can be finished by either open line or tube line. Cotton weft knitted fabrics are prone to shrinkage during finishing processes and customer usage. The effect of various fabric characteristics on the shrinkage behavior of weft knits is as important as that of the fiber characteristics. Weft knitted fabrics tend to undergo certain dimensional changes that causes distortion in which there is a tendency of the knitted loops to bend over, causing the wales to be at diagonal instead of perpendicular to the courses. This is a very common problem in single jersey knits and it may exist in greige, washed or finished state and has an obvious influence on both the aesthetic and functional performance of knitwear. Spirality is a particularly serious problem for plain knitted fabrics due to asymmetric loops. The aim of this study is to compare the performance of same parameters knitted fabrics finished by both open and tube line. This study has been investigated comparative about Shrinkage & Spirality of mechanical finishing process of different knitted fabrics which has been subjected to both open and tube line finishing process. The data has been taken very carefully for same fabric after each step of both open and tube line. The tested data has been statistically analyzed and it has been found that  if one wants to get better hand feel, excellent looking appearance and spirality free fabric, then the fabric should be finished by open line.

CHAPTER-1
INTRODUCTION

Finishing is a sequence of operations, other than scouring, bleaching and coloring to which fabrics are subjected after leaving the loom or knitting machine. It is the last manufacturing step in the production of textile fabrics. As an integral part of wet processing where the final fabric properties are developed. Finish can be either chemicals that change the fabric’s aesthetic and/or physical properties or changes in texture or surface characteristics such as appearance, hand feel etc. are brought about by physically manipulating the fabric with mechanical devices. It can also be a combination of the two.

Though- there are two types (Chemical & Mechanical ) of finishing processes are available for both woven and knitted fabrics, we were done comparative study (GSM, Shrinkage & Spirality) about  mechanical finishing process of different knitted fabrics. In our comparative study- the same parameters knitted fabrics were subjected to both open line and tube line mechanical finishing process and we were compared to both line finished fabrics.

1.1 Objective:

• To compare the Finishing performance (GSM, shrinkage, spirality) of different knitted fabric in open and tube line finishing process.

1.2 Open and tube line finishing process:
After dyeing, the dyed knitted fabrics can be finished in both open line and tube line finishing process. Tube line finishing process finishes fabrics in tubular form. There is no option of tube line finishing process for finishing tubular body fabrics.

Open line finishing process finish the fabrics in open width form. Spirality is a major problem in knit fabric. It is created during knitting due to high twisted yarn. Tube line increases this problem during squeezing and compacting. Open line reduces this problem during stentering by mahalo. The fabric finishing cost in open line is high than the tube line. The quality of fabric such as hand feel, appearance and luster are excellent in open line finishing process. On the other hand the quality of fabric such as hand feel, appearance and luster are comparatively low in tube line finishing process. The open line finished fabric wastage in garments cutting section is comparatively lower than the tube line finished fabric, as a result the price per garments made by open line finished fabric is low than the tube line finished fabric.

CHAPTER-2
LITERATURE

2.1 Open line finishing:
After completing knitting, the knitted fabrics are subjected to wet processes such as scouring, bleaching and dyeing. After dyeing knitted fabrics with required dyes, these dyed fabrics are finished either open line or tube line. The general description of open line finishing is given bellow –

2.1.1 Slitting machine:
Knit fabrics which are processed in rope form must be opened to full width for further processing. The machine consists of a turntable, a rope de-twister, a drop stitch sensing slitting unit with draw rollers and a plaiting unit. The equipment is mounted on its own structure for smooth operation. The Twist detector consists of 2 sensor rollers and one proximity sensor. The turntable arrangement with its drive offers smooth and fast working.

2.1.2 The basic function of the slitting machine:

• To remove the water from the fabric.
• To slit the tube fabric by the knife for opening of the fabric and ready for stentering
• To control the grain line of the fabric.
• To control the over feeding system
• It can control the diameter of fabric and GSM and shrinkage by over feeding mechanism
• To impart soft finish to the fabric by using required softener.

2.1.3 Main parts of slitting m/c:

1. J-box
2. Detwister
3. Pulley
4. Slitting unit
5. Centering/screw roller
6. Padder
7. Conveyor belt

2.1.4 Schematic diagram of slitter:

2.1.5 Stentering m/c:
The main mechanism of the stentering machine, under feed roller to feed the fabric, over feed roller to increase and decrease GSM, spending roller to remove the crease mark, mahalo to adjust the bowing angle, Fabric wheel to stretch the fabric and contact with chain.

2.1.6 The main function of the Stentering machine:

• To control the Dia of fabric.
• To control the GSM of fabric (Increase & decrease).
• To control the Shrinkage.
• To control the Spirally of Fabric.
• To stable the dimension of Fabric.
• Decrease Bowing effect.
• Silicon Softener application
• Heat set for cotton Lycra fabric & fabric dry.

2.1.7 Schematic diagram of stenter or open width finishing machine:
Figure showing the Schematic diagram of the Stenter machine.

2.1.8 Different view of the Stenter:

2.1.9 Open Compactor:
The mechanism of the compactor machine classified in the four sections. The section wise mechanism in the first section to entry the fabric in to the machine by the open form. In the second section Edge driver. The function of edge driver to increase & decrease the GSM & dia of the fabric. Here also passed the steam to soft the fabric & slightly shade match. This is the third section of the machine it’s also called the compaction station. Here to control the GSM & calendaring the fabric. Here also a blade to smooth the fabric surface. In the section four the output section of the machine. Here the fabric keeps on to the up & down moveable table. The up & down movement of the table control with the photo detector (Sensor). In case of deep shade the steam & roller pressure high & light shade steaming & roller pressure low. In this m/c 5 compact is possible.

