Küsters high performance machines ensure uniform dyeing, perfect steaming and excellent fastness.
Uniform dyeing

For dyeing Küsters provides the S-roll padder with two swimming rolls. Even in case of large fabric widths this padder achieves exactly the same color from one edge of the fabric to the centre and to the other edge. By the 2 S-rolls a completely uniform nip pressure is achieved, even at working widths of 3000 mm and above. This is absolutely necessary for uniform dyeing. The technology of the dyeing padder with two S-rolls is unique worldwide.

This padder can be equipped with different dyeing troughs. Small liquor contents lead to economical dyeing solutions and a high flexibility. Low wastage amounts occur during color changes. Furthermore, a tailing length is substantially shortened. High turbulences in the dyeing trough lead to an intensive exchange. One example for a dyeing trough with small liquor content in combination with a long web path under liquor is the U-Shaft, which is shown in combination with two S-rolls in Figure 1.The level of the trough contents is kept constant by a level control system. This works closely together with the highly recommendable dosing system Contidos, which mixes the color online and feeds it into the dyeing trough. By this way the dyeing liquor has exactly the same formulation from the first drop to the last, the level of the trough content is constant and only the needed amount of dyeing liquor is prepared.

Small liquor contents and the dosing system in combination with a quick cleaning device lead to highest flexibility. All relevant parameters are computer-controlled. The control system also includes a temperature control as well as a tailing correction system.

The Küsters dyeing padder may be introduced in different ranges like a Pad Steam range, a Pad Flex Steam range or a CPB centre. It is also possible to design a range in a way that it is suitable for continuous dyeing as well as for CPB dyeing.

Perfect Steaming
Uniform pretreatment and dyeing results depend on uniform steam conditions in a steamer. Küsters provides steamers for both processes. They are equipped with precision rolls, drives for the rolls are available. To achieve best steam conditions for both purposes a cloud control system is used. This cloud control system measures the steam conditions at the bottom of the steamer. By this way it is possible to introduce only the amount of steam which is really necessary for the process. This steam is introduced at the top of the steamer. Numerous steamers are already equipped with the cloud control system. By this way it was possible to reduce the steam consumption substantially and to improve economics of continuous processes.

Excellent fastness
Especially in case of processing terry towel washing plays an important role. In most cases production speeds are below 60 m/min. The objective is to achieve highest fastness with low water and energy consumption. Another important point is the cloth guiding through the machine without any creases or deviations of the fabric.

Küsters recommends the washing machine TurboFlush (Figure 2) for the washing of terry towel fabric. This machine is equipped with a highly efficient circulation system. The circulation system causes a high turbulence in the washing machine and an intensive contact and exchange between the washing liquor and the fabric. This intensity does not depend on the production speed as the circulation is done by a pumping system. High washing efficiencies are obtained over a wide range of production speeds, starting already at very low speeds. Each TurboFlush has two circulation systems. Each circulation system has a flow rate of up to 35 m³/h. Water, which enters the machine, e.g. as fresh water or by a counter flow, is circulated several times before leaving the ma-chine. If the machine is entered by a flow rate of 7 m³/h the water circulates 10 times between entering and leaving a TurboFlush. Figure 2 shows this different flows in the machine. Furthermore in the TurboFlush there are 6 small troughs and 2 application pipes. By leaving the application pipe and every small trough the liquor is applied on the textile again, so that in total washing liquor is applied to the textile 80 times in this example. Furthermore in every small trough and in the troughs at the bottom of the machine a turbulent washing takes place.

These are the main reasons for the high efficiency of the TurboFlush even at low production speeds, as the turbulences and the contacts between washing liquor and textile are not introduced by the textile but by the circulation systems.

It is possible to equip each circulation system with an automatic drum filter to extract loose fibers. This filter is automatically cleaned. Of course the filters are suitable for the full circulation flows.
The TurboFlush is essentially a completely steam tight machine, which works at boiling temperature.
As also shown in Figure 2 the TurboFlush has small troughs at its bottom with low liquor contents. This leads to shorten set up times as only small amounts of water have to be heated to boiling temperature. This results also in very small water quantities which have to be exchanged during changing lots.

Another important point is the short distance between the rolls in the TurboFlush. This leads to an optimum cloth guiding and avoids creases and deviations of the web.

Many ranges exist which are equipped with the TurboFlush, even for the treatment of terry towel. This machine has proved in many applications that excellent fastness are achieved with minimum water and energy consumption. The washing results are also achieved at low production speeds. For the treatment of terry towel additional equipment is available for the TurboFlush which gives a further enhancement to the fluff and bulk of the terry towel material.

