Compact Spinning for Improved Quality of Ring-Spun Yarns

In spite of modernisation and rapid tech-

nological development in the field of ring

spinning,the mechanism ring-traveller

spindle has remained almost the same

until now.Furthermore,ring spinning

remains the dominant spinning technol-

ogy even today.The producers of modern

spinning frames have been developing

the machines with improved construction

of different working elements and opti-

mal spinning geometry,with a ring diam-

eter of 36 mm,a tube length of 180 mm

and spindle speed of up to 25,000 min -1 .

All serving and transport functions have

already been automated.A high link-

ing level of spinning and winding,and

even of the winding and twisting tech-

nological processes,has been achieved

using the elements of computer-assisted

automation and control.Besides the

conventional functions (spindle speed,

delivery speed,productivity,twist,draft,

machine efficiency),computer-based

systems control and enable the optimisa-

tion of spinning conditions (formation of

bobbins,position of ring rail,automated

doffing and setting of empty tubes,clean-

ing and oiling of main machine parts).

Construction improvements of different

working elements of the ring-spinning

frame and optimised spinning geometry

of the continuous form of fibres (roving

or sliver)enable increased productivity,

better yarn quality,as well as flexibility

and profitability of the process.

All these optimisations and improve-

ments of the ring spinning frame,howev-

er,have not enabled the reduction of the

spinning triangle,which can be defined

as the most problematic and weakest spot

in the yarn formation process using the

ring-traveller system [1,2 ].The spinning

triangle that occurs while the yarn is

formed is the cause of many fibres leav-

ing the drafted roving,or being partly

spun into the yarn with one end only.

This causes greater waste of fibres,lower

exploitation of fibre tenacity in yarn,

poorer appearance and greater hairiness

of the spun yarn.The newest research in

the field of ring spinning has shown that

modification of a three-cylinder drafting

equipment with tow aprons in a region

after front drafting rollers enables ring

spinning to proceed with a minimised

spinning triangle,or even without it at

all.This modified process is called com-

pact or condensed spinning [1,3,4 ].

The purpose of the study presented with-

in this article was to produce,analyse and

compare the yarns using two different

systems for the production of compact

and conventional ring yarns,offered by

two well-known producers of ring spin-

ning machines.In Predilnica Litija (Lit-

ija Spinning Mill),one of the Slovenian

short-staple spinning mills,a need exists

to modernise the existing ring spinning

frames for medium-fine yarns produced

from cotton fibres and blends consisting

of cotton and chemical fibres,mainly

PES and viscose.Today,the main goal of

the company is to achieve improved yarn

quality that will ensure better competi-

tiveness and higher yarn prices.There-

fore,a decision was made to compare

the quality of conventional and compact

yarns and (also taking into account the

production costs),to explore whether

the quality parameters of compact yarns

had been improved significantly enough

to justify the purchase of new machines,

or the adaptation of drafting equipment

of the existing ring spinning frameS

the same roving with a linear density of

588 tex produced by the Litija Spinning

Mill,and to produce a certain amount of

yarns using the Suessen and Zinser ring

spinning frames equipped with compact

and conventional drafting systems under

comparable technical and kinematical

The tests were directed and supervised

by the leading technical personnel of

the Litija Spinning Mill,together with

the specialists of Suessen and Zinser

workshop spinning mills,where the pro-

duction of yarn samples was carried out

over approximately the same time pe-

riod.20 kilograms of each yarn type (one

compact and one conventional from each

ring spinning machine producer)was

produced in order to ensure sufficient

yarn quantity for testing purposes.Yarn

testing was done by both machine pro-

ducers in the laboratories of Suessen and

Zinser,using valid standard methods and

procedures that guaranteed the statistical

significance of test results.The informa-

tion on yarn quality was then sent to the

Litija Spinning Mill,where the data was compared

Conventional Versus Compact Ring Spinning Technology

The twist that is transmitted to the yarn

in the ring spinning process originates

along the curve between the traveller and

front drafting rollers.Transmission of

twists is opposite to the yarn movement

in this area.The traveller transmits twists

to already drafted fibres as close as pos-

sible to the clamping point after the front

rollers.However,the twists never reach

the clamping point,because after leaving

the front rollers the fibres tend to direct

towards yarn axis.The different length of

part 2

form the yarn cause a so-called spinning

triangle in ring spinning [5 ].The length

of the spinning triangle depends on spin-

ning geometry and twisting intensity

[6,7 ].The form and dimensions of the

spinning triangle significantly influence

the structure,surface characteristics,

physical and mechanical characteristics

of spun yarn.Not all fibres that are placed

at the external edges of the triangle can

be spun into the yarn structure,and can

leave the drafting equipment without

having been spun into the yarn.Such

fibres also increase yarn hairiness.