2.1.10 The main function of open compactor:

• To control the GSM (Increase & decrease)
• To control the dia.
• To control the shrinkage (Increase & decrease)
• To control the spirality of the fabric.
• To smooth the fabric surface.
• To calender the fabric

2.1.11 Schematic diagram of open compactor or open width finishing Machine:
Figure showing the schematic diagram of the open width compacting machine with the fabric flowing path.

2.2 Tube line finishing process:
The general description of tube line finishing process is given bellow –

2.2.1 De-watering m/c:
After the dyeing process from the dyeing machine then the fabrics are ready for de-watering. This is the process to remove the water from the fabric completely by squeezing. This is the main function of the de-watering machine. But here also control the some important factor of the fabric quality.

2.2.2 The basic function of the de-watering machine:

• To remove the water from the fabric.
• To remove the crease of the fabric
• To control the width of the fabric.
• To soft the fabric if necessary
• To control the GSM by over feeding system

2.2.3 Dryer:
After de-watering then the fabric is passed through the dryer. The main function of the dryer to dry the fabric & full fill the other fabric properties according to Buyer’s requirement. This dryer has three chambers. The speed of the dryer depends on the temperature of the machine & the GSM of the fabric. When fabric GSM low, then set the m/c high speed and low temperature. Oppositely when fabric GSM high, then set the m/c low speed and high temperature. Normally temperature remains 140 -190 and speed 40-80m/min.

2.2.4 The basic functions of the dryer is as follows:

• To dry the fabric.
• To control the shrinkage by over feed system.
• To increase the GSM by over feed system.
• To control the vibration. (To increase the GSM)
• To control the shade matching such as for white shade if need few yellowish or reddish increase temperature & low speed. if need few red or yellow increase temperature & low speed

2.2.5 Schematic diagram of dryer:

The temperature of different chambers according to the shade of the fabric are:

Table 2.1: The temperature of different chambers according to the shade.

2.2.6 Tube Compactor:
The mechanism of the compactor machine is classified in the four sections. In the first section, entry the fabric in to the machine by the tube form. The second section is Edge driver. The function of edge driver to increase & decrease the GSM & dia of the fabric. Here the steam also passed to soft the fabric & slightly shade match. The third section of the machine & it’s also called the compaction station. Here to control the GSM & calendaring the fabric. There is also a blade to smooth the fabric surface. In the section four the out put section of the machine. Here the fabric keep on to the up & down moveable table. The up & down movement of the table control with the photo detector (Sensor). In case of deep shade the steam & roller pressure will be high & for light shade steaming & roller pressure will be low. Suppose, we input fabric GSM 220. Then we control the out put GSM maximum 225 & minimum 212.

2.2.7 The main functions of tube compactor:

• To control the GSM.(Increase & decrease)
• To control the dia.
• To control the shrinkage. (Increase & decrease)
• To smooth the fabric surface.
• To calendar the fabric.

2.2.8 Influence of Compacting on Knitted Fabric
Wet processing of knitted fabrics, often causes distortions in the fabrics like creases and wrinkles. In knitted fabrics, all types of shrinkage takes place when the moisture content is below 50%. The loop length is the only main factor influencing the dimensional properties of the knitted fabrics.

Yarns of different counts knitted to the same loop length display different physical properties such as drape, openness, permeability, handle, etc. Recently, factors influencing the quality of knitted fabrics have been reviewed individually by many authors.

Compaction is carried out as a measure of increasing the dimensional stability and much attention have been given in the assessment of shrinkage and progressive shrinkage properties. Now, there is a well established theory exists regarding the relationship between these two parameters.

Positive feeders are often employed to ensure much closer tolerances between feeders in respect of course length. The weight (GSM) of the fabrics is determined by two factors that interact in the knitted fabrics, i.e., the loop size and the yarn count. The cover factor, i.e., fractional area or space occupied by the knitted loop is given by the ratio of area covered by yarn in one loop and area of one loop.

This is also represented by T 1/2/L, where L is loop length, T, the direct count of the yarn. The term 1/L × N 1/2 or T 1/2/L is known as tightness factor where N is the indirect count.

2.2.9 Schematic diagram of tube compactor:

2.3  Over Feeding:
To feed the extra fabric on the machine. Here feed roller speed is higher than machine (Chain Speed). In over feeding width wise tension is higher & Length wise tension is loose. Thus GSM is become higher. It is happened in the top roller. If over feeding is increased then the GSM is also increased. Maximum over feeding is 40 -100%.If over feeding is increased 5% then the GSM is increased 4-5 gm. Over feed 60% means that if the chain speed is 100 m/min then their top roller is delivered 160 m/min.

+ Over Feeding: In case of Positive over Feeding the Fabric is Loosely Feed in the Chain.

– Over Feeding: In case of Negative over Feeding the Fabric is tight feed in the Chain.

+ Under Feeding: In case of Positive under Feeding the Fabric is loosely feed between the Top & Bottom Roller.

– Under Feeding: In case of Negative under Feeding the Fabric is tightly feed between the Top & Bottom Roller.

The Feeding which is bellow 0  is called Negative Over or Under Feeding.

2.4 Under Feeding:
To feed the extra fabrics on the Top Rollers. Here feed roller (Bottom) speed is higher than the top Roller. In over feeding Length wise tension is higher & GSM is become higher. It is happened in the Bottom roller. Under feeding is may be positive or negative. In case of positive feeding Length wise tension is increased & GSM is increased. Feeding Length wise tension is increased & GSM is increased. If over feeding is increased then the GSM is also increased. Maximum under feeding is 16%. If under feeding is increased 5% then the GSM is increased 2-3  gm. 16% positive under feeding means that if the top roller speed is 100 m/min then ther top roller is delivered 116 m/min. In case of negative feeding Length wise tension is decreased & GSM is decreased.

2.5 Definition of GSM :
The standard measurement for weight and quality of fabrics is grams per square meter, usually abbreviated as GSM. This is the accepted standard in the United States as well as in foreign countries. Towels and bath robes typically vary from 300 to 800 GSM; other fabrics may have values as low as 100 to 300 GSM. The same units are used for toilet paper and other tissues 18 to 22 GSM is typical as well as paper towels 35 to 50 GSM is typical.

