Dusseldorf - Before K 2013, it was simply known as E-24. And at K, if you wanted to find out what E-24 was code for, an employee of German-based engineering company Windmöller & Hölscher (W&H), had to escort you inside the 'experience' tunnel.

While the company kept the machine hidden behind a red curtain so competitors couldn't get a glimpse - the secret is now out: E-24 is the Varex II.

At the W&H stand, visitors saw a 2200 mm 5-layer extrusion line featuring the Maxicone P die, which is specially designed for polyolefin films. The demo product is 40-micron collation shrink film.

"As people go through the tunnel, their eyes get wider in amazement," Lennart Ederleh, technical sales director of extrusion equipment for W&H, told PlasticsToday. "The exterior is what they first notice, but the big changes have been the interior. It's an important message that it not only looks nice, but there have been some very technical changes."

With the Varex II, W&H touts this "innovative successor" to the Varex blown film system lifts the secret of one of the most significant development projects in the company's history.

Ederleh said that right after K 2010, the company went to work on upgrading each and every component of the line. The underlying goal was to increase productivity and flexibility as well as improve the film quality, while at the same time consider sustainability and an ergonomic design.

"We're always focusing on functionality," he said. "Design follows function."

The footprint of the line is the same, and while the Varex II is priced at a higher price point than the original, Ederleh said it's not due to the new design, but rather inflation. 

The details

The Varex II is modularly designed and W&H said it can be tailored to any user specific requirements. The modular concept allows for later retrofitting with optional modules and new technologies to accommodate future requirements when the need arises.

The company says that due to its flow-optimized barrier screws, the extruders can provide maximum flexibility with processing various resins. The broad selection of Maxicone dies ensures that there will be the correct die for any product specification.

The patented melt distribution system reportedly allows for a compact design and keeps pressure losses low. Optifil P, W&H's gauge profile control system, is said to enable a targeted control of the melt temperature on the bubble circumference, which reduces film gauge tolerances.

Another highlight of the Varex II is the new bubble collapsing unit in the film haul-off. Due to the automatic adjustment of the lateral guide elements, film flatness is improved and film curvature minimized. The new Filmatic S II wider can be tailored to any application. The new Arctis Air ring, an upgrade of the Opticool air ring presented in 2009, contributes to a further increase in output. The air flow concept is said to lead to maximum cooling efficiency and the integrated design concept of the air ring provides easy access to the die components.

Sustainability was a factor throughout the development of Varex II, Ederleh said. Due to a number of "innovative engineering," the Varex II hopes to set a new standard in regards to raw material and energy efficiency.

Ederleh said that one key component is the elimination of the need for edge trimming in the majority of applications.

Other automation modules available for the Varex II are aimed at a greater transparency of the production process. The energy monitoring module displays the energy usage of the individual modules while the ISP module collects and saves all production parameters and enables detailed monitoring of the production process.

The ISP based module PPS is a new feature permitting, which for the first time, decentralized job preparation and control. Order specifications and product formulations can be directly transmitted from the on-site ERP system to the extrusion line, without the operator having to entry any order data locally on the machine.

Technical details

The Varex II is available with working widths up to 3600 mm and for up to 11-layer films. It is designed for outputs up to 1500 kg/h. Extruder sizes include 50, 60, 70, 90, 105, 120 and 135.30 D. Die diameters range from 120 to 900 mm.

Partnership with Exxon

At K 2013, W&H introduced Varex II with running a 5-layer, 40 micron collation shrink film based on ExxonMobil Chemical's Exceed and Enable metallocene polyethylene (mPE) resins.

ExxonMobil says that compared to conventional 3-layer polyethylene films, converters can benefit from higher productivity and greater flexibility to produce a broader range of film solutions from a single line. For packaging, brand owners can benefit from a source reduction in materials and more packaging impressions delivered per roll of film. 

"Designing exclusive film formulations tailored to the latest in machinery technology, is like having computer software updated to take advantage of the latest computer hardware," said Dirk Van der Sanden, global processing and converting advisor, polyolefins technology for ExxonMobil Chemical.  "The performance opportunities for 5-layer films are huge."

The additional two layers in the film structure allow the optical and performance properties to be tailored to meet the needs of the application. Exxon says that to achieve similar flexibility with 3-layer technology would possibly require two lines that could be more expensive to buy and to operate.

A 5-layer structure allows specific functionalities, such as sealability or optics, in each of the discrete layers. It also reportedly allows more control over the thickness of the layers to meet the needs of the application. For example, higher output can be achieved by using layers of high melt strength materials. Also, a film with a thick core layer and thin skin- and sub-skin layers can provide downgauging opportunities of up to 20%.

"It is about the power of numbers," said Van der Sanden. "The additional two layers compared to a 3-layer structure greatly expands the design options."