Welcome

ELEMENTARY KNOWLEDGE ON NON-WOVENS

JAFFAR TAYABALLY

Preface

My interest in the non-woven field started at the early age, when I joined my dad’s establishment and trading firm.
My first job given to me, was to make written note of all the goods sold, to who it’s sold, etc. As time progressed, I got first-hand feeling of the products regularly required by customers.

This led me slowly to investigate a product which was consumed mostly by auto-makers. Our firm was a regular & trusted supplier and as such the buyer repose full confidence in our timely supplies.

But one day, something happened - the goods did not arrive. The phone started ringing. My dad, frustrated - I saw his face dejected. On any enquiry, he just said “If we can make this product ourselves, we can make our customers happy!”

This sparked me on my journey to study, investigate, travel and learn about the product. The job was tough, but I had the gut feeling I will succeed.
The name of the product - was “cotton-wadding”.

My first job was to visit the places where this was manufactured.

But I could not gather much information except a small visual of an old ramshackle apparatus making lot of noise, with dust & smoke everywhere.

Chapter: 1

The non-woven industry has grown in technology by leaps & bounds to such an extent that it has gained status in a unique way and has been accepted as a separate prominent products-oriented field with vast scope.

Hence, it is necessary for the student—for the maiden entrepreneur—to understand its basic knowledge and technology in a short and simple manner as possible.

So what is Non-woven? Something which is not-woven. It is sheet made of natural or synthetic fibres, such as cotton, jute or polyester fibres etc.

This sheet is made by keeping small tufts of fibres in the required width, bonded by natural gums, or by synthetic adhesives or pressed by mechanical means which can be dealt later.

So what are the fibres which can be processed in such a way, so as to form sheets of non-woven form (1 mm to 200 mm thickness).

Therefore let us understand the raw materials - which form the basic component of any non-woven product.

The fibers generally used are:

1.        Cotton - virgin long staple

2.        Cotton wastes emanating from spinning mills

3.        Jute

4.        Flax

5.        Polyester Fibres

6.        Nylon Fibres

7.        Viscose Fibres - produced from wood

8.        Wool

9.        Shoddy - wastes etc.

10.     Fabric wastes

There is an organized trading community procuring and selling these fibers in all parts of India especially in Mumbai, Coimbatore, Ahmedabad etc.

Now, we shall turn our attention to the first machinery which cleans the fibers from all burrs, dirt etc.

This is known in the industry as:

1.        Ginning

2.        Fibre Recycling

3.        Willow machine

4.        Openers etc.

Most of the above machines have opening rollers / saw toothed or pinned as shown in figures. These rollers run at high speed & remove trash etc. from the fibers. The dust is sucked out through an air-pneumatic system.

These waste fibres after having gone through a cleaning process, known as willow-cleaned or openers, are again used in blend with virgin fibres for products demanding economic rates of usage. Most of these are consumed in large quantities in paper manufacturing/paper products—disposable plates, cups, egg trays etc.

However, these are now used in making a new breed of non-wovens known as sanitary napkins, wipes, insulation quilt/bounders etc. etc.

The list goes on increasing day by day as intense research is being carried out all over the world.

Now, we shall deal in the machinery aspect of cleaning system in detail to comprehend the cleaning process.

The first machine which starts in the field zone is known as Ginning Machine.
A ginning machine consists of sheet metal structure housing a saw-toothed roller (Fig 1) and a pair of 2 feed rollers (Fig 2) which feed the fibres in slow motion into fast rotating saw-toothed or pinned roller (Fig 3) which removes all seeds, burrs, dust etc.

The trash so removed falls below a receptacle through a sieve and the cleaned fibres move out to be packed for further operation.

These virgin fibres are packed in bale form to an organized market place known as mandi where it is sold.

From here, these fibres after entering an organized textile mill, are further processed in Bale breakers Fig (4), Hopper feeder Fig (5), Scutcher and finally the cleaner Fig (6). The process culminates into forming a yarn which are then sold to weaving mills to make fabrics in weaving machines. This is a short narration of the mill where the virgin fibres after due process, cleaned and soft cotton wastes / short fibres are used for blending non-wovens or to make short-staple yarn etc.

The machine as depicted in figures are standard machines in all mills.
Some mills have adopted latest machinery where the percentage of waste generated is minimized to achieve fuller economics.

Having gained first preliminary knowledge on the fibres and their initial cleaning machinery, we shall now proceed in a step by step manner, the special machines which produce them so called non-wovens.

The formation of a sheet as a web consists of several machines generally termed as non-woven cards, webletting machines, web-maker, lap makers including an glue application unit, dryers, winders etc.

Each of these require details of their unique function, so shall now proceed in a synchronized manner.

The first fibre opening plant is from a feeder pressed bale is known as bale breaker. From here it is connected by air ducts to a vertical air-chute machine where the loose fibres are again cleaned to form a batt. A batt is a sheet of loose fibres but is not a web.

This batt is again fed to a non-woven carding machine having a pair of feed rollers, and a large diameter pin or lickering (saw toothed) roller which after process send out a web of non-woven in a required width and required weight per sq meter or per square yard.

As the case may be, these webs are sprayed with binders and closed to form.

