Film technology

Cast extrusion film production upped

Production records were broken for a cast extrusion line for CPP film during commissioning trials at Italian producer Gruppo Colines. Prior to shipping to the customer in South America, the 2,100mm Polycast five-layer film line was tested over five days producing different structures and gauges from 15-50micron.

A record of 1,050kg/hour for polypropylene film was achieved under the customer's close supervision, says the company. Success is attributed to developments in the extrusion section and winding unit.w

The line is destined to produce twist cast PP film for confectionery, but can also produce the whole range of CPP and cast PE structures.

Gruppo Colines recently inaugurated a second plant - a 5,000m² facility in Azzate. The €4M investment includes an 18m high tower destined for the erection of blown film extrusion lines.

Linear technology speeds winder

In co-operation with Manuli Film, Italy, Brückner has developed and tested new high speed film winding technology. The winder of the leading film producer's high performance 10m BOPP film line – claimed to be the world's largest and fastest – has been significantly improved. The original mechanical/pneumatic/hydraulic contact roll positioning system was replaced by a linear motor winding system. Patents are pending on the LIWIND-system.

A linear motor controls the motion and contact pressure of the contact roll. It moves the roll to the desired position and provides the required contact pressure. The pressure is controlled dynamically from 10-400N/m in a 0.01 N/m resolution. The benefits are said to include perfectly wound mill rolls for all film types, wide operating windows and therefore supreme flexibility for parameter adjustment. There is an impressive reduction of required mechanical components, leading to less wear and tear and thus enduring performance, says Brückner.

Two years in development, the system was installed at Manuli in August. "Before production start two jumbo rolls were successfully rewound at 570m/min. Right after re-starting the line absolutely perfect film rolls have been produced at high speed," reports Brückner.

"We reached our goal by 100 per cent," say Manuli's technicians. "Our film production now benefits from very high winding speeds, assuring an optimal winding quality."

Taking an intelligent route on bags

Producing wicketted bags for applications such as bread, salad, vegetables, and female hygiene products, the INTERmat ST-N new machine generation operates with an intelligent control and offers easier handling, higher speeds and quick set-ups, says Lemo. This is achieved by data storage for repeat orders, the user friendly graphic interfaces with touchscreen and the pre-positioning of devices and modules for remote access. For example, the output of the new corner sealing device is now 450cycles/min.

Since K the company has taken a large number of orders for the equipment. It recently announced that the intelligent control is now to be extended to other models in its range, including the diaper bag machine. The increased number of cycles and the shortened set-up time allow customers to augment production figures significantly while simultaneously reducing unit costs, adds Lemo.

Lemo has also launched a shaftless unwind unit allowing easier handling of film reels and the motorized positioning of the machine.

Contour lines selling well

Since Extrusion Dies Industries (EDI) introduced its Contour Die at the NPE show in 2003, manufacturers of cast film, sheet, and coated products have already ordered 35 dies based on this design, whose special shape embodies a very different concept from conventional flat dies.

The die is claimed to improve productivity and product quality by eliminating a longstanding trade-off between gauge uniformity and streamlined melt flow, according to Christopher W Curtin, executive vice president of marketing and sales. The resulting benefits are available to most extrusion processors and web converters, he notes, but are particularly great for operations with frequent product change-overs.

"Most of the 35 Contour Dies sold thus far have been ordered within the past year," he says. "This is a remarkable pace for any new die, let alone one that differs so distinctly from all conventional ones."

"Just as remarkable is the range of industries in which the Contour Die is being put to use," says Kelly M Harings-Mrozinski, customer service manager. "We've sold them to manufacturers of cast film, stretch film, raffia tape, sheet, and extrusion coated products.

"These dies have included both single-layer and coextrusion systems and have ranged in size up to 4.7m. Just recently we sold two Contour Dies that have been slightly modified to accommodate our CL-EPC internal deckle."

"Called the Contour Die because it has a tapered, sculpted shape instead of the standard block-like configuration," says Christopher W Curtin, "the system exhibits die body deflection that is uniform across the width of the die yet avoids the sacrifice of melt flow streamlining incurred by earlier constant-deflection dies."

Small is beautiful

Reports from customers purchasing the Maxicone five to seven-layer die are excellent says Windmöller & Hölscher. One company says it has achieved reductions in product change time of some 80 per cent.

The die allows barrier films as well as polyolefin structures to be processed with high output, adds W&H. "Short change-over times are attributable to the compact design. Maxicone is only about half the size of previous die concepts. Featuring the patented conical distributor system, the die is the smallest one known in the marketplace when it comes to the amount of melt it holds during production."

Resulting advantages include minimum product change and purge times, long uninterrupted production periods, minimum pressure losses of melt flows combined with high outputs, tight tolerances and excellent optical properties says the company.

No trouble with bubble film

Patented worldwide, Air-Basic, Torninova's latest air bubble film model, is claimed to allow flexible and reliable production with minimum energy consumption for an economical price. For example, it is possible to halt production with film remaining in the machine, says the company.

  Just one operator is required to produce any type of multi layered air bubble film through different materials and bubble size, changing production within a few minutes and without scratches, claims the company.

The Air Basic system is automatic and PLC controlled with touchscreen to program roll length, distance between perforations, temperatures and nip roll speeds.

Patented winder eases change-overs at high speed

At its recent open house Dolci Extrusion exhibited a new five-layer high speed cast film line for stretch film.

The H8 Stratocast, built and balanced for a speed of 800m/min, features a 1,500mm diameter Jumbo chill roll and the Contrawind 2000 robotized winder that allows automatic change-overs at speeds exceeding 600m/min, claims Dolci.

Besides having three supports for the expansion shaft at rewinding (to avoid vibration), the patented winder is equipped with a winding calender, which, instead of being fixed, is hinged on two pivoting arms and moves away from the winding shaft with the increase of reel diameter.

During change-over a second calender keeps the finished reels at winding speed while the blade cuts the film and, with the help of a flow of electrostatic charges, the winding on a new set of cores begins.