Demonstrations of cast and blown film set throughput records at K 2007. Not only have machinery makers increased speed of extruders, but they have displayed faster downstream chill rolls, winders and surface inspection systems too. Larger drive motors contribute to high-speed extrusion, especially bigger sizes of permanent magnet, synchronous torque motors. The latter have reached a new milestone- sizes big enough for 100 mm dia extruders. Previously �syn-torque� motors could power extruders only up to 90 mm.
Several extruder builders announced modifications of screws and barrels to take advantage of the output capacity and energy efficiency available with syn-torque motors. Reifenhauser developed new low-temperature screws to boost efficiency of a 70 mm Reitorque extruder from 400 w/kg/hr to 300.
Blown film outputs also reached new highs at the show. W&H demonstrated a three-layer coex line with a 90 mm extruder driven by Siemens' 11,000-Nm (192-hp) syn-torque motor, the largest at the show, and two 70 mm extruders with 150-hp syn-torque motors. The line ran at 1000 KG/HR with a 250 mm die and dual air ring.
Film extrusion has enjoyed some periods of rapid growth
in recent years, particularly within the packaging industry,
where it has been highly successful in substituting other
materials such as paper, cellulose and aluminum, due to
its superior characteristics. Plastics now account for
approximately 47% of consumption in the production of
flexible packaging, as per a report by AMI.
Growth in flexible films for food packaging has been
sluggish in volume terms but this masks a significant
increase in usage by square foot of film. This growth has
been driven by changing consumer demands around
issues such as extended shelf life for fresh food and less
spoilage which hasled to the development of highly
sophisticated flexible film products. Changing lifestyles
have been a key influence on the development of
packaging as consumers demand more snack,
convenience and pre-prepared foods, make greater use
of the microwave. Consumers demand ‘healthy’ foods, improved
food hygiene, individual portions and clear packaging to
allow inspection of goods without handling them. These
trends have all helped to contribute to the growing use of
film.
Consolidation among players within the food packaging
industry has also been a major influence affecting the film
industry in recent years.
As food production and distribution increasingly takes
place on an international scale, film extruders serving this
industry have had to employ high levels of investment to
serve these customers, resulting in consolidation
amongst the leading film extruders. This process of
mergers and acquisitions has also been driven by thin
profit margins in the business due to fluctuating raw
material costs and high levels of imports from Asia and
South America, particularly of low cost goods and bags.
Because of all these various pressures, growth in the PE
film extrusion sector has been variable over the past
decade. More traditional areas such as trash liners and
garbage sacks have shown little growth in volume terms
due to downgauging and the increasing use of recyclate,
often compounded by the loss of production to lower
cost regions outside NAFTA. Strongest growth within PE
film sectors has tended to be the stretch film market,
hygiene films and technical coextrusions.
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