A sheet of non-woven web or felt as it is generally called.

Again, a second process known as needling is carried on a special machine having a large number of needles which makes the web stronger having more tensile strength.

Once this process is over, a winder does the rolling work.

What we discussed is a carded web using the traditional carding machine.

As modernisation progresses, a new system of making web was developed.

This was known as air-laid web making machine.

"In the early period, there was a process known as hand-felting where goat hair was used.

In Rajasthan, where the temperature is high in summer, people used to make felts from goat hair. The hair was first cleaned in their old style & dried.

A plate or sheet-metal plate of a size of 12x4 was changed into a tray form. It was poured soap-wahi as some natural form of glue liquid in measured quantities. The hair was then spread in two layers padded and made into as thick. This was left to dry in the hot sun for a few days. This would form a thick sheet of felt which was removed from the tray and rolled for packing.

This felt either was black, gray or white mostly in tanning industry situated in South India. It was consumed in high quantities and it was flourishing trade.

As time passed, woollen was added to this process and also color. This wool & color changed goat hair felt to the industry which was not only used in tanning but also found its place in insulation spectrum boxes, air-conditioning, polishing etc.

This was the first non-woven product."

"As time passed, leading mills in South India started making felts from virgin wool locally procured or wool imported from overseas countries. This was called endless felt as it was exclusive used in paper making process. The machinery & plant was hugely sophisticated and one can manufacture felts in any textile upto 10 mts width continuous and this required professional people to run the plant.

Printing industry, especially the newspaper industry, required these specially needled felts and even other printing units require this non-woven felt for their printing needs.

As time passed, music loops started using a little less costly felt to circulate their music boxes for acoustic purposes.

A special grade non-woven felt was largely consumed in the piano music players but this was initially largely imported."

The earliest effort of non-woven manufacturing was started in Japan in Rajasthan and later in Egypt.

Small units started making woollen felts, cotton-mix hand-made felts, bonded felts.

These were made by using less-sophisticated opening & carding machines. The first step was to feed the lap between 2 feed rollers which fed the fibres into a large diameter carding drum clothed with sharp hooked needles. This carding drum speed was 800 to 2000 RPM depending on the type of fibre fed and degree of opening required. The fibre was then laid on top of the other to form a consolidated web - ready for bonding into a thick sheet from 1mm to 1" (25mm). Length generally was 10 to 18 feet long.

Then woollen felt was widely consumed by leather tanning industry, polishing industry, heat insulation, lubricating oil-immersed felt strip in roller bearing housing, optical industry, picture framing industry, etc. etc.

As time progressed, the quality of felt was improved having uniform density & thickness. This resulted in the printing industry using in their offset printing units.

The felt-making business has expanded manifold and a large dealer network meets the demands of consumers. 2011

"As our main subject was to understand nonwoven, its initial making and its usual usages which we have explained in a detailed manner in the foregoing chapters, we shall now try to understand the modern way of making nonwoven products in a more elaborate way.

So we shall start in informing the reader the first preliminary machinery required to make all nonwovens."

The first-requisite in nonwoven product manufacture is to prepare, open, clean all fibers, whether they are organic or synthetic. To achieve this, there are several machines available with textile machinery mfrs. The first machine is named a Bale-Breaker. This is known as Bale-Breaker which has as the illustration shows 1) a straight conveyor lattice on which the bale is placed. 2) an opening system that opens the bale & spreads the fibers 3) the fibers then pass thru a spiked inclined conveyor as lattice cocks further opens the fibers with several pairs of spiked rollers offering a thorough opening before the fibers land into the subsequent machine for next operation. The job of this machine is to open large bundles of fibers into small tufts of fibers.

These small tufts of fibers are then fed into the 2nd stage cleaning machine which is known as the Hopper-Feeder. This consists of a large BIN with a conveyor at its base where fibers are deposited. The conveyor feeds these into an inclined spiked roller having sharp points at close end. Over the hopper there is a tower known as Stepper opening rollers. These opening rollers function at different speed to facilitate gentle opening of tufts into smaller tufts of individual flock of fibers. The hopper-feeder job is to remove all dust particles from the cot fibers. Then a suction system collects fibers.

"a revolving cage of perforated drums the fibers land on this in to form a lap same time removing too all micro-dust from the fibers

So all the fibers are now ready for non-woven production."

As we proceed to the next stage of non-woven sheet or web making, we have to understand that a web is made of small heaps of fibres homogeneously held together to form a web.

This sheet or web is now ready for the next stage such as coating with binders, felting or needling as per requirement of the desired product.

A liquid made of starch or polymer compound binder is sprayed on the web to bind strongly the loosely-held fibres. Once the binder thickens the body of the web, it is then heat-treated to form a dry-sheet or wadding which is the final product.

These are used for various uses or application for thermal insulation in garments, blankets or home-clothes.

There are several processes of applying the liquid as semi-viscous binders by special designed spray-systems or by roll-coating depending upon the properties of the webs.

To dry the well-bond product, there is a long oven having hot-air inlet using blowers running at specific speeds as the case may be.

"After drying, the continuous web which comes out is rolled on roller as a whole and rolls cut as per requirement."