Objectives:

The main or primary objective of this report is to understand the working principals of the machines on the production floor ,the productive potential of those machinery, the flaws in the working which interfere during the production and results in loss of production, Quality, Efficiency, and material loss and in short results in the increase of yarn manufacturing cost. These faults can be of different types, It could be a manufacturing fault, or it could be because of poor handling of the material, or it could be because of the Quality of material processed, because if we are dealing with material of not a very good quality then it will not doubt effect the production, quality, efficiency of the machine.

There are different types of yarn manufacturing technologies available i.e.

o Ring Spinningo Compact Spinningo Rotor Spinningo Air jet Spinningo Misc

Above mentioned are the technologies that are mostly used for the manufacturing of yarn. Each of the above mentioned techniques for yarn production compromises of different working principal and work on whole different idea of yarn manufacturing. They differ in yarn quality, production speed, efficiency, and material processing method.

Production Speed/Quality:

When talking about the capacity of a machine to manufacture a good, production speed is a very important factor along with the Quality prospective. Because it is permissible to obtain a very high production speed but neglecting the Quality factor. The above mentioned technologies differ with each other very much in production speed and quality of yarn produced by these machines. e.g.

o Rotor spinning is 7 times faster than Ring Spinningo Compact spinning is also faster than Ring spinningo Air jet spinning is 3 times faster than Rotor spinning it means Air jet is 10 times faster than

Ring Spinning.o Similarly Vortex spinning is a technology that is the fastest technology available in the market.o Rotor Spinning shows produced less hairy in yarn than Ring spinningo Compact Spinning by eliminating spinning triangle produced finer, high quality and less hairy

yarn.o Air jet produced very fine yarn with less hairiness than Ring Spinning.

But besides of so much advantages achievable with the technologies other than Ring Spinning still RING SPINNING is considered to be the most reliable technology when dealing with different types of fibers for different end uses.

o Rotor spinning is used only for manufacturing of coarser yarns because of low torque generation for the twist insertion, therefore its usage has restricted only to coarser yarns.

o Air jet Spinning is no doubt very fast yarn manufacturing technology but still a limitation of this machine is that it cannot be used for the production of coarser yarns. So, its usage has restricted only to finer yarns.

o Vortex spinning is a technology, which has been implemented successfully only by Murata Tech and its usage has restricted mostly to fashion purposes.

But Ring Spinning vs. All Technologies:

o Production of high strength yarns.o Spinning of fine count yarns.o Proper for special yarns.o It is universally applicable (any material can be spun).o The know how for operation of machine is well established accessible to everyone.o It is flexible as regards quantities (blend and lot size).o Since the speeds in drawing section are best controlled, yarn evenness is excellent. But if short

fibers are too much, yarn unevenness occurs.o Fine yarns can be produced as compared to open-end system

But Also Disadvantages:

o Process stages are more numerous. Roving stage exists as an extra process compared to the other systems.

o Yarn breakages are more numerous as a result of ring traveler friction and yarn air friction. Interruptions, broken ends and piecing up problems exist because of the yarn breakages.

o The high speed of the traveler damages the fibers.o The capacity of the cops is limited.o Energy cost is very high.o Low production rate.

Industrial Revolution

After the Industrial revolution (1764-1784) Mule Spinning gained attention throughout the world. Continuous efforts were being made to refine this system of spinning. Later, Ring Spinning was introduced after some modifications in Mule Spinning System. The basic technology of the Ring Spinning remained unchanged.

In spite of significant developments and refinements of the system, following the commercial acceptance of the Open-end spinning, many new spinning systems were developed, some of which have gained popularity.

Open-end spinning machine, specifically manufactured for short staple fibers, was considered a good rival because of much higher production and better evenness of the yarn. However, further development of this system showed that the best performance of the OE system is limited to the coarse categories of yarn.

On the other hand, Ring Spinning Systems have been refined during the last 30 years, the ultimate objectives of spinning dialectologists are focused on higher production speed, combined with adequate quality. The quest for higher yarn quality has become in line with the much more exacting requirements and the performance criteria of the knitter, weaver etc.

INTRODUCTIONSince drafting at Ring Frame is a major influence on yarn qualities & ultimately tells on even fabric appearance, conversion of drafting to upgrade ring frame is a worthwhile exercise.

Among the various components of ring frame, drafting has the maximum influence on yarn quality&ring performance. Drafting at Ring Frame considerably influences not only evenness and appearance of yarn, but also performance of yarn, appearance of fabric, and rejections due to yarn faults. Therefore conversion of drafting is given a high priority in the efforts to upgrade a Ring Frame and the payback from such investments is attractive.

IRREGU L ARI T Y IN DRA F TING

Irregularity added in drafting is mainly caused by:

1. Inadequate control over the movement of short and floating fibres.

2. Slippage of strand and fibres under the drafting roller.

3. Variations in speed of drafting rollers.

4. Mechanical faults.

Developments in drafting have therefore focused mainly on reducing the contribution from these factors.

CA S AB LA NCA DRAFTING

Casablanca A500 drafting represents the first development to improve the control over floating fibres. Prior to that, a self-weighted light middle top roller was used to control the short fibres while allowing the long fibres to slip underneath. In Casablanca drafting a pair of endless aprons, driven by middle top and bottom roller and held together by a tensor, is used to control the floating fibres in the front zone. The back zone is merely a break draft zone with low drafts. The main drawbacks of this system are:

1. Being self-weighted, the back top roller is subjected to slippage.2. Because of bigger diameter of back top roller, the back zone setting is 55mm, which

is too wide for short staple fibres.3. The pressures on front and middle top rollers, which are already low, are further

affected by ageing of spring over a period of time.4. Top rollers are guided by cap bar nebs at the end. Misalignment of roller often

occurs because of grooving of cap bar nebs and disturbance in the cap bar settings.5. Plain bearings are used for top rollers, which need frequent lubrication. The

lubricant used to attract fluff.

