HTHP Package Dyeing Machines

High Temperature Dyeing Machines (Guidance Note)
Package dyeing machines are the most widely used now a days for dyeing of almost all type of yarns ,due to economical ,automatic and accurate dyeing results. The term package dyeing usually denotes for dyeing of any type yarn wound on the compressible dye springs/perforated solid dyeing tubes or cones. Yarn dyeing in package form is done at high temperature and under high pressure ,with the packages mounted on hollow spindles .These spindles are fixed on the dyeing carriers ,which is inserted into the dyeing vessel after closing the lid of the machine ,the dyeing liquor is forced through the packages in two way pattern (inside to out and outside to in) and goes on circulating throughout the vessel and yarn. Heat is applied to the dye liquor to achieve the dyeing temperature, time –temperature and flow reversal are controlled through a programmer.

All operations from pre treatment to finishing can be performed in the same machine ,without taking out the material out of the machine.

A series of technical developments in the recent past has resulted into package dyeing machine being developed into a highly sophisticated dyeing equipment.

The main advantages of package dyeing over other yarn dyeing methods are

1.The material is dyed on cross wound packages ,therefore bigger unit weight( 1.2 kg -1.5 kg for cotton) in dyeing is possible. The bigger weight makes the process sequence from winding to end use economical due to less handling and less changeovers.

2.Economical dyeing due to lower liquor ratio, compact and enclosed dyeing vessels .different liquor ratio is possible in different process steps such as partial filling in washing and soaping and fully flooded in rinsing make the process economical.

3.More uniform dyeing is possible due to higher number of contacts at high and optimized flow rates .The automatic flow control through programmer in critical steps and depending upon the material permeability make the processing trouble free.

4.High temperature ,high pressure and high flow rates results into shorter dyeing cycles.

5.Due to complete automation ,the machines are less labor intensive.

6.Modern machines with partial loading spindles are more flexible for different size lots ,the air pad system allows to maintain the material to liquor ratio and automatic flow control system maintains the flow through the packages ,thus whether the machine is fully loaded ,partially loaded or half loaded ,the dyeing parameters remain the same and results into better reproducibility as well economical dyeing.

7.Bigger dye lots are possible by coupling or linking one ,two, three or even four similar machines. The machines after linking works as a single unit and same shade is produced as a single lot. The coupling allows to serve the bigger lots without going for such bigger machines .The use of coupled machines makes the market service more efficient.

8.Very less handling and damage to dyed substrate ,due to shorter dyeing cycles.

9.All operations from pretreatment to hydro extraction in single machine are possible.

10.The package dyeing machines are more versatile because almost all type of substrates can be dyed and almost all types of dyestuffs applications is possible.

11.The same machines can be used for multiple make ups such as yarn, fiber, tow ,tops, bumps and beams on suitable dyeing carriers.

12.Certain new developments and instrumentation allows to go to very high flow rates

( more than 50 ltrs/kg/minute) without channeling or damaging the yarns and shortening the dyeing cycles considerably. Most advanced machines are equipped with pH regulators and controllers and salt sensors to for achieving very reliable and reproducible results.

Main parts of the machines
1.Main kier or the main vat in which the actual dyeing is being carried out.
2.Expansion or addition tank
3.Stock or preparation tank
4.Main pump
5.Injector or dosing pump
6.Dyeing carrier
7.Sampling device
8.Back cooler in fully flooded models
9.Control panel
Working of Package Dyeing machines

The material to be dyed is wound on the dye springs, perforated plastic cheeses or steel cones and loaded in the carrier spindles ,which are compressed and bolted at the top to make a uniform and homogeneous dyeing coloumn. The liquor containing dyes chemical and auxilliaries is forced through with the help of pump, and circulated through the material from inside –out and is reversed periodically so that each and every part of the material get the same and uniform treatment. The dyeing cycle is controlled through a micro computer and different chemicals may be added through the injector pump or color kitchen at any stage of dyeing.

In case of fully flooded machines ,the liquor expands with the rise in temperature (approximately 5% volume increases from 30-130 degree centigrade temperature) is taken back in the expansion tank through a back cooler. This extra water is then again injected to the dyeing vessel through an injector pump. Expanded volume of the dye liquor is thus remains in continuous circulation in the system.

Any type of addition can be done to the machine through the injector pump, the quantity and time of injection can be controlled through the programmer.

In case of air pad machines ,the air above the liquor acts as a cushion ,which is compressed with the increase in liquor volume, the pressure is controlled by pre set pressure control valve .In air pad machines have an advantage ,that entire dye liquor participate in dyeing and dye exhaustion is perfect. In case some addition has to be done in air pad machines , if the machine temperature is less than 80 degrees ,the liquor is taken back by back transfer valve to addition tank ,and injected back to machine vessel. If the machine temperature is above 80 Degree then cooling has to be done to bring down the machine temperature.

Air pad technology is possible in all types of machines such as vertical kier, horizontal kier and tubular dyeing machines.