GSM is defined as the weight in grams per square meter of materials (Fabrics, Papers etc).

2.6 Factors influence the knitted fabrics GSM:

• Yarn count: In case of English count, if the count yarn count is high, the GSM of knitted fabrics will be low.
• Stitch length: Higher the stitch length lower the GSM.
• Machine gauge: If the number of needle per unit length i.e. machine gauge is high, the GSM will be high.
• Over feeding during finishing: Over feeding always increase the GSM of knitted fabrics during finishing.
• Using of special chemical: Sometimes special chemical is used for increasing the  fabrics GSM.

2.7 Fabric  shrinkage:
Cotton is a natural vegetable fibre obtained from the seed pod of the cotton plant. The cotton fabrics that are currently available in the market are blended with other fibers such as polyester, silk etc. So the shrinkage of the fabric depends upon different fibers which constitute the fabric. Generally ,the cotton fabrics tend to expand when wet and tend to shrink as they dry. Desizing or shrinking the fabrics is aimed at degrading the starches to more soluble products such as dextrin.

• Shrinkage is defined as “the width wise or lengthwise contraction of a fiber, yarn, or fabric usually after wetting, redrying or on exposure to elevated temperature.”

Shrinkage is a problem that gives rise to a large number of customer complaints. It can cause problems in two areas, either during garment manufacturing or during subsequent laundering by the ultimate customer. Knitted fabric construction is very loose. At various stages of wet processing fabrics are subjected to different strains in the presence of water, fibres swell water, expand in width direction, shortened in length direction which causes the shrinkage of ultimate fabrics.

2.8 Causes of fabric shrinkage:
Knitted goods are 3-dimensional arrays of crimped yarns. Fabric forming processes take straight lengths of yarns and force them into 2-dimensional crimped lengths. The degree of crimp is a function of the yarn size and fabric construction. When fabric is completely relaxed, the crossing yarns will move around in relation to each other until a stable configuration is reached. This stable arrangement, the point where the relaxed fabric no longer shrinks in width and length, is also related to yarn sizes and fabric construction. When stretching tensions are applied to the fabric, the crimped amplitude decreases and the fabric grows in the direction of the stress. Later when the tensions are relieved and the fabric allowed to relax, the crimp amplitude returns to its stable configuration and the fabric shrinks. Many fabrics are stretched during wet processing as they are pulled from one operation to another. This is the major cause of fabric shrinkage.

2.9  How shrinkage template & scale works?

• The marking template should be placed on the specimen to be tested, making sure that the fabric is in flat position before marking.
• Hold the template firm, and carefully mark the fabric through the eight slots of the template, to ensure that it does not move.
• Now put the fabric in the washing machine.
• Dry the sample as per any of the method. It can either be Line Dry or Flat Dry or Tumble Dry.

2.10 Factors affecting the shrinkage of cotton fabrics:
There are four major variables, which affect the dimensions after shrinking of cotton circular kitted fabrics. The effects of these four variables are most easily understood by  thinking about the shape and size of wash knitted loop in the fabric. Any circular knitted fabric is composed of row of interlaced loops. Different types of fabrics are made by different methods of interlacing the loops. Therefore, the dimension of any knitted fabric are simply a reflection of the average shape and size of the individual loops, summed over the total number of loop in the given area.

The four major variables are:

I. The Yarn:
The type and size of the yarn (yarn count, twist, spinning system) governs the weight of wash loop and also determines its shape (length/width ratio).

II. The stitch length :
The average length of yarn in wash loop (stitch length) determines its weight and also the overall size of the loop (no. of loop per unit area).

III. The knitting machine:
The size of the knitting machine (number of needles) determines the number of loops across the width of the fabric, and hence the fabric width.

IV. The wet process:
The effect of wet processing is to change the shape of wash loop, mainly by changing the stiffness, the specific volume, and the twist liveliness of the yarn. In addition, wet processing will change the weight of the yarn, by removing impurities and adding chemicals (such as dyestuffs), and will change the average length of yarn in wash loop, through yarn shrinkage. Different types of wet processing procedure will change the shape, the weight, and the length of the loops by different amounts and, therefore, they affect the length, width, and the weight of  the fabric by different degrees.

From this simple analysis, it now becomes clear that, in order to set up a system for predicting the dimensions and shrinkage of cotton knit fabrics, the first requirement is that we must be able to calculate the average dimensions of the loops from a knowledge of the knitting parameters and the types of wet processing. In other words, it is necessary to have a set equations which link the dimensions of a given fabric after shrinking to the yarn type and size, knitting machine used, the average stitch length, and the wet process route. Comparison of these dimensions with the specification demanded by the customer will then yield the values for weight, width and shrinkage in the “as delivered” cloth.

2.11 Spirality:
Spirality is an unwanted effect especially on single Jerseys. If garments are made out of Single Jersey with a high spirality the side seams of the garments will twist after washing and it will be as good as impossible for the end user to “iron” them straight. Before we talk about the cure, we have to understand the reasons and the shortcomings (i.e. with shrinkage behavior).

It is well known that weft knitted fabrics tend to undergo certain dimensional change that causes distortion in which there is a tendency of the knitted loops to bend over, causing the wales to be at diagonal instead of perpendicular to the courses

For measuring spirality, firstly, samples were collected from stenter. They were marked with two sets of marks in each direction (length and width), a minimum of 50 cm apart and at a distance of approximately 3 cm from the edge. It is recommended that, the samples should pre conditioned at standard textile testing atmosphere.

2.12 Definition of spirality:
“Spirality” arises from twist stress in the constituents yams of plain fabric,causing all loops to distort and throwing the fabric wales and courses into an angular relationship other than 90 degree.

