Dref Friction Spinning
Encyclopedia
Friction Spinning or Dref Spinning is a textile technology that allows very heavy count yarn
s and technical core-wrapped yarns to be manufactured. These are most commonly used in mop
yarns, flame retardant
s and high tech fancy yarns such as Raydon
and Kevlar
. The technology was developed by Dr. Ernst Fehrer.
There are three current technologies used today for spinning fibres, Roving spinning
which uses the legacy ring -spinning technology of the twentieth century, Open end
, Rotor or Break Spinning used for high quality threads and Dref friction spinning for other yarns. Friction spinning is the fastest of all these techniques though the yarn is irregular and bulkier, making it only suitable for some applications.
The mechanism of yarn formation is quite complex. It consists of three distinct operations, namely: feeding of fibres, fibre 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 much 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, the core, 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 a 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 a 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.
Dr. Ernst Fehrer, chairman of Dr. Ernst Fehrer AG, Textilmaschinenfabrik, Linz-Leonding, Austria
, died in December 2000 at age 81. Dr. Fehrer's 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. He 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.
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 professional textile companies to develop the technology; Rieter AG in Switzerland and Oerlikon Schlafhorst in Germany. With this co-operation the last machine developed by DREF was the DREF 3000, which was available for testing in the new facility in Linz, Austria in 2001. Saurer AG purchased Fehrer AG in 2005. The friction spinning technology is now being developed further by Stewarts of America, who manufacture parts for the original Fehrer Dref II, Dref III, Dref 2000 and Dref 3000 friction spinning machines.
The first Dref machine was 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 had negative pressure for fibre collection. The rotation of the drum imparted a twist to the fibre assembly. The ratio of perforated drum to yarn surface was very large, hence the drum speed could be kept relatively low, even with the unavoidable slippage. 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 1975 at ITMA exhibition. The feasibility of using two perforated rotating cylinders (as fibre collectors) while at the same time the spinning-in of fibres into yarn occurred. It operated on the basis of a mechanical/aerodynamic spinning system with an internal suction and same direction of drums rotation. Drafted slivers were opened into individual fibres by a rotating carding
drum covered with saw tooth type wire clothing. The individualized fibres were 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 were held by suction. The fibres were sub-sequentially twisted by mechanical friction on the surface of the drums. Suction through the perforations of the drums assisted 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 fibres in the yarn cross-section (minimum 80-100 fibres) restricted the DREF-2 to 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 including chemicals, 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 micrometres.
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. http://www.fehrerag.com/Fehrer/Artic08.htm
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:
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; intended to improve 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
The DREF V 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 200 m/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
The DREF 2000 was first 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 up to 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 from 0.3Ne to 14.5Ne. The features of DREF 3000 include 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:
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 excellent Uster values.
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.
Yarn
Yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, embroidery and ropemaking. Thread is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or...
s and technical core-wrapped yarns to be manufactured. These are most commonly used in mop
Mop
A mop is a mass or bundle of coarse strings or yarn, etc., or a piece of cloth, sponge, or other absorbent material, attached to a pole or stick. It is used to soak up liquid, for cleaning floors and other surfaces, or to mop up dust, or for other cleaning purposes...
yarns, flame retardant
Flame retardant
Flame retardants are chemicals used in thermoplastics, thermosets, textiles and coatings that inhibit or resist the spread of fire. These can be separated into several different classes of chemicals:...
s and high tech fancy yarns such as Raydon
Raydon
Raydon is a village and civil parish in Suffolk, England. Located around two miles south-east of Hadleigh, it is part of Babergh district. The parish also includes the hamlets of Lower Raydon and The Woodlands...
and Kevlar
Kevlar
Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...
. The technology was developed by Dr. Ernst Fehrer.
There are three current technologies used today for spinning fibres, Roving spinning
Ring spinning
Ring spinning is a method of spinning fibres, such as cotton, flax or wool, to make a yarn. The ring frame developed from the throstle frame, which in its turn was a descendant of Arkwright's water frame. Ring spinning is a continuous process, unlike mule spinning which uses an intermittent action...
which uses the legacy ring -spinning technology of the twentieth century, Open end
Open end spinning
Open end spinning or open-end spinning is a technology for creating yarn without using a spindle. It was invented and developed in Czechoslovakia in Výzkumný ústav bavlnářský / Cotton Researching Institute in Ústí nad Orlicí in the year 1963....
, Rotor or Break Spinning used for high quality threads and Dref friction spinning for other yarns. Friction spinning is the fastest of all these techniques though the yarn is irregular and bulkier, making it only suitable for some applications.
The Processs
Yarn formation in friction spinning systemThe mechanism of yarn formation is quite complex. It consists of three distinct operations, namely: feeding of fibres, fibre 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 much 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, the core, 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 a 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 a 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.
History
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 with the objective of surmounting the physico-mechanical limits on capacity and yarn engineering and production speeds to which these traditional systems are subject.Dr. Ernst Fehrer, chairman of Dr. Ernst Fehrer AG, Textilmaschinenfabrik, Linz-Leonding, Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
, died in December 2000 at age 81. Dr. Fehrer's 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. He developed the first high-speed needle loom
Loom
A loom is a device used to weave cloth. The basic purpose of any loom is to hold the warp threads under tension to facilitate the interweaving of the weft threads...
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.