TOP ARM DRAF TING

Top arm drafting represents a major break through in improving the quality and performance of drafting. Most of the problems that encountered with Casablanca drafting are overcome by Top arm drafting by adopting pendulum system of central arbour guidance. The top rollers are held at the middle of arbour by means of a saddle, which are weighted by heavy-duty springs. The advantages of Top Arm are:

1. Self-alignment of top roller in relation to bottom roller results on better grip over fibres.

2. Heavier weighting by the use of better grade springs reduces slippage. The spring pressure is also constant over a long period of time.

3. Higher drafts are achievable because of better control over fibres.4. Cleaning of draft zone and removal of roller lapping is facilitated because of easy access to

parts as top arm together with top rollers can be lifted up.5. About 1-1.5% units better U% and 15-20% reduction in imperfections are obtained by

conversion to top arm drafting.

The major improvements in second-generation top arms are:1. Higher pressure on top roller.2. Provision for varying the pressure on top

rollers as per the requirement.3. Modified top arm support bar.4. High stability cradle.

TOP ARM SUPPORT BAR

Top arm support bar with a cross-section of ‘D’ shape instead of circular, found in first generation, is used in UT 600 to minimize disturbances in height of top arm. In SKF PK225, top arm support bar has two grooves, in one of which arm is securely locked by a screw and in another setting the height of the arm is done by another screw. This minimizes disturbances to height setting because of slippage of top arm around support bar.

HIGH STABILIT Y CRADLE

High stability cradle is another improvement in UT600 top arm. The weighting from retainer spring acts directly on cradle and from there the pressure is transmitted to the middle top roller. This eliminates the yarn defects caused by lifting of front edge of cradle due to defective cradle spring; a defect sometime encountered in other drafting systems.

PRESSURE SETTING

Setting of pressure to the desired level is done by means of height gauge as shown in figure. To minimize subjective error in height setting, “pointer height gauge” is used in Suessen drafting. Pressure checking with the help of a top roller pressure checking device which has a dial gauge in it is the best way to minimize variations in pressure. In SKF PK225, there is a provision for adjusting the pressure in front top roller to three different levels by means of a cam that is adjusted by a wrench.

LATEST TOP ARMS

P3-1 top arm represents the latest top arm of Reiter and Laxmi Reiter used in G5/series of Ring Frames. The bottom and top rollers have bigger diameter and front top roller has a higher of 4mm. To minimize torsional vibration of back rollers, the drafting system has a separate drive operated by its own motor in Reiter G30 ring frame. The 1008 spindle machine is divided into two modules, each of which is driven by its own motor for the same purpose.In HP drafting, which is the latest version of Suessen drafting, the weighting is effected by a spring plate, which distributes 75%of load to the middle top roller and balance 25% on front top roller. An anti-friction clip of synthetic material fitted on cradle brings top roller nip close to front roller nip. Pressure release systems are provided on all modern drafting systems to bring down pressure to 10-20% of the full load when frame is stopped for long duration of time.

TOP ROLLERS

Originally the top rollers were of detachable types being made of two components, viz;

1. Bearing unit2. Top roller boss.

The boss can be removed from bearing unit to facilitate greasing. The boss is retained on the bearing by means of a snap ring. With such a design play was found to develop between the units after years of usage leading to irregularities. To overcome this non- detachable type of top rollers were developed. The inner wall of top roller forms the outer race of the bearing in this design as shown in figure. Hence the inner wall has to be precision ground, thereby ensuring accurate movement of top rollers even after years of usage. Double row of bearings is used to minimize the play further. To minimize bending of top roller, a saddle collar is introduced instead of recessed top roller in the middle.

COTS

Hardness, diameter and width are important characteristics of cots influencing irregularity. Softer cots on front roller, with a shore hardness of 65%, bring down the U and thick and thin places in yarn significantly in cotton counts. The improvement arises from the improved grip over the strand because of the extended contact at the nip. As a result, slippage of fibres under the nip is reduced. Softer cots are however more susceptible to wear and tear and roller lapping and are therefore not preferred for polyester blends. Bigger cot diameter up to 30mm diameter brings down slubs, crackers and other classimat faults particularly with polyester blends. Roller lapping is also reduced with bigger diameter. Lower cot width up to 25mm improves pressure over the nip and so contributes to better drafting.

OFFSET DRAFT I NG

Offset drafting by INA represents another development for improving yarn quality. The back bottom roller is raised by height of 13.5mm and back top roller is offset backward by24mm so that the nip point is taken back by 15mm around the circumference of bottom roller as shown in figur e . The incoming roving therefore wraps round the circumference of bottom roller over a considerable length before it leaves it.

Further, back zone bottom roller setting is reduced from 51 to 44mm. As a result of these actions the strand takes a V-shaped path as twist in roving is broken down. The strand width is reduced leading to improved inter fibre friction in the main drafting zone. Detailed studies show that thick and thin places and U% of yarn are significantly reduced in cotton counts with offset drafting. The improvements are more prominent in carded counts from short staple cotton and at high ring frame draft.

