CARPET CONSTRUCTION


It is important to understand carpet construction in order to apply the variables that affect performance of a specific installation. Tufted carpet consists of the following components: the face yarn, which can be cut pile, loop pile, or a combination of cut and loop pile; primary backing fabric; a bonding compound, usually SB latex, but may be polyurethane, PVC, or fabric; and (often) a secondary backing fabric.

The development of the broadloom tufting machine and the introduction of synthetic carpet yarns in the early 1950s transformed the American carpet industry from low-volume production of woven luxury products to mass production of high quality and comfortable, yet popularly priced, goods. The explosive growth of carpet sales in the United States in the ensuing years paralleled the continual development of tufting technology, the proliferation of high-speed tufting machines, and the development of synthetic carpet fibers and alternative backing systems. As a result, today’s carpet is both better and less expensive.

Figures 1.1 and 1.2 illustrate how these elements are combined to form carpet.

image

The primary carpet fabric construction methods include tufting, weaving, knitting, needle punching, and bonding.

TUFTING

Over 90% of carpet produced is tufted, the most prevalent carpet construction method. Tufting machines are similar to giant sewing machines, using hundreds of threaded needles in a row across the width of the machine. Today’s machines are increasingly complex and sophisticated, providing a wide variety of styles and constructions.

The creel, located in front of the tufter, may be racks of many yarn cones or multiple large spools, referred to as beams, and containing many individual strands of yarn. From the creel, the yarns are passed
overhead through guide tubes to puller rolls. The speed of the puller rolls controls the amount of yarn supplied to the tufter and, along with other factors, determines the carpet’s pile height.

The eyed needles, which number up to 2,000 for very fine gauge machines, insert the yarn into a primary backing fabric supplied from a roll of  material located in front of the machine. Spiked rolls on the front and back of the tufting machines feed the backing through the machine.

Below the needle plate are loopers, devices shaped like inverted hockey sticks, timed with the needles to catch the yarn and hold it to form loops. If a cut pile is called for, a looper and knife combination is used to cut the loops. For cut-loop combinations, a special looper and conventional cutting knife are used.

image

Tufting has reached a high degree of specialization, utilizing a variety of patterning devices, many of which are computer-controlled. Stepping, or zigzag moving, needle bars, and individually controlled needles greatly expand patterning possibilities. Such patterned carpet is frequently referred to as a graphics pattern. Other advanced tufting techniques are loop over loop and loop over cut (LOC) machines

After completion of tufting, the unbacked tufted carpet is dyed (if precolored yarns were not used) then followed by a finishing step to add an adhesive compound backing and, usually, a secondary backing material.

Tufted carpet styles range from loop, cut pile, and combinations of both in solids, tweeds, stripes, and patterns from the most simple to the exotic and complex. The designer has an endless variety of carpet choices due to advances in tufting–technology, coloration options, and finishing techniques.

WEAVING

While there are several methods of weaving and several types of looms, there are basic similarities to all. In general, woven carpet is formed by the interweaving of warp and weft yarns. The warp yarns are wound from parallel or heavy beams that unwind slowly as weaving progresses. Two main types of warp yarns form the carpet back: chain and stuffer. Chain yarns provide structure and stability while stuffer warp yarns increase bulk and stiffness of the fabric. The face yarns of woven carpet are also pre-dyed warp yarns that are normally fed into the loom from a yarn creel.

image

The warp yarns run through a heddle, a series of vertical wires, each having an eye in the center through which the yarn is threaded. The heddle controls the action of the warp yarns. The wires are  mounted on two frames that rise alternately to form a space or shed.

The face of the carpet is formed with warp yarns moving into the loom from yarn creels. These pile yarns are looped over wires that lie at right angles to the warp yarns that are then bound with a yarn known as the weft, which is shot through the shed with a shuttle or other means. When a cut pile carpet is desired, wires with a knife blade at one end are used.

KNITTING

A carpet knitting machine, known as a double needle bar knitter, has a row arrangement of hundreds of latch needles that move in an up-and-down motion in conjunction with yarn guide bars. Yarn guide tubes are attached to a guide bar that passes the yarns between and about the needles, thus laying down the pile face yarns and weft backing yarns. Separate sets of guide bars control each of the yarns–knitting, backing and face yarns. Additional bars may be used for color and design variety.

Knitted carpet is used mainly for commercial loop construction and is sometimes referred to as woven interlock. It often is used in school applications.