The material after dyeing is washed and finished properly in the same machine and taken out hydro extracted or pressure extracted in the same machine and dried subsequently.

Yarn Package Dyeing Machine Instruction :- Animated Video

The dyeing of cotton in high-temperature dyeing machines (Technical circulars)
Different type of Package Dyeing Machines are
1.Vertical Kier Dyeing Machines
2.Horizontal Kier Dyeing Machines
3.Tubular Dyeing Machines
The dyeing of viscose rayon with direct and vat dyestuffs in high-temperature dyeing machines (Technical circulars)

Vertical Kier Dyeing Machines

These machines have a vertical cylindrical dyeing kier, in which material loaded into carriers with vertical perforated spindles, is dyed .The machine could be fully flooded or air pad type .These are high pressure machines and suitable up to 1350C temperature dyeing.

Horizontal HTHP Dyeing Machines

These machines are similar to vertical type machines in which the cylindrical dyeing kier is in horizontal position. The dyeing carriers with vertical spindles are used in these machines, which are inserted into the machine via trolleys. These machines are erected at the ground level and hence do not need an overhead hoist as well as platform, thus making the dyehouse design and layout is simple .
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Tubular HTHP Dyeing Machines

These machines may be of vertical or horizontal type ,and have one or many tubes acting as small dyeing vessels, each with a single individual spindle. The spindle is taken out of the tube ,loaded and then inserted back into it. These machines can be operated either fully loaded tubes or to partial loads by using dummies. Since all individual tubes in a machine are connected and serviced by a main pump, therefore it is also possible to operate as many tube as required and disconnecting others.

These machines can be erected at ground level and hence do not need a platform or hoist.

These machines are most flexible as for as the capacity variation is concerned ,without altering the material to liquor ratio.
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Hank Dyeing In HTHP Machines

Dyeing of hanks in multipurpose HTHP dyeing machines The HTHP dyeing machines can also be used for dyeing and bleaching of yarn in hank form ,by using suitable carriers on which the hanks can be loaded. The fiber dyeing carriers can also be used in which the hanks are piled ,just like in kiers, and dyeing or bleaching can be done. The last method is useful for hard twisted and coarser yarns, which are difficult to penetrate under normal atmospheric conditions of cabinet dyeing machines. The hanks are loaded into suitable dyeing carriers , which are having either straight sticks or circular sticks for loading of hanks. The hanks of different sizes can be accommodated as in the case of cabinet dyeing machines. The carriers are then put into the dyeing machine kier and rest of the process is carried out as in case of cheese dyeing . The flow rate and reversal of dye liquor direction are optimized as per the quality of the yarn.

Spray Dyeing Machines

1.Lid
2 .Regulation valve
3 .Addition/expansion tank
4 .circulating pump
5.window
6. injection tube( spray arm)
7.Collection tank Intake
8.Machine body

These machines can be defined as an improved version of roller dyeing machines or hybrid type of machines with combination of features of roller dyeing and cabinet dyeing.

The features incorporated in these machines are especially important to overcome the problems related to delicate yarns such as silk , viscose and wool yarns.

These machines are made of rectangular shaped box type enclosed main body, in which the spray arms are located ,there is collection tank with heating coils at the bottom.

These machines have removable loading arms ,same as in roller dyeing machines ,but having perforations for spraying the dye liquor from inside the rollers. These arms have an arrangement also fitted with suitable spray pipes for spraying the dye liquor from outside as well inside of the hanks . The arms rotate on their axis with the hanks thus spraying the dye liquor from both inside and outside of the

hanks ,covering uniformly the entire hank.. The excess liquor is collected at the bottom tank ,from which it is again fed to the spray system with the help of a centrifugal pump. The spray pressure and flow rate can be adjusted as per the material quality and type of hanks. The RPM and direction of rotation of the arms can be varied according to the yarn quality and process parameters, to get uniform dyeing results and to avoid the yarn entanglements.

Main features of spray dyeing machines are
1. The machines are specially built for processing of delicate yarns such as wool , wool blends, silk and viscose yarns.
2. the yarn is treated very gently , and have minimum mechanical abrasion , the impact of dye liquor turbulence on the yarn is also minimum ,thus minimum entanglement and mechanical damage during processing.
3. The liquor is fed through an inverted controlled centrifugal pump ,so the liquor circulation in liters / min/ kg can be adjusted as per requirement as well as when the machines are used at a reduced capacity.
4. Total liquor volume of the machines can be adjusted as per loading or number of arms in the use.
5. The entire dyeing cycle can be carried out in fully automatic mode with the help of with the help of microprocessor based programmer.
6. The arms can be removed and replaced easily, therefore it is also possible to keep a lot ready on a spare set of arms ,which can be easily replaced after the completion of a dyeing cycle. The machines can be used at reduced capacity by reducing the number of arms in operation and more flexible.
7. The machines are available with air pad facility to run the machine at higher temperature and pressure and also keeping the constant liquor ratio when used at reduced loading.
8. Similar machines can be coupled together for dyeing of bigger lots in the same shade.
9. The machines are equipped with a single addition tank ,which is used for injection of dyes and chemicals through a separate pump. Fully automatic machines can be connected with automatic color kitchen also.
10. The machines are equipped with a sampling device to draw a sample for shade inspection without interrupting the dyeing operation .