The gradual transmission of twists with

the traveller along the yarn balloon caus-

es a certain tension in the fibre bundle

that forms the spinning triangle,a tension

which is not distributed symmetrically

in the yarn cross section.It is greatest

in fibres that are positioned at the edges

of the spinning triangle,and smallest in

fibres lying in the middle of the triangle.

This asymmetric distribution is the rea-

son for fibre breakage according to their

position in the spinning triangle during

thermore,the fibres gradually take over

the external axial yarn loading;therefore,

they also break one after another.The

consequence is lower yarn strength and

poorer utilisation of the fibre tenacity

(35 to 50%).

Much has already been done to minimise

the influence of the spinning triangle

in the ring spinning process.Different

mechanical devices such as condensers

have been used in the past to retard the

widening of the roving [10 ].However,

these measures were only partly success-

ful.The length between the mechanical

condenser in the main drafting area and

clamping point between the front rollers

was too long to ensure the condensing

effect.As soon as the condensed fibre

bundle left the mechanical condenser,the

fibres were relaxed and again formed an

undesirably wide fibre bundle.

Minimisation or even elimination of

the spinning triangle,enables almost all

fibres to be incorporated into the yarn

structure with maximum possible length

and pre-tension of the fibres,irrespective

of their position in the spinning triangle.

The uniform pre-tension of the majority

of fibres enables more synchronic break-

age of the majority of the fibres,which

contributes to higher yarn strength and

better utilisation of the fibre tenacity

(from 65%up to even 80%).

All compact yarns,whether produced

of short-staple fibres (cotton,cotton-

type chemical fibres and their mixtures)

or long-staple fibres (wool,wool-type

chemical fibres and their mixtures)rep-

resent a whole new range of yarns as re-

gards their quality and appearance.When

compared with conventional ring-spun

yarns,compact yarns have significantly

higher tenacity and elongation,work to

break,and abrasion resistance.In addi-

tion,their surface smoothness,elasticity

and softness are much better thanks to

the almost ideal structure of compact

yarns.To achieve tenacity comparable

with conventional ring-spun yarns,a

lower number of turns per metre can be

used,which enables higher productivity

of the spinning machine,as well as better

textile products.

The better use of the fibres ’ tenacity in

compact yarns enables the use of cheaper

raw material.Yarn singeing is not re-

quired because of minimal secondary

hairiness,caused by the fibres exceed-

ing the length of 3 mm.One should also

mention savings in the sizing process of

up to 50%compared to the conventional

yarns.In some cases,sizing is even not

required [11 ].Lower primary hairiness

(hairs with a length of 1 to 2 mm)and

significantly lower secondary hairiness

(hairs with a length of 3 mm and more)

result in less prominent pilling in yarns

and in the finished textile products.

Lower yarn hairiness enables the produc-

tion of flat textiles with better appearance

and more explicit,sharp contours,for

example in jacquard-woven and printed

fabrics.When smooth surface,high gloss

and durability of the end product is re-

quired,compact yarns should be used for

production in spite of the slightly higher

price.In spite of the difficult situation of

the whole textile sector,there are still

some spinning mills in Slovenia that

continue production and successfully

compete on the national and international

markets.Most of them use conventional

ring and rotor spinning [12 ].The most

successful yarn manufacturers are al-

ready testing different compact spinning

machines and searching for the most

appropriate way to modify the drafting

equipments of their existing ring spin-

ning machines.

n Comparison of the Two Compacting Principles

The drafting equipment of the Fiomax

E1 compact spinning machine (Figure 1)

consists of a pair of delivery rollers (1-

11),a double aprons area (2-21),a pair

of front rollers (3-31)and a condensing

zone (S1-S4).The condensing unit con-

sists of a profile tube (S),the lattice apron

(G)and the delivery top roller (4).

Regarding the configuration of the drafting

unit (1-11)to (3-31),it is a standard three-

cylinder system with two aprons,and

enables the processing of a wide spectrum

of raw materials.The tube (S)has a built-

in slot in order to create negative pressure

in the area (S1-S4).Drafted roving comes

into the condensing field (S1-S4),where

the fibres are condensed up to the clamp-

ing point (4-S4)consisting of the top roller

(4)and sucking tube (S).

part 3

with the top roller (4)by the gear wheel.