Spirality can be defined as a fabric condition resulting when the knitted wales and courses are angularly displaced from that ideal perpendicular angle. Other terms such as torque, skew, bias and shear distortion are often used to refer to the same phenomena. Regardless of the term used, this displacement of the courses and wales can be expressed as a percentage or as an angle measurement in degrees.

Examples of skew can be seen in Figure ii

2.13 Angular relationship of course and wales in a knitted structure:
Spirality occurs in knitted fabric because of asymmetric loops which turns in the wales and course of a fabric into an angular relationship other than 90 degree. This is a very common problem in single jersey knits and it may exist in grey, washed or finished state and has an obvious influence on both the aesthetic and functional performance of knitwear. However, it does not appear in interlock and rib knits because the wale on the face is counter balanced by a wale on the back. Course spirality is a very common inherent problem in plain knitted fabrics. Some of the practical problems arising out of the loop spirality in knitted garments are: displacement or shifting of seams, mismatched patterns and sewing difficulties. These problems are often corrected by finishing steps such as setting / treatment with resins, heat and steam, so that wale lines are perpendicular to the course lines. Such setting is often not stable, and after repeated washing cycles, skewing of the wales normally re-occurs.

2.14  Causes of generation of spirality:
The main reason for spirality is the twist in the yarn which we use. Spun yarns have an inner torque due to the twist. This inner torque tries to “untwist” the yarn. Later, once the yarn is knitted into the fabric this inner torque of the yarn is the force which tries to alter the square network of wales and courses into a rhombus shaped network. If we imagine one loop in the knitted fabric, the torque in the yarn forces the loop to “lift one leg”, by that deforming the square network. Another reason for spirality is that we actually do not knit “straight” on a circular knitting machine but on a “slope”. That means that in the moment where the loop is formed we form it into a rhombus shaped network.

In other words, The residual torque in the component yarn caused due to bending and twisting is the most important phenomenon contributing to spirality. The residual torque is shown by its twist liveliness. Hence the greater the twist liveliness, the greater is the spirality. Twist liveliness of yarn is affected by the twist factor or twist multiple. Besides the torque, spirality is also governed by fibre parameters, cross-section, yarn formation system, yarn geometry, knit structure and fabric finishing. Machine parameters do contribute to spirality. For instance, with multi-feeder circular knitting machines, course inclination will be more, thus exhibit spirality.

2.15 Influencing factors of spirality:

2.15.1 Influence of yarn properties :

I. Count:
Degree of freedom of yarn movement in the fabric structure contributes significantly to the increase in spirality. Dimensional parameters of fully relaxed single jersey fabrics depend on the yarn linear density and tightness of construction. If diameter is reduced, its resistance to deformation is lowered. It indicates that, deformation of loop structure is influenced by yarn count. In other words, the finer the yarn, the more will be the spirality due to more twisting.

II. Twist:
Usually in knitting, low twisted yarns are used. High twisted yarn has a great impact on spirality due to its unrelieved torque. With the increase in twist, the twist liveliness increases, this in turn, causes the angle of spirality to increase. The direction of spirality in the fabrics knitted from short staple ring spun single yarns is determined by the yarn twist direction. Thus, the technical face of single jersey fabric exhibits spirality in the Z direction if a Z twisted yarn is knitted.

Effect of twist liveliness on spirality:
The twist liveliness is strongly related with the spirality. In general it can be seen that if the yarn snarled at S direction then fabric spiraled at Z direction and vice versa. From the experiment we can seen that if the twist liveliness is increased then spirality of fabric is increased along both direction

a) Yarn Twist Multiplier ( TM ):
This index is represented by the following formula:

TM = T.P.I. / √N, where T.P.I. indicates twist per inch and N represents yarn number in an indirect system, the cotton system unless otherwise specified. With the increase in twist multiplier, the angle of spirality increases.

b) Yarn Twist Factor (TF):
TF is related with the following formula:

TF = TPCm x √T, where T signifies yarn number in Tex.

Raising the twist factor of two ply yarn increases the left hand or S-direction spirality, whereas increasing the twist factor of single yarn increases the right hand or Z-direction spirality.

III. Conditioning:
The minimum Spirality level that can be achieved by several ways such as storing yarn at appropriate temperature and relative humidity or by thermal conditioning with low temperature saturated steam in vacuum that results in a speedy relaxation. This process balances the twist so that it does not regain its original state. However, there is no systematic study carried out to understand the effect of yarn conditioning on spirality of single jersey fabrics.

IV. Spinning method:
Yarn produced by different spinning technique has a direct bearing on spirality of knitted fabric. Friction spun yarn made of 100% cotton produce fabrics with highest degree of spirality, followed by ring spun yarns. Both rotor spun and air jet yarns produce fabrics with a low degree of spirality.

V. Blend:
In general, 50/50 cotton/polyester blends have a lower tendency to produce spirality in fabrics than the 100% cotton yarns. Spirality can be virtually eliminated by using 50/50 cotton/polyesters blend of air jet and rotor yarns.

2.15.2 Influence of Fabric Properties

I. Fabric Stitch Length:
This is the length of one loop in knitted fabric. Spirality increases with the length of loop.

II. Fabric Structure:
More spirality in single jersey due to non-arrest of loops. By adding moisture to such a structure, the twist will try to revert as it swells, that distorts the shape of the loop. In double jersey, the effect of spirality is nullified. Pique and honey comb also show spirality even if sometimes two beds are used. Spirality can be noticed in certain jacquard structures. In stripe pattern, it increases with the size. No appreciable problem of spirality is there in ribs and interlocks.

III. Fabric Tightness:
Slack fabric presents higher spirality angle compared to tightly knitted fabrics. At each level of yarn twist factor, the degree of spirality decreases linearly with fabric tightness factor.

IV. Fabric Relaxation:
Fabric relaxation (dry and wet) treatment removes the residual knitting tension in the yarn introduced during the knitting process. The relaxation treatment relieves the residual yarn torque as a result of changes in the molecular structure and increasing yarn mobility.

