In the former case, minimal resetting times are a priority issue, in the latter, the emphasis is on operating simplicity and the prevention of faults.
In recent times, the quality stipulations imposed on a knitting factory by its customers have become ever more precise, placing ever greater emphasis on reproducibility when producing repeat orders. Any operation seeking to knit quality fabric in bulk will be looking primarily to cut yarn costs, while a producer specializing in fashion fabrics – in other words knitting in small batches with frequent changes of pattern – is looking to achieve the simplest and most reliable possibilities for pattern resetting. Just these few examples are indicative of the wide-ranging problem situations faced by the modern knitting factory, and consequently the different requirements imposed on the circular knitting machine manufacturer. All these requirements have to be addressed in the implementation
of comprehensive solutions in order to produce – wherever possible- standardized circular knitting machines.
Simplified automation.
As a consequence of the industrial revolution at the end of the 19th and beginning of the 20th Century and the introduction of labour saving technologies, the next developments in the field of automation moved towards the simplification of handling. Simplification in this context is synonymous with in-creased speed and primarily also reduced susceptibility to error. In the field of circular knitting machines, automation can accordingly address a whole range of requirements.
– "Guaranteed" quality in accordance with customer requirements.
– Optimized yarn consumption.
– Lower personnel costs.
– Less scope for faults.
– Reproducibility of repeat orders.
– Greater machine capacity utilization.
Taken in total, these benefits demonstrate how automation can ensure more reliable processing of production orders and more precisely calculable costs, and so exert a positive effect on economy.
Electronics long since in control!
When we hear the word electronics mentioned in connection with circular knitting machines, we think first and foremost of needle selection. This is something we will be looking at later on. A modern circular knitting machine is controlled nowadays largely via its switchbox with processor control and operator display. Components such as feed wheels, take-down settings, oilers etc are already integrated with facility for central setting with the aid of user-friendly display technology featuring easily understood symbols and a variety of language options. Electronically controlled monitoring components – from yarn supply through the yarn infeed to the finished tube of fabric – ensure the immediate detection of faults and an automatic halt of production.
To this extent, electronics have long since assumed a major role in the so-called mechanical circular knitting machine and, most importantly, have proven highly successful.
A new development from Mayer & Cie. presented for the first time at the ITMA 1999 in Paris is MCTmatic. This concept – long since developed to the series stage and tried and tested in practical application – is used to automate a whole range of settings.
MCTmatic: fast, simple setting automation.
The ability to automate certain settings performed at the circular knitting machine not only saves time but reduces the incidence of faults (particularly operator error) and ensures greater profit coupled with a guaranteed standard of quality. The settings can be stored in the machine database and accessed again as required.
What is MCTmatic capable of?
– Automatic calculation of fabric take-down speed by simple input of the knitting feeders, feeders per course, stitches per cm and elongation at the display.
- Automatically controlled thread infeed by entering the required thread infeed per cm.
- Automatic central height adjustment by means of an entry at the display. The cam plate height is electronically traversed precisely to the hundredth of a millimetre.
- Automatic monitoring of the yarn infeed and yarn tension by entry of a tolerance value at the display.
What is the benefit of MCTmatic?
MCTmatic guarantees a consistently high standard of fabric quality – practically from the first to the last machine revolution. It reduces setting times and consequently increases productive machine running time. But also of major significance are the yarn savings made possible by optimized yarn consumption, exact reproducibility of stitch lengths and avoidance of grade 2 quality goods. Deviation of just one graduation on the quality wheel of a conventional machine, for instance, can result in several kilograms of yarn wasted every day. With MCTmatic, orders can be set up precisely to the standard of quality stipulated by the customer, and also repeated to an identical standard in the case of repeat orders by simple and immediate accessing of the relevant order data from the database.
Electronics used in pattern preparation.
The PC has long since been an established feature of pattern and production preparation. Using a scanner or digital camera, it is possible to load patterns into the system. Using the keyboard and the relevant software, patterns can also be directly constructed. With the aid of the pattern preparation system at the PC and the relevant software, patterns can be generated, entered and archived. Work and machine programs are also generated and stored.
These are transmitted online to the circular knitting machine, not only allowing the fast, simple generation of patterns, but also their transmission to the machine in just a matter of seconds.
With the Mayer & Cie. PIC 3 system, even striped patterns involving more than 4 colours are supported. The three components pattern editor, repeat editor and striping editor are simple and convenient to use, and are also available in a wide choice of languages.
The pattern editor is used to transfer and process pattern originals, for example from a scanner. The repeat editor is used for programming machine parameters with patterns in up to 16 colours, whereby up to 8 different pattern areas can be defined and repeatedly knitted. The pattern height is independent of the number of machine revolutions.
The striping editor automatically calculates all the data for striping control on the basis of the pattern editor. Even when using four-colour striping attachments, the PIC 3 is capable of realizing six and more colours without repeat restrictions.
