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Quality, versatility, productivity.

Faced with rising production costs and slowing growth in traditional markets, blown film processors need to develop new strategies to compete in today's challenging economic environment. Upgrading extrusion equipment to improve product quality, productivity, and production versatility increasingly seems to be a necessary tactic for success - or just for survival.

Those who can produce superior goods without sacrificing production rates clearly have a leg up on their competition. Quality advances can help processors break into new markets, cut production costs, and even improve productivity. For those whose bread and butter is specialty films for laminating or packaging, quality has already become the paramount concern. Market share for these products hinges directly on their quality, notes Alpine American senior v.p. Werner Hofer. Equipment manufacturers argue, however, that other types of processors still think of quality improvements as a luxury rather than necessity. "Some processors will tell you they care about quality, but they really want rate," says extrusion systems sales manager Andrew Wheeler of Windmoeller & Hoelscher. "Suggest anything that would lower their output and they say, |Forget it."

Yet, producing better products need not entail a sacrifice. Instead, quality advancements often accompany a host of related productivity benefits because the same equipment that makes superior products can have a positive effect on all of manufacturing's economic factors.

Better gauge control, for instance, means better film. At the same time, it creates opportunities for downgauging by enabling tighter adherence to specifications, ultimately chopping resin costs. Robert Krycki, president of Future Design Inc., notes that downgauging increases yields and can also permit faster line speeds if the downstream equipment is up to the task. To take another example, manufacturers of control systems that help improve quality changeovers and reductions in both scrap and downtime with the aid of these controls. Similar reasoning extends to dies, extruders or any other extrusion component when it cuts production costs or boosts rates while helping to make a better product. Quality, then, isn't just about meeting tight product specs, but also about more economical manufacturing.

Along with quality improvements, increasing production versatility of extrusion equipment ranks high as an effective survival tactic because it allows film processors to roll with fluctuating markets and resin prices. "Recently, the two most popular products our customers want to run are Everything and Anything," says Peter Gates, product manager for blown film dies at Davis-Standard. Though versatility on a given extrusion line and quality across the entire range of products are not always compatible, the same equipment upgrade can often benefit both areas.

Coextrusion exemplifiers this point - while producing superior products with less resin, it also presents unparalled opportunities for product diversity. Hartmut Ossmann, sales manager at American Barmag, attributes a recent "rekindled interest" in coextrusion to its application in areas as diverse as processing post-consumer scrap and making multilayer, EVOH-or nylon-based barrier films. Likewise, an air-collapsing frame can help preserve the quality of a whole range of specialty and stretch films or just a single product.

Alpine technical director Robert Hitchins points out that the flexibility to run LDPE, LLDPE and HDPE on a single system allows processors to "keep up with resin prices and markets." Some argue, however, that the need for versatility may apply more to smaller processors. W&H's Wheeler contrasts his larger customers "who want to run one product and run it well" with smaller custom houses that exist only by virtue of their ability to make several products.

Despite the potential benefits from raising quality, versatility or productivity, equipment manufacturers claim that advances in extrusion technology, materials and markets over the past decade have left a lot of processors behind the times. Davis-Standard's Gates claims that "any die over five years old is obsolete." Filmaster sales v.p. Frank Goffreda voiced the same opinion on air rings. Ironically, the same recessionary conditions that put a damper on new equipment purchases also engender a greater need to upgrade existing lines to stay competitive.

Fortunately, there are a host of affordable, retrofittable components and hardware packages that can increase quality, versatility and productivity. At the other end of the price spectrum, more sophisticated upgrades are almost like getting an entirely new line.


Upgrading existing lines has become an especially attractive tactic in these frugal times because it can couple small investments with big paybacks. Equipment companies that pursue aftermarket upgrades reported a dramatic upswing in the popularity of retrofitting. "The retrofit part of our business has been very good this year, but that's not unexpected in this kind of economy," says Anthony Cline, general plastics business manager at Davis-Standard. Battenfeld Gloucester has similarly experienced an increasing interest in retrofits that senior blown film product manager Bill Hellmuth links to economic conditions. Meanwhile, the Western unit of Egan Machinery has seen a "return to its roots" with increased component sales, according to Ron Beaudoin, blown film product manager. Merritt Extruder Corp. has also seen an interest in getting more performance from existing equipment.

Even companies not normally associated with retrofitting have seen some activity it that area. Matt Bangert, sales v.p. at Reifenhauser Film Systems, has found customers "putting an emphasis on improving quality" by upgrading equipment that's already in place. And Wheeler notes that W&H recently fitted one of its Optifil P automatic dies to a line made by another company.

The magnitude of gains associated with retrofitting varies, but cost savings are impressive across the board. Assuming that the nips, winders and towers can be saved, even an upgrade from single extruder to coextrusion costs one-third to one-half as much as a brand-new line. "You can change the nature of an existing line for under half the money of a new one," notes Alpine's Hitchins.


