Q: What are the factors involved with proper blown film extrusion?

Yadav: The major factors involved with proper blown film extrusion include: end product/application of the film; properties and attribute of the film required with respect to raw-material combination, processing parameters and blown film line configuration; quality of input conditions such as electrical power supply, utilities, web guide, Corona treater, etc.; environmental/ambient conditions when a blown film line is being operated; blown film line technology with respect to extruders, gear boxes, motors and drive combination; die technology; cooling technology; outer- and internal bubble cooling systems; gauge randomization technology; winding technology; and level of automation, including width control, peripheral gauge control and linear global system for mobile communications (GSM) control. At the end of the day, we need to have fully customized line to arrive at proper blown film extrusion.

Nunes: Many factors are involved in proper blown film extrusion, and it begins with specifying the optimum blown film line. This is a methodical, step-by-step procedure. Starting with the basics: materials and applications, gauge range and blow-up ratios, total system width and die size – all of which determine extruder sizes based on rates and layer percentages. Total height and floor space requirements, power and cooling, resin handling and related infrastructure are all important factors to consider.

The right machine for your specific manufacturing needs will allow you to be highly productive and efficient. Taking advantage of your equipment to maximize uptime and yield through careful planning and scheduling is very important for profitable and proper film extrusion. Modern control systems are a tool that makes the entire process controllable and repeatable for reliable long term performance. 

Nigro: The number one factor, as I see it, is clearance height in the customer’s high bay. All too often, processors want to add new, state-of-the-art blown film equipment to older-existing buildings, and for one reason or another, do not invest in the infrastructure modifications.

Years ago, a 45-foot ceiling height or lower was fine for the limited output of vintage equipment. Nowadays, processors need – and W&H can supply – very high-output extrusion lines; therefore, 60 or 70 feet is a standard requirement.

Since the only effective cooling for blown film is air ring, IBC (internal bubble cooling) and tower height, it plays a huge roll in successful, achievable output and quality. There are, of course, many other factors which are not to be overlooked, like proper die and screw design as well as extruder sizing, but you would presume these to be correct if purchased from a reputable supplier. Not having the proper height high bay can thwart even the best designed lines and equipment.

DeSpain: The blown film process, like many extrusion operations, is a step-by-step process with each subsequent step being dependent on the stability and optimization of the previous step. Starting at the material handling/blending system to the extrusion process, including bubble formation and cooling, these steps all have to work in harmony with each other. 

After the bubble is formed, collapsing and web handling, and finally winding come into play. If any of these steps are not performed or set up correctly, they directly impact the next step and ultimately the film quality and output of the system.

Q: Are there any developing trends/technologies you are seeing in the blown film sector?

Nunes: Die and cooling technology, in conjunction with the latest in hardware and software needed for correct gauge control, are driving significant improvements in current day blown film.

These highly evolved technologies are allowing processors to be 50 percent more productive than just a few years ago. Higher rates are just one part of the equation – improved thickness control, material savings, superior converting performance and significantly reduced scrap rates are all collateral benefits.

Most of these new technologies (i.e. dies, air-rings, auto-gauge systems) can and are being adapted to older machines and offer similar benefits as brand new machines.

Nigro: One of the biggest trends that we have seen lately has been the interest in post-annealing- and machine direction orientation equipment. W&H has extensive offerings in both in-line and out-of-line models, and many of our customers have incorporated these in-line units into recent purchases of new lines.

DeSpain: More layers – whether it is three to five or seven to nine, or beyond the trend to add layers –continue giving processors flexibility in their extrusion systems. Flatter film to increase printing and converting speeds are now possible with systems such as our Ultra Flat haul off.

Energy efficiency is a big subject around the world, and it will only become more demanding here in North America as well. Food safety and freshness along with recloseable packages continue to drive the market along with sustainability and efficiency.

Yadav: There are many trends and technologies expected ahead in the blown film sector. As there are still many mono-layer blown film lines in market, there is a need to either upgrade or replace them with at least
a three-layer line.

This trend will need a joint cooperation with machine- and resin manufacturers, and film producers to add value to the whole process in a phased manner. Ultimately, there will be no need of any mono-layer, since three-layer will be able to offer better and cheaper solutions.

The slim packaging ahead will force the industry to control the resource by producing thinner films without compromising the core properties. A film today of say 25 microns will have to be down gauged to 12-15 microns. To achieve this, we will have to develop very high-line, speed-based post extrusion equipment.