COMPACT SPINN I NG

In traditional ring spinning, fibres in the selvedge of strand emerging from front roller nip do not get fully integrated into the yarn because of the restriction to twist flow by the spinning triangle. These fibres show up partly as protruding hairs or as wild fibres. The spinning triangle is because of higher width of the strand as compared to final yarn diameter. Further the fibres are tensioned to varying extent depending upon their position in the spinning triangle. As a result full realization of fibre strength is not achieved in the yarn. The hairiness gives a rough feel to the yarn. Variation in hairiness is a source of weft bars and warp way streaks in the fabric. Long protruding hairs from the yarn contribute to multiple breaks in weaving and fabric faults like stitches and floats.

The length of the spinning triangle depends upon the spinning geometry and upon the twist level in the yarn. If the spinning triangle is too short, then the fibres on the edge must be strongly deflected to bind them in. This is not possible with all fibres, and lost as fly. Thus with shorter triangle, smaller weak point resulting into fewer end breaks but makes the yarn hairy. On the other hand, a long spinning triangle implies a long weak point and hence more end breaks giving smoother yarn and less fly.

In Compact Spinning, incorporating a condensing zone after main drafting zone, thereby overcoming the drawbacks of conventional spinning, eliminates spinning triangle. This will be clear from a comparison of mode of yarn formation in the two systems as shown in figure.

The condensing zone has a revolving perforated apron with suction underneath. The fibrescollected on the perforated track of the apron and get condensed. A low-tension draft is kept in the condensing zone to assist in the condensation.Compact Spinning systems are offered by:

• REITER [COMFOURSPIN]• SUESSEN [ ELITE SPINNING SYSTEM ]• LAKSHMI [ RoCos COMPACT SPINNING SYSTEM ]• ITV-ZINSER [ CompACT3 ]

REIT E R

In Reiter Comfourspin, a perforated drum replaces front bottom roller of drafting system. A second top roller also presses on the drum. There is a suction system-generating vacuum under the drum. Condensing of strand takes place between the two top rollers under the perforated drum non- rotating insert inside the drum with specially shaped slots helps in achieving condensation.

SUESSEN

In the Elite system of Suessen, condensing zone consists of profile tube with a perforated lattice apron running over it. A delivery top roller pressed on the apron drives the apron. A suction system under the profile tube causes condensation of the strand.

Z I NS E R

.

In ITV-Zinser system, illustrated in figure, condensing zone consists of a revolving perforated apron. The size of perforations in the apron is varied as per the count of the yarn to get the desired condensation.

LAKSHMI

The Lakshmi RoCos Compact System, works without air suction & uses magnetic mechanical compacting principle.

Compacting yarn is produced by compacting the strand of fibres in the condensing zone to such an extent thereby avoiding spinning triangle and makes control over the strand of fibres.The contour & the path of the fibres enables all the fibres to align itself along with the axis of yarn more uniformly.

² SALIENT FEATURES:• Magnetic compacting is more user friendly & avoids• Air suction• Air pipes• Perforated drums or apron• Additional air conditioning requirements

ADVANTAGES OF ANY KIND OF COMPACT SPINNING TECHNOLOGY:-

• 15-20% reduction in hairiness of yarn, the

• reduction being more pronounced in long length hairs

• 10-15% improvement in yarn tenacity

• Twist in yarn can be reduced by 10% while maintaining same yarn strength

• Better evenness of diameter and hairiness.

• Better abrasion resistance of yarn leading to fewer ends

• breaks in weaving. Loom shed droppings and linting in knitting are reduced.

• Singeing can be omitted.

• Lower twist can be employed in doubling.

• Improved appearance and lustre of fabric with a softer.

• Reduced pilling and better dye uptake.

Friction Spinning:

Dref Friction Spinning

Dref Friction Spinning is a textile technology that allows very heavy count yarns and technical core wrapped yarns to be manufactured. These are most commonly used in Mop yarns, flame retardants and high tech fancy yarns such as Raydon and Kevlar.

The father of Dref Spinning

Dr. Ernst Fehrer invented and patented the DREF friction spinning process in 1973, and named the system after himself. DR Ernst Fehrer... DREF. He had begun work on the development of this alternative to mule, ring and rotor open end spinning at the beginning of the decade with the objective of surmounting the physico-mechanical limits on capacity and yarn engineering and production speeds to which these traditional systems are subject.

Sadly, Dr. Ernst Fehrer, chairman of Dr. Ernst Fehrer AG, Textilmaschinenfabrick, Linz-Leonding, Austria, died in December 2000 at age 81. Dr. Fehrer's long career in the development of nonwovens and spinning technology had produced more than 1000 patents. He began his career in research, development and inventing at age 14 and received his first patent at age 18. Dr. Fehrer is be remembered for having developed the first high speed needle loom featuring sophisticated counterbalancing technology as well as "Dref" the first commercially successful friction spinning systems. In 1988, Fehrer received the TAPPI Nonwovens Division Award for his outstanding contributions to nonwovens manufacturing technology. In 1994 Dr. Fehrer received Textile World's first Lifetime Achievement Award. Obituary

Development

By 1975, Dr. Fehrer already had Dref I in development, a 3-head machine undergoing trials and in 1977 the first DREF 2 for the coarse yarn count range came onto the market. In view of its

success, Dr. Fehrer then created the DREF 3, which was designed for the medium yarn count range and made its debut at the ITMA ’79 in Hanover, before entering serial production in 1981.

New generations of the DREF 2 followed in 1986 and 1994 and the DREF 3/96 was launched at the ITMA in Milan. The 1999 ITMA in Paris witnessed the arrival of the DREF 2000, the first of which was sold prior to the fair. Full production of the DREF 2000 commenced in the autumn of 1999 in co-ordination with presentations at the ATME, USA and the SIMAT in Argentina. In 2001, the DREF 2000 also went on display in Asia at the ITMA Singapore and in Central America at the EXINTEX, Mexico.