NEEDLEPUNCHING

In the needle punching process, several webs of staple fibers are superimposed to create a thick, loose batting. The batting is then tacked, or lightly needled, to reduce its thickness before it is fed into the  machine. As the batting is fed into the machine, it passes between two plates. The stationary lower plate contains many holes, while the upper plate, or headboard, contains several rows of barbed needles. The batting passes between the plates and the headboard moves up and down, passing the barbed needles through the fibers. As the needles pass through the fibers, they carry fiber ends from the top of the batting to the bottom, and when they are withdrawn, vice versa. The needles are passed repeatedly through the batting as it moves through the machine to form the carpet.

Needlepunch carpet is used mainly for outdoor applications and may include uses like entrance mats, marine uses, wall coverings and automotive applications. Surface patterning creates a large number of design possibilities.

BONDING

Fusion bonded carpet is produced by implanting the pile yarn directly into a liquid polymer, usually PVC, which fastens it directly to the backing. This results in very little buried yarn compared to other processes. The yarns can be closely packed, producing very high densities suitable for high-use areas. This process is used most frequently to produce carpet to be cut into carpet tiles or modules. Fusion bonded carpet may be loop construction, but most often is a cut pile product, made by a two-back process, slicing apart two simultaneously made carpets that are mirror images.

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Knitting Calculations


Knitted fabric is made with the help of yarn loops. Yarn of different counts is used to produce fabric of different grammage. There is also a need to calculate optimum production of knitting machines. It is the job of knitting manager to do certain calculation for proper use of machines and production of fabric according to the demands of the customer. This chapter is aimed at explanation of different calculations.

Most suitable count for knitting machines

As it has been discussed in Chapter Two that needle hook has to take yarn to convert it into a loop and finally latch has to close the needle hook so that loop is properly held by the needle hook and ultimately this helps in passing new loop through the previously held loop. It is clear from this explanation that there should be a proper balance between needle hook size and the thickness of the yarn or filament. If the yarn is thicker than needle hook then there will a chance that needle hook will not able to hold this loop and consequently there will be a small hole in the fabric. If the situation is reverse, means yarn is thinner than the size of the needle hook then the fabric produced will look like a net. Both situations are not wanted. This situation demands a balance between needle hook size and count of yarn. It is worth to note that needle hook size depends upon the machine guage. Furthermore for different garments, fabric of different grammage is required. Every time knitter has to decide about the yarn count. There are many ways for the selection of proper count. In the following lines we will discuss most common methods to select count for different machines of different guage. It is also important to note that selection of yarn counts also depends upon the machine manufactures and type of machines, like, single and double knit machine. However a general guideline will be given hereunder.

As a thumb rule knitting experts prefer to use such knitting machine whose gauges is near to count of yarn (English count) i.e. for 20-gaugemachines most suitable yarn count is 20s. This rule is has certain limitations, like, for 28-gauge yarn of 26s to 30s is most suitable. But for very fine counts this rule is not applicable and also machines have maximum gauge 32. Normally fine counts are not used as such rather they are make double, like count 60s double, which means that net count is near to 30s. And this 60 double count is suitable for 30-gauge machine.
To solve this problem some authors have suggested following formulas.

For single Knitting Machine
Suitable count = G*G/18

For Double knitting machine
Suitable count= G*G/8.4
Where G is gauge of knitting machine

Some knitting machine manufacturers suggest a range of yarn count for their machine. There is another way to solve this problem and that is to take help from old record. Every firm is producing many types of fabrics and on the basis of experience they develop a database for ready reference. In the following line we give a table for guidance (table is under construction). One can get a ready reference from the table to produce fabric of certain grammage. We are also giving expected width of fabric after wet processing. This table can provide just a reference. Knitters have to decide by themselves after doing a trial production, since there are many more factors, which can affect yarn and gauge selection process.

Knitting Machine Parameters
Every knitting machine is made to fulfil certain demands of the customer. There are number of characteristics of machine which are intimated by the machine manufacturers while delivering the machine to customers/users. It is helpful for the user to be well aware about these parameters. Furthermore machine specifications are given in different unit. We will explain these parameters and will also give the conversion factors to convert parameters from one system to other.

Machine Gauge
As per Oxford Dictionary the word “gauge” is a noun and as well as verb. It is used to measure level of any thing or for an instrument to measure width, length or height of any thing. In knitting it is used to express the number of needle in a unit length of the needle bed. This needle bed may flat or circular. In double knit circular machine it is used for cylinder and as well as dial. Generally gauge is defined as number of needles per inch. According to German standard DIN 60917 (Iyer et al1995) alphabet “E “ is used to denote knitting machine gauge.

E = Number of needles
1 inch (25.4 mm)

Machine Pitch
As per German DIN 62125 (Iyer et al1995) the notation “gauge” is to be avoided in the future. Rather they prefer to use notation “pitch” for comparison purpose. Machine Pitch means the distance between the centres of two neighbouring needles. It is denoted with small “t”. It is given in mm.