The top rollers (31)and (4)are driven by

the delivery drafting cylinder (3).Using

friction,the top roller (4)drives the end-

less lattice apron,which slides over the

profile tube (S)that is not moving.To

guarantee a slight axial tension of fibres

in the condensing zone (S1-S4),the roller

diameter (4)is slightly larger than that of

the top roller (31).In this way,a small

drafting of fibre bundle is ensured in the

condensing zone,which enables optimal

axial tension and fibre orientation.

The profile tube (S)has a small slot in the

area (S1-S4)and is closely embraced by

a lattice apron.The porosity of the apron

and the negative pressure in the slot area

result in a condensed fibre bundle that

is transported up to the zone (4-S4).

The oriented fibres remain completely

condensed and closed up to the delivery

clamping and twist insertion line (4-S4)

because of the slot length.Therefore,

no spinning triangle is formed,which

enables literally all the fibres to be wound

into the yarn and optimal yarn structure.

The slot in the profile tube (S)can be

positioned in the direction of fibre move-

ment or at an incline to the direction of

fibre flow,for instance when processing

shorter fibres,such as carded cotton.This

ensures the firm incorporation of outer fi-

bres into the yarn because of a transverse

force on the fibre band during the fibre

transport and the rotation of fibres around

their axis.The lattice apron is made of

the cotton fabric in plain weave,and has

more than 3000 holes per square centi-

metre.The drafting unit of the Fiomax

E1 spinning machine enables the fibres

to stay condensed up to the clamping

and twist insertion line,which results in

a minimised spinning triangle.The result

is spun yarn with maximum strength and

minimal hairiness.Besides the condens-

ing effect,a light tensioning of the fibre

bundle during condensing is also crucial

for this process.

700 spinning machine (Figure 2)consists

of the standard three-cylinder drafting

unit with two aprons (1-11-2-21-3-31)

and condensing unit (4-41).

The top roller (41)is covered by the end-

less apron with a set of holes in the mid-

dle.The apron runs over the profile tube

(H),which has a suction slot in the zone

(H1-H2).The drafting unit construction

in zones (1-11),(2-21)and (3-31)is a

modern three-cylinder drafting system

that enables the processing of a wide

range of fibre lengths.The final draft-

ing occurs between the zones (2-21)and

(3-31).The fibre bundle is condensed

under suction on a perforated surface in

the zone (H1-H2).In a short zone be-

tween (H2)and (4-41),the fibre bundle

is not under suction and therefore loses

some of its hitherto gained condensed

form.Therefore,in the zone (4-41)the

spinning triangle is not reduced to the

minimum,which negatively influences

the quality of spun yarn.This undesired

effect is more obvious when processing

shorter fibres.The suction slot is directed

in the fibre bundle axis in the area (H1-

H2).It is not possible to set it under a

certain incline regarding the fibre bundle

axis.The drafting system construction

enables light axial tension acting on fi-

bres in a condensing zone between (3-31)

and (4-41),which has a positive effect on

increased adhesion between fibres that

are incorporated into the yarn.The tech-

nological data of the Suessen and Zinser

compact and conventional ring spinning

machines used for production of yarn

samples is given in Table 1.

Direction of Yarn Samples ’ Production and Raw Material Characteristics

The production of yarn samples was

directed and supervised by the leading

technical personnel of the Litija Spinning

Mill together with the specialists from

Suessen and Zinser.Since we wanted to

compare the compact and conventional

yarns produced on at least two different

spinning machines types,the production

of yarn samples was carried out at the

Suessen and Zinser workshop spinning

mills at approximately the same time

period.20 kilograms (20 bobbins with

roving)of each yarn type (one compact

and one conventional from each ring

spinning machine producer)was pro-

mills at approximately the same time

period.20 kilograms (20 bobbins with

roving)of each yarn type (one compact

and one conventional from each ring

spinning machine producer)was pro-

compare the compact and conventional

yarns produced on at least two different

spinning machines types,the production

of yarn samples was carried out at the

Suessen and Zinser workshop spinning

mills at approximately the same time

period.20 kilograms (20 bobbins with

roving)of each yarn type (one compact

and one conventional from each ring

spinning machine producer)was pro-

duced in order to ensure sufficient yarn

quantity for testing purposes.

The following fibrous material was used

for the production of yarn samples:

100%combed cotton (CO),fibre

length 1 3/32 " – 1 1//8 ",Micro-

naire=4.5,

polyester fibres (PES),fibre length 38

mm,fineness 1.5 dtex,

viscose fibres (CV),fibre length 38

mm,fineness 1.3 dtex.

The following fibre blends were proc-

essed:§

100%combed CO (noil extraction:

15.5%),

50%combed CO /50%PES and

87%combed CO/13%CV.