Cabinet Hank Dyeing Machines

These are the most popular hank dyeing machines, these machines are designed to have liquor flow parallel to the yarn and they work with low liquor ratios to save substantially in consumption of thermal energy ,water and chemicals.The material to be dyed in hanks is loaded on the sticks ,generally two sticks are used one at the top and other at the bottom. The bottom stick is used to avoid the yarn entanglement during the liquor flow. The carriers are loaded with the sticks having hanks ,the sticks are supported into slots made in the body of the carrier.

The loaded carriers are then put into the dyeing machine and door is closed. In a second variant of the machine , the machine is open at the top and career is loaded from the top , which ,a rubber gasket is provided around the periphery on which the machine career rest, and vessel is sealed by the weight of the career and material, thus making closed circuit. The liquor circulation and flow remains the same as in ordinary cabinet machine.

The dye liquor in these machines moves while the material remains stationary. The flow direction is reversed frequently to ensure level dyeing.

A cabinet dyeing machine consists of following main components,

1.Main dyeing vessel made of SS
2.Carriers for loading of hanks with SS sticks for loading of hanks.

3.An internal axial pump or an external pump for liquor circulation.

4.An indirect heating system(with internal or external heat exchanger)

5.An addition tank with injector pump

6.Prepartion tank

7.An internal or external sampling device
8.Color kitchen

Main features of the cabinet dyeing machines are,

1.These machines are most researched ,developed and technically advanced ,and these are most preferred choice for the dyeing of all types yarn in hank form.

2.Modern machines are more flexible and capable of partial or half loading ,without changing the M:L, by using either dummies or by using special loaders , which can be easily adjusted in the machines. The new machines are equipped with continuous variable volume control and monitoring system ,which maintains the M:L even at reduced load .

3.Machine capacities available with same material to liquor ratios ,from lab scale to 1000 kgs for bigger lot size. Coupling of similar capacity machines is also possible to get even bigger lots.

4.All features such as inverter controlled pumps ,dosing and automatic color kitchen and fully automatic dyeing controllers ,same as package dyeing machines are available in these machines.

5.These machines are suitable for dyeing of various sizes of hanks ( from 48” to 90 “) in different qualities such as cotton, viscose, cotton blends, acrylic, wool and its blends and nylon etc. without any problem.

6.The liquor ratio of machines varies between 1:10 to 1:15, depending upon the machine and quality of material to be processed.

7.In the machines with air pad technology , the air pad acts as a air cushion to take care of expanded dye liquor and it is possible to work with higher pressure and temperture The machines with air pad are capable of working up to a maximum temperature of 135 0 C and there is no need of an extra heat exchanger to cool down the expanded dye liquor. Since the machine works in a closed circuit mode ,therefore the entire dye liquor participate in the dyeing.

8. The machines may be having a preparation tank with a quick transfer pump for faster liquor transfer from and to the machine without losing time and reducing the overall dyeing cycle. New machines are equipped with automatic color kitchen , multiple feeding and drainage points for more efficient and cleaner working.

9.The machines are equipped with an internal or external sampling device ,which allows the inspection of samples at any point of dyeing cycle ,without disrupting the actual dyeing process.

10. The machines with interchangeable extra careers offer mach more flexibility in terms of saving in loading /unloading time as well as automation of loading and unloading.

Roller Hank Dyeing Machines

Roller hank dyeing machines
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These machines are based on Hussong type of hank dyeing machines in design .These machines are very simple in design and operation. In the basic design of machine there is rectangular SS tank with proper heating mechanism (either a heating coil or direct steam injection through a perforated steam pipe) and have a false bottom above the heating coil.
The tank is fitted with a temperature indicator and control sensor. There is an array of SS rollers/poles which are fitted on a suitable frame .The rollers can rotate in clockwise or anticlockwise directions with the gears arrangement. The machine is fitted with a stop /start system to control the roller movement.
The hanks loaded on rollers can be lowered in the tank or lifted out by lifting or lowering the frame with the help of hydraulic system. The speed (RPM) of rollers can be varied by changing the gears and rotation cycles are controlled by timers which change the direction of movement of motors.
The dyeing vat have the filling and draining facility of dye liquor. The dyes and chemicals are added directly into the dye vat.
Operation of the machine
The hanks to be dyed are loaded onto the rollers bars by avoiding overlapping of hanks, in lifted position. The dye bath is kept ready with proper liquor level ,and mixed homogenously ,preferably with an external circulation pump .The hanks are lowered into the dye bath and movement is started , approximately 40-50% part of the hanks remain the liquor and rest is exposed to atmosphere . The material is lifted up for addition of colors ,chemicals ,salt, alkali etc or for raising the temperature of dye bath(in case of direct steam injection). In case of indirect heating the dye bath temperature may be increased at set rate of heating ,but in case of direct heating the temperature rise is step by step. The sample may be drawn at the completion of dye cycle and checked for shade, without stopping the machine. All operations can be done in the same machine