Knitting Machine Production calculation

Before explaining the method to calculate the nominal production capacity of the knitting machine it is imperative to be well aware of count and denier system and one should also be familiar with the conversion factors. Yarn is sold and purchased in the form of cones and bags. Cones and bags have certain weights. Still in the international market yarn is sold in pounds not in kilograms. Bags are of 100 pounds, which is equal to 45.3697 kgs. Previously there were 40 cones in a bag but now there are bags available of 25 cones. In other words cones are of 2.5 pounds and four pounds. Big size cones are most suitable for knitting. When these cones are used in warping then there is a need to know the length of certain weight of yarn. And some time length is available and some one wants to know the weight of the yarn and in some cases count of the yarn is required. In the following lines we will give methods to calculate above-mentioned figures.
It is imperative to be well aware of count system. In the end of the book we have given different tables and explanation of different terms. Before going ahead students are asked to consult tables and explanation for better understanding of this chapter.

Relationship between count, length and weight of yarn
Length (in yards) = Count *840 *weight of yarn in pound
Count = Length / weight of yarn in pounds*840
Weight of yarn = length/count *840

Note: as per definition count is a relationship between length and weight of yarn. English count is defined as number of hanks in one pound. Hank means a certain length. It is different for different fibers. For details see tables given in the end of book. For explanation purpose we will use English count of cotton. For cotton length of hank is 840 yards. For other fibers use relevant length of hank

Examples:
Example:01
Calculate count of cotton yarn from the given data:
Weight of yarn = 2.68 pounds
Length of yarn = 33600 yard

Formula: Count = Length / weight of yarn in pounds*840
=33600/2.68*840
Answer =14.93s

Example :02
Calculate length of cotton yarn from the given data:
Weight of yarn = 3.5 pounds
Count = 40s

Formula: Length (in yards) = Count *840 *weight of yarn in pound
= 40*840*3.5
Answer =117600 Yards

Example :03
Calculate weight of cotton yarn from the given data:
Length of yarn = 40600 yards
Count = 30s

Formula:
Weight in pounds = Length of yarn in yards/ Count *840
= 40600/30*840
Answer = 1.61 pounds

Next examples are related to filament. Note that for filament we use direct system. In which most popular is denier. There are other units too. For detail consult the tables at the end of the book. Denier is number of grams per 9000 meters of filament.

For calculation related to denier we use following equations:

Length of filament in meters = Weight of filament in grams* 9000
Denier

Weight of filament in grams = Length in meters * denier 9000

Denier = 9000* Weight of filament in grams
Length of filament in meters

Example 4

Calculate length of polyester filament from the given data:
Weight 690 grams
Denier 75

Equation: Length of filament in meters = Weight of filament in grams* 9000
Denier
= 690 * 9000
75
Answer =82800 meters

Example 5

Calculate weigh of polyester filament from the given data:

Length in meters = 50900
Denier = 50

Equation: Weight of filament in grams = Length in meters * denier 9000

= 50900*50
9000
Answer =282.8 grams

Example 6
Calculate denier of polyester filament from the given data:

Length in meters = 550,000
Weight = 4.5 kgs (4500 grams)

Equation: Denier = 9000* Weight of filament in grams
Length of filament in meters

= 9000*4500
550,000

Answer= 73.66 Denier
Note: this calculation is up to two digits. For more accurate answers use calculation up to 9 digits.
Nominal Production of knitting machines
One very simple way to calculate knitting machine production by weighing the total production of one hour or one shift or one day. This will be most realistic production value but we cannot get knitting machine capacity in this way. There is a scientific way to calculate optimum production figure of any machine. This needs certain information and some calculation. In the following lines we will explain this method in detail and will give some example so that one can be familiar to this process. In the end we will give an equation to calculate the knitting capacity of the machine. In this method following information for production calculation are required:

• Machine Guage and Dia
• RPM Knitting Machine
• Yarn Count
• Stitch Length

From these figures we can calculate the length of yarn being used by the machine in one hour and then by converting this length into weight with the help of count given we can calculate the quantity of yarn being consumed by machine in one hour. This would be the optimum production of the machine. This optimum production can be converted into nominal production by multiplying it with efficiency. In the following pages we will explain this with few examples.

In the following pages we will explain the method to calculate nominal production capacity of knitting machine. It is commonly believed that we can run knitting machine up to 85% efficiency. However, by creating most suitable environment one can increase machine efficiency.

