MACHINERY | BLOWN FILM DIES
structures – including those using temperature- sensitive resins – can be produced. Multi-layer films formed with an ADSS die can achieve the proper- ties required for highly demanding applications, says Alpha.
Film line supply Davis-Standard recently supplied three film lines – one 2.5m cast film hygiene line and two five-layer agricultural blown film stretch lines – to one of its leading existing customers, Sigma Plastics. The line included the supply of blown film dies. The cast hygiene line – scheduled for installation
this year – is the second of its kind purchased by Sigma in the last three years. It will be engineered for A/B/A structures with in-line printing capabili- ties. The five-layer stretch lines include Davis-Stand- ard Optiflow LP dies, as well as vertical oscillating haul-off technology. “Davis-Standard has been exemplary at support- ing our business demands and growth,” said Alfred Teo, chairman of Sigma Plastics. Davis-Standard has been expanding its offerings
in blown film dies – and to this end recently installed an in-house machining centre. The centre is home to innovative designs that deliver high outputs and reliable gauge control, says the company. It has also expanded its operations by acquiring
Brampton Engineering of Canada – which, among its offerings, supplies multi-layer blown film dies.
Below: Davis-Standard recently installed an in-house machining centre for
blown film dies
Die retrofitting At NPE – prior to the takeover being announced – Brampton said that its SCD 4.0 die technology had been made available for retrofit on all existing lines – regardless of age, model and manufacturer. “The market demands more layers and SCD 4.0 is the only co-extrusion die that enables producers to process each polymer in a multi-layer barrier film
structure at its ideal temperature,” said Gary Hughes, Brampton CEO. Brampton says that the die has a direct path
from the extruders and streamlined melt channels, to achieve “the shortest melt residence time and lowest wetted surface area in the industry”. It says that SCD 4.0 dies ensure optional film quality and minimal downtime for purging and die cleaning for two reasons: n They minimise average residence time and eliminate dead spots where resin can move very slowly – gradually bleeding black specks of degraded resin; and,
n They ensure that each resin can be processed optimally by selecting the right SCD 4.0 technol- ogy and profiling their temperatures according to the film structure. Retrofitting is ideal for lines that require specific
process improvements, says Brampton. Results include boosting productivity, improving quality and product performance, and increasing profit- ability – at a fraction of a cost of a new line. “If your existing line is in good condition – but limited to a number of layers – a viable option is to replace the die and add new extruders to match the number of layers required for greater portfolio flexibility,” said the company. “The most recom- mended course of action is to upgrade to a seven-layer system. This will allow production of a wide range of films, from co- extruded monolayer to high-barrier films. These projects typically require an outlay of 35-50% of that of a new line – and the payback is achieved in a shorter period of time.”
Cooling assistance While blown film dies are crucial to getting attrib- utes like film thickness correct, some of the down- stream equipment – such as cooling systems – also help to maximise product quality. Brampton also supplies these types of system. At NPE, for instance, Brampton expanded its Vector air ring product line. The new Vector S offers an auto gauge option by using segmented air. It reduces starting gauge by up to 80% compared to conventional air rings, says the company. It also has very high resolution, as it has 180 digital control points adjacent to the lip compared to the usual 60-80 controls in conven- tional air rings. Brampton engineers used aerospace engineer-
ing to create the Vector line – distributing chilled air uniformly around the bubble using a single inlet while controlling the flow to secure stable ‘bubblel- ock’ and boost output on the blown film line. Vector reduces starting gauge variability thanks to uniform airflow around the lip, while Vector S
42 FILM & SHEET EXTRUSION | June 2018
www.filmandsheet.com
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