Advantages and disadvantages of Roller Hank Dyeing machines
1.Roller dyeing machines are simple in design and operation
2.Cost of the machine is not very high
3.Almost all type of dye classes such as direct, reactive, vat, naphthols, pigments, soluble vats can be applied to cotton ,mercerized cotton or rayon filaments.
4.All types of yarns can be processed such as cotton, mercerized cotton, viscose filament or even silk can be processed . The machines with simple modifications can be used to produce tie and dye effects in bigger lots particularly in cellulosic substrates.
5.The machine capacity depends upon the number of rollers ,which could be from 1 to even 10 rollers, and each roller can handle from 2 to 4 kg of yarn.
6.Only 40-50% of yarn takes part in dyeing and rest is exposed to atmosphere, therefore hydrosulphite consumption is high in these machines.
7.The machines are open type ,therefore maximum dyeing temperature is 95-98 0C .
8.The liquor ratio increases with heating in case of direct injection of steam.
9.Liqour ratio is high ,generally 1:15 to 1:20, therefore chemicals, steam and water consumption is comparatively high.
10.The yarn entanglements takes place during running which reduce the hank to cone winding efficiency.
11. Only limited automation is possible.
12. The dyeing is carried out under atmospheric pressure and there is no liquor pressure ,therefore the color penetration in hard twisted material is poor.

Hank Dyeing Machines

Processing of yarn in hank form
why hank dyeing?
Although package dyeing route is much simple and easy to follow for dyeing of different kinds of yarn ,but still the hank route is popular for certain qualities, there are two reasons for this,
1.The quality and nature of the product does not allow to follow package route
2.The package route is non practical and non economical.
Product quality
Certain kinds of yarns which are so delicate that their physical properties such as strength appearance ,texture and construction can not be retained while following the package route in which yarn is processed under stretched conditions at elevated temperatures. The examples of such products are natural silk, viscose rayon., voluminous yarns, High bulk acrylic , shrink resist treated wool and its blends. Cashmere ,its blends with wool and nylon ,nylon and hand knitting yarns of different fancy constructions.
Economy of process
In case of mercerized cotton yarns , the yarn mercerizing is done in the hank form and material has to be neutralized before dyeing ,therefore it is not economical to convert these hanks to packages for dyeing.
Process sequence for yarn dyeing in hank form
1.Singeing(for mercerized cotton yarns)
2.Reeling
3.Mercerization (for mercerized cotton yarns)
4. Dyeing
5.Hydro extraction or squeezing
6.Drying
7.Hank to cone wiinding
Process Flow Chart of Hank processing

Dyeing in Hank Form

Type of different Hank dyeing machines

1.Roller hank Dyeing machines

2.Cabinet Dyeing Machines

3.Spray Dyeing Machines

4.Vertical Kier Machines
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Machinery For Optimum results in hank dyeing Click here

Naphthols and Bases

Azoic Dyes (Naphthol Dyes)
Naphthol dyes are insoluble azo dyestuffs that are produced on the fiber by applying a Naphthol to the fiber and then combining it with a diazotized base or salt at a low temperature to produce an insoluble dye molecule within the fiber. Naphthol dyes are classified as fast dyes, usually slightly cheaper than Vat dyeings; the methods of application are complex and the range of colors limited.
Azoic combinations are still the only class of dye that can produce very deep orange, red, scarlet and Bordeaux shades of excellent light and washing fastness.The pigments produced have bright colors, and include navies and blacks, but there are no greens or bright blues. Crocking fastness varies with shades but washing fastness is equal to Vat dyeings, generally with less light fastness than the Vats.
Naphthols :-The Naphthols are phenols, soluble in alkaline solution and substantive to cotton, particularly in the presence of salt. The anilides of BON acid(beta-oxynaphthoic acid or BON acid) are soluble in dilute NaOH solution and form the corresponding naphtholate ion. These relatively small molecules are of only low to moderate substantivity for cotton, but they diffuse rapidly into the fibres. In general, the higher the substantivity the better the rubbing fastness as less azo pigment forms on the fibre surfaces. The naphtholate ions are always coplanar and preferably have elongated molecular structures. They behave essentially as colorless, low molecular weight direct dyes. The substantivity increases with increase in the molecular size of the naphtholate ion, but the diffusion rate in the fibres and solubility in dilute aqueous alkali decrease. Addition of salt promotes better exhaustion of the bath, more being needed for Naphtols of lower substantivity.
Bases:-These are available as the free amine base or as amine salts such as the hydrochloride.Many of the amines used are simple substituted aniline derivatives with no ionic substituents. The so-called Fast Colour Bases require diazotisation. This usually involves reaction of the primary aromatic amine in acidic solution or dispersion with sodium nitrite, at or below room temperature. Successful diazotisation requires careful weighing of all the chemicals and regard for the supplier’s recommendations. Diazotisation of a primary aromatic amine is often difficult and solutions of diazonium ions are inherently unstable. They undergo decomposition even at low temperature and particularly on exposure to light. Storing prepared diazonium ion solutions is not usually possible.
General Dyeing Procedure

