Knitting Productivity Improvement Tips

8/13/2019 Knitting Productivity Improvement Tips

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Knitting is the first process in the series of the whole knitting process of converting the greige

yarn into a saleable garment. In this department, yarn is converted into fabric with the help of

knitting machines. This department is critical for the total productivity of knitted garments

manufacturing mills. It has been observed during a survey when at the time of panel

inspection in the cutting department, knitting faults accounted for more than 50% rejection of

panels. Knitting department is found to be responsible for more than 20% rejection of

garments. Loss can be reduced in knitting by more than 50% and its productivity can be

increased through getting more production per machine, using better fabric quality, having

lesser wear and tear of knitting parts and improving productivity of labor etc.

This article is aimed at identifying the improvement areas in knitting and recommending

measures for improving the knitting productivity. In the first part, we'll introduce the knitting

technology; second part will explain the key areas of improvement and finally, the third part

will suggest methods for improvements.

Knitting History

It is quite difficult to say when knitting actually started. Many authors and researchers have

presented different views about the evolution of knitting process. However, almost all the

researchers believe that the art of hand knitting is thousands of years old. It is a mystery thathow ancient humans learned this art and so are the place and time of its origin. However,

some researchers believe that this art originated in Persia. Others claim that it started in

Israel, Jordan and Syria. Some researchers opine that mountainous areas of North Africa are

the origin of this craft. Knitted socks, which were discovered in Egyptian tombs, date back

from 3rd to 6th century BC.

First knitting frame was invented four hundred years ago, which could knit 600 courses per

minute and today, the latest machine can knit more than 15 million stitches per minute while


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a skilled hand knitter can produce only 120-150 stitches per minute. Until 1980, most of the

knitting machines were mechanically controlled. Today, most of the machines are

electronically operated and controlled with the help of computer systems and the use of

electronic and computer technology is increasing day by day. Jacquard knitting machines

were equipped with design wheels and drums for producing a certain fabric design but today,

computer is attached with machines for the design purpose. Same is the case with stripper

knitting machines. Earlier, machines had manual controls for changing the yarn supply but

now electronic controls have been introduced for this purpose while the whole process is

managed by using computing devices.

Before the invention of knitting frame by William Lee in 1589, hand knitting was the main

method of producing knitted fabrics and a skilled person could knit 120 150 stitches per

minute. Even now, some people like wearing hands knit garments and some women

especially elderly women do it mainly for a pastime. Hands knit sweaters are sold in the

market but its share in the total business is negligible.

Knitting in Current Times

Some machines can work at a speed of more than 50 RPM [revolution per minute] with

gauge more than 40, diameter more than 60 inches and feeders up to 316. Now fully

automatic garments knitting machines have built-in stripers and jacquards, interchangeable

structures and fully computerized operations. In addition to that, people have invented

machines (still not in commercial use), which process sliver (aligned fibres) into yarn. In this

way, full-fledged spinning mills will not be needed in the upcoming industrial era.

Furthermore, these machines produce yarn according to the requirements.

Just 20 years back, maximum production from one machine was 300 Kg/day and today, wecan get a productivity of 1500 Kg/day. Textile Industry of Pakistan needs to keep pace with

the new technology. Unfortunately, we have old machines, which are incapable of making

Pakistan competitive in the international market. Furthermore, we are still having old and

outdated facilities in knitting departments. In addition, our management practices are

ineffective and outdated. Pakistan needs latest technology, modern management practices and

latest operating procedures for improving its knitting output.


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Knitting Process Explanation

Knitting is a process in which fabric is made by inserting loop into loop. In this process yarn

loops are made with the help of needle hook and these loops are passed through previously

made loops already held by the needle. From the above-mentioned definition, it is clear that

knitted fabric is mainly composed of loops. These loops are formed with the help of a needle

while yarn is provided through any warp sheet or through a feeding mechanism. Loops

formation is the basic and fundamental differentiation of knitted fabrics from woven fabrics.

All knitted fabric characteristics are based upon loop structures. Loops create elasticity and

resilience in the fabric.

Knitting Fabric Production Process

As discussed in the first part of the chapter that knitting is the only one way of making a

fabric. For this purpose, yarn is supplied to knitting machines and machines convert this yarn

into fabric with the help of its various parts. There are many factors involved in the

production process, which have a significant impact on the knitting productivity and output.

Some of the factors are mentioned below:-

1. Controlled environment in knitting hall (moisture and temperature)2. Machine maintenance3. Quality of compressed air4. Skill of workers5. Yarn storage requirements and procedures6. Fabric storage7. Lubricants' quality8. Quality of needles and sinkers


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9. Fluff level in the environment

In this part of the article, we'll discuss different factors affecting the productivity and methods

to enhance their positive impact on the total productivity.