A standard spinning preparation and

modern machinery were used to produce

the roving with a linear density of 588 tex

from each fibre blend at the Litija Spin-

ning Mill using the same fibre lots for

each blend.After that,conventional and

compact yarns with a linear density of

20 tex were produced under comparable

technological and kinematical conditions

on the Suessen and Zinser ring spinning

frames.

n Quality Properties of Produced Yarns

After production,the quality of yarns

was tested in the laboratories of the Sues-

sen and Zinser machine producers,where

the yarn samples were spun using valid

standard methods and procedures that

guaranteed the statistical significance of

test results.Ten bobbins of each compact

and conventional yarn were tested.The

information on yarn quality was then

sent to the Litija Spinning Mill,where

the data was analysed and compared.The

following physical,mechanical and mor-

phological properties of the compact and

conventional yarns produced were tested

ing force,elongation at break and work

to break,Uster properties,hairiness and

length distribution of hairs on 100 m of a

yarn.An Uster Tester 3 was used for test-

ing the hairiness of the produced yarns.

The results are given in Tables 2-4.

 Discussion

Based on the researched and compared

mechanical,physical,morphological

and Uster values of the conventional and

compact ring yarns spun on the Zinser

and Suessen spinning machines,the fol-

lowing conclusions can be drawn:

Properties of compared yarns made of100%cotton fibres

The breaking force of the compact

yarn with a nominal linear density of

20 tex and spun on a Zinser ring spin-

ning machine is 18.88%higher than the

conventional ring spun yarn,produced

on the same machine but without the

condenser unit.The breaking force of the

compact yarn spun on the Suessen ring

spinning machine is up to 29.48%higher

when compared with the conventional

ring spun yarn,produced on the same

machine but without the condenser unit.

A higher difference in breaking force

between the compact and conventional

yarns produced on the Suessen ring spin-

ning machine can be explained with the

construction of the drafting system that

enables maximum fibre condensation all

the way up to the clamping line,which is

not the case in Zinser ’s drafting system.

A greater breaking force was measured in

the yarn produced on the Zinser spinning

machine.

is 7 to 8%higher compared to conven-

tional yarns.The tenacity of a compact

yarn produced on the Zinser spinning

machine surpasses the conventional yarn

by 17%,while this value is higher by up

to 23.24%in the yarns spun on the Sues-

sen spinning machine.A slightly higher

value is noted in the yarn produced on the

Zinser spinning machine.

The work to break of a compact yarn

spun on a Zinser spinning machine is

21.82%higher than in conventional

yarn.In the compact yarn produced on

the Suessen spinning machine,the work

to break is 32%higher than that of the

conventional yarn.the higher absolute

value of work to break was determined in

the compact yarns produced on the Zin-

ser spinning machine.The physical and

mechanical properties of the compact

and conventional yarns are represented

in Figure 3.

No significant changes regarding Uster

properties (Uster CV%,number of thin,

thick places and neps)in the convention-

al and compact yarns were determined.

This can be explained by the use of the

same three-cylinder drafting equipment,

which is proven to be the major influence

on these yarn properties.

The Uster hairiness (H)of compact yarns

is significantly lower when compared

with the hairiness of conventional yarns

(Figure 4).Conventional ring spun yarn

produced on the Suessen spinning ma-

chine has an Uster hairiness H=5.80,and

the yarn spun on Zinser spinning machine

has an Uster hairiness H=5.54.A lower

value of Uster hairiness,H=3.80,was

determined in compact yarn produced on

the Suessen spinning machine,while that

spun on the Zinser spinning machine has

for this is the construction of the drafting

equipment,as explained above.

The morphology of the yarn,defined as

the number of hairs of different length

per 100 metres,shows the significantly

lower primary hairiness (1 to 3 mm)and

secondary hairiness (4 to 12 mm)of com-

pact yarns.Better results and significant

improvements were achieved with the

Suessen spinning machine,which can

also be explained by the special construc-

tion and elements of the drafting unit.

Properties of compared yarns made of

50%CO/50%PES fibre blend

When comparing the physical and me-

chanical properties of conventional and

compact yarns produced of 50%CO/50%

PES fibre blend,we found no significant

differences.This can be explained by

the greater bending rigidity of polyester

fibre component,which reduces the fibre

condensing effect and its contribution to

better physical and mechanical properties

of compact yarns.

The analysed Uster properties of con-

ventional and compact yarns are very

similar,which confirms the fact that the

condensing effect significantly influ-

ence neither the yarn irregularity nor the

number of yarn faults.

The Uster hairiness (H)of compact yarns

is significantly lower when compared

with the hairiness of conventional yarns.