The application of the naphthols is consists of following steps,
1.Dissolution of the naphthol component.
2.Exhaustion of the naphthol dolution onto the substrate or absorption of the naphtholate ion by the cotton;
3.Removal of excess naphthol from the material by squeezing, partial hydroextraction or brine washing.
4.Diazotization of the base component.
5.Development or treatment with the diazonium ion solution to bring about coupling.
6. Neutralisation ,Soaping at the boil to remove superficial pigment, followed by rinsing and drying.
The process can be carried out in almost any type of dyeing machine determined by the form of the goods.
Dyeing Methods

Precautions in Naphthol Dyeing

1.The alkalinity of the naphthol bath shall not drop below the prescribed limit , otherwise the naphthol may presipitate.

2.Formaldehyde shall not be used when working at more than 50 Deg C or when the material is to be dried after naphthol application.

3.Material shall be protected from water spotting,steam,acid and chlorine fumes , and exposure to sunlight after naphthol application.

4.Use of excess salt in naphthol bath may result into precipitation of the bath.

5.The temperature is very important in base preparation stem , otherwise diazotization may not take place.

6.Sodium acetate must be added to the developing bath just before the use , otherwise base will become unstable due to fall in concentration of HCl.

7.Hydroextraction time must not be too long , which may result into light spots after development.

8.Material shall be rinsed without delay after developing , otherwise the mechanically held excess developing liquor will undergo some decomposition and cause deposition of dark colored spots , which will be difficult to remove.

9.It is important to use sufficient amount of alkali binding agents , otherwise it will result into presipitation of developing bath.

Stripping of Faulty Dyeing

-Treat the dyed material with Non ionic detergent and 3-5 gpl caustic soda at boil for 15 min. cool to 85 degC

-Add 3-5% sod. hydrosulphite for 30-45 min at 85 deg.

-Rinse hot and cold

-Bleach with 1-2 Gpl Available chlorine for 20 min.

-Antichlore and neutralise.

-Soap at Boil for 15-20 min.

-Cold rinse.
Role of Different chemicals

T.R. oil :-Wetting agents for naphthol pasting and dissolution and penetrating agent in fiber in naphthol application.

Caustic Soda:-For solubilising of naphthols and keeping proper alkalinity of naphthol bath.

Formaldehyde:-Protective agent of naphthol impreganated material from effect of air.

Salt:-Electrolyte for exhaustion of naphthol during naphtholation and to prevent the desorption of naphthol in the bath during brine rinsing and development phase.

HCl acid:- Dissolution of base and to produce nitrous acid in diazotization phase.

Sodium Nitrite:- Producing nitrous acid in diazotization process.

Sodium Acetate:-For neutralization of excess HCl in developing bath.

Acetic Acid:-As an alkali binding agent in developing bath.

Non Ionic Dispersing agent:-To keep the azoic pigments in fine dispersion phase , which are formed by the coupling of free naphthol in developing bath. Also helps in better color fastness during soaping operation.

Fastness properties on cotton

Correctly prepared dyeings with azoic combinations on cotton have fastness properties often comparable, or only slightly inferior, to those produced using quinone vat dyes. They complement the vat dyes because of the wide range of orange, red and Bordeaux shades that they provide.
The fastness to washing of azoic combination dyeings on cotton is usually very good to excellent but only after careful elimination of particles of azo pigment loosely adhering to exposed fiber surfaces. Intermediate drying or rinsing of fabric containing the Naphtol, and the soaping of the final dyeing, are key processes ensuring optimum fastness. The same argument applies to rubbing fastness. Deep dyeing that have not been well soaped easily transfer color onto adjacent white fabric, even under conditions of gentle rubbing.
There are two other problems associated with the fastness properties of azoic combinations on cotton. In pale shades, the dyeings often have much reduced light fastness, particularly under humid conditions. Some sensitive azoic combinations also give dyeings of only fair resistance to chlorine and peroxide bleaching.

Vat vs Azoics

A.Azoics are economical than Vat dyes.

B.Bright reds , oranges and deep maroon shades are possible in Azoics.

C.Limited Shade range in Azoics.

D.Bright pinks , bright Blue . olive green , green and blacks are not possible in Naphthols.

E.No fear of photodegradation in Naphthols.

F.Rubbing na dlight fastness is inferior in Naphthol dyeing.