Looking into the future with global concerns to keep this Earth as green as possible, we need to produce 100 percent recyclable flexible packaging laminates. This means we will have to produce blown films to replace existing non-recyclable substrates like PET, BOPP, etc.

Q: Is your company in the midst of any new developments?

Nigro: W&H is in constant R&D mode. We invest a significant amount of our annual turnover back into our huge R&D department and technology center. It’s recognized worldwide by processors and resin manufacturers who make use of our facilities year-round.

Last November at the 2013 K-Show in Düsseldorf, W&H unveiled its complete redesign of our flagship
Varex II blown film line. It incorporates many of our well- known patents such
as IBC, oscillating haul-off, auto-die gauge control (Optifil), but goes much farther with many energy-efficient features, our new Arctis air ring, improved extrusion, and our intuitive Procontrol integrated logic and control system for ease of operation.

DeSpain: At Reifenhauser we are always working on new developments, and if you visited us during the recent K-Show or one of our open houses, you would see how we live up to our motto of “Rethinking technology” not only in our blown film systems, but across the board on all of our products.  From our Ultra Fusion system – which includes twin screw extrusion on a blown film line to compound in-line and avoid the masterbatch costs – to our new sheet stack that allows thinner products to be run, we are always working
on something

Yadav: Yes. To encourage the small converters who are unable to install a 3-layer line due to price- and investment barriers, we are launching an entry-level line to suit converters whose monthly requirements are around 60,000 – 150,000 pounds per month. The quality of these films will be similar to high-output, fully loaded lines.

Nunes: Alpine is constantly involved in new developments through our intensive R&D, as well as working directly with customers for their specific needs.

We are preparing our new 11-layer X-die technology that will provide the ultimate versatility and performance.  More layers provide producers with unlimited possibilities to produce films with exacting properties and performance characteristics with material optimization, without sacrificing the ability to produce conventional three-layer films of varying layer ratios.

Q: Do you feel there are any improvements that need to be made in the blown film sector? If so, please elaborate.

DeSpain: There are always improvements to be made, whether it is higher throughputs, tighter film tolerances, flatter film, etc., processors are always looking at ways to improve the process.

Nunes: There is always room for improvement and all reputable equipment and resin suppliers continue to strive for improvement towards excellence.  Most of the comments provided within this article are evidence of that. 

The concern for producers and converters that have aging equipment is: will they be able to compete with new technology without significant investments and upgrades?  Assets that are unable to compete with today’s technology will need to be upgraded or replaced.  To paraphrase something we have said for many years and heard someone elaborate on recently “Don’t fall in love with your assets, they don’t love you back, they HOLD you back!”

Yadav: There are many improvement areas where the industry is trying to come up with new inventions and innovations. No need of any heat addition through heaters or cooling through blowers is still to be achieved. Use of melt pump and continuous screen changers in multi-layer blown film lines are also to be achieved. Although the die design has reached a very high maturity level, there are still improvements to be made in internal spiral geometries with built-in flexibilities. The cooling systems for the bubble surfaces before and after frost line also still have a lot of scope for improvement.

Nigro: If a processor already has the right equipment and infrastructure to compete, then operator training and plant safety are procedures that can make the difference between a market leader and an also-ran. W&H provides extensive training, both classroom and hands-on, in our Technology Center in Lengerich, Germany and specifically tailored training and safety classes at a customers' facility. We have seen vast improvement in quality and efficiency when companies take advantage of these programs.

Q: What are your customers requesting in terms of products or services?

Yadav: With our absorbed Canadian technology, European performances and Indian manufacturing, our customers are requesting prices offered in the Chinese market.

Nigro: Our customers expect and deserve the highest quality and most dependable equipment available. With the relentless growth and competition in our industry today, it is simply not possible for processors to compete unless they run state-of-the-art, highly energy-efficient and high-output extrusion lines.

W&H provides exactly that, with our blown-film- (Varex), cast-film- (Filmex) and water-quench (Aquarex) extrusion lines. Combined with services such as our 24/7 live information and diagnostic center; real-time remote system access; quick spare parts turnaround; and a large team of seasoned service technicians and process engineers, W&H shows its commitment

DeSpain: Today, without question, customers demand fast service, quick spare-part delivery when needed and technical assistance, whether on new line purchases or upgrading existing equipment.

We have developed our web shop to allow customers to order parts online and see what is in stock, with delivery within 24 hours. When customers need things, they want them now – not later –and we must address these needs in order to survive.

Nunes: Performance and service – and Alpine is committed to providing both.