Slitting and rewinding is one of those processes that is often taken for granted in the converting industry – it’s functional and essential, but hardly exciting. But, in today’s competitive market where margins are under pressure and converters need to maximise efficiency, slitting and rewinding has an opportunity to make a significant impact on production. Nick Coombes looks at some of the technology that goes to make up this new generation of machines
Along with most parts of the printing and converting process, the main thrust in slitting and rewinding is for greater efficiency. This is largely being brought about by the increased use of automation that essentially reduces downtime between jobs, and by both de-skilling the job and reducing the operator’s time input, allows for redeployment of labour elsewhere in the production environment. Manufacturers in this sector are all focused on designing technology that complements the changing market demands. Converters want speed, efficiency, flexibility, consistency, and above all, profit! Where once this might have been the preserve of the developed and mature markets, it now holds true for those areas just emerging into a demand economy, where branded packaging is growing fast and the sales potential is huge.
The diverse nature of work that today’s slitting and rewinding machines have to cope with highlights the great need for a flexible capabiliity. The range of substrates includes very thin reverse printed plastics film to normal lamination for snack food, triplex lamination for pet food, and heavy duty lamination for toothpaste tubes. In a market where margins are tight and competition is fierce, most converters need to be able to offer versatility, and that means a mix of work in any one shift, without loss of reel quality.
Atlas Converting Equipment
At Atlas, the new Titan SR9 Series DS (Dual Shaft) cantilever slitter rewinder, launched at Drupa 2012, was designed specifically in response to these market demands. It replaces the Titan SR8 range and significantly is of modular construction that allows the rewind section to be replaced or upgraded to a single or double turret, to meet a change in demand and increased volumes. The company says this global demand for de-skilling the operation by increased use of automation also improves quality and output, with fewer but more sophisticated machines handling a greater variety of work. Another trend it notices is the need to add value to the operation, and this can be done with cleaning, perforating and embossing units. The benefits are two-fold for converters: it allows them to compete more effectively by offering something extra to the customer, and it also creates an opportunity for improved margins. From the customer’s point of view, brand impact is improved with a resultant increase in sales.
The concept of the Titan SR9 is based on separate modules for unwind, slitting, and rewind. This allows the converter to upgrade the machine from a dual shaft to a single or double turret configuration, without disturbing the unwind and slitting sections. Available in web widths of 1,650 and 2,250mm, it is capable of 1,000m/min in operation. New features, such as the Turret Support Device (TSD) which, by rotating the turret faster has improved setup time and the quality of slit reels, and Linear Tracking Slitter (LTS), which keeps the web length between the knives and rewind shafts to the minimum to ensure consistent quality and lower waste levels, are seen as significant in the drive to boost production efficiency in the converting plant.
Other innovations on the SR9 include improved control of acceleration and stopping (ASC and PSC respectively), a highly versatile knife positioning system (KPS3), rewind core positioning and rewind clamp cut-off (RCP3 and RCC), an automatic device for securing tails to rewind cores for fast restarts (ATD), and a knife positioning guide that saves time and material waste (GKP3). Yes, there’s an acronym for everything, except it seems, for the regenerative braking system and the elimination of hydraulics, which combine to give a cleaner working environment and consume less energy.
Ashe Converting Equipment
Another UK manufacturer, Ashe, is reporting high levels of interest in its Diamond slitter rewinder, with international sales on the up. The machine range features a shaftless unwind with electric reel lift and digital edge guider. The company’s own vacuum system offers the level of tension control required for multi-substrate working, and it is available with an energy saving coreless trim winder, which, in addition to handling trim efficiently, also eliminates the need for bundling waste from bins.
Capable of running at 500m/min, this slitter is designed to match the capacity of today’s highly productive printing presses, like the W&H CI flexo press, recently installed at ACF Labels in South Africa, which has just invested in a Diamond.
Czech manufacturer Soma claims to have enjoyed a highly successful Drupa, and used the Düsseldorf expo to launch its Venus III slitter rewinder. Available in web widths of 1,100 and 1,850mm, it has an overhead web path for enhanced cleanroom operation, said to make it ideal for both food and pharmaceutical production environments.
A waste management system connects the press to the slitter, allowing bad material to be identified and removed during the slitting phase. Another advantage of the frame height of the machine is that ancillary equipment can be retrofitted without significant integration costs. These ancillaries could include corona treatment or perforating units, along with web cleaning devices.
Soma has also uprated its Pluto range. The Pluto III includes automatic knife positioning, designed to speed up job changes, which are now reduced to less than two minutes. Other features on the company’s machines that are said to make positive contributions to high production efficiency include: an automatic core guiding system that uses the same data as the knife positioner; a vacuum splicing table; strip holders; automatic cross slitting; and a shaftless unwinder with a hydraulic lift.
The key to accuracy, especially with many of today’s lightweight thin substrates, is tension control, and Soma claims its Tensomat II system can maintain unwind between 50 and 400N/m and the rewind between 50 and 900N/m. Unwind tension variation is detected by a dancer roller which sends a signal to the servomotor to increase or decrease speed as appropriate. A PID control system manages the slitting of thin or difficult substrates.
For the rewind, tensometers, which measure tension throughout the production process, compare data with pre-set values and make adjustments by varying the air pressure under the friction tapes in the rewind shafts. This friction is then converted by rings into tension in the split web strips, and software converts it to a value per web width, taking into account the rewind diameter.
Spanish manufacturer Comexi continues to develop its Proslit line, and at Drupa showed the single turret Proslit S that the company hopes will take it into new markets for the slitting and rewinding of different substrates such as rigid and semi-rigid materials. The company claims to have had a very positive reaction from potential customers to this diversification, and says it will continue to develop the range by drawing on its 50 years of experience in slitter rewinders. The Proslit S has three different diameter capabilities (1,000, 1,250, and 1,550mm), and crucially three weight capacities of 1,350, 2,150, and 3,000kg, which allow it to handle the thicker materials used in this new market for Comexi.
The range features a control system known as Advance Lineal Winding which, by moving the rewind shaft as its diameter increases with processed material, actually controls the distance between it and the slitting section to maintain constant tension.
Forefront of development
The common theme with all the manufacturers is the need to offer more than just a slitting and rewinding machine. Converters are under pressure from their customers, the brand owners, to offer more for less. They pass this pressure back up the line to the machinery manufacturers, whose R&D departments have to deliver innovation that is both practical and economic. For so long seen as a backwater of development, slitting and rewinding technology would appear to be experiencing a whole new beginning.
Atlas Convertingâ€™s modular SR9 series was launched at Drupa 2012 to meet the global demand for increased automation and versatility Atlas Converting Ashe Converting has recently sold one of its Diamond slitter rewinders to ACF Labels in South Africa Ashe Converting Somaâ€™s latest Venus model is designed for use in cleanroom operating environments Soma External weblinksConverting Today is not responsible for the content of external internet sites.Ashe Atlas Converting Equipment Comexi Soma