Development
The Dref I was in development in 1975; a three-head machine, 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
Milan
Milan is the second-largest city in Italy and the capital city of the region of Lombardy and of the province of Milan. The city proper has a population of about 1.3 million, while its urban area, roughly coinciding with its administrative province and the bordering Province of Monza and Brianza ,...
. 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 professional textile companies to develop the technology; Rieter AG in Switzerland and Oerlikon Schlafhorst in Germany. With this co-operation the last machine developed by DREF was the DREF 3000, which was available for testing in the new facility in Linz, Austria in 2001. Saurer AG purchased Fehrer AG in 2005. The friction spinning technology is now being developed further by Stewarts of America, who manufacture parts for the original Fehrer Dref II, Dref III, Dref 2000 and Dref 3000 friction spinning machines.
Models
DREF IThe first Dref machine was a three-headed research and development
Research and development
The phrase research and development , according to the Organization for Economic Co-operation and Development, refers to "creative work undertaken on a systematic basis in order to increase the stock of knowledge, including knowledge of man, culture and society, and the use of this stock of...
spinning machine. The fibres were opened with an opening roller and allowed to fall on a single perforated cylindrical drum slot,which had negative pressure for fibre collection. The rotation of the drum imparted a twist to the fibre assembly. The ratio of perforated drum to yarn surface was very large, hence the drum speed could be kept relatively low, even with the unavoidable slippage. 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 1975 at ITMA exhibition. The feasibility of using two perforated rotating cylinders (as fibre collectors) while at the same time the spinning-in of fibres into yarn occurred. It operated on the basis of a mechanical/aerodynamic spinning system with an internal suction and same direction of drums rotation. Drafted slivers were opened into individual fibres by a rotating carding
Carding
Carding is a mechanical process that breaks up locks and unorganised clumps of fibre and then aligns the individual fibres so that they are more or less parallel with each other. The word is derived from the Latin carduus meaning teasel, as dried vegetable teasels were first used to comb the raw wool...
drum covered with saw tooth type wire clothing. The individualized fibres were stripped off from the carding drum by centrifugal force
Centrifugal force
Centrifugal force can generally be any force directed outward relative to some origin. More particularly, in classical mechanics, the centrifugal force is an outward force which arises when describing the motion of objects in a rotating reference frame...
supported by an air stream from the blower and transported into the nip of two perforated friction drums where they were held by suction. The fibres were sub-sequentially twisted by mechanical friction on the surface of the drums. Suction through the perforations of the drums assisted 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 fibres in the yarn cross-section (minimum 80-100 fibres) restricted the DREF-2 to spinning with coarser counts (0.3–6s Ne).
DREF 2 friction spinning can be used for everything from asbestos
Asbestos
Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...
substitutes and secondary carpet
Carpet
A carpet is a textile floor covering consisting of an upper layer of "pile" attached to a backing. The pile is generally either made from wool or a manmade fibre such as polypropylene,nylon or polyester and usually consists of twisted tufts which are often heat-treated to maintain their...
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
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
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 including chemicals, pulp
Pulp (paper)
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
, paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
, cosmetics
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
, pharmaceuticals, nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...
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 micrometres.
DREF 2 is also used in friction spun yarns for drinking and industrial water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
, 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. http://www.fehrerag.com/Fehrer/Artic08.htm
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 cottonCottonCotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
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, texturised, PES sub-standard filament), or of a core-sliver from PES regenerated fibres (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 bobbinBobbinA bobbin is a spindle or cylinder, with or without flanges, on which wire, yarn, thread or film is wound. Bobbins are typically found in sewing machines, cameras, and within electronic equipment....
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; intended to improve 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
The DREF V 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 200 m/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
The DREF 2000 was first 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 up to 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 from 0.3Ne to 14.5Ne. The features of DREF 3000 include 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 aerospaceAerospaceAerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...
and object sectors. - Cut-resistant textiles.
- TentTentA tent is a shelter consisting of sheets of fabric or other material draped over or attached to a frame of poles or attached to a supporting rope. While smaller tents may be free-standing or attached to the ground, large tents are usually anchored using guy ropes tied to stakes or tent pegs...
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 excellent Uster values.
Yarn 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 a high %age of core have a 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.
See also
- Ring spinningRing spinningRing spinning is a method of spinning fibres, such as cotton, flax or wool, to make a yarn. The ring frame developed from the throstle frame, which in its turn was a descendant of Arkwright's water frame. Ring spinning is a continuous process, unlike mule spinning which uses an intermittent action...
- SpinningSpinning (textiles)Spinning is a major industry. It is part of the textile manufacturing process where three types of fibre are converted into yarn, then fabric, then textiles. The textiles are then fabricated into clothes or other artifacts. There are three industrial processes available to spin yarn, and a...
- Open End SpinningOpen end spinningOpen end spinning or open-end spinning is a technology for creating yarn without using a spindle. It was invented and developed in Czechoslovakia in Výzkumný ústav bavlnářský / Cotton Researching Institute in Ústí nad Orlicí in the year 1963....
- CardingCardingCarding is a mechanical process that breaks up locks and unorganised clumps of fibre and then aligns the individual fibres so that they are more or less parallel with each other. The word is derived from the Latin carduus meaning teasel, as dried vegetable teasels were first used to comb the raw wool...
- Cotton-Spinning MachineryCotton-spinning machineryCotton-spinning machinery refers to machines which process prepared cotton roving into workable yarn or thread. Such machinery can be dated back centuries. During the 18th and 19th centuries, as part of the Industrial Revolution cotton-spinning machinery was developed to bring mass production to...