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Demand for better slitting accuracy and longer run length has led to the design of advanced slitters and the development of new winding technologies, reports Adolf Mueller Maschinenfabrik

Demand for better slitting accuracy and longer run length has led to the design of advanced slitters and the development of new winding technologies, reports Adolf Mueller Maschinenfabrik

Over the last few years Mueller has become known for developing new machines to slit and level wind various materials, especially to narrow widths. “A good example of the improvement in this technology is a new line for tear tapes which was recently commissioned for a south east Asian customer. The machine was built to handle both MOPP and BOPP, as well as PET based adhesive coated materials. It produces narrow strands mainly used as tear tapes designed to provide easy opening packs,” says Mueller.

  The line comprises a cantilevered driven unwind suitable to take up printed and non printed materials. A new style of splicing table allows convenient splicing of printed tear tapes meeting a need for consistent register and reliable splices. A speed influenced edge guide on the unwind is claimed to ensure straight movement and the best alignment of the web.

Web tension is maintained by a dancer roller that is claimed to eliminate tension variations caused by eccentric wound rolls. The specialist equipment builder says that it conducted a great many trials and spent a long time researching to produce a new machine layout which reduced this problem dramatically. In addition a second edge guiding system – also influenced by speed – further improves the pre-alignment of the web coming from the unwind of the slitter.

Fast change

The machine features a slitting cassette system for shear cut knifes, which allows the operator to set the knifes in a convenient location away from the line. This also reduces the downtime for changing the slitting width to a couple of minutes, explains Mueller. Several slitting cassettes, each equipped with a pre-tooled set of knifes for a certain slitting width, are supplied to the customer with the equipment. The slitting cassettes are carried on a loading carriage that can be docked on to the machine for fast change-over. And they feature several new and unusual approaches that have been designed to improve extensively the lifetime of the shear cut knifes.

High accuracy

“Slitting accuracy has been improved to a level which seemed to be out of reach,” boasts Mueller. “A tolerance of less than 0.04mm to a printing line has been achieved and recorded over a long strand length.”

Behind the slitting section, the adhesive tear tapes are separated into three different levels and spread to reach the individual winding stations. Further technologies have been developed to improve web and strand transport, to reduce and remove the glue penetration to the knives and to improve the winding quality.

In addition to shear cut technology, a special razor blade slitting section in the cassette design is also available using the same loading trolley. This cassette allows fine adjustment of slitting depth and angle for the blade holder while the machine is running.

After strand separation, the tear tapes are led to individual winding heads that traverse wind into a stable package of many thousand metres. Each winding head has its own idle rollers for strand guidance, a dancer roller for tension control and a traversing lay-on roller which builds up the traverse winding package.

It is possible to wind on 32mm, 3in and 6in cores – made of either plastics or paperboard. Flanged cores as well as keyed cores can be used on the winding shafts, which allow fast change-over from size to size. The core locks have excellent centring capability to ensure high speed, good quality winding, claims the company. With the ability for individual setting of winding parameters for each winder, it is possible to run different cores and strand widths within one job run, it adds.

Machine controls allow setting and viewing of various winding parameters and ensure consistence and repeatability of those chosen parameters.

The company offers a wide range of different traverse winders, which are specially selected and tailored for its customers’ materials. Narrow slitting is typical of its specialist expertise, but it also produces equipment capable of handling difficult materials, multi layered and non symmetrical materials and to a wider slitting width suitable for level winding.

  “Level winding technology gets more and more popular because it reduces the machine downtime for roll change and web splicing and improves product quality while ensuring constant and long lasting application conditions,” concludes Mueller.