G.More Suitable for Tie-dye and space dyeing.

Reactive Vs Azoics

A.Limited shade range in Azoics.

B.Dyeing method is very complex with too many variables in naphtholation , diazotisation and developing baths.

C.Color fastness to Chlorine is better in naphthols.

D.rubbing and Light fastness are inferior in azoics.

E.Dark and bright reds , maroons and ornages can be produced in azoics which are difficult in reactives.

F.Azoics are suitable for Tie-dye and space dyeing.
Space dyeing and Tie dye with naphthol dyes

Soft Package Winding

The winding technology
The soft package winding is the most important pre dyeing operation ,which directly affects not only the dyeing quality but also post dyeing operations such as rejects,wastages and poor unwinding ,thread breakages etc.Well wound is half dyed, is the popular saying which is very correct in the context of package dyeing ,because we cant expect miracles from the most advanced dyeing machinery ,if our packages are of poor quality. Although different technologies of winding when operated carefully provides satisfactory results ,but in order to insure uniformity and consistently good winding ,precise adjustment and careful maintenance of the equipment is necessary and the operators must be trained and closely supervised.
Factors like count of the yarn, angle of winding, yarn tension during winding, diameter and traverse of the package, the stability of the package, the winding ration,the compactness and size of the feed package all affect the package make up and must be considered while selecting a machine for soft package winding.Hard and soft places can occur within a single package if a poor winding is chosen ,causing some parts to dye lighter or heavier.The most compact part of any package is edges or shoulders ,where the yarn turns the corner and this is the most difficult place to wet out and to penetrate.incomplete penetration will cause will cause it to dye lighter or not at all,Cupping or crimping is the only workable solution to this problem.

What is crossing or Winding angle 
It is the angle at which the yarn cross each other on a wound package, smaller the crossing angle denser will be the package.
What is a winding ratio ?
It is number of turns of yarn per revolution of the package, or distance between the threads of layer. More the number of turns per revolution more is the density. Increasing the distance between the threads of a layer decreases the density.
What is package stability ?
It is the tendency of wound yarn on the package holder to remain stable. It the yarn layers does not hold good on the package holder ,the package may deform easily in subsequent processing. For example on precision winding machines the winding angle reduce with increase in package diameter thus making the packages a little bit harder from outside layer, which may fall off during handling.

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There are two different types of winding machines are available now a days,
1.Random soft package winding machines

2.Precision winding machines

The Package
The yarn to be dyed is first to be wound into a package .The weight and diameter of the package is limited by the space available between the spindles (pitch) and by the levelness obtainable when a dyeing is carried out using a particular dyestuff. The package dimensions and weight are influenced by the type and construction of yarn to be processed, class of the dyestuffs , machine flow rate ,end use of the dyed substrate and package holder eg spring ,cheese or cone. 

                                         Image:A package wound on compressible SS Spring

                                                A package wound on Rigid plastic cheese

   Yarn wound on SS cones

The yarn package must be stable enough ,to withstand the handling during loading, processing and unloading from the machine. It should withstand the temperature change and flow volume and flow direction of liquor. It should accommodate a small amount of shrinkage and swelling during processing with temperature increase as well as wetting.

Package Holder
The package holder may be a ss dyespring ,a perforated plastic cheese (reuseable or disposable) or perforated cones made of SS or plastic.
Each and every holder type has advantages and disadvantages which are explained below,
A dyeing package is characterized by its geometry and its density profile , the bigger dia dye center has advantages over the smaller ID packages because it offers lesser resistance to the flow of liquor in case of in to out and at the same time area exposed to dye liquor is gtreater for better uniformity of the dyeing.
As a thumb rule the main objective from the dyers point of view is to get the material uniformly dyed throughout the package, the machine is used to its full capacity ,the hydro extraction and drying is done without affecting the quality of the dyed material and unwinding is trouble free.

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SS Dye Springs
The dye springs are most commonly used package holder ,on which the yarn is wound offers the advantages such as these are reusable ,compressible ,making a perfect coloumn after pressing,spacers etc are not used between the individual packages ,thus reducing the possibility of channeling , dye spring offers much lesser resistance to the liquor flow through the packages. Due to the higher compression possibility the dyeing machines can be loaded to a higher capacity and liquor ratio can be reduced for better economy of the process.

The main disadvantage is the higher initial investment, in some cases due to the shrinkage of the yarn channeling takes place which causes uneveness and poor unwinding behaviour at bottom particularly ,a thread reserve is difficult to restore due to pressing in case of dyesprings and replacement /repair required due to damage of lacing wire and deformation during use.

Cones
Conical dye packages have conventionally being used for their comparatively good run off behaviour .