Whether you're shooting primarily for enhanced quality or productivity, the advantages of installing an up-to-date die can't be undervalued. Expanding on his claim that many existing dies are obsolete, Davis-Standard's Gates explains that the staggering number of new materials coming onto the market necessitates having current die technology if you want flexibility to run different resins. As for productivity, newer dies often permit quicker changeovers and lowere maintenance downtime, and they can handle increased throughput rates when compared with the dies of 10 years ago.

Davis-Standard, for instance, has made several design changes aimed at boosting both quality and productivity. First, the company manufacturers its dies with AISI 4340 steel hardened to 32 Rockwell C. Flow surfaces can then be highly polished to minimize melt degradation and aid purging. These benefits, however, do carry a price premium of 20% for the added machining and polishing time needed for the harder steel, Gates concedes.

Davis-Standard dies are custom designed by computer for different applications, but Gates says all designs feature longer-than-average spirals with at least an eight-port overlap. These reportedly eliminate dead spots and provide better flow control over land areas. Gates says these design changes completely eliminate port lines and optical defects caused by the die.

Associated gauge-control improvements allow downgauging, while other productivity gains come from faster changeovers and maintenance-saving features, he adds. Aside from improving quality, Gates claims the increased port-overlap drops changeover times by one-third when compared with dies that have a more standard six-port overlap. He likens the ease and speed of changeovers to "flicking a light switch" and claims color changes can be accomplished in 1-2 min. The ability to perform common maintenance functions without taking the die off line further trims downtime.

Similarly, Alpine recently doubled the number of spirals on its dies for better melt homogeneity and improved gauge control. Hitchins says this new design can help reduce gauge variations to 5-8%.

Western has also focused on gauge variation, approaching the problem with added spirals and shear-reducing designs. Beaudoin says that upgrading to the latest Western die can cut gauge variation in half for obvious material savings. He also touts the dies' versatility for running a wide range of polymers with different viscosities.

Western, Sano Inc. and W&H differ from other equipment suppliers in building dies with nonadjustable lips. The companies assert that this approach ensures consistent gauge control and eliminates potential operator error. Sano technical director Rick Knittel says his company couples the non-adjustable design with low machining tolerances to bring gauge variation down to 5%.

As for versatility, many suppliers now design their dies specifically to run the broadest latitude of resins. To illustrate this point, Gates notes that one customer was able to run sample rolls of seven different combinations of LDPE, LLDPE, medium-molecular-weight HDPE and HMW-HDPE on a three-layer die within a 3-hr time span. He acknowledges, however, that tradeoffs do exist, since no one die can run all materials at equal quality levels. All the companies surveyed also offer multilayer capabilities.

Among recent developments, the newest coex die from Brampton Engineering reportedly can handle temperature variation of up to 100 F between the different layers. Jones says this ability is of "critical importance when temperature-sensitive resins are being processed." Gloucester, meanwhile, has introduced a three-layer, nonrotating IBC die designed to speed changeovers and boost quality by simplifying adjustments and maintenance.


Like dies, many extruders have been made obsolete by the proliferation of new materials and ability of modern equipment to achieve higher throughputs, equipment manufacturers argue.

HDPE exemplifies the changing demands upon extruders. Existing LL/LDPE lines can be changed to run HDPE, whether in a coex or monolayer structure. Alpine and Reifenhauser tout the ability to downgauge as much as 25% and to tap a growing market as key benefits that can offset slightly lower production rates and higher material costs. Bangert notes, however, that the relative prevalence of older extruders complicates such an upgrade because a smooth-bore design can't simply be changed to run HDPE well. So, converting LL/LDPE lines usually requires at least a new grooved-feed extruder, not to mention a die and downstream equipment. In the "best-case scenario" where existing equipment can be used, Bangert estimates an upgrade to HDPE could be accomplished for as little as one-third the cost of an entirely new line.

As HDPE becomes increasingly popular, more extruders will require grooved feed sections - which are also recommended for LLDPE. Alpines' Hitchins says his company designs extruders with versatility in mind, so they can run either HDPE, LDPE or LLDPE with only "minor screw modifications." Bangert makes a similar point: "Clearly, grooved feed gives you the most versatility." W&H has built grooved-feed extruders for the last 10 years, Wheeler says.

Gloucester, too, stresses versatility and offers grooved-feed and smooth-bore extruders, coupling both types with proprietary barrier screws. Davis-Standard, Western and W&H also emphasize barrier screws in their extruders. Davis-Standard technical director William Kramer says the barrier screw provides both higher and more consistent output, thereby boosting productivity as well as quality. Western adds that barrier screws allow a reduction in screw speed and melt temperatures, improving both melt quality and energy efficiency. Though barrier screws are more expensive, Davis-Standard claims the 5-10% output gains they bring can pay for any cost differential.