For this we need following figures:
Machine speed RPM
Machine guage
Machine Dia
Count/ denier of yarn being used
Stitch length

From the above-mentioned figures we can calculate the length of yarn being used in one revolution and if we know the length and count of yarn then it is quite easy to calculate weight of yarn (see Example: 03 for more details)

Example 07
Calculate nominal production of a single jersey-knitting machine per hour from the data given:
Machine Gauge 24
Machine Dia 30 inches
Number of Feeders 90
Machine RPM 26
Yarn Count 24
Stitch length 4 mm
Efficiency 85%
Solution:
Step one
First we will calculate number of needles and number of stitches produced in one revolution. This would help us in calculating the total length of yarn consumed in one revolution.
Number of needles = machine dia * gauge *  (3.14)
= 30* 24*3.14
=2260 (exact 2260.8 but needles are always in even number
so we will take nearest even figure)

Number of stitches produced in revolution
Every needle is making one stitch on every feeders because machine is producing single jersey fabric (full knit fabric).
Number of stitches produced in one revolution = Number of needles * number of feeders
= 2260*90
= 203400
This figure shows that machine is making 203400 stitches in one revolution.

Step Two
Length of stitch is 04 mm (stitch length is always calculated in metric system)
From this figure we can calculate yarn consumption in yards in one hour

Yarn Consumption (in yards) in one hour
= number of stitches * length of (mm) * RPM *60 (minutes)
1000(to convert mm into meters)

=203400 * 4 * 26 * 60
1000
= 1269216 meters or
= 1388015 yards

Step Three
In previous step we calculated quantity of yarn consumed in yards. We can easily calculate weight of this yarn while its count is known (see example 03).

Weight of cotton yarn = length of yarn
Count * 840

= 1388015
840 * 24
= 68.85 pounds or
= 31.23 Kilo grams
Efficiency 85% = 26.55 Kilo grams
Answer: this machine can produce 26.55 Kgs fabric in one hour at 85 % efficiency

Example 08
For Filament yarn
Calculate nominal production of a single jersey-knitting machine per hour from the data given:
Machine Gauge 28
Machine Dia 26 inches
Number of Feeders 120
Machine RPM 30
Yarn Denier 75
Stitch length 4.5 mm
Efficiency 85%
Solution:
Step one
First we will calculate number of needles and number of stitches produced in one revolution. This would help us in calculating the total length of yarn consumed in one revolution.
Number of needles = machine dia * gauge *  (3.14)
= 26* 28*3.14
=2286 (exact 2285.92 but needles are always in even number so we will take nearest even figure)

Number of stitches produced in revolution
Every needle is making one stitch on every feeder because machine is producing single jersey fabric (full knit fabric).
Number of stitches produced in one revolution = Number of needles * number of feeders
= 2286*120
= 274320
This figure shows that machine is making 274320 stitches in one evolution.

Step Two
Length of stitch is 04.5 mm (stitch length is always calculated in metric system)
From this figure we can calculate yarn consumption in yards in one hour

Yarn Consumption (in yards) in one hour
= number of stitches * length of (mm) * RPM *60 (minutes)
1000(to convert mm into meters)

=274320 * 4.5 * 30 * 60
1000
= 2221992 meters

Step Three
In previous step we calculated quantity of yarn consumed in yards. We can easily calculate weight of this yarn while its count/denier is known (see example 05).

Weight of filament in grams = Length in meters * denier 9000

= 2221992*75
9000
Answer =18516 grams or
=18.516 Kgs

Efficiency 85% = 18.516*85%
=15.74 Kgs

Answer: this machine can produce 15.74 Kgs fabric in one hour at 85 % efficiency

Note: if we are producing any textured fabric, like fleece, then we use two different yarns at different feeders and ultimately stitch length is also different. In such case we should calculate separately consumption of different yarn at different feeders. Following example will help in calculating production in case of use of more than one kind yarn.

Example 9
Calculate nominal production of a fleece-knitting machine per hour from the data given:
Machine Gauge 18
Machine Dia 30 inches
Number of Feeders for 60
Front yarn
Number of feeders 30
For loop yarn
Machine RPM 28
Yarn Count 26s for front
Yarn count for loop 16s
Stitch length of 4.5 mm
front yarn
Stitch length of 2.5 mm
Loop yarn
Efficiency 85%
Solution:
Step one
First we will calculate number of needles and number of stitches produced in one revolution. This would help us in calculating the total length of yarn consumed in one revolution.
Number of needles = machine dia * gauge *  (3.14)
= 30* 18*3.14
=1696 (exact 1695 but needles are always in even number
so we will take nearest even figure)

In this example we will calculate consumption of yarn in Kgs of both yarns and then we will add them to get final production per hour

Consumption of yarn for front knitting
Every needle is making one stitch on every feeder because machine is producing single jersey fabric (front of fleece).
Number of stitches produced in one revolution = Number of needles * number of feeders

= 1696*60
= 101760
This figure shows that machine is making 101760 stitches in one revolution.