Fehrer entered co-operations with other professional textile companies to develop the technology. Rieter AG in Switzerland Rieter and Oerlikon Schlafhorst in Germany Oerlikon Schlafhorst. With this co-operation the last machine developed by DREF was the DREF 3000, which was available for testing in the new DREF facility at FEHRER headquarters in Linz, Austria in the autumn of 2001. In 2005 Saurer AG Saurer purchased Fehrer AG in 2005. In 2009 Fehrer shut the doors on the DREF factory altogether. The friction spinnning technology is now being developed further by Stewarts of America Stewarts of America, Inc., who manufacture parts for the original Fehrer Dref II, Dref III, Dref 2000 and Dref 3000 friction spinning machines.

DREF I

The first Dref machine, a three headed research and development spinning machine. The fibres were opened with an opening roller and allowed to fall on a single perforated cylindrical drum slot ,which has negative pressure for fibre collection. The rotation of the drum impart twist to fibre assembly. The ratio of perforated drum to yarn surface is very large, hence the drum speed can be kept relatively low, even if one takes the unavoidable slippage into account. Due to the absence of positive control over the fibres assembly, slippage occurred between the fibre assembly and perforated roller, which reduced twist efficiency. Hence this development could not be commercialized.

DREF II

The Dref 2 was exhibited in the year 1975 at ITMA exhibition. The feasibility of using two perforated rotating cylinders, (as fibre collecting means), while at the same time the spinning-in of fibres into yarn occurred. It operates on the basis of mechanical/aerodynamic spinning system with an internal suction and same direction of drums rotation. Drafted slivers are opened into individual fibres by a rotating carding drum covered with saw tooth type wire clothing. The individualized fibres are stripped off from the carding drum by centrifugal force supported by an air stream from the blower and transported into the nip of two perforated friction drums where they are held by suction. The fibres are sub-sequentially twisted by mechanical friction on the surface of the drums. Suction through the perforations of the drums assists this process besides helping in the removal of dust and dirt, thereby contributing to production of cleaner yarn. The low yarn strength and the requirement of more number of fibres in yarn cross-section(minimum 80-100 fibres) were restricted the DREF-2 spinning with coarser counts (0.3-6s Ne).

DREF 2 friction spinning can be used for everything from asbestos substitutes and secondary carpet backing yarns, to technical products such as cartridges for liquid filtration.

At present, around 80 DREF 2 machines are spinning 30,000 t of yarns for liquid filtration. The main markets are Europe and the USA, where approximately 150 million filter cartridges are manufactured with DREF 2 yarns, or 65-70% of global production.

The leading US and European filter producers spin a wide range of DREF 2 PP-yarns at speeds of 160 – 180 m/min. One particular application is for PPFDA washed filters, which are employed in all types of industries includingchemicals, pulp, paper, cosmetics, pharmaceuticals, nuclear power and electrical power.The filter is formed using polypropylene Meraklon fda fibre over a supporting core and can withstand up to 5 bar of differential pressure and temperatures of 80 °C. The filters come in all lengths from 4´´- 40´´ and have filtration ratings of 1-150 micro metres .

DREF 2 is also used in friction spun yarns for drinking and industrial water, pure water and activated carbon filters. The yarns employed generally consist of PP fibres in the 3.3 dtex, 40 mm range, which are highly resistant to micro-organisms and have a wide scope of chemical applications.

Friction spun yarns offer 20-40% more air volume in the yarn and less flow resistance than flyer yarns, as well as up to twice the service life. The fibre structures are relatively random and subject to high degree of twist. The yarns offer great regularity and increased strength, while their round yarn cross-section ensures limited deformation under transverse load. Production costs can be cut by up to 50% through reduced preparation, spinning and personnel expenses. At present, 8,481 DREF 2 spinning heads manufacture approximately 318,000 metric tons of yarn annually in the Nm 0,5 - Nm 6 (2000 - 167 tex) yarn count range. 230 of these machines, with yearly yarn production of 80,100 metric tons, are employed in the cleaning cloth and mop sector.

Following the world market launch of the DREF 2 in 1977, leading cleaning cloth and mop manufacturers from Europe and overseas began to switch from conventional carded yarn operation to friction spinning.

This decision was influenced by the following notable advantages:

- Savings in material costs due to the use of 100% regenerated fibres, spinning waste and cotton waste blends. - The economic and problem-free, high-performance processing of extremely short staple materials (10–20 mm staple length) through the feeding of a yarn core (e.g. 167 dtex, textures, PES sub-standard filament), or of a core-sliver from PES regenerated fibers (instead of a yarn filament core). - Reductions in personnel costs (simpler preparation as the material passes directly from the card to the spinning machine). - Increased efficiency (up to 95%) due to greater bobbin weights of up to max. 8 kg and spinning without yarn breaks. - Considerable increases in performance due to the production of heavier slivers with weights of up to 15 g/m. - Greatly improved water absorbency capacity and improved retentive volume. - Higher fabric weights and a cleaner cloth appearance.

Furthermore, DREF allowed the manufacture of both S- and Z-twist yarns with the same machine. This means that the cloth ends do not curl, which is a major advantage with regard to further processing on automatic sewing machines.