Due to the growing need to process resin blends and reclaimed material, several manufacturers have increased the L/D ratios on their extruders and now offer 30:1 as standard. Sano's Knittel says the longer extruders allow for improved mixing with less shear stress. Reifenhauser has taken a similar approach, according to blown film manager Hector Marchand, because of the special needs associated with running in-plant scrap and post-consumer reclaim. Both companies, as well as W&H, now make the longer barrels standard and offer shorter extruders only at customer request. Western also offers the longer size and Davis-Standard's specialized, dual-diameter recycling extruders have a 30:1 L/D.

Extruders present other upgrade opportunities. Davis-Standard additionally recommends gearbox retrofits as an easy way to increase output rates and consistency. Gloucester builds air-cooled extruders, which cost roughly 7% less than comparable water-cooled models and are also cheaper to maintain, Hellmuth says.



Though individual designs differ, equipment makers agree that adding a modern air ring to an older line can boost both production rates and quality by up to 30%. Macro Engineering claims its latest design can even deliver a 15-30% rate increase over even brand-new air rings.

In general, the improvements over older rings come from advances in aerodynamic design for better bubble stability, faster quench rates and more consistency - all of which translate not only to rate increases and less downtime but also improved film clarity and gauge control. "When ever you keep the bubble more stable, you get better quality," says Mirek Planeta of Macro.

The price of these benefits is relatively low too, starting at under $10,000 for smaller air rings. Yet many equipment manufacturers say far too many processors are still using obsolete and therefore less efficient designs - if they use an air ring at all. Based on his visits to processors, Filmaster's Goffreda estimates that air rings today average 10 years old. Western's Keller also reports that "a phenomenal number" of outdated rings are still up and running.

As the closest thing to a stock item in film equipment, most suppliers appear to have access to similar air-ring technology, and most are willing to supply retrofits for equipment from other manufacturers.

Additional cooling technologies such as internal bubble cooling (IBC) or various iris devices can be added to extend bubble stability and rate gains offered by air rings (see Technology Newsfocus). Alpine claims a 100% gain in high-stalk HDPE output from the combination of its Internal Cooling System, air ring and PEAC system - the latter being an external cooling collar that channels air from the air ring along the exterior of the bubble. Wheeler also reports a doubling of HDPE output rates when comparing W&H dies with IBC to systems without internal cooling. Western recommends that its air rings be coupled with a double-iris device called Entrac for similar gains.

For retrofitting, however, Wheeler and Rick von Kraus of Addex Inc. both note that IBC can only be added to an older line if the processor had the foresight to buy a compatible die in the first place. Otherwise, an IBC upgrade would have to accompany more substantial upstream changes. W&H, for instance, sells IBCs only in conjuction with a die, Wheeler says.


Any system that can tighten process control has obvious quality implications, but manufacturers of computer control systems focus more on associated productivity gains. Suppliers note, for example, that the recipe-storing abilities of many control systems can cut downtime and scrap by getting lines up and running on-spec faster. And gravimetric-based, or weigh-feeding, extrusion control systems are praised unanimously by equipment manufacturers for improving gauge control in the "machine direction" and are readily available from several suppliers.

The top of the line in both features and price are automatic, self-adjusting gauge control systems. Though prices start at over $100,000, all the manufacturers who offer these systems claim they can slash circumferential gauge variations by half for hefty material savings, quality improvements, faster setup times, and scrap reduction. W&H's system, the first and by far most widely used, focuses compressed air on sections of the die body's outer wall, which in turn cools appropriate areas of the melt. Reifenhauser has built systems that mechanically adjust segments of the die lip. Battenfeld Gloucester, Kiefel Inc., and now Alpine use a segmented air-ring approach with the latter two focusing cool air on specific zones of the bubble. At least some of these systems can be retrofitted. In fact, Reifenhauser has quoted on modifying existing non-Reifenhauser dies to accept its new Reicoflex II for significantly less money than an entirely new system. (see PT, Aug. |91, p. 43). Similarly, Battenfeld Gloucester has retrofit its Autoprofile profile Air Ring, which works by applying heat to thin the bubble where necessary. Both Bangert and Hellmuth say their upgrades can cost just over $100,000 as long as the line has compatible die, controls, gauging system, and gravimetrics in place.


With price tags between $100,000 and $500,000, coextrusion upgrades, like auto-die systems, may represent the Cadillac of retrofits. But in terms of versatility, coextrusion's unparalleled potential could justify the price for monolayer processors who seek to compensate for fluctuations in commodity film markets. Jones of Brampton Engineering says coextrusion "gives you the ability make a higher value-added product on what may have been a commodity-producing line" and enter new markets. Conversely, Sano's Knittel says a customer who primarily manufacturers food packaging was able to minimize the effects of an overcapacity situation by producing a monolayer, non-packaging film on an otherwise idle coextrusion line.