Step Two
Length of stitch is 04.5 mm (stitch length is always calculated in metric system)
From this figure we can calculate yarn consumption in yards in one hour

Yarn Consumption (in yards) in one hour
= number of stitches * length of (mm) * RPM *60 (minutes)
1000(to convert mm into meters)

=101760 * 4.5 * 28 * 60
1000
= 769305 meters or
= 841312 yards

Step Three
In previous step we calculated quantity of yarn consumed in yards. We can easily calculate weight of this yarn while its count is known (see example 03).

Weight of cotton yarn = length of yarn
Count * 840

= 841312
840 * 30
= 38.52 pounds or
= 17.43 Kilo grams
Efficiency 85% = 14.85 Kilo grams
Answer: this machine will consume 14.85 Kgs of yarn to knit front of the fleece fabric in one hour at 85 % efficiency
Step Four
Yarn consumed for loop knitting (back of the fabric)
Every needle is making one stitch on every feeder because machine is producing single jersey fabric (front of fleece).
Number of stitches produced in one revolution = Number of needles * number of feeders

= 1696*30
= 50880
This figure shows that machine is making 50880 stitches in one revolution.

Note: that we have put 30 cones of course count for loops after every two feeders.

Step Five
Length of stitch is 2.5 mm (stitch length is always calculated in metric system)
From this figure we can calculate yarn consumption in yards in one hour

Yarn Consumption (in yards) in one hour
= number of stitches * length of (mm) * RPM *60 (minutes)
1000(to convert mm into meters)

=50880 * 2.5 * 28 * 60
1000
= 213696 meters or
= 233696 yards

Step Six
In previous step we calculated quantity of yarn consumed in yards. We can easily calculate weight of this yarn while its count is known (see example 03).

Weight of cotton yarn = length of yarn
Count * 840

= 233696
840 * 16
= 17.39 pounds or
= 7.89 Kilo grams
Efficiency 85% = 6.70 Kilo grams

Step Seven
Now we can add both yarn consumed
Yarn for front 14.85
Yarn for back 6.70
Total 21.55

This machine can produce 21.55 Kgs fabric in one hour at 85% efficiency

All above discussion to elaborate the way to calculate the optimum production of a knitting machine. We have develop a equation which is useful in evey situation to calculate the optimum production capacity of a knitting machine at 85% efficiency.

For cotton count

Production in one hour=

Gauge * Dia * 3.14 * RPM *60 * Stitch length (mm) *1.0936 * 1 * 85
1000 *840 * yarn count * 100

Grammage Expressions

Generally grammage is expressed in Grams per Meter Square (GSM) but in certain cases it is also expressed Ounces per Yard Square (OSY). People, particularly working in marketing and merchandising departments face problems in converting GSM into OSY. We will explain this conversion method with examples before that it is imperative to know the standard conversion factors of different measuring units. A complete conversion chart is given at the end of the book. One should be much familiar with these conversion factors.

Conversion of GSM (grams per square meter) into OSY (ounces per square yard)

250 GSM means that weight of one meter square fabric is 250 grams and 10 OSY means weight on one yard squares is 10 ounces. In the following lines we will explain the method of conversion from GSM to OSY and vice versa with the help of examples.

Example 10

Convert 10 OSY (ounces per square yard) into GSM (grams per square meter).

It means weight of one yard square is 10 ounces or
Weight of one square yard is 280 grams (one ounce is equal to 28 grams) or

Weight of one 0.836 meter square (one yard square is 0.836 meter square) is 280 grams or

Weight of one meter square = 280* 1
0.836

Answer = 344.9 grams per meter square

Example 11

Convert 250 GSM (grams per square meter) into OSY (ounces per square yard)

It means weight of one meter square is 250grams or

Weight of one square meter is 8.93 ounces (28 grams are equal to one ounce) or

Weight of 1.196 yard square (one meter square is equal to 1.196 yard square) is 8.93 or

Weight of one yard square = 8.93* 1
1.196

Answer = 7.47 ounces per yard square

Relation between length, width and grammage

It was observed during interaction with the people working in garment business that they face difficulties in calculation related to grammage, width and length of the fabric. In the following lines we will explain relationship among these factors with examples.

Example 10
Calculate weight of fabric from the given data.