The material to be wound on the SS or polypropylene cones of adequate weight and dimensions and taken for dyeing . Generally spacers are provided between each individual cones to make the dyeing column .The biggest advantage of cones is considered to be their subsequent use in next operation without rewinding, however these are no more popular due to their numerous disadvantages, such as

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Use of spacers is itself a big problem ,which causes the liquor blow out at the joints.
The liquor flow through the cone is also not uniform due to the different dimensions at the bottom and tip of the cone. The dye center is defined by the cone tip ID ,which also reduces the liquor flow .The solid cones also pose more resistance to the liquor flow resulting in unlevel dyeing results. There is much more space remains unutilized due to the shape of the cone which reduces capacity utilization and also higher material to liquor ratios. The solid cones can not be compressed ,hence the machine remains under loaded.
Perforated Plastic and SS Dyetubes

These tubes are an alternative to the dye springs ,are made of polypropelene material , either for multiple use or single use or Stainless steel. These are available either radially compressible or axially compressible type, which are very cheap and can be disposed off after single use. Winding is uniform and perfect on the perforated dye tubes due to accentrical design of the tube.The flow through the package is Improved, with radiused holes The perforated plastic tubes are available in various colors to identify denier and thread , different qualities can be processed simultaneousily without fear of mix up.Consistent dimensions and remains intact when used properly Built-in M/F adaptor ends eliminate need for separators and perfect fitting minimize the chances of liquor blow out at the joints. The density of the dyeing column is governed by the individual packages and hence it can be controlled at the winding stage itself. The thread reserve remains intact because these are not compressed. The dyeing cheeses are suitable particularly in case of materials which are delicate in nature and having higher wet shrinkage properties.

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The main disadvantage of perforated solid tubes is non compressibility ,which reduces the loading and hence machine capacity. The yarn generally slough off in case of the yarns which got relaxed after heat treatment. These are easily damaged if the hydro extraction facility is not upto the mark. If winding and density are not uniform within a package and package ,the dyeing results would be poor.

Package weight and density
The package weight and density are two important parameters which are to be standardized for uniform and trouble free dyeing .The packages may be soft or hard these should conform to the standards,when too soft liquor flowing through it will find the course of least resistance and cause channelling ,which leaves some parts of the package relatively undyed or lighter. If the packages are wound too hard ,a point can be reached where the flow of liquor is impeded to such an extent that poor dyeing or none may occur.The package weight and dimensions depends upon the type of the machine ,its flow rate ,automation, type and construction of the yarn to be dyed, dye class to be used and type of package holder to be used.The typical density norms for different type of yarns is between 350-450 gm/ltr.The most important requirement of soft package for dyeing are,
1.Density of the package should be uniform throughout of the package diameter, ie the layer to layer density is controlled.
2.The packages should not have the hard edges ,or these must be broken or cupped by a suitable device or manually.
3.The package weight must be controlled and all the packages must fall within the standard norms.
4.The density variation from one package to another must be controlled statistically and CV5% should not exceed 5%
Following factors affect the flow of liquor through the packages
1.Yarn or filament fineness:-The permeability increases with increase in the yarn diameter.
2.Yarn twist:- The permeability decreases with the increase in the twist .Low twisted yarns can adopt a flat rather than circular shape ,which makes the packages more permeable.

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3.Winding ratio :- More the number of revolutions per round of package makes the package less permeable.
4.Winding angle:- The smaller winding angle makes the packages less permeable.
5.Yarn tension in winding:- The higher the yarn tension in winding makes the package harder and denser and hence less permeable.
6. Swelling and Shrinkage:- The higher swelling and shrinkage during dyeing makes the packages less permeable.
How to calculate the package density

The package density is expressed in gm/cc or gm/ltr
Let the gross weight of the package = W1 gms
The weight of the cheese/spring = W2 gms
Net weight of the yarn W = W1-W2 gms
Hight of the package in cm = h cm
Outer radius of the cheese /spring = r₁ cm

Outer radius of the package = r₂ cm

Volume of the package V = p (r₂² – r₁² ) h CC

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Density of the package = W/V gm/cc

The density of the cone is also expressed in gm/cc or gm/ltr 
How to calculate the cone density

Let the Gross weight of the package is =W₁

The weight of the empty cone is =W₂

Net weight of the cone W = W₁-W_{2 gm}

The perpendicular height of the cone = h cm
The radius of the cone at bottom = R₁ cm
The radius of inner cone at bottom =r₁ cm

The radius of the cone at top =R₂ cm

The radius of inner cone at top =r₂ cm

The volume of the cone is V =1/3 p h {(R₁²+R₂²+R₁R₂)-(r₁²+r₂²+r₁r₂)} ccThe density of the cone is D = W/V gm/cc
Random soft package winding machines

Random soft package winding machines are conventional winding machines ,in which a grooved drum acts as both the driving as well as the traversing element. The winding is done through indirect drive to the package ,which we call the friction drive. The yarn lay formed is random ,that’s why is called random winding.

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The main characteristics of random winding are

1.Winding angle(a) :-Since grooved drum is used for winding the winding angle remains the same.
2 Winding ratio :-The number of coils per turn of the package decreases as the diameter of the package increases, so the package is softer at the outer layers.