Even in commodity applications like trash liners, coextrusion can allow processors to make stronger film with less resin, thus saving on material costs. According to Davis-Standard's Gates, even a coex structure with two layers of the same resin yields 10% better physical properties than monolayer film of the same thickness. "Single-layer just can't compete," he says. "The majority of our proposals are now for coex." Reifenhauser's Bangert adds that the associated opportunities for downgauging can bring material cost savings ranging between 20% and 30%. Equipment makers also note that coextrusion helps processors meet growing demand for post-consumer recycle content by allowing them to "bury" the reclaim between virgin layers.

The popularity of coextrusion has already grown to the point where two companies have instituted standard upgrade programs. Western offers basic packages that upgrade monolayer lines to three-layer capability. They consist of a second extruder, three-layer die and dual-lip air ring. The company can also offer upgrades to five layers. Filmaster has a similar retrofit program for three and five layers. Davis-Standard's Gates says three-quarters of his coextrusion orders are retrofits. His company will upgrade a monolayer line with two additional extruders, controls, and a 20-in., oscillating, three-layer die for $400,000 - less than half the cost of a brand-new line. Battenfeld Gloucester, Alpine and Reinfenhauser and have also done some coex retrofits, though the latter two companies focus on supplying new lines.


Upgrading may be good way to make do with older equipment while enhancing your competitive ability. But equipment makers are unanimous in putting to rest any notions of a free lunch.

Air rings aside, most situations require the replacement of a combination of components in order to obtain maximum quality and productivity gains - not always an inexpensive proposition. For example, as Brampton's David Jones notes, just replacing the extruder and die could equal 15% of a new line's cost. Or given the added complexities of coextrusion, some suppliers prefer a stationary coex die, potentially imposing the cost of an oscillating hauloff to distribute gauge variations.

Coextrusion upgrades have other downside factors that must be measured against their benefits. Multilayer capabilities bring about increased operating costs and complexities. Going multilayer requires more than just an extruder and die, but also a suitable control system and, most suppliers agree, gravimetric feeding.

Alpine's Hitchins joins others in arguing that a key factor in determining whether a retrofit is economically sensible is whether the existing nip, tower and winder can be utilized as part of the upgrade. While acknowledging that some fairly radical improvements can be made while leaving the downstream equipment intact, Reinfenhauser's Bangert cautions that "some equipment just isn't worth saving." Aging or inappropriate downstream equipment simply can't always handle the increased rates or maintain the quality improvements a retrofit can bring.

While upgrading downstream equipment often costs more, it too can offer substantial quality-related benefits. Take oscillating hauloffs: they can be retrofitted to produce more uniform and salable rolls. W&H's Wheeler links the proliferation of oscillating hauloffs to converters' growing demand for "accountability" from their film suppliers.

Yet, unlike the previously mentioned upstream retrofits, oscillating hauloffs don't actually fix film quality problems, but rather "hide" gauge defects by distributing them across the roll. Moreover, the relatively high cost and physical bulkiness of most oscillating hauloffs made them unlikely retrofit candidates for many processors. Addex, however, offers an unusually compact, 3-ft-high oscillating hauloff system specifically designed for aftermarket installation. It's competitive in cost with other oscillating units. And Battenfeld Gloucester reports retrofits for its oscillating hauloff unit. "It's not always easy, but the problems are not insurmountable," Hellmuth says. Also, two other suppliers have conceived of novel aftermarket approaches to oscillation (see sidebar).

In the end, all the manufacturers offered the same caveat about retrofits - an extrusion line is only as good as its weakest component. Says Kiefel president Steven Engel, "A lot of the time, you're better off with a whole new system."

A New Twist on


Novel oscillating devices have just been introduced by newcomer Sierra Technologies and Macro Engineering. Both companies tout their systems as alternatives to the more expensive and bulky oscillating haul-offs.

Positioned between die and collapsing frame, Sierra's Randomizer gently grips and twists the still-round bubble perimeter. The device "grasps" the bubble by drawing a vacuum through an octagonal roller pattern. The Randomizer reportedly causes no lateral film-edge movement and even acts as a bubble stabilizer. The company says the device also costs 75% less than comparable oscillating hauloffs and can be installed without removing existing equipment.

Macro's approach adds an oscillating device to existing bubble cages which then twist the bubble. Macro's Mirek Planeta says the system can be had for as little as $15,000.
COPYRIGHT 1992 Gardner Publications, Inc.
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Copyright 1992, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:includes related article on production machinery
Author:Ogando, Joseph
Publication:Plastics Technology
Article Type:Cover Story
Date:Feb 1, 1992
Previous Article:Here's more on the newest SMA resins.
Next Article:Buyers' guide to twin-screw compounders.

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