Grammage 300 GSM
Width of fabric 35 inches (in tubular form)
Length of fabric 20 meters

First we will calculate area of the fabric

Area of fabric = Fabric length * fabric width

= 20 * 35*2 (since fabric is in tubular)
39.37 (one meter is equal to 39.37 inches)

= 35.6 meter square

Weight of one meter square is = 300 (GSM)
And weight of 35.6 meter square = 300*35.6
= 10680 grams or 10.680 Kgs

Example 13

Calculate GSM from the data given

Total Weight of fabric = 15.5 Kgs
Length of fabric = 35 meters
Width of fabric in open form = 65 inches

Solution:

First we will calculate area of the fabric

Fabric length = 35 meters
Fabric width = 65 inches or 1.65 meters
Fabric area = Length * width
=35 * 1.65
=57.75 meters square

Weight of 57.75 Meter square is 15.5 kgs or 15500 grams
So weight of one square meter = 15500/57075

= 268.39 grams per meter square of GSM of

the fabric

Calculation of different fibre percentage in knitted fabric

Normally fabrics are knitted with one kind of yarn but in some cases more than one type of yarn of different counts and combination (mixing of two different fibres) are used. One very common example is knitting of fleece fabric, which is knitted by using fine and course yarns, and one yarn is made of polyester and cotton. Another example is knitting of fabric by using spandex filament and cotton or pure polyester. In such condition there is a requirement to mention exact percentage of different fibres in the fabric. Supplier has to mention this ratio on label. In the following lines we discuss the methods to calculate such percentage with the help of examples.

Example
Find exact composition of different fibres in fleece fabric from the following data:
Yarn count front 30s 100 cotton
Yarn count for loop 20s 50:50 P/C
Consumption ratio Front: loop 2:1 (by weight)
Suppose for front we need 2Kg yarn and for loop we will be requiring 1 Kg yarn
Front yarn 2 KGS 100 % cotton Cotton 2000 grams
Loop yarn 1 Kg 50:50 P/C Cotton 500 grams and Polyester
500 grams
Exact Ratio

Cotton total 2.5 Kgs
Polyester 0.5 Kgs

Ratio:
Cotton: 83.33%
Polyester : 16.66

Ref:- http://munawarz321.blogspot.in/2008/07/knitting-calculations.html

Spinning standards for mill planning


Spinning table

Staple length

In inch

Lap weight oz/yd

Spinnability (warp) Ne

Lap hank oz/yd

7/8

16

<20

0.00119

7/8 to 15/16

15

20-30

0.00126

15/16 to 1

14

30-40

0.00136

1 to 1(1/8)

13

40-50

0.00146

1(1/8) to 1 (1/4)

12

50-60

0.00158

1 (1/4) to 1(1/3-/8)

11

60-70

0.00173

1(1/3-/8) to 1(1/2)

10

70-80

0.00190

1(1/2) to 1(9/16)

9

80-100

0.00211

Sliver weight and sliver hank table

Count

Sliver weight

Sliver hank

Sliver weight

Grains/yd

g/yd(ktex)

Ne

g/yd

Upto 15

65

4.60

0.1284

4.21

15-20

65

4.60

0.1284

4.21

20-30

60

4.24

0.1392

3.88

30-50

55

3.89

0.1518

3.56

50-70

50

3.54

0.1668

3.24

70-90

45

3.19

0.2022

3.92

90-120

35-40

2.48 to2.83

0.260-0.2279

2.27-2.59

TM values for various staples:

If the staple length of fibre is 7/8” than TM value would be 4.75 and if staple length increases by 1/16” than TM value goes down by 0.1.

 

Machine its draft, doubling and waste%

Machine

Draft

Doubling

Waste%

Blow room

According to the count to be spun

Card

90-120

According to the count and between 3.5-5.5%

Draw frame

6-8

6-8

0.5

Lap former

1.2-1.7

16-24

0.5

Super lap former

2-5

24-60

0.5

Sliver lap

1.3-1.7

16-24

0.5

Ribbon lap

6

6

0.5

Comber

Old 40-70

New 40-90

6

4

<6 scratch comb

6-10 semi comb

10-18 regular comb

18-25 double comb

Simplex

8-12

If required 2

0.5

Slubber

3-5

0.5

Inter

4-6

0.5

Roving

5-8

If required 2

0.5

Ring frame

Conv.

10-20

2

Modern

20-50

2

Rotor

Conv.