The PIC 3 does not require any special hardware. All devices supported by Windows 95, Windows 98 or Windows NT can be used.
Fully electronic knitting.
Patterns generated using PIC 3 are transmitted online in just seconds to all electronically controlled Mayer & Cie. circular knitting machines – no matter whether basic structure, jacquard, striping, transfer or plush machines, both in single and double jersey. This allows unproductive resetting time to be converted into profitable production time. Given today's headlong fashion changes and the wide variety of fashion styles, this facility makes even small batches an economically viable proposition.
Electronically controlled individual needle selection in circular knitting machines.
Fast, flexible patterning using electronically controlled individual needle selection is a matter of course for today's fashion-oriented knitwear producers. Wherever pattern changes have to be performed quickly and – most importantly – also reliably, electronics have a decisive role to play.
The introduction of electronically controlled needles dates back to 1963. Mayer & Cie.'s electronically controlled permanent magnets have proven particularly successful in the field of electronic individual needle selection. A current pulse results in the release of a control sinker by the magnet, causing
the assigned cylinder needle to move to the knit position. If no current pulse is applied, the control sinker continues to adhere to the magnet and the assigned needle remains in the miss-knit position.
The cylinder needles are automatically guided to the miss-knit/knit and miss-knit/tuck positions in accordance with the pattern. For the latter, the cylinder cam is fitted with controllable cams.
The benefit of this system of electronic needle selection lies in its durability and high degree of operational reliability, as mechanical parts and movements are reduced to a minimum. Only spring pins are used to secure the needles against unwanted movements. It is the fastest operating system and enjoys an extremely long service life without the need for maintenance, and is also fully insensitive to contamination by lint or oil. Both in single and double jersey machines, the Mayer & Cie. electronic individual needle selection system operates with just one magnet per feeder. In double jacquard machines using the full three-way technique, two magnets are used per feeder. This solution, which has been tried and tested countless thousands of times over, offers an impressive degree of reliability and handling simplicity.
Fully electronic individual needle selection –
also for dial needles.
At the ITMA '99 in Paris, Mayer & Cie. presented the OVJA 1.6 EE: a machine capable of producing full jacquard design and structure on both sides, featuring patterning by both the cylinder and the dial needles. This electronic solution in the cylinder and dial cam permits the production of jacquard in every conceivable structure and pattern, as the dial needles are fully involved in the patterning process. The resetting work involved is minimal.
Electronic resetting – mechanical knitting.
To complete our look at the topic of automation and electronics, let us turn our attention to the subject of "Mini jacquard at the press of a button"
In exactly the same way as fully electronic operation, here, the patterns are prepared at the computer. Each feeder of the circular knitting machine, for example the OV 2.4 SE (3WT) from Mayer & Cie., is equipped with a selector. For pattern resetting, a module is simply affixed to the selector and the number of the feeder accessed at the module display. By pressing a button, all the selectors are automatically set, whereby the pattern information is
directly entered in the selection control system via a laptop. Knitting then takes place in the same way as in a classical mechanical circular knitting machine.
The patterns can be stored on a data carrier and so entered at several machines – even in different locations. This speeds up the patterning process also for repeat orders.
The benefit of this solution is that the error-susceptible manual pattern resetting process is replaced by electronics, not only accelerating the resetting process but providing a guarantee of absolute freedom from human error.
Conclusion.
As in many other sectors, the degree of automation and a decision whether or not to opt for electronic patterning are up to the individual. Increasing attention to cost considerations and the savings which can be achieved by minimizing inventories have turned the ability to deliver just-in-time into a decisive argument for or against certain suppliers. The trend is moving unmistakably towards more stringent quality expectations by clothing manufacturers on the fabrics they use, making precise quality definitions increasingly into a condition for the placement of orders. Needless to say, automation is not just an enormous help but actually also a guarantee that customer expectations will be met in full.
Due to their short resetting times, partially or fully electronic circular knitting machines are naturally a particularly viable solution in the world of fashion. But for streamlining and increasing productivity, the human factor and the risk of error this entails is becoming ever more important also in this sector when it comes to taking the right purchase decision. Automation and electronics always result in simplified setting and operation, so enhancing reliability and minimizing the risk of error. This fact exerts a major influence in any kniting factory on cost factor number one – the yarn costs. The savings which can be made here also by using modern high-tech production methods are so great in relation to the increased investment that any additional outlay is guaranteed to be recouped within a short period.
There is one more factor to be considered: The growing significance of factory data acquisition, the networking of circular knitting machines and the central control and monitoring functions this permits logically call for an appropriate degree of machine automation.
In the communication age, facilities such as diagnostic systems, remote diagnosis over the Internet, electronic spare parts catalogues with integrated order capability to name just a few will further serve to further accelerate the application of electronics.
Given these factors, automation and electronics are certain to gain an ever stronger footing the circular knitting factory for reasons of time management, quality assurance and customer satisfaction as well as such as productivity and economy benefiting from factory data acquisition and diagnostics.
