PRA March-April 2015 Extrusion Machinery

Extrusion Industry Machinery News

New dies reduce edge bead and improve adjustments

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n extrusion coating die designed to reduce edge bead has enabled a producer of aluminium foil and foil-laminate flexible packaging to actually eliminate edge bead, as well as reduce coat width variation by half or more.

After a die for applying LDPE on an existing production line for flexible food packaging had been causing problems with die lines and leakage, Korea Aluminium replaced it with the Nordson Extrusion Dies Industries Edge Profile Control (EPC) die.

While the degree of edge bead reduction achievable with the manual EPC die depends on a number of factors, the reduction in the line was 100%, says the processor, adding that coat weight variation was reduced by 50% to 60%. An EPC die includes an external deckle as a secondary seal to prevent leakage and an internal deckle system that sets coat width and seals polymer at the die exit.

Meanwhile, Nordson Corporation has introduced a patentpending SmartGap technology for sheet dies. It uses a singlepoint adjustment mechanism that changes the lip gap while simultaneously modifying the length of the lip land to provide appropriate conditions for the newly adjusted thickness as the sheet exits the die. The lip land is the final gap in the die that forms the lip exit. By mechanically linking the adjustment of these two key process variables for the first time, the SmartGap system ensures a proper set-up of the die and takes substantial time and guesswork out of the process for achieving desired sheet properties.

The SmartGap system, available only on new dies, eliminates the extended shutdowns for changes in lip components that have often been necessary when transitioning to new job runs, reducing changeovers to less time. Also overcome

EPC extrusion coating die installed by Korea Aluminium

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MARCH / APRIL 2015

Die with SmartGap is a new mechanism for changing sheet thicknesses

are previous limitations on thickness range caused by the complexities of die modification; allowing for die gap adjustments over a range of 10.2 mm, enabling

processors to run with multiple product changes per day.

Foam line for PLA extrusion

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ilm and sheet extrusion machinery supplier Macro Engineering & Technology (Canada) has introduced a new extrusion line to produce polylactic acid (PLA) foam. The line uses tandem extruders to produce foamed PLA sheet 1.2-5 mm thick and up to 1,270 mm wide with a foam density of 0.07 g/cc (16x expansion ratio). The sheet can be thermoformed into

Macro’s PLA foam extrusion line

compostable clamshell packaging and trays used for cold food applications.

Macro uses a proprietary new extruder design to address obstacles that are inherent to foaming PLA, namely, working around the material’s low melt strength, melt crystallinity and narrow processing window. The result is uniform melt temperature distribution and reliable foaming.

Extrusion Machinery

PET sheet output maxed; layer flipping technology

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S-based sheet extrusion machinery maker Processing Technologies International (PTi) showcased at the NPE exhibition in Orlando recently an 85mm/52D HVTSE extruder and a GCH661824 horizontal roll stand, capable of producing 57” wide PET/ PLA sheet at thicknesses down to 0.2 mm or PP sheet at thicknesses down to 0.3 mm. This system operates at 1,0 0 0 kg/ hour or a total of 8,0 0 0 tonnes/year of PET production. It will be the fourth installation in the last six months, and, in addition to the units sold from the 2011 launch, will represent a theoretical installed capacity of 180,0 0 0 tonnes/year of North American PET production.

The “dryerless” sheet extrusion system is an eco-conscious manufacturing solution, which delivers major energy and cost savings, according to the firm. In terms of sustainability, the HVTSE process provides a reduction of about 80-85 kWh/450 kg in energy consumption versus conventional PET processing.

The line unit boasts several novel features including PTi’s new GSeries configurable roll stand, PTi’s Titan Plus Integrated PLC control system, multi-resin capability and rapid resin changeover.

Meanwhile PTi is also in the final

PTi’s thin-gauge dryerless PET/PLA sheet system

stages of formalising a commercial agreement with a tooling manufacturer for the exclusive sourcing of its patented layerflipping technology.

This technology allows processors to quickly change the position of extrudates from two extruders in a coextruded structure without disassembly and shutdowns.

Changeovers in piston position due to hydraulic actuation of the piston cylinder and unique flow design are accomplished in a matter of seconds as opposed to conventional techniques which require some machine disassembly and could take up to several hours, according to PTi.

The diverter valve, which can be utilised on new or existing systems, features

a dual-piston valve that is moveable in a stationary body. The body has two entrances that feed from separate extruders. The first position of the valve allows the material to enter the piston valve and permits a straight through flow path. Normally, this would produce an A-B structure. When the alternated position two is selected, the materials are routed through crossover flow paths that changes extrudate positions.

This produces a B-A structure.

During position changes, a unique flushing channel design keeps flow from stagnating for quick and efficient changeovers.

The practical use for the diverter valve is its quick “realtime” purging of cap layers in a multilayer

co-extrusion structure for sheet production.

The diverter valve enables the processor to purge the cap layer extruder back into the inner layer of the structure while an alternate cap layer extruder runs a specific resin formulation (i.e., different colour). Each cap layer (both inner and outer layers) can utilise this special valve to permit this real-time purging for rapid changeovers.

This occurs without shutting down the line, thus permitting recovery of the purged resin directly back into the structure instead of losing the material onto the production floor and recovery through a grinder.

PTi will offer the layer-flip technology on new co-extrusion systems or as a retrofit to existing machines.

MARCH / APRIL 2015

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