100-150

2-3

Modern

100-250

2-3

Winding

1

M/c and its production capacity in terms of speed

1. Blow room

Production capacity in terms of speed Efficiency %
With chut feed system= 300-500 Kg 90
With 2 scutcher per blow room line and lap roll dia. 10” and rpm 7(+/-)1. The production varies from 180-240 Kg/hr/line 90

2. Card

Production capacity in terms of speed
Type Doffer rpm Efficiency
Conv. 5-15 90-92%
SHP 10-20 90-92%
HP 20-40 90-92%
VHP 40-120 90-92%

3. Draw frame

Production capacity in terms of speed
Type Efficiency No of delivery Mpm
Conv. 70-75% 4 20-30
SHP 70-75% 3 200
HP 70-75% 2 250-500
VHP 70-75% 1 750-1000

4. Lap former and super lap former

Delivery speed-50-70 mpm

Efficiency-70-75%

5. Comber

Feed per nip- 3.5 to 7mm

Type Neps/min No of heads No of delivery Efficiency
Conv. 60-70 6 1 90
HP 15-225 8 2 90
VHP Upto 400 8 2 90

6. Speed frame

Type Spindle speed No of spindles Efficiency
Slubber 500-550 72 85
Inter 55-600 138 85
Roving 600-1000 168 90
Simplex 1200-1500 132 85

7. Ring frame

Ring dia Count Spindle rpm Efficiency
50 <20 12000 90
45 20-40 13500 90
42 40-60 14500 90
42 60-80 15500 90
38 >80 16500 90
TM values for speed frame
machine Staple length
7/8” 1” 1 (1/4)” 1(1/2)”
Slubber 1.2 1 0.95 0.7-0.8
Inter/simplex 1.2 1.1 0.95 0.7-0.8
Roving 1.2 1 0.8-.9
The value for PET and VR for length of sliver and devices 2 or 3 is 0.6

8. Winding machine specification

Delivery rate 1000-2000 mpm

Efficiency- 90%

No. Of spindle- 60

Maintenance allounce
machine % maintenance allounce
Blow room
Card 10% of total no of cards
DF
LF
Comber
Simplex
RF 2% on number of spindle
Rotor -do-

9. Rotor specification

Rotor rpm 80000-100000 rpm

Efficiency- 90%

YARN WAXING


It is common practice to wax staple-spun yarns for knitting applications, given the problems of friction associated with the many thread line deflection points of the thread guides and the knitting needles on knitting machines. For optimal running of yarns during knitting, there needs to be a uniform wax distribution along yarns and a minimum of wax rub-off.

The amount of wax deposited on the yarn has a marked influence on the dynamic frictional characteristics of the yarn. Figure 1a shows that, at a given running speed, the yarn coefficient of friction decreases to a minimum with increasing wax deposited and then increases with further yarn waxing. Of the three zones indicated, clearly, Zone II is the preferred range of deposition, usually 0.5 to 1.0 g/kg of yarn. Wax grades vary according to melting point, oil content, microstructure, and hardness. Little has been published in the way of selecting a wax grade for optimal running performance. However, it would seem that selection depends on many factors such as fiber type; yarn structure, count, and moisture content; as well as room temperature and humidity in the winding area and during storage and shipment.

The preference with the commonly used wax disc is for a coarse microcrystalline structure, which allows small wax particles to be removed and held onto the yarn surface as shown in Figure 7.17b, as this should enable a uniform distribution of deposition. Steaming or high-humidity conditioning of wax yarns can result in an increased friction coefficient. Steaming will melt the wax particles and also give a partial penetration of wax into the yarn. If the yarn has to be relaxed in this way, then the deposition should be increased to offset the effect.

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FIGURE 1 Yarn thread line friction with increased wax take-up. (Courtesy of W. Schlafhorst AG & Co.)

Classification of Knitting Machines


The machines used for the manufacturing of knit fabrics can be divided into machines with individually driven needles and needle bar machines.

The former type of machine incorporates needles which are moved individually by cams acting on the needle butt; they are used for producing weft knits and are subdivided into circular knitting machines and flat-bed knitting machines. The needles used can be latch needles or compound needles.

The needle bar machines incorporate needles which move simultaneously, since they are all fixed to the same bar; we distinguish full-fashioned knitting machines and circular loop-wheel machines for the production of weft knit fabrics, which only use spring-beard needles, and warp knitting machines which use spring-beard needles, latch needles and compound needles.

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knitting


Knitting is fabric-or garment-making by forming a series of interlocking loops in a continuous yarn or a set of yarns. In production situations, the work is carried out through the movement of hooked needles. (Hand knitting is normally performed with straight needles.) Each row of loops is vertically interlocked with the preceding row. With a sufficient number of loops, the yarn becomes a fabric. Knitted fabrics have the advantage of stretchability, a property not possessed by woven fabrics. Stretching can be in any direction even if the yarn used has little elasticity. Fig. 10D illustrates two types of knitted fabric. Mechanized production knitting utilizes a series of needles commonly operated by cams.