3.Ribbon formation may occur at certain points within the package when diameter of package reaches to a certain ratio to drum diameter.

4.The package stability is good.
5.Layer to layer density is not very uniform throughout of the package.
6.Hard edges formation may occur at the yarn turning at the ends.

7.The machine speed can not be very high ,because it is very difficult to maintain good density profile at high speeds on random winding machines.
8.Cost of the machine is low.
However when selecting a random winding machine for Soft package winding we should look for following features
1.Ribbon breaking or anti patterning device
The machine must be equipped with a good and effective anti patterning device ,which will minimize the ribbon formation. The ribbons formed during winding not only results into poor dyeing due to liquor flow obstruction but also cause problems in unwinding by creating high tension zones and resulting into thread breakage, high hairiness due to increase friction and wastages. However it is impossible to overcome the ribbon problem completely.
2.Hard edges formation 
Due to the nature of friction winding with the groove drum ,the yarn stays for a relatively longer time at the edges ,and creates edges hard. The machine must be equipped with a proper arrangement in which the cradle or the bobbin holder slides slightly (by few mm) on the drum through a lateral movement device which reduce the chances of hard edges formation by widening the edge area.
3.Traverse of the package

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While winding particularly on the solid perforated cheeses ,we should take care that the perforations on both the sides are covered completely and equally. If these are not covered equally there may be un Dyed parts if yarn is wound on blind areas and channeling may take place ,when there is no winding on a particular end.
4.Weight release mechanism
Since the weight of package increases with the increase in the diameter of the package which increase the cradle pressure on the drum and affects the density of the packages. Therefore the machine must be equipped with a proper weight release mechanism to balance out the increased package weight. (new machines are equipped with a programmed cradle weight regulation system)
5.Length measuring device
The machine must be equipped with a good length measuring meter control system to control the package weight variation .The uniform package weight helps in reducing the losses weight variation in dyeing and also reduce the chances of excess dyeing and short falls.
6.Balloon breakers
The machine must be fitted with an adequate balloon breaking device ,which provide more flexibility to use different size of feed packages and also reduce the breakages rate
7.Yarn tension controlling

It is very important that the machine have a good yarn tension control system ,that will insure the uniform package density within the package and package to package.
8.Winding Speed
The winding speed is also a constraint in random winders ,but now machines are available with individual drum drives which can run at speeds and it is also possible to make soft packages on automatic winders which can run upto 1400 mtr/min. The cost, flexibility of running different counts etc. and quality parameters must be considered in this case.

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Precision winding

                                                       a precision wound package
In precision winding the package or dyeing spool is driven through a spindle with the help of an individual motor and yarn is displaced with the help of a guide or propeller blades( yarn laying system with counter rotating blades),there is is no slippage in the device or uncontrolled displacement of the yarn ,therefore it is called precision winding.
These machines are equipped with electronic or digital yarn tension control devices which vary the tension as the diameter of the package increases ,so that the layer to layer density remains the same. Each drum is driven through an individual motor which in combination with a micro computer controlled meter counter ,results into much more flexibility of operations.The machine productivity is high due to high running speeds and lesser labour is required to run the machine.
The main features of the precision winders are,
1.Since propeller blades or guide is used for yarn displacement the winding angle does not remains the same and decrease with the increase in package diameter.

                                             image :-rotating propellers yarn guide system
2.The number of coils per turn of the package remains same as the diameter of the package increases because the number of displacement remains constant per rotation of the package.
3.There is no ribbon formation.
4.The package stability is moderate.
5.Layer to layer density is very uniform throughout of the package.
6.Hard edges formation do not occur at the ends.

7.The machine speed is high .
8.Cost of the machine is medium to high.
Hybrid winding
The recent advancement in the precision winding technology is step precision winding or DIGICONE winding ,which ensures the perfect winding of packages by eliminating the technological problems of both the random winding and precision winding.

                                       A Digicone wound package
1.The winding angle remains almost constant.
2.The winding ratio is also constant
3.The package stability is good.
4.Density does not change with diameter.

5.No ribbon formation.
6.Very good unwinding performance.
7.The cost of the equipment is high.
What is the best combination
Technologically and from the dyers and post dyeing point of view the precision winding machines with a digital tension control device and solid perforated plastic cheese is the best combination to achieve
1.Uniform package to package weight and density.
2.uniform layer to layer package density and for all the packages.

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3.Unintrupped flow of liquor through the package.
4.No yarn tension variation due to pressing disturbances and smooth and break free unwinding.
5.Thread reserve remains intact for further applications.
6.Optimum utilization of the dyeing machinery.

Further Reading on soft package winding

FAQ on Soft Packages for Dyeing
Quest for Ideal Yarn dye Packages

FAQ on package dyeing

Winding Ribbon Free packages

Soft winding AP Corghi 

Precision Soft Package Winding Reshmi

SSM Precision winding 

Top Soft package Winding Techniques

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