New machine goes through its paces for knitters.

A knitting machine that is energy efficient, environmentally acceptable, capable of handling complex fibres - yet user friendly - has been developed by a Hong Kong private-public venture. It's set to bring major advantages to the territory's players when it goes into commercial use.

The prototype machine was unveiled last month to positive feedback from knitters. Its development was shepherded by the Hong Kong Productivity Council (HKPC), drawing on some US$200,000 from the territory's Innovation and Technology Fund (ITF) and involving five industrial enterprises, with research and development carried out by the Council with the help of consultant ML Cheung of Hong Kong firm Winmount Limited.

The aim is to market the multi-functional machine at a price reasonable enough to help the knitting industry maintain its quality standards and global competitiveness.

The HKPC decided to research development of the new so-called "wet processing machine" with the goal of achieving several technical advantages. These include adequate supply and control of water and steam, varying rotating speed settings and controls for maintaining, raising and lowering the temperature. The optimum liquor ratio between the content and the process bath as well as offering a suitable chemical dispensing device for dyeing and special finishing were additional objectives.

The project is part of the Hong Kong government's aim to provide an environment conducive to the development of value-added and high technology industries. Some US$333 million from the government's ITF is earmarked to support the operation and projects of research and development centres over the next five years.

Multi purpose: Cheung (right) explains the operation.		Washing and electric unit side by side.

The centres are hosted by local universities and technology institutions to assist the target industries to move up the value chain through collaborative applied research activities.

The knitting sector in Hong Kong's textile and apparel industry is robust, with most of the production taking place in Guangdong Province. Knitters are suppliers to international brands and the garments are knitted on the best knitting machines such as Shima Seiki of Japan and Stoll of Germany but the wet finishing process of the garments is not up to par with the knitting.

The principle of knitwear wet finishing is to improve dimensional stability, handle and appearance, remove additives and apply added value finishes such as functional properties. Wet finishing is widely adopted by Hong Kong knitters to remove relaxation shrinkage potential and improve the bulk and fluidity of the garment.

In the past, wet finishing treatment mainly depended on the experience of the technicians that operate the machine on a trial and error basis. This is neither dependable nor necessarily repeatable and the result varies from technician to technician. There are also a number of problems with the existing models of wet finishing machines presently used in Hong Kong and Guangdong.

Disadvantages of current machines corrected

The side loading rotary drum machine of currently used equipment is cheap and particularly popular in Asia but the rotary speed, which can't be controlled, is generally too fast. The side paddle machine is good as the action is gentle. It is good for finishing delicate fibres and garment dyeing, but the liquor ratio is very high at a minimum ratio of 1:25, and so consumes a lot of water and energy so doesn't fit into current eco concepts. Besides it takes a lot of energy and time to load and unload; in the process, garments tend to get stretched.

The overhead paddle machine relies on paddle for circulation with steam or compress air to move the contents. Garment tend to sink to the bottom of the vessel as garments get heavy when wet. Also, the fibres used for a garment nowadays are quite mixed. The existing machines, described above, are inadequate to handle the complex fibre composition of today's knitwear.

The front loading, combined finishing and extracting machine made by European companies incorporates a build-in hydro-extractor, which is considered the most advanced in the industry. It is fully automatic, multi-programmable with automatic chemical dispensing features and can be tilted forward for easy unloading of the garments. But it is very expensive, so not cost effective for Asian suppliers.

By contrast, the new machine is a rotary type one designed for knitwear washing, adding functional finishes and even dyeing with independent bath circulation with minimal disturbance of the garment. The machine has an effective circulation of bath that permits an optimum liquor exchange between the content and the bath while keeping the movement and agitation under a controlled mode to minimise disturbance, its developers say.

Washing, finishing and dyeing in one machine.		Wash load.

With electronics built in, all washings can be recorded and repeated with accuracy and consistency. In the course of the research, it was decided not to include the water removal feature (as with the European-made machine) as it adds greatly to the total cost.

In the prototype's test runs, a wide range of variable programmes was tried out seeking the optimum results for each knitwear fibre type. Then a group of industry specialists was engaged to inspect and compare the results of washing in a traditional rotary washer and the prototype in trial runs. They found the hand-feel and shade results are better when the prototype is used.

Technicians can operate and record.

The result was not affected significantly when the liquor ratio was reduced but quite significant when the chemical was reduced. Shorter processing time was achieved when tested on easy care cashmere and bulkier and fluffier hand feel as achieve with lambswool.

Functional finishes added during the wash took very little additional time. The average length dimensional change was almost zero at -0.1%, actually faring much better than the usual standard. The tested garments were sent to test labs in the UK and all of them passed with flying colours.

According to its developers, the beauty of this new machine is that it allows technicians to record their test parameters and the results are retrievable down the line. Though it can't be said that it is an advanced technology machine, it is a great improvement to existing machines and can assist the knitwear industry become more efficient, with stability and repeatable results.

The machine is not just for washing, with functional finishes applied - and it can be used as a garment dye machine. Garment dye in the knitting industry is not new but not used liberally because it is only good for small lot production and it consumes a lot of water. But small lot orders are preferred in the production trend these days, so a wet finishing machine that can operate with less water and also do garment dye of knitwear is attractive. Knitters can leave the dyeing process to the last minute, allowing for a quick response to the ever-changing colour fashion trends.

	Small but green machine.

The machine consists of the washing vessel, side bins for dyes and solvents dilution and dissolving as well as a wash and an electronic unit to control chemical releases and record all activities.

Completed in 2007 after a year of testing, trial runs and improvements, it was officially launched in March this year. The prototype machine was in action at Hong Kong's Crystal Group factory in Dongguan.

The prototype machine is small, handling only 10 to 15 kg. It can save 30% more water, uses less chemicals or solvents and shortens the washing time. A demonstration on site with a cotton wash took just 45 minutes.

With positive results from the trials and from the industry, HKPC hopes to move to the commercialisation stage soon and select one or more manufacturers to produce machines that can handle commercial loads.

from special correspondent Vicky Sung, Hong Kong