DREF cleaning rags and mop yarn production data

Sold spinning heads: 1335 Yarn count: Nm 1.2 Delivery speed: 200 m/min Production/spinning head: 10 kg/hour Production/1335 spinning heads: 13,350 kg/hour Production hours/year: 6000 Production/year: 80,100 t

DREF III

The DREF-3 machine was the next version of DREF 2 for improving the yarn quality. It came to the market in the year 1981. Yarns up to 18s Ne. can be spun through this system. This is a core-sheath type spinning arrangement. The sheath fibres are attached to the core fibres by the false twist generated by the rotating action of drums. Two drafting units are used in this system, one for the core fibres and other for the sheath fibres. This system produces a variety of core-sheath type structures and multi-component yarns, through selective combination and placement of different materials in core and sheath. Delivery rate is about 300 m/min.

DREF V

It was developed by Schalafhorst, Suessen and Fehrer Inc. The range of count to be spun from this system is from 16s to 40s Ne. Production speed was up to 200m/min. The individualized fibres from a single sliver are fed through a fibre duct into the spinning nip at an angle to the yarn axis, so that they are stretched as far as possible, when fed into the nip. This spinning system was not commercialized due to various technical difficulties.

DREF 2000

Was first announced and demonstrated to the open market at ITMA in 1999. The DREF-2000 employs a rotating carding drum for opening the slivers into single fibres and a specially designed system being used for sliver retention. The fibres stripped off from front the carding drum by centrifugal force and carried into the nip of the two perforated spinning drums. The fibres are subsequently twisted by mechanical friction on the surface of the drums, which rotates in the same direction. The process assisted by air suction through the drum perforations. Insertion of twist in X or Y direction is possible without mechanical alterations to the machine. Yarns upto 14.5s Ne can be produced at speeds of 250 m/min.

DREF 3000

At the ITMA 2003, the first public appearance of the DREF 3000 was made. The yarn can be spun form 0.3Ne to 14.5Ne.The features of DREF 3000 included a drafting unit and opening head with infinitely variable drive control, spinning units with two infinitely variable suction spinning drums, take-off and winding units with infinitely variable speeds and filament guide with monitoring device. The drafting unit could handle all types of synthetic fibres, special fibres such as aramid, FR and pre-oxidized fibres, polyimides, phenol resin fibres (e.g. Kynol), melamine fibres (e.g. Basofil), melt fibres (e.g. PA, PES, PP), natural fibres (wool, cotton, jute, linen, flax, etc.), as well as glass fibres in blends with other materials. The DREF 3000 processes these fibres in the form of slivers composed of one type of fibre, or using slivers with differing fibre qualities at one and the same time. Slivers with a homogenous fibre mixture ccould also be

employed. DREF 3000 core yarns offer high output, breakage-free spinning and weaving mill operation and thus up to 95% efficiency could be achieved with uniform yarn strength and elasticity, not to mention soft yarns with sufficient strength.

DREF 3000 multi-component yarns can be employed for a wide variety of products, which are utilised in the following areas:

High-strength and FR protective clothing for the civil and military sectors. Fire blockers for the aerospace and object sectors. Cut-resistant textiles. Tent fabrics (military and civil), transport tarpaulins, sacks, covers and sun blinds. Fibre composites for the aerospace, automotive, mechanical engineering and construction industries. Woven filters for dry and wet filtration. Transport belts. Sealing belts. Interlinings for outerwear. Elastic yarns. Knits All types of technical textiles.

The multi-component yarns manufactured using DREF 3000 technology are mainly employed for technical textiles. They provide heat and wear protection, dimensional stability, suitability for dyeing and coating, wearer comfort, long service life and strength. Apart from their strength, DREF 3000 yarns are also notable for their abrasion-resistance, uniformity and excellentUster values.

How Dref spinning works

Yarn formation in Friction spinning system

The mechanism of yarn formation is quite complex. It consists of three distinct operations, namely: Feeding of fibres, Fibres integration and Twist insertion.

Feeding:

The individualized fibres are transported by air currents and deposited in the spinning zone. The mode of fibre feed has a definite effect on fibre extent and fibre configuration in yarn and on its properties. There are two methods of fibre feed 1) Direct feed and 2)Indirect feed. In case of direct feed, fibres are fed directly onto the rotating fibre mass that outer part of the yarn tail. In indirect feed, fibres are first accumulated on the in-going roll and then transferred to the yarn tail.

Fibres Integration:

The fibres through feed tube assembles onto a yarn core/tail within the shear field, is provided by two rotating spinning drums and the yarn core is in between them. The shear causes sheath fibres to wrap around the yarn core. The fibre orientation is highly dependent on the decelerating fibres arriving at the assembly point through the turbulent flow. The fibres in the friction drum have two probable methods for integration of incoming fibres to the sheath. One method, the fibre

assembles completely on to perforated drum before their transfer to the rotating sheath. In the other method, fibres are laid directly on to rotating sheath.

Twist insertion:

There has been lot of deal with research on the twisting process in friction spinning. In friction spinning, the fibres are applied twist with more or less one at a time without cyclic differentials in tension in the twisting zone. Therefore, fibre migration may not take place in friction spun yarns. The mechanism of twist insertion for core type friction spinning and open end friction spinning are different,which are described below.

Twist insertion in core-type friction spinning:

In core type friction spinning, core is made of a filament or a bundle of staple fibres is false twisted by the spinning drum. The sheath fibres are deposited on the false twisted core surface and are wrapped helically over the core with varying helix angles. It is believed that the false twist in the core gets removed once the yarn is emerged from the spinning drums, so that this yarn has virtually twist less core. However, it is quite possible for some amount of false twist to remain in the fact that the sheath entraps it during yarn formation in the spinning zone.

Twist insertion in Open end type friction spinning

In open end type friction spinning the fibres in the yarn are integrated as stacked cone. The fibres in the surface of the yarn found more compact and good packing density than the axial fibres in the yarn.