Controlled Moisture Percentage and Temperature

In Pakistan, knitting industry is confined only to three major cities: Lahore, Faisalabad

(Punjab) and Karachi (Sindh). There is a significant difference in climate of Punjab and

Sindh. Even in Punjab, temperature varies from -2 to 50 C while moisture levels also vary in

different seasons. In rainy season, moisture content exceeds 80% and in dry season, it reduces

to 20% and sometimes drops to even less than that.

Cotton is very absorbing. It can absorb up to 8.5 % moisture. Tensile strength of cotton

increases with the increasing moisture. Furthermore, it also gains weight after absorbing

moisture, which is quite logical. To avoid problem of variation in the strength and weight,

which changes with the variation in moisture and temperature, international standards of

moisture and temperature have been set. As per standards, moisture content must be 65% 2

(Relatively Humid) and temperature must be 20C 1.

All knitting machine manufacturers recommend controlling environment in the knitting hall.

Mayer and Cie, one of the largest and most popular knitting machine manufactures

recommend maintaining 20 C temperature and 65 % RH humidity in the knitting hall. They

have given their recommendations in their book, "Knitting Technology".

There is a direct impact of moisture and temperature on knitting productivity. It was observed

during a survey of the industry that only one mill in Lahore and one mill in Faisalabad have

installed air conditioning plants. Both of them are producing better with same machines. Air

conditioning system provides the required temperature and humidity along with fluff control.

Air circulation system is attached to water chillers and humidifiers, which provides filtered

air to the knitting hall.

A production raise of 20-25% can be obtained only by installing air conditioning systems and

it is evident from experts' opinions, claims of air conditioning plant manufacturers and

observational surveys. In addition, 50% less faults and 50% less consumption (breakage) of

needles and sinkers is expected. Above all, we'll be fulfilling our moral duty by providing ahealthy environment to workers, which keeps them healthy. As per doctors opinion, fluff in


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the air can cause allergies, respiratory tract infections and other respiratory disorders. Using

air conditioning, we have a neat, clean, free of fluff and healthy environment, which

definitely improves productivity.

It is presumed that pay back period of all recommended changes and investment is less than

six months. In addition, there is a 50% less consumption of needles and sinkers besides better

fabric output quality and a healthy and pollution free environment for workers.

Other than increase in production, a manufacturer can also enjoy the following benefits:-

1. No tripping of electronic parts, which is quite common at high temperature2. Less breakage of needles due to low temperature3. Clean environment with suitable temperature and humidity4. Better knitted fabric quality, less yarn breakage and low machine stoppage frequency5. Better health of workers6. Less yarn wastage7. Conducive environment for better productivity and quality output

It is quite clear that air conditioning plant is one of the most important investments in a

knitting mill. Based on all this discussion, it is recommended that all knitting mills should

have air conditioning plants to improve their productivity. It should not be consideredexpensive but a viable and productive investment. Its pay back period is less than a year.

Manufacturers should focus on efficient knitting workspace rather than larger spaces because

air conditioning costs are high when workspaces are small but efficient.

Cool and Dry Compressed Air

Compressed air of 125-150 pounds per square inch pressure is used in knitting for cleaning

and oiling purposes. It goes into the deeper parts of the knitting machine to remove excessive

fluff from the machine. Furthermore, it is also used with oil to lubricate the inner parts of

machines.

It is one of the most important inputs in knitting productivity factor. When air is compressed

in a vessel, its temperature increases and at the same time, moisture percentage in the

compressed air also increases. Extra high temperature and high level of moisture are

dangerous for the knitting process. High temperature further raises the machine's temperature,

which is already too high because of mechanical movements of the machine at a high speed.

High level of moisture reduces the lubrication efficiency. Since all lubricants (mainly white


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oil) are water-soluble, moisture present in the compressed air dissolves in the oils and

ultimately reduces its lubrication. It decreases efficiency of lubricants and it might result in

breakage of knitting parts particularly needles and sinkers. To avoid it, all machine

manufacturers recommend using compressed air, which is free of moisture and it should have

low temperature (less than 20C).

In our knitting industry, manufacturers mostly use untreated compressed air despite the fact

that it can increase wear and tear of machines. Many machines and equipments are available,

which can reduce the moisture level and air temperature. Based on this discussion, using cool

and moisture free compressed air is strongly recommended for knitting.

We can have following advantages of cool, free-of-contaminants and dry air:

1. Helps reduction in needle breakage2. No rust on machine3. Smooth machine function4. Reduction in accidents5.Other than the two above-mentioned areas, knitter should focus on the following factors:

Yarn and greige fabric storage Machine maintenance Using lifters to move yarn and fabric in the knitting hall

It is expected that by focusing on these points, a manufacturer can gain the following

advantages:

1. Avoiding Mixing of yarn2. Less yarn variation3. Less leftover yarn4. Less yarn wastage5. Better machine maintenance helps in better production (A Universal Truth)

After implementing all these recommendations, it is expected that knitters can improve their

profitability by more than 25% as well as their image in the minds of local and overseas

customers.

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Knitting Productivity Improvement Tips