2.15.3 Influence of Machine Settings

I. Number of Feeders:
The number of feeders in a circular knitting machine also influences the angle of spirality. Due to more course inclination, spirality will be more.

II. Direction of Machine Rotation:
The direction of machine rotation has influence on spirality. For Z twist yarns, the wales go to the right and thus, giving Z skew and S twist yarns makes the wales go to the left, giving S skew to the fabric. With multi-feed machines, the fabric is created in helix, which gives rise to course inclination and consequently wale spirality. Direction of spirality depends on the rotational direction of the knitting machine. Earlier research work revealed that, for a clockwise rotating machine, the wale would be inclined towards the left, thus producing the S spirality.

III. M/C Gauge:
In knitting terminology, number of needles per inch is called the gauge. Smaller the gauge, lesser will be the spirality keeping other parameters constant. A proper combination of linear density and gauge is required to reduce spirality e.g. torque can be controlled in 20 gauge and 40s count.

IV. Knitting Tension:
The effects of various knitting tensions including the whole process of loop formation on fabric spirality had been investigated by the researchers. Experimental investigation could not establish consistent trends with respect to variations in fabric quality with knitting tensions. The twist factors of ply and single yarn, loop length, and fiber diameter have significant effects on the angle of spirality, while yarn linear density and fabric tightness factor have comparatively lesser effect.

2.16 Options for Reduction of Spirality

I. Compacting:
Compaction reduces the length of the fabric based on its elongation during processing which, in turn, reduces the width. It helps in controlling the shrinkage of the fabric. There are two types of compactors – open and tubular. In tubular compactor, the squeezing line gets on the sides in this process and is done on natural movement thus controlling spirality. If the wales are straightened manually then it results in spirality.

II. Resin Treatment:
Cross-linking the fabric by means of inter fiber bonding also reduces spirality. Resin in the form of aqueous solution is applied and set by passing the fabric through a high temperature stenter. This method is not recommended for cotton fabrics, since it weakens the cotton yarn.

III. Heat Setting:
Steam or hot water setting reduces twist liveliness and hence spirality. Mercerization is recommended for cotton yarns, so that fibers are made to relax permanently.

IV. Balancing Yarn Twist Factor:
In an earlier investigation on plain knitted wool fabrics, it was been revealed that raising the twist factor of a ply yarn increases the left-hand of S-direction spirality of fabrics. But while increasing the twist factor of a single yarn, there is decrease in left-hand of S-direction spirality with an increase in right-hand or Z-direction spirality. Thus, there is possibility to balance twist factors for both ply and single yarns with a view to achieve zero spirality. Experimental study by Chen, Q H on wool knits

indicates that, when the ratio of twist factor of the ply yarn to the twist factor of single yarn is about 0.73, zero spirality may be achieved.

CHAPTER- 3
MATERIALS & METHODS

3.1 Raw materials:
The raw materials of this comparative study were different types of knitted fabrics such as single jersey, 1×1 rib, 2×1 rib, double pique, single lacoste, double lacoste, interlock. The GSM, Shrinkage, Spirality of these fabrics were compared which were subjected to both tube and open line finishing process. The GSM, Shrinkage, Spirality were compared between after dryer & stenter, after tube compactor & open compactor.

3.2 Apparatus:
The following Apparatus are used in this study

Table-3.1: Apparatus used in study

3.3 Selection of  factory:
This study is completely related to knit dyeing factory which has both open and open tube line. For this purpose the following factory was selected:

• Texeurop (Bd), Vogra, Chandona, Chourasta, Gazipur
• Oli Knitting  Fabrics, Ganak Bari, Savar, Dhaka.

3.4 Methodology:
In order to compare the GSM, Shrinkage, Spirality of same knitted fabric, after dyeing the same fabric were finished both tube & open line. During finishing, sample fabrics after dryer & stenter for the test results of GSM, Shrinkage & Spirality were taken. Then the GSM, Shrinkage, Spirality of both samples were measured & compared the results. Then according to the test results of dryer & stenter, the tube & open compactor were set & finally finished the fabrics. After tube & open compactor, both line finished sample fabrics were taken for the test results of GSM, Shrinkage & Spirality. Finally the GSM, Shrinkage & Spirality of both line finished fabrics were measured & compared.

3.5 Specification of Slitter:

• Brand name           : BIANCO
• Capacity/day          : 7000 kg
• Country of origin   : italy
• Maximum speed    : 90 m/min.
• Year built               : 2008

3.6 Technical data of Stenter:

• Brand name             : UNITECH
• Country of origin     : ITALY
• Capacity/day            : 10000 kg
• Year built                 : 2004
• Speed                       :  (15- 40 )m/min.
• Working  width        : 41˝-96˝
• No. of chamber        : 08
• Maximum over feed : 75
• Minimum over feed  : 30
• Temperature             : normally-160, maximum-210
• Fuel type                  : Gas
• Maximum Presser    : J-box-2.50 bar, 1st padder-5bar, 2nd padder-4bar

3.7 Technical data of open Compactor

• Brand name               : FERRARO
• Country of origin       : ITALY
• Capacity/day              : 7000 kg
• Speed                         :  20- 25 m/min.
• Working  width          : Maxm- 96˝, Minm- 40˝
• Fuel type                     : Steam
• Maximum over feed   : 35
• Minimum over feed    : 15
• Max. compaction        : 10%

3.8 Technical data of Squeezer:

• Brand name             : BIANCO
• Country of origin     : ITALY
• Capacity/day            : 7000 kg
• Year built                 : 2004
• Maximum speed      : 80 m/min.
• Maximum Presser    : J-box-2.50 bar, 1st padder-5bar, 2nd padder-4bar