Structure of the yarn tail:

The yarn tail can be considered as a loosely constructed conical mass of fibres, formed at the nip of the spinning drums. It is of very porous and lofty structure.The fibres rotating at very high speed.

Friction Spun Yarns Properties:

Friction spun yarns DREF yarns have bulky appearance (100-140% bulkier than the ring spun yarns).The twist is not uniform and found with loopy yarn surface. Friction spun yarns with high %age of core have high stiffness. Friction spun yarns are usually weak as compared to other yarns. The yarns possess only 60% of the tenacity of ring-spun yarns and about 90% of rotor spun-yarns. The increased twist and wrapping of the sheath over the core improve the cohesion between the core and sheath and within the sheath.

The breaking elongation ring, rotor and friction spun yarns have been found to be equal. Better relative tenacity efficiency is achieved during processing of cotton on rotor and friction spinning as compared to ring spinning system.

Depending on the type of fibre, the differences in strength of these yarns differ in magnitude. It has been reported that 100% polyester yarns, this strength deficiency is 32% whereas for 100% viscose yarns, it ranges from 0-25%. On the other hand, in polyester-cotton blend, DREF yarns perform better than their ring-spun counterparts. A 70/30% blend yarn has been demonstrated to be superior in strength by 25%. The breaking strength of ring yarns to be maximum followed by the rotor yarn and then 50/50 core-sheath DREF-3 yarn.

DREF yarns have been seen to be inferior in terms of unevenness, imperfections, strength variability and hairiness. DREF yarns occupy an intermediate position between ring-spun and

rotor spun yarns as far as short hairs and total hairiness s concerned. For hairs longer than 3mm, the friction spun yarns are more hairy than the ring spun yarns. Rotor spun yarns show the least value in both the values. DREF yarns are most irregular in terms of twist and linear density while ring spun yarns are most even.

Textile technologists have studied the frictional behavior of ring, rotor, friction spun yarns of 59 and 98.4 Tex spun from cotton, polyester, viscose fibres, with varying levels of twist. The yarn to yarn and yarn to guide roller friction was measured at different sliding speeds and tension ratios. However for polyester fibres, the rotor spun yarn showed highest friction, followed by friction and ring spun yarns.

Advantages of Friction spinning system

The forming yarn rotates at high speed compare to other rotating elements. It can spin yarn at very high twist insertion rates (ie.3,00,000 twist/min). The yarn tension is practically independent of speed and hence very high production rates (up to 300 m/min) can be attainable. The yarns are bulkier than rotor yarns.

The DREF II yarns are used in many applications. Blankets for the home application range, hotels and military uses etc. DREF fancy yarns used for the interior decoration, wall coverings, draperies and filler yarn

Murata Vortex Spinning

Murata Vortex Spinning (MVS) is best judged as a development of jet spinning specifically created to overcome the limitations of fiber type. The major marketing feature of MVS was that it was capable of spinning uncombed cotton slivers into acceptable yarns at speeds that were significantly higher than with any other system. The yarn structure is different from jet-spun yarn with many more wrapper fibers, and in parts the vortex yarn resembles a two-fold yarn. There were concerns that there is excessive fiber loss using this spinning machine. But, even though the fiber loss may be about 8 percent, most of this is short fiber, which would not contribute to yarn quality.MVS was introduced with a remarkable potential processing speed of 350 to 400 m/min. Successful spinning systems historically have had a significant increase in production speed within a few years of introduction. If this trend were to be true of MVS, it is possible that the industry could have a staple spinning frame capable of speeds in excess of 500 m/min.

Even though it is claimed that MVS is capable of processing 100-percent cotton, it is believed that the major use of this system is in the processing of cotton-rich blends with polyester. The machine utilizes a roller drafting system working at high drafts and high speeds. There is proof that indicates these systems may give rise to unacceptable yarn variations, which become apparent in terms of fabric defects or weak spots in the yarn. This is a problem that could be addressed by using the rotor spinning beater opener.

New developments likely for MVS include modifications to enable the production of coarser counts and a possible re-examination of the concept of spin assembly winding, where yarns from two spinning positions are combined onto one package that is subsequently two-for-one twisted. It is also evident, from a cursory review of patents, that other machinery makers have invested in significant research into technology similar to vortex spinning and perhaps there soon may be alternative machines available.

It is clear that at the present time, there is a lull in investment in new spinning machinery in the United States. This could be explained partly by a downturn in the industry, which seems to be supported by the reduction in positions shown in Table 1, and partly by the fact that the current technologies are mature.

An additional factor in this consideration is that as spinning machines become more productive, the number of machines needed to satisfy a particular market will decline. It is quite evident from the data shown in Table 2, that among all the major spinning technologies used in the United States, there has been a very substantial increase in productivity over the past 10 years. The table does not include the impact of changing from jet spinning to vortex spinning, which would show an even greater increase in productivity for this type of yarn

Rotor Spinning

Rotor or open-end spinning is now a mature technology, and since the 1960s, it has seen a five-fold increase in twisting speeds. During the early stages of development, debates concerned such questions as Were self-pumping or evacuated systems better? Was roller drafting feed superior to a beater opener? Was spin through better than feed and withdrawal from the same face of the rotor? Were twin disc bearings the best solution for higher speeds? These issues were seemingly resolved, and most modern rotor machines are very similar in layout with relatively subtle differences between machines from the major manufacturers.

