Garment Dyeing | How to Garment Dyeing? | Why Garment Dyeing? | Garment Dyeing Machines
Garment Dyeing
Garment dyeing is the process of dyeing fully fashioned garments (such as pants, pullovers, t-shirts, jeans, sweaters, dresses, bathrobes, casual jackets, shirts, skirts, hosieries) subsequent to manufacturing, as opposed to the conventional method of manufacturing garments from pre-dyed fabrics. Most garments are made of cotton knit goods and/or cotton woven fabrics.
Although several other fabrics can be found in the whole or in part such as wool, nylon, silk, acrylic, polyester, and others. Due to cost savings and fashion trends, garment dyeing has been gaining importance and popularity in the past years and will continue to do so in the future.
Why Garment Dyeing?
Traditionally, garments are constructed from fabrics that are pre-dyed (piece dyed) before the actual cutting and sewing. The advantage of this process is the cost-effectiveness of mass producing identical garments of particular colors. A major drawback with this approach is the risk associated with carrying a large inventory of a particular style or color in today's dynamic market.
Garment Dyeing Machines
Paddle machines and rotary drums are the two types of equipment regularly used for garment dyeing. Rotary drum machines are sometimes preferred for garments, which require gentler handling, such as sweaters. A high liquor ratio is required for paddle machines, which is less economical and may limit shade reproducibility. Many machinery companies have developed sophisticated rotary dyeing machines, which incorporate state-of-the-art technology. Following machines are generally used for garment dyeing.
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| Fig: Garment dyeing machine |
1. Paddle Dyeing Machines
A process of dyeing textiles in a machine that gently moves the goods using paddles similar to a paddle wheel on a boat. This is a slow process, but there is extremely little abrasion on the goods. Horizontal Paddle Machines (overhead paddle machine) consist of a curved beck like lower suction to contain the materials and the dye liquor. The goods are moved by a rotating paddle, which extends across the width of the machine. Half immersed paddles cause the material to move upwards and downwards throughout the liquor. The temperature can be raised to 98o C in such a system.
In lateral / oval paddle machines consist of oval tank to enhance the fluid flow and the processing the goods. In the middle of this tank is a closed oval island. The paddle moves in a lateral direction and is not half submerged in the liquor and the temperature can be increased up to 98o C.
HT Paddle Machines work according to the principle of horizontal paddle machine, however, the temperature can be raised up to 140o C. PES articles are preferably dyed on HT paddles. In paddle machines, the dyeing can be carried out with 30:1 to 40:1, lower ratios reduce optimum movement of the goods, lead to unlevel dyeing, crease formation. For gentleness, the blades of the paddle are either curved or have rounded edges and the rotating speed of the paddle can be regulated from 1.5 to 40 rpm. Circulation of the liquor should be strong enough to prevent goods from sinking to the bottom. Paddle machines are suitable for dyeing articles of all substrates in all forms of make ups. The goods are normally dyed using PP/PET bags.
2. Rotary Drum Dyeing Machines
These machines work on the principle of “movement of textile material and a stationary liquor”.The rotary drum dyeing machine consists of rotating perforated cylindrical drum, which rotates slowly inside a vessel of slightly bigger in size. The internal drum is divided into compartments to ensure rotation of goods with the drum rotation, and the outer vessel holds the required quantity of dye liquor. High-temperature drum machines are capable of processing the garments up to 140o C.
Features of modern rotary-dyeing equipment include the following:
- Lower liquor ratio
- Gentle movement of goods and liquor (minimizes surface abrasion)
- Rapid heating and cooling
- Centrifugal extraction
- Variable drum speed with reversal capability (adaptable to a wide variety of goods)
- Continuous circulation of goods (improves migration control)
- Easy of sampling
- Variable water levels with overflow rinsing capabilities
- Large diameter feed and discharge lines (minimizes filling and draining time)
- Microprocessor controls
- Lint filters
- Pressure dyeing
- Auto-balancing drums
One feature that can be used to reduce abrasion on delicate garments or to minimize tangling is a compartmental chamber, sometimes referred to as a "Y" pocke.The rotary drum machines are very simple to operate and are quite compact in size. The cost of unit is also not high.
Drum dyeing-centrifuging machines are also called “multipurpose drum machines” or “multi-rapid dyeing centrifuging machines” since these machines can perform scouring, dyeing, centrifuging and conditioning successively with automated controls. The goods are treated in a perforated inner drum housed within an outer drum (dyeing tank). Inner drums without dividing walls are provided with ribs that carry the goods along for a certain time, partially lifting them up out of the liquor. These machines can operate at very low liquor ratios and can dye the goods up to 98 -140o C. This is suitable for knits as well as other garments. Liquor circulation can be intensified using additional jets. Drums can be rotated in both directions.
3. Tumbler Dyeing Machines
These machines are being used for small garments either in loose form or in open mesh bags. Design wise the tumbler dyeing machines are similar to the commercial laundering machines.
The principle of operation is to load the material into perforated inner SS tanks, which rotates around a horizontal shaft fixed at the back of the drum. The drum is divided into compartments for moving the goods with rotation of drum. A variety of tumbling machines have higher rotation speeds and can spin dry at the end of the cycle. These are similar to dry-cleaning machines.
Rotating drum machines are more efficient and cleaner to operate than paddle machines. The more vigorous mechanical action often promotes more shrinkage and bulking, which may be desirable for some articles. In order to handle higher quantities and large production of similar pieces, the latest machines are provided with several automatic features and sophistication.
4.Toroid Dyeing Machines
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| Toroid Dyeing Machines |
In these machines, the garments circulate in the liquor in a toroidal path with the aid of an impeller situated below the perforated false bottom of the vessel. Movement of the goods depends completely on the pumped action of the liquor. High-temperature versions of this machine operating at 120 to 130°C were developed in the 1970s for dyeing fully-fashioned polyester or triacetate garments. The liquor ratio of such machines is about 30:1.
5. The Gyrobox
The machine has support in the form of a large wheel, which is divided into 12 independent non-radial compartments. The goods are placed in these compartments. The wheel runs at a moderate speed of 2-6 rpm. The main advantage of this machine is,
- Reduced M:L
- Different types of garments can be dyed simulteneously.
- Flexible loading
- Fully automatic operation.
- The MCS Readymade garment dyeing machine
The rotodye machines are suitable for dyeing pure cotton,wool, polyester,cotton blends in the form of T-shirts, sweaters, bath rugs and accessories, socks and stockings.
6. Modified Pegg Toroid Whiteley Garment Dyeing Machine
This is an improved version of Toroid machines, the additional features are
- The machine is suitable for both atmospheric and pressure dyeing.
- Full automation up to hydro-extraction.
- The design features, speed, and performance are simplified to make the machine more versatile and free from operating problems.
Advantages of Garment Dyeing
- Handling of smaller lots economically
- Enables various special effects to achieve
- Distressed look can be effectively imparted
- Unsold light shades can be converted into medium and deep shades
By the time the garment has been in a boiling dyebath and then tumble-dried, it will have adopted its lowest energy state and will not suffer further shrinkage under consumer washing conditions
Latest fashion trends can be effectively incorporated through garment wet processing by immediate feedback from the customer
Disadvantages of Garment Dyeing
- High cost of processing
- A little complicated dyeing
Garment accessories like zips, buttons, etc impose restrictions. The garments produced from woven fabrics create many problems and it has been found that the existing textile treatment styles as developed for piece dyed fabric cannot be just assembled for garment wet processing operation such as garment dyeing unless they have been engineered from the original design stage for garment dyeing.