The most interesting result in washing is fastness. In many cases during washing after dyeing same fastness could be achieved with less water, but until now a suitable measurement and control system is not available for this purpose. Küsters actually develops a measurement device, which was already presented during ITMA 2003 in Birmingham. With this measurement device it will be possible to determine the concentration of dyestuff in the washing bath. It will be possible to adjust the water consumption of a washing range exactly to the desired fastness of the product. Trials have been done and show that in several cases water consumption could be reduced substantially. This measurement system will be available soon. It will also be possible to install this measurement system in already existing Küsters washing machines.

Flexnip application for bleaching and dyeing
The Flexnip is a machine for the application of chemicals to the fabric. It is used for wet in wet processes as it allows to add the chemicals to the textile. This machine is suitable for the application of bleaching liquor to the fabric as well as for the application of chemicals in case of VAT dyeing. In case of reactive dyeing this machine is also suitable to achieve dark shades. Numerous ranges in the US are equipped with the FlexNip for the dyeing of terry towel fabrics. Making use of the combination of Küsters S-roll padders and the FlexNip led to high savings in dyestuff consumption for both reactive dyes and vat dyes. In case of reactive dyestuff the consumption could be reduced about some 20%. Range layout for pretreatment and dyeing

Processing of terry towel fabrics has the following characteristics:
· Large production amounts per lot.
· Growing production amounts, especially in Asia
· High economic pressure.
· Increasing quality demands from the customers with constant results all over the year.
To meet these characteristics Küsters designed continuous pretreatment and dyeing ranges adapted to the demands of Asian Terry Towel finisher.
These ranges are suitable for a start with small production amounts and to get extended if production amounts grow. Different ranges are available for production amounts of 6 t/day, 12 t/day, 25 t/day and 50 t/day. Of course further extensions of these ranges are possible for increasing production amounts.

The modular system gives the following solutions:
In case of small daily production amounts a CPB bleaching is recommended. This includes the step of desizing as well. Washing after bleaching is done on a TurboFlush washing range, followed by a can dryer. CPB dyeing will be done on the same padder as used for CPB bleaching. Washing after dyeing will be done on the same range as washing after bleaching.

For growing production amounts dyeing is done on a CPB padder. Desizing and bleaching are done on a continuos range. The washing line of this range is also used for washing after dyeing. As an alternative it is possible to use a separate padder with one S-roll for bleaching. Dyeing is done continuously. Washing after bleaching is done on the washing line of the dyeing range.

For high production amounts a continuous bleaching range and a continuous dyeing range are proposed. Especially for continuous dyeing of dark shades a combination of a Küsters dyeing padder with 2 S-rolls and a FlexNip lead to best results. This is in many cases proved by ranges in the US.
This shows that the proposed ranges can grow with increasing production amounts. All range proposals make use of the above described Küsters machines with their unique advantages.
Economical point of view

From the economical point of view a continuous treatment of terry towel fabrics is highly recommended, especially in comparison with a discontinuous treatment. Continuous treatment leads to a low consumption of water and energy. Furthermore the handling properties and the internal logistics for the batches are very easy in case of a continuous treatment in open width, especially in case of large production lots.

Additionally Küsters provides outstanding machines like the Küsters S-Roll padder, the FlexNip, the TurboFlush and the steamers. All of these machines are to be combined in a modular system, exactly adapted to the needs of the customers. Furthermore they all give their tribute to an economical production by low liquor contents, low wastage and low water and energy consumption in combination with optimized finishing results.

An excellent example for the economy of Küsters machines is the water efficiency of the Turbo-Flush. Figure 3 shows data which were measured during washing trials. In this case two ranges were compared. One range was made from three Compacta up-and-down-washing machines with a cloth content of 30 m each. Between the washing machines intermediate squeezers were situated. The other range was made from three TurboFlush with a cloth content of 20 m each, also with intermediate squeezers between each washing machine.

Tests were done by washing out of caustic soda. The test results show that a TurboFlush achieves at a water amount of 3 l/kg the same washing results as a Compacta at a water amount of 6 l/kg. As a result washing with the TurboFlush is found to be very efficient and economical.

Conclusions
Processing of terry towels has some very special demands, particularly in growing markets as Asia. Küsters collected much experience with processing of terry towels in the US. For bleaching and dyeing Küsters S-roll padders and the FlexNip, an application machine for an add-on application, are well known and established. They are solutions of which terry towel manufacturers know that they are very important for economic processes. Steamers with a cloud control lead to uniform bleaching and dyeing results and minimized steam consumption. Most finishing results depend on efficient washing processes. For this purpose the TurboFlush is used, which is recommended be-cause of its optimized fabric paths and the very low water and steam consumption.