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Figure 1A: Two examples of knit fabrics made by interlocking continuous strands of yarn—a) a plain knit made on a weft or filler knitting machine. The path of each crosswise yarn is called a course. b) a single-warp tricot knit.

somewhat more common. In weft knitting, the courses (crosswise rows of loops) are composed of continuous yarns. Weft knitting can be done by hand or machine but production weft knitting is a machine operation. The individual yarn is fed to one or more needles at a time. In warp knitting, the wales (predominantly vertical columns of loops) are continuous.3 Separate yarns are fed to each needle. The warp knitting operation is always produced by machine.

Knitted fabrics can be either flat or tubular in form. Warp knits are usually flat; weft or filling knits are most often tubular.

1 Two types of hooked needles are used in production knitting machines, the bearded or spring needle and the latch needle. They are illustrated in Fig. 1B. With both designs, the needles draw new loops through the previous loops that they have retained. Once the needle head and new loop have gone through the old loop, the old loop is cast off. The latch needle is most often used. It operates more automatically than the bearded needle which requires other machine elements to present the loop and close the hook. Fig. 1A illustrates stitch formation with a latched needle in a circular machine.

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Figure 1B Production knitting needles. a) the bearded spring needle used for fine knitted fabrics and b) the more common latch needle.

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Figure 1C: Stitch formation in weft knitting with latch needles in a circular machine. (from Knitting Technology by David J. Spencer. Reprinted by permission of Elsevier Science.)

Weft or Filling Knitting
Can be produced on either flat or circular knitting machines. In weft knitting, one continuous yarn runs crosswise in the fabric and makes up all the loops in one course. The needles either act in succession or the yarn is fed in succession, so that loop formation and interlocking is not simultaneous. Fig. 1C, view (a), illustrates a basic weft knit jersey cloth. Fig. 1C illustrates weft knitting with latch needles and shows that the multiple, evenly-spaced, needles have hooks with latches at the end. The needles are moved upward or downward by cams. As each needle rises, the needle hook loops over the yarn which it hooks on the down stroke, and the yarn is held in place by the needle latch. At the bottom of the needle stroke, a previous loop slips off the needle, and the new loop is held in place with the latch. On the next cycle,the loop is released from the latch as the needle rises, another loop is formed and the process is repeated.3 Fig. 1D shows six stages of weft knitting with bearded needles.

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Figure D: Six stages of stitch formation in weft knitting with bearded needles. In this example, all stitches in one row are formed at the same time. (from Knitting Technology by David J. Spencer. Reprinted by permission of Elsevier Science.)

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Figure E: Warp knitting with bearded needles. Loop forming is performed simultaneously with separate yarns fed through warp guides.

Several different stitches can be formed in weft knitting. In the knit stitch, the loop is drawn from the back and passed through the front of the preceding loop to the front of the cloth. In the purl stitch, the loop is drawn from the front through the back of the preceding loop to the back of the cloth. In the miss stitch, no loop is formed. In the tuck stitch, two courses on one wale are looped over a third. The stitches, and various combinations of them, make all the patterns of knit and double knit cloth. Distinct patterns can be made from combinations of the knit and purl stitches since the knit tends to advance and the purl to recede.1 Double knits are made by machine only, using two yarns and two sets of needles. These knits use a variation of the rib and interlock stitches, drawing loops from both directions.1 Jersey is a common knitted
cloth, made from only knit or only purl stitches.
Circular weft knitting machines are used to make hosiery, underwear and simulated furs. They can knit shaped garments. Jacquard effects are possible, and are now generally controlled electronically. Flat knitting machines can also produce shapes by increasing or decreasing loops. Full-fashioned garments can be made on flat knitting machines.

Warp Knitting

The previous loop to slip off the hook while a new loop is held.3 If bearded needles are used, a yarn guide, called a sinker, positions the yarn across ascending needles and then retracts as the needles descend. Fig. E illustrates warp knitting.
Warp knitting is a versatile process, but standard warp knitting machines make just three basic stitch variations: open loop, closed loop or no loop. Various fabric patterns are created from different combinations of these stitches. One simple pattern produces tricot knit, which consists of a zigzag pattern of closed loops of parallel wales. Tricot fabrics are run-resistant. Other warp-knit patterns are simplex, milanese and raschel. Milanese knitting produces run resistant fabrics with a diagonal rib pattern. Several sets of yarn are used. The raschel knit is made with latched needles rather than the spring beard needles used for other knits. One or two sets of latch needles are used. Raschel knit fabrics are used frequently for underwear. Warp knitting is used to produce fabric for dresses, lingerie, upholstery and draperies. among other products.

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