These differences are typically associated with the aerodynamics of the transfer tube, rotor design and navel design. While it is still possible to obtain low-tech rotor spinning frames, present state-of-the-art machines have significant integrated automation such as doffing, piecing, cleaning and process/product monitoring. Additionally, the machine can be part of a material handling system from sliver through to packaged yarn.

It is generally accepted that, while rotor yarns are different from ring-spun yarns, they tend to offer advantages in processing through weaving and knitting. This difference is a result of structural differences introduced during yarn formation. This structure which is responsible for the lower strength of rotor yarns, but improved hairiness and yarn abrasion is an inherent feature of the system. While it is possible to control the formation of wrapper fibers by optimizing rotor and navel designs,

Open-end or Carded or Break or Rotor Spinning

Rotor Spinning is a more recent method of yarn formation compared to Ring Spinning. This is a form of open-end spinning where twist is introduced into the yarn without the need for package rotation. Allowing for higher twisting speeds with a relatively low power cost. In rotor spinning a continuous supply of fibres is delivered from delivery rollers off a drafting system or from an opening unit.

The fibres are sucked down a delivery tube and deposited in the groove of the rotor as a continuous ring of fibre. The fibre layer is stripped off the rotor groove and the resultant yarn wound onto a package. The twist in the yarn being determined by the ratio of the rotational speed of the rotor and the linear speed of the yarn.

The use of this system has two basic advantages. It is fed by sliver, not as with the ringframe by roving, and so eliminates the speedframe from the process line. It can also be modified to remove any remaining trash, thereby improving the yarn quality.

Open-end spinning produces a different type of yarn to ringframe spinning. Open-end yarns tend to be more uniform, lower in strength, more extensible, bulkier, more abrasion resistant and more absorbent. It is likely then with all of these differences, only some of which are beneficial, that open-end spinning will not replace ringspun yarn as originally thought, but will be a complimentary product.

Open-end spinning operates at a rate up to five times that of ring spinning and can be effectively used for cotton, polyester-cotton blends, as well as other short and medium staple systems. Synthetic staple fibers such as polyester alone can not be effectively open end spun due to dusting of oligomer from the fibers that interferes with the spinning action of the rotor.

Ring vs. Open-end Spinning

Ring Spinning Open-end Spinning

Bobbin rotates constantly for insertion of twist

Spool does not need to be rotated to insert twist

Cannot handle spools of bigger size

Much larger spools can be wound

Can spin finer yarns 3-5 times faster than ring spinning

Uniform and strong yarn Uniform but flexible yarn with better dye ability

Combed yarns (finer) Carded yarns (coarser)

Yarns for varied applications Yarns for heavier fabrics such as denims, towels and poplins

Stronger 20% more twisted but 15-20% weaker as the yarn is coarser

Suitable for all staple fibres Not suitable for man-made staple fibre spinning except rayon as the fibre finish clogs the rotor

Air jet Spinning;

INTRODUCTION

Since its introduction in 1980, air jet spinning has offered yarn manufacturers the opportunity to

produce yarn at relatively high production rates. Some of the obstacles for the earlier generations

of air jet machinery included difficulty to make 100% cotton yarns and the generally harsh hand

of the fabrics produced from them. Starting with the first air jet spinning machine, Cotton

Incorporated, in close cooperation with Murata, worked extensively to develop a working

knowledge of the fiber selection parameters and preparation procedures necessary to produce

100% cotton and cotton-rich air jet yarns. Machine design changes, based on Cotton

Incorporated’s research, affected the evolution of air jet spinning from the early Murata Jet

Spinners (MJS) to the recently developed Murata Vortex Spinner (MVS). Because the MJS

machine remains largely a cotton blend and 100% synthetic spinning technology, the focus of

this technical bulletin is exclusive to the MVS technology.

Unlike other spinning methods in which productivity is limited by the amount of twist in the

yarn, air jet yarns, in general, can be produced at the same production rate regardless of yarn

counts. MVS machines excel at producing finer yarns (Ne 40/1-60/1), because of the improved

strength imparted to the smaller fiber bundle. MVS technology is not suitable for spinning yarn

counts coarser than Ne 12/1. Compared to ring yarns made from the same fiber properties, the

primary drawback of yarns produced by the MVS system relates primarily to their lower

tenacity. It is also important to note that the MVS system removes significant amounts of short

fiber during the spinning process. Waste percentages typically range from 3-8%, depending on

whether combed or carded cotton is being used. The removal of short fiber improves the yarn’s

total imperfections and resultant fabric appearance/sheen. In addition, with new components

available from Murata, MVS yarns can be made with varying levels of hairiness that can directly

influence the fabric’s hand/softness while maintaining excellent resistance to pilling and

abrasion.

MVS SPINNING CONCEPT

The vortex design represents a radical departure from the basic MJS design. This new and

innovative design differs from its predecessor almost entirely in the air jet (or vortex) area itself.

These changes facilitate an improved preservation of fiber alignment/orientation and a more

efficient transfer of the air vortex’s energy into an actual twisting action on the fiber bundle (see

Figure 1). As a result of these innovations, the system makes more efficient use of fiber length

and provides an improved yarn structure. These improvements are largely responsible for this

machine’s ability to spin 100% cotton.

Figure 1. Murata Vortex Spinning Components

For the same reasons that these design changes have impacted spinning, they have also

influenced the resulting yarn qualities and important fabric characteristics. Yarns are smoother to

the touch because of the absence of “wrapper” fibers and improved fiber alignment. These same

aspects are also responsible for improved fabric appearance and fabric “hand” when compared to

previous MJS results.

FIBER SELECTION FOR MVS YARNS

The fiber selection for the MVS system should be approached in the same manner as ring

spinning. The laydown properties must be selected in accordance with the desired quality of the

end product.

