Too many slitters?

The amount of displayed ‘facsimiles’ of slitter rewinders at the recent ICE show is not surprising, this happens in a congested market place, but to me it seemed as if the market was rephrasing an ancient question: “Given two objects that look exactly alike, how far is it possible for one of them to be a work of art and the other to be just an ordinary object?  Whilst most business owners visiting ICE tend to leave it to their better halves to buy art, surely we can all expect to get art in the form of innovation, high production and minimal down time from the new machines bought and sold and surely, by their own definition machines must be innovative?

The fitting of digital drives and universal differential shafts to basically 1980’s design does not make a modern machine yet with 52 manufacturers’ offering slitter rewinders at ICE (I counted them) the basis of real innovation and machine development seemed largely lost amongst the goal for ever lower prices and increased market share.

Over the years many film and tape manufactures and converters have found added value manufacturing technology to be critical for their business as they aim to maintain and improve market and financial competitiveness. For virtually everyone I spoke to at the ICE show the value of high quality production was a central factor in machine selection that initially a cost competitive system may not always prove to provide.

In the late 80s we saw the market request rigid machines, machines dedicated to converting mono sizes and products. This in turn led to over investment in machinery and low return with a factory full of stiff, inflexible machines, unable to cope with changes in the market and the requests the sales department placed upon the manufacturing cell.

This consequently led to a general trend of labour intensive machines that, with the touch of an experienced hand, many knives and drawers full of lock core differentials could be turned to convert an extremely large proportion of products, albeit at relatively low outputs with ludicrously long change over times.

If a machine can theoretically run for eight hours without stopping then that’s 100 percent machine ultilsation, but stop that machine to off-load the master and slit rolls, cut the web and stick down the tails, change products and widths etc and this all eats in to and can kill machine efficiency which in turn effects output and ultimately profitability.

The recent trend has been to use machinery designed to convert most materials adequately with an emphasis on flexible changeovers and efficient production utilization.

These modifications made to these machines, which aim to concentrate on flexible more efficient changeovers, found their way onto market in additions such as the universal differential shaft, easy to adjust manual knife positions; lasers indicating the core position on the shaft to register with the corresponding knife, with AC digital drives being perhaps the most profound. Whilst one can never underestimate the sophistication of these modern drives and the improvement to tension control and reel profile, they actually add little if anything to an improvement in outputs on what is the Achilles heel of the common duplex slitter rewinder, the two fixed rewind shafts.

Even with these more efficient features we still see a multitude of duplex machines, running on average at 200 metres per minute, invariably giving the user an average output of up to 80 cycles in one eight hour shift. This equates to a theoretical machine utilisation of anywhere between 15-30 percent (I have used general tape converting with a basic premise of slitting a 1000mm wide jumbo with 50mm slit widths by 50 metre lengths on a three inch core to establish the actual percentage of machine ultilisation)

If we look at certain mid range machines, those automating the rewind section with duplex turrets, running let’s say up to 350 metres per minute, users can still only expect to achieve a theoretical production utilisation of up to 50-55 percent and achieve out puts of up to 200 cycles per eight hour shift, not bad you may say, but still way off, in my consideration, of where future outputs and competitive conversion will need to be.

Innovative solutions invariably come as a result of increased capital expenditure, so it’s not for everyone’s business model.  But larger investment leads the end users to investigate more productive machines such as semi automatic duplex turret rewinders which only leave the cores to be either manually placed on the universal diff shafts (as in most flexible packaging slitters) or to remove the shafts for placing in the roll stripping and core loading device (as employed by most modern adhesive tape slitter rewinders).

Employing automated end cut and wipe down facilities does more in terms of output then any auto knife positioning system or AC digital drive ever could and hence we can see results of up to nearly 500-600 cycles per eight hour shift with some semi-automatic duplex turret machines, that’s almost a machine ultilization of 70 percent.

The ability to adequately load cores automatically, to automatically end cut and wipe down the finished rolls, apply the tail to the new cores and remove the rolls with delivery to the packing units, all tend to go hand in hand with robust machine frames, the highest quality combination of motors and drives, design, R&D, knowledge and ultimately price.  In my experience you can’t just decide to produce a machine like this.  It takes years of research and development and hundreds of machine installations to learn the nuances and idiosyncrasies that allow the manufacturer to design and construct such a technological marvel that is the fully automatic slitter rewinder.

Unfortunately though this level of technology and attention to detail comes at a price and that price has to be passed on to market. Several suppliers have gone a long way to meeting the request of the market by offering high speed, flexible production, quick product and size changes but with a fully automatic operation.  These features where only available a few years back on machinery costing three times as much.  With an operating cycle every 30 seconds these machines can, with an experienced crew, change over sizes and materials and in very short space of time.  Coupled with a very sophisticated tension control system allows end users to benefit from a flexible production but ultimately much lower conversion costs.

If we investigate the very top end of the market in terms of adhesive tape slitter rewinders, then these fully automatic machines are truly automatic in nearly every respect. 

With 1000 cycles achievable in eight hours these fast, fully automatic machines can have a machine utilisation of up to 80-90 percent.  Very few slitter rewinders can surpass this figure, however the faster you run the more automation you need to employ.  Imagine you’re producing 3 -4 cycles every minute, your using a jumbo every 10-20 minute there’s absolutely no way one can expect to have such a productive machine waiting for a new jumbo roll to be delivered to the machine, so the buyer needs to take in to account the increased investment needed in order to get as much out of the total package as possible.  Such additional investments can see a return of up to 1700 cycles in an eight hour shift.

It’s the same case when looking at more productive slitter rewinders in the flexible packaging sector. The distinction between high end tape slitter rewinders and flexible packaging slitter rewinders have becomes less pronounced these days, as the quality and price increases and so does the machine ultilsation.  Tape slitters produce relatively small length rolls whereas flexible packaging slitters can easily rewind many thousands of metres, so even though cycle times maybe vastly different between the two, machine ultilsation usually remains constant.

High end flexible packaging slitter rewinder design now commonly employ’s an overhead web path and good access to the slitting area, with the possibility for adding assistance to the positioning of knives and counter knives, as well as automatic extraction of finished reels.  These machines handle mother reels up to 1,200mm OD and run at speeds approaching 600m/min.  However the major factor in reducing downtime on these machines is still the turret rewind with automatic changeover.  Add this and machine ultilisation is extremely high whilst down time due to product, size changes or roll removal and core loading can be minimized accordingly.

So as the speed increases and the turret system gets us up and running faster and the bottle neck moves from the slitter to the packing area. Recent developments that assist the  Automatic off loading come in the form of packaging and identification of every single reel, Automatic palletisation, Product traceability from slitting through to forwarding, Dimensional check of every reel: width, diameter and weight, Management of any non-compliance: defects, out-of-tolerance dimensions, quality and complete Production reporting, with local and remote supervision. 

The expense in devising such a comprehensive range of technological solutions requires heavy investment in terms of design, selection and research and development by the constructors.   That cost has to be passed on, I’m afraid.

Again, it’s not suitable for every single business but added value manufacturing technology is crucial for converters and manufacturers alike as they aim to maintain and improve market and financial competitiveness in today’s market.

If the trend toward ever lower cost machines, in this congested market place continues, end users could well lose sight of the opportunity that buying a new slitter rewinder can bring to a whole organization.   The total reassessment of the needs of sales/marketing from machinery, the improved production efficiency and increased profitability is eroded, sometimes requiring secondary investment not too long after the original.