A 360-degree look at resin conveying systems: types, operation, economics, design, installation, components and controls.
This Knowledge Center provides an overview of resin moisture and the drying process, including information on the best drying practices for your manufacturing facility. 60ga transparent stretch film
Combat the skilled labor shortage using this comprehensive resource to train your own plastics processing experts.
Deep dive into the basics of blending versus dosing, controls, maintenance, process integration and more.
This Knowledge Center provides an overview of the considerations needed to understand the purchase, operation, and maintenance of a process cooling system.
Learn about sustainable scrap reprocessing—this resource offers a deep dive into everything from granulator types and options, to service tips, videos and technical articles.
Despite price increase nominations going into second quarter, it appeared there was potential for generally flat pricing with the exception of a major downward correction for PP.
First quarter was ending up with upward pricing, primarily due to higher feedstock costs and not supply/demand fundamentals.
Despite earlier anticipated rollover in prices for most of the volume commodity resins, prices were generally on the way up for all going into the third month of first quarter.
While price initiatives for PE and PVC were underway, resin prices had rollover potential for first two months of 2024, perhaps with the exception of PET.
Flat-to-downward trajectory for at least this month.
A mixed bag, though prices likely to be down if not flat for all this month.
Resin drying is a crucial, but often-misunderstood area. This collection includes details on why and what you need to dry, how to specify a dryer, and best practices.
Take a deep dive into all of the various aspects of part quoting to ensure you’ve got all the bases—as in costs—covered before preparing your customer’s quote for services.
In this collection of articles, two of the industry’s foremost authorities on screw design — Jim Frankand and Mark Spalding — offer their sage advice on screw design...what works, what doesn’t, and what to look for when things start going wrong.
In this collection, which is part one of a series representing some of John’s finest work, we present you with five articles that we think you will refer to time and again as you look to solve problems, cut cycle times and improve the quality of the parts you mold.
Gifted with extraordinary technical know how and an authoritative yet plain English writing style, in this collection of articles Fattori offers his insights on a variety of molding-related topics that are bound to make your days on the production floor go a little bit better.
In this three-part collection, veteran molder and moldmaker Jim Fattori brings to bear his 40+ years of on-the-job experience and provides molders his “from the trenches” perspective on on the why, where and how of venting injection molds. Take the trial-and-error out of the molding venting process.
Mike Sepe has authored more than 25 ANTEC papers and more than 250 articles illustrating the importance of this interdisciplanary approach. In this collection, we present some of his best work during the years he has been contributing for Plastics Technology Magazine.
In this collection of content, we provide expert advice on welding from some of the leading authorities in the field, with tips on such matters as controls, as well as insights on how to solve common problems in welding.
Mold maintenance is critical, and with this collection of content we’ve bundled some of the very best advice we’ve published on repairing, maintaining, evaluating and even hanging molds on injection molding machines.
Thousands of people visit our Supplier Guide every day to source equipment and materials. Get in front of them with a free company profile.
NPE2024: Following the company’s recent partnership buyout, new North American geographic territories are in its sight.
New materials and machinery offer processors the means to run their businesses more efficiently and more inline with the circular economy. But you have to say yes.
Firing up a cold blown-film line after a shutdown involves multiple pieces of equipment that all interact. Here’s a look at those components individually and some best practices on how to get your line up and running as quickly and safely as possible.
NPE2024: Purgex team hosting technical seminars throughout the show with industry pros.
NPE2024: Advancements and forward-thinking initiatives in plastics manufacturing will be highlighted.
Plastics processing activity didn’t make its way into expansion territory in March, but seems headed in that direction.
Beyond Plastic and partners have created a certified biodegradable PHA compound that can be injection molded into 38-mm closures in a sub 6-second cycle from a multicavity hot runner tool.
There are many things to consider, and paying attention to the details can help avoid machine downtime and higher maintenance costs. In this installment, the focus is on design and placement of sucker/puller pins.
Despite last-minute design changes and other unexpected roadblocks, thermoformer TriEnda works with a key supplier on innovative reusable shipping container.
NPE 2024: Teknor Apex discusses its recyclable thermoplastic elastomers and much more between Tuesday and Thursday
Topping five other entries in voting by fellow molders, the Ultradent team talks about their Hot Shots sweep.
Serendipitous Learning Opportunities at PTXPO Underscore the Value of Being Present.
Introduced by Zeiger and Spark Industries at the PTXPO, the nozzle is designed for maximum heat transfer and uniformity with a continuous taper for self cleaning.
Ultradent's entry of its Umbrella cheek retractor took home the awards for Technical Sophistication and Achievement in Economics and Efficiency at PTXPO.
technotrans says climate protection, energy efficiency and customization will be key discussion topics at PTXPO as it displays its protemp flow