3.9 Technical data of Dryer:

• Brand name             : DINMENLER
• Country of origin    : TURKEY
• Year built                : 2004
• Capacity/day           : 1000 kg
• Type of machine     : Linea Aprituboiere
• Maximum speed     : 80 m/min.
• Working width        : 2600 mm
• Temperature            : 150-190
• No. of chamber       : 03
• Heating system       : Steam

3.10 Technical data of Compactor:

• Brand name             : TUBE-TEX
• Country of origin     : U.S.A
• Name of company   : American Textile Mechinary Association.
• Working  width        : Maxm-60˝, Minm-16˝
• Capacity/day            : 7000 kg
• Maximum overfeed  : 30
• Max. compaction     : 18
• Maximum speed       : 80 m/min.
• Max.Temperature     : 210
• Heating system         : Steam
• Year built                  : 2004

3.11 Procedure of GSM measurement by GSM cutter :

At first cut the fabric with the G.S.M cutter

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The area of cut sample is 100 cm²

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Weight the cut sample fabric with the electric balance

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The weight of the cut sample is multiplied by 100

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The result is the G.S.M of that particular fabric

Suppose ,
The weight of the fabric is 2.10 gm. That means the G.S.M of the fabric is 210 gm.

3.12 Shrinkage and spirality test procedure:
The shrinkage properties is one of the most important properties to be checked for the knitted fabric. This property is minimized as it is possible. Shrinkage ±5  along length & width wise are allowed. The Shrinkage test procedure is given bellow-

At first fabric was relaxed from dryer/stenter
(Lycra/PK fabrics 2 hour & normal fabrics 40 minutes)

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Take The sample according to one of the following
(50 cm × 50 cm)

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Sewing the sample three side by over lock sewing machine and one side open

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Put sample in washing machine and run according to buyer’s choice.
(Std recipe detergent 2 g/l for 45 mins. at 45)

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Then drying (temperature 60 for 20 mins) the sample by tumble dryer

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Conditioned the sample with (65±2)% RH & (20±2) for 4 hours

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Measure the sample after wash & calculation

3.13 Shrinkage test calculation:
Shrinkage (%) is generally measured by using following equation:

…………………….After wash – Before wash
Shrinkage% = ———————————————– ×100
…………………………….Before wash

After wash length = 45cm

After wash width = 51.5cm

……………………………………45-50
Shrinkage% (length) =——————– ×100 = -10%
……………………………………..50

………………………………..51.5 – 50
Shrinkage% (width)= ——————×100 = 3%
……………………………………50

This is not ok, because buyer requirement Shrinkage. So it must be compact lengthwise.

3.14 Spirality Test Calculation:

S = (S1+S2) / 2

Spirality = (S x L)/100.

Suppose,

S1 = The right side distance of the specimen from the stitch line after wash.
S2 = The left side distance of the specimen from the stitch line after wash
S = Average spirality
L = Length before wash

…………………2.5 x 50
Spirality% = ————— = 1.25
……………………100

CHAPTER-4
RESULT & DISCUSSION

4.1 Comparative performance of shrinkage & spirality for Single jersey fabric finished by both open & tube line:
The average value of ten single jersey fabrics knitted from 26Ne (100% cotton) yarn of different GSM has been shown in following graphs:

From the above graphical presentation, it can be said that, the length wise shrinkage Before Compacting (B/Com.) for tube line is almost two times than open line. In case of tube line, the width wise shrinkage before compacting for this fabric is always positive i.e. the fabric width extends. The Maxm. acceptable range of shrinkage (Length & Width) After Compacting (A/Com.) for this fabric is ±5%. The better value of shrinkage is zero or nearest zero. The width wise shrinkage after compacting finished by tube line has been exceed this value. The Maxm. acceptable range of spirality for this fabric is 5%. The tube line finished fabric has been exceed this value which is 5 times than the open line finished fabric.

Now it can be said that for getting spirality problem free Single Jersey fabric, it should must be finished by open line.

4.2 Comparative performance of shrinkage & spirality for 1×1 Rib fabric finished by both open & tube line:
The average value of five 1×1 Rib fabrics knitted from 28Ne (100% cotton) yarn of different GSM has been shown in following graphs:

The graph is showing that, the length wise shrinkage before compacting for tube line is almost two times than open line. The width wise shrinkage before compacting for this fabric is very high (4 times) for open line than tube line. The Maxm. acceptable range of shrinkage (Length & Width) After Compacting (A/Com.) for this fabric is  ±5%. The length & width wise shrinkage after compacting finished by tube line & open line is not exceeded this value. So it is suitable for both line. The Maxm. acceptable range of spirality for this fabric is  5%. The better value of shrinkage and spirality are zero or nearest zero. Actually Rib fabric has no spirality problem after finish, though both line has been shown little spirality, it is negligible.

Now it can be said that 1×1 Rib fabric may be finished by both open & tube line finishing process, but  most suitable for tube line.

4.3 Comparative performance of shrinkage & spirality for Double Pique fabric finished by both open & tube line:
The average value of three double pique fabrics knitted from 24Ne (100% cotton) yarn of different GSM has been shown in following graphs:

From the above graphical presentation, it is seen that, the length wise shrinkage before compacting for tube and open line is almost same. The width wise shrinkage before compacting for this fabric is very high (4 times) for open line than tube line. The Maxm. acceptable range of shrinkage (Length & Width) after compacting for this fabric is ±5%. In our study the both line finished fabric has been exceed this value but it is controlable. The Maxm. acceptable range of spirality for this fabric is 5%. The better value of shrinkage & spirality are zero or nearest zero. From this respect, both open & tube line are suitable for this fabric but tube line possess has higher spirality than open line.

Now it can be said that double pique fabric may be finished by both open & tube line but for better hand feel & appearance open line is the most suitable.