Fiber Length

The MVS drafting mechanism incorporates roller drafting as a means of reducing/controlling the

number of fibers in the cross section of the resultant yarn. Previous studies show that overall

fiber length and short fiber content (SFC%) in the laydown play significant roles in obtaining

desired yarn properties. In general, the MVS system requires medium to long fibers in the

laydown. The MVS cotton laydown should be more similar to a ring-spun laydown than an openend (OE) laydown.

Short Fiber Content

An inherent trait of MVS is the removal of short fibers during spinning. A higher SFC% in the

virgin cotton lint or the introduction of waste into the laydown negatively affects yarn quality

and the amount of waste removed during spinning. Yarn count range and yarn strength are also

influenced by the amount of SFC% in the sliver.

Micronaire

Spinning trials indicate that decreases in fiber fineness or increases in micronaire can limit count

range and spinning performance in the same way as it might on ring spinning.

Trash Content

Cotton should be clean and absent of seed coat fragments. The presence of trash has a negative

effect on spinning performance. Seed coat fragments can collect on top and bottom drafting rolls,

which can cause lapping and ends down. Furthermore, trash and seed coat neps can cause choke

in the spindle also leading to ends down. At the high surface velocities normal for this spinning

system, any lapping or fiber chokes can quickly damage spinning components.

Fiber Tenacity

Fiber tenacity is another important parameter, because it is directly related to the resultant yarn

and fabric strength.

FIBER PROCESSING PARAMETERS

Fiber processing parameters should be chosen to protect the fiber from breakage and overworking. This ensures that the finisher sliver is uniform and consists of highly parallel fibers and

a low short fiber content.

Opening and Cleaning

The opening action must be as gentle as possible to avoid excessive breakage of fibers. The raw

cotton stock should be opened into the smallest possible tufts to ensure thorough blending action

and good cleaning efficiency. Do not exceed manufacturer’s recommendations for throughput

and maintain an 85-90% material run time on all machines in the blow room.

Carding

Carding is the most important phase in the entire production process. Settings, wire condition,

waste removal, and nep extraction dictate the resultant spinning performance and yarn quality.

Visible foreign matter and nep content should be monitored for each card in the mill not just as a

room average.

Drawing

Previous drawing trials indicate that three processes of drawing tend to attain maximum fiber

alignment and provide for the best yarn quality for carded cotton. Only one process of drawing

after combing is recommended for combed yarns. The sliver weight is determined by the yarn

count being spun.

Combing

Combing the carded cotton allows for finer yarn counts to be spun. Reduction of SFC% reduces

waste at spinning, improves yarn tensile and evenness characteristics, and enhances fabric

appearance and drape. Spinning performance may also improve with combed fiber.

MURATA VORTEX SPINNING

Like any other spinning system, the MVS performs best with properly prepared fiber. The

cotton fibers should be parallel and free of extraneous matter. The MVS Model 851 machine can

reach speeds of up to 400 meters/minute. New piecing and clearer technology and tension

control may allow future models to exceed production rates of 450-500 meters/minute.

Cotton Incorporated conducted extensive research on the MVS Model 851 spinning frame

installed in the Fiber Processing Laboratory in Cary, NC. Controlled comparison studies (Murata

Vortex Spinning Comparison – Report Number 1999-1) were conducted in the late 1990s, which

clearly show the quality relationships among MVS, ring, and rotor-spun yarns and the resultant

knit and woven fabrics. MVS yarn strength improved as yarn count became finer (see general

strength trend in Chart I).

The overall yarn evenness is equal to ring and rotor yarns. Total imperfections (thin places, thick

places, and neps) are generally lower than ring and rotor yarns, especially for finer yarn counts.

The knit fabrics made from MVS yarns had better overall surface definition, especially compared

to ring yarns. The MVS knit fabrics exhibited better surface appearance after repeated

launderings. There was slightly less torque or skew with the MVS fabrics compared to ring-spun

fabrics.

Soft Hand MVS Technology

Historically, fabrics made from air jet yarns have a harsher hand when compared to ring and

rotor spinning systems. Recent developments at Cotton Incorporated led to breakthrough results

with respect to this important aspect. Through proper raw material selection, component

selection, and machinery settings, “soft” MVS yarns are attainable and well suited for knit end

uses. Soft hand developments performed at Cotton Incorporated, comparing ring and MVS spun

fabrics made from the same cotton laydown, showed indistinguishable differences with respect

to resultant fabric softness. In addition, the appearance and pilling/abrasion resistance is as good

as if not better than the MVS fabrics, especially after multiple home launderings and tumble

dryings.

Core Spinning Technology

The MVS spinning frame has core-spinning capability. This is a process in which a filament or

staple yarn is fed behind the front roll of the drafting system and covered (or wrapped) with

another fiber during the spinning process. Figure 3 shows the composition of a core spun yarn.

Figure 3.

MVS technology is ideal for this type of end use, mainly because of the wrapping effect

imparted at the spindle. The fibers are literally wrapped around the self-centering core

component. A key advantage of MVS core spun technology compared to ring core-spun

technology is that the core is not twisted during spinning. As a result, fabric torque is reduced in

MVS core spun fabrics.

Novelty Yarns

Splash yarn is a novelty yarn, which can be easily made by supplying colored yarns to each part

of a draft. Thanks to the unique formation method, colored yarn is scattered through the yarn,

giving the spinner the possibility of creating value-added yarns. The combinations and types

have infinite potential.Future developments could include mechanical slub attachments, twin spinning (two parallel yarns on same package), and specialized spinning components.