A slightly better hairiness value was de-

termined in yarn spun on the Zinser spin-

ning machine (H=3.26)when compared

with the yarn produced on the Suessen

spinning machine (H=3.20).

The primary and secondary hairiness of

a compact yarn made from this mixture

chine are better than in yarn produced

on the Suessen ring spinning machine.

Both compact yarns have significantly

improved primary and secondary hairi-

ness when compared with conventional

ring yarns.

Properties of compared yarns made of

87%CO/13%CV fibre blend

The breaking force of the compact yarn

with a nominal linear density of 20

tex and spun on a Zinser ring spinning

machine is 18.32%higher than the con-

ventional ring spun yarn produced on the

same machine but without the condenser

unit.The breaking force of the compact

yarn spun on the Suessen ring spinning

machine is up to 32.30%higher than the

conventional ring spun yarn produced on

the same machine but without the con-

denser unit.

Elongation at break of compact yarns is 4

to 11%higher compared to conventional

yarns.The tenacity of a compact yarn

produced on the Zinser spinning machine

15.90%,while this value is higher at up

to 28.87%in yarns spun on the Suessen

spinning machine.A higher absolute

value of tenacity is determined in yarn

produced on the Suessen spinning

machine.

The work to break of a compact yarn

spun on the Zinser spinning machine is

20.87%higher than in conventional yarn.

In compact yarn produced on the Suessen

spinning machine,the work to break is

up to 41.88%higher compared to the

conventional yarn.A slightly higher

absolute value of Work to break was

determined in compact yarns produced

on the Suessen spinning machine.

The analysed Uster properties of conven-

tional and compact yarns have very simi-

lar values.Conventional ring spun yarn

has an Uster hairiness of H=5.20,and the

yarn spun on the Zinser spinning ma-

chine has an Uster hairiness of H=4.72.A

lower value of Uster hairiness,H=3.40,

was determined in compact yarn pro-

duced on the Suessen spinning machine,

while the yarn spun on the Zinser spin-

ning machine has an Uster hairiness of

H=3.60,which can be explained by the

inability of Zinser ’s drafting system to

keep thoroughly condensed fibres up to

the clamping line.The Uster hairiness

(H)of compact yarns is significantly

lower when compared with the hairiness

of conventional yarns,irrespective of the machine system.

Both the primary and secondary hairi-

ness of a compact yarn made of this fibre

blend and produced on the Zinser ring

spinning machine are lower when com-

pared with the yarn spun on the Suessen

spinning machine.Both primary and

secondary hairiness of compact yarns

tional yarns,irrespective of the machine

system.The improvement is more obvi-

ous when comparing conventional and

compact yarns spun on the Suessen ring

spinning machine,with or without a con-

denser unit.

n Conclusions

The aim of the study presented herein

was to analyse and compare the yarns us-

ing two different systems for the produc-

tion of compact and conventional ring

yarns from the producers Suessen and

Zinser.The same roving produced by the

Litija Spinning Mill with a linear density

of 588 tex was used to produce 20 kg

of yarns from cotton,cotton/PES and

cotton/viscose fibre blends under com-

parable technical and kinematical condi-

tions.The tests were directed and super-

vised by the leading technical personnel

of the Litija Spinning Mill together with

the specialists of the Suessen and Zinser

spinning mills,where the production of

yarn samples was carried out over ap-

proximately the same time period.Yarn

testing was carried out by both machine

producers in laboratories using valid

standard methods and procedures that

the test results.An analysis of results

obtained within the comparative research

into the quality properties of conven-

tional and compact ring yarns produced

at the Suessen and Zinser companies led

to the following conclusions:

§ Compact yarns can be regarded as

completely new ring spun yarn types

as regards their morphological,physi-

cal and mechanical properties.With

regard to fibre straightening,light

axial tension and condensing of the fi-

brous bundle that form compact yarn,

the new yarn structure can be defined

as near-optimal.

§ The compact yarns have the follow-

ing advantages when compared to the

conventional ring yarns:significantly

reduced primary and secondary hairi-

ness,smooth surface,high gloss,im-

proved mechanical and physical prop-

erties (with the exception of compact

yarn produced from 50%CO/50%

PES fibre blend),similar Uster prop-

erties,better resistance to rubbing,

softer touch,and lower pilling effect

in woven and knitted fabrics.

§ It is obvious that in the future compact

yarns will be used as referential samples and benchmarks,based on which

the quality of different types of spun

yarn will be estimated.

of compact spinning,it can be as-

sumed that the new spinning tech-

nique represents a promising impulse

for ring spinning and spun yarn pro-

duction.

§

If the spinning mills ’ customers -pro-

ducers of woven and knitt