4.4 Comparative performance of shrinkage & spirality for 2×1 Rib fabric finished by both open & tube line:
The average value of five 2×1 Rib fabric knitted from 24Ne (100% cotton) yarn of different GSM has been shown in following graphs:

From the above graphical presentation, it is seen that, the length wise shrinkage before compacting for tube line is two times than open line. The width wise shrinkage before compacting for this fabric is very high (5 times) for open line than tube line. The Maxm. acceptable range of shrinkage (Length & Width) after compacting for this fabric is ±5%. The length wise shrinkage after compacting finished by both open & tube line is not exceeded this value, but open line has possessed more. The width wise shrinkage after compacting finished by open line has  been exceed this value but it is controable. Besides someone allow it up to -8%. So it is suitable for both line. The Maxm. acceptable range of spirality for this fabric is  5%. The better value of shrinkage & spirality are zero or nearest zero. Actually Rib fabric has no spirality problem after finish, though both line has been shown little spirality, it is negligible.

It can be said that 2×1 Rib fabric may be finished by both line but most suitable for tube line & for higher quality open line is recommended.

4.5 Comparative performance of shrinkage & spirality for Interlock fabric finished by both open & tube line:
The average value of five Interlock fabric knitted from 40Ne (100% cotton) yarn of different GSM has been shown in following graphs:

From the above graphical presentation, it is seen that, the length wise shrinkage before compacting for tube line is higher than two times from open line. The width wise shrinkage before compacting for this fabric is always positive in case of tube line i.e. the fabric width extends after wash. The Maxm. acceptable range of shrinkage (Length & Width) after compacting for this fabric is ±5%. The length wise shrinkage after compacting finished by both open & tube line has been exceeded this value, but open line has been exceeded more. The width wise shrinkage after compacting  has not been exceed the acceptable range but open line has been possessed more. The Maxm. acceptable range of spirality for this fabric is 5%. From this respect, both open & tube line are suitable for this fabric but tube line possess higher spirality than open line.

From the above discussion, it can be said that the tube line is most suitable for inter lock fabric.

4.6 Comparative performance of shrinkage & spirality for Double Lacoste fabric finished by both open & tube line:
The average value of three double lacoste fabric knitted from 40Ne (100% cotton) yarn of different GSM has been shown in following graphs:

From the above graphical presentation, it is seen that, the length wise shrinkage before compacting for tube line is 3 times higher than open line. The Width wise shrinkage before compacting for this fabric is very high (2.5 times) for open line than tube line. The Maxm. acceptable range of shrinkage (Length & Width) after compacting for this fabric is ±5%. The length wise shrinkage after compacting finished by both open & open line has not exceeded this value, but open line has been possessed more ( 2 times). The width wise shrinkage after compacting finished by open line has  been exceed this value but it is controable. The Maxm. acceptable range of spirality for this fabric is  5%. From this respect, both open & tube line are suitable for this fabric but tube line possess higher( 2.5 times) spirality than open line.

From the above discussion, it can be said that for medium quality & if spirality is not a major factor tube line is suitable for double lacoste, otherwise  open line is appropriate.

4.7 Comparative performance of shrinkage & spirality for Single Lacoste fabric finished by both open & tube line:
The average value of three single lacoste fabric knitted from 40Ne (100% cotton) yarn of different GSM has been shown in following graphs:

From the above graphical presentation, it is seen that, the length wise shrinkage before compacting for tube line is higher than open line.The width wise shrinkage before compacting for this fabric is always positive in case of tube line i.e. the fabric width extends after wash. The Maxm. acceptable range for length wise shrinkage after compacting & width wise shrinkage after compacting for this fabric is ±5%. The length wise shrinkage after compacting finished by both line has not exceed this value, but tube line has been possessed more. The width wise shrinkage after compacting finished by tube line has  been exceed this value but it is controable. The Maxm.acceptable range of spirality for this fabric is 5%. From this respect, both line are suitable for this fabric but tube line possess higher spirality than open line.

From the above discussion, it can be said that for medium quality & if spirality is not a major factor tube line is suitable for Single lacoste, otherwise  open line is appropriate.

4.8 Graphical presentation of Length wise shrinkage after finishing of various type of knit fabrics:
The following graph contain the average value of each fabric.

From the above graphical presentation, it has been seen that the length wise shrinkage of most fabrics has been remained acceptable range without the interlock because it is a loose structure fabric. It has been also seen that tube line is most suitable for controlling length wise shrinkage.

Now we can say that for medium hand feel & appearance the above all fabric may be finished by tube line but for better quality such as hand feel & appearance, open line is recommended.

4.9 Graphical presentation of Width wise shrinkage after finishing of various type of knit fabrics:
The following graph contain the average value of each fabric.

From the above graphical presentation, it has been seen that for controlling width wise shrinkage, tube line is most suitable without single jersey and single lacoste.

Now we can say that for medium hand feel & appearance the above all fabric may be finished by tube line but for better quality such as hand feel & appearance, open line is recommended.

4.10  Graphical presentation of spirality after finishing of various type of knit fabrics:
The following graph contain the average value of each fabric.

From the above graphical presentation, it has been seen that all fabric spirality both for tube and open line has been remained within the acceptable range without single jersey. It has been also seen that the spirality of Rib & Interlock fabric is very poor which is negligible. Actually these fabric has no spirality problem.

Now we can say that for getting spirality problem free Single Jersey fabric, it should must be finished by open line. The other fabrics may be finished by tube line but for better quality (hand feel & appearance) & waste minimization of fabric in cutting section, open line is most suitable.

CHAPTER-5
CONCLUSION AND RECOMMENDATION

5.1  CONCLUSION:
This study was comparative performance between tube line and open line finishing process for same fabric. In this case- Single Jersey, 1*1 Rib, 2*1 Rib, Interlock, Double Pique, Single Lacoste and Double Lacoste were included. The GSM, shrinkage & spirality both tube and open line for same fabric were studied. After this study the following things have found –

• For getting spirality problem free Single Jersey fabric, open line is most suitable.
• For getting medium hand feel & appearance with low cost Rib (1*1 & 2*1) finished fabric, tube line is most suitable. But for better hand feel and appearance open line is appropriate.
• Tube line may be used for double pique but for better hand feel and appearance open line is appropriate.
• Both Tube and open line are suitable for interlock fabric because interlock fabric does not possess spirality problem, but for higher quality open line is appropriate.
• If spirality is not a major fact, then tube line is suitable for single and double lacoste.
• In some case, the shrinkage results have exceeded the acceptable range. In this situation the fabric is tumble drying and then again finished.
• In this study, it has been found that the Rib and Interlock fabrics do not possess the spirality problem.
• It has also been found that dimensional stability of tube line finished fabric is good than open line finished fabric.

5.2  RECOMMENDATION:
The major objective of this study was to compare the shrinkage and spirality of same knitted fabrics such as single jersey, 1*1 rib, 2*1 rib, double pique, interlock, single lacoste, double lacoste finished by both open line and tube line. From this study, it has been clear that for medium quality with low cost and spirality, tube line is suitable but for better hand feel and appearance without spirality, open line os more appropriate. In this study, the count of same fabric was same but the stitch length and GSM was different.

The major recommendations for continuation of the present work in the future are summarized below-

• To compare the shrinkage and spirality between same fabric finished by both open and tube line, the same stitch length but different GSM and Yarn count may be considered for future study.
• The same GSM but different yarn count and stitch length may be considered for future study.
• The same GSM and same stitch length but different yarn count may be considered for future study.
• The same GSM, same stitch length and same yarn count may be considered for future study.
• The variation of GSM after different processing stage of both open and tube line finishing may be considered for future study.

REFERENCES

1. Charles Tomasino,“Chemistry & Technology of Fabric Preperation & Fnishing”.
2. Mikucioniene, D., Tvarijonaviciene, B. Investigation of Influence of Stretching Knitted Fabric on Value of its Shrinkage Materials Science (Medziagotyra) 2 1997: pp. 55 – 59.
3. Technical Bulletin.; “Knit fabrics and the reduction of torque”, 6399 Weston Parkway, Cary, North Carolina, 27513.; TRI 2002.
4. Shah, D.L.; “Latest Techniques of Processing Knit Fabrics Containing Elastomeric for Fashion Garments”, Man–Made Textiles in India, vol. 12, 2003.
5. Saufley C.E.; “Continuous Finishing of Circular Knit Fabrics”, AATCC Review, vol. 24, no 3, 1992, pp. 17–19.
6. Mikucioniene, D., Tvarijonaviciene, B. The Influence of Knitting and Finishing on Shrinkage of Cotton Weft Knitted Fabrics Architektura Tekstyliow 1 – 2 1999.
7. Euscher, G. and Jayachandran, S.; “Knit Goods Processing”, Indian Textile Journal, 4, 1997, pp. 19–21.
8. De Araujo, M.D. and Smith, G.W.; 1989, Textile Research Journal, 59.
9. Tao, J., Dhingra, R., C., Chan, C., K., Abbas, M.,S.; “Effects of yarn and Fabric construction on spiralitv of Cotton Single Jersey Fabrics”, Textile Research Journal, 67, 57-68. 1997.
10. ; “Dewatering and Overstretching Machine for Finishing of Knitted fabrics”, Express Textiles, vol. 22, February 2001.
11. Saravanan, D.N.B., Timble, Gunasekar, E., Kandasamy, V.A.; “Influence of Compacting on Knitted Fabrics”, IE (I) Journal–TX pp, 15. Vol. 88.
12. Das, Subrata.; “Causes and Remedial Measures of Spirality in Knitted Fabrics”, Published on Saterday, December, 13, 2008.
13. “Parameters influencing plain knitted fabric spirality”, The Indian Taxtile Journal, November, 2008.
14. SPENCER, J, DAVID.; “Knitting Technology”, Second Edition, 1989.
15. Saville, B.P.; “Physical testing of textile”, The Textile Institute, 2004.

APPENDIX

4.1 Comparative study of single jersey fabric:
The average values of ten Single Jersey fabric knitted from 26Ne (100% cotton) yarn of different GSM  which was finished by both tube & open line test results were as follows:

Table-A-1: Average values of ten Single Jersey fabric

4.2 Comparative study of 11 Rib fabric:
The average values of five 11 Rib fabric knitted from 28Ne (100% cotton) yarn of different GSM  which was finished by both tube & open line test results were as follows:

Table A-.2: Average values of five 11 Rib fabric

4.3  Comparative study of Double Pique fabric:
The average values of three double pique fabric knitted from 24Ne (100% cotton) yarn of different GSM  which was finished by both tube & open line test results were as follows:

Table A-.3: Average values of three double pique fabric

4.4 Comparative study of  2×1 Rib fabric:
The average values of five 2×1 Rib fabric knitted from 24Ne (100% cotton) yarn of different GSM  which was finished by both tube & open line test results were as follows:

Table-4.4: Average values of five 2×1 Rib fabric.

4.5  Comparative study of Interlock fabric:
The average values of five Interlock fabric knitted from 40Ne (100% cotton) yarn of different GSM  which was finished by both tube & open line test results were as follows:

Table A-5: Average values of five Interlock fabric.

4.6 Comparative study of Double Lacoste fabric:
The average values of three double lacoste fabric knitted from 40Ne (100% cotton) yarn of different GSM which was finished by both tube & open line test results were as follows:

Table A-6: Average values of three double lacoste fabric.

4.7 Comparative study of Single Lacoste fabric:
The average values of three single lacoste fabric knitted from 36Ne (100% cotton) yarn of different GSM which was finished by both tube & open line test results were as follows:

Table-4.7 Average values of three single lacoste fabric

You may also like:

1. Causes and Remedies of Spirality in Knitted Fabric
2. Spirality Correction System (SCS) for Knitted Fabrics
3. How to Control Fabric Shrinkage, GSM and Dia in Compactor Machine
4. How to Measure Fabric Shrinkage in Textile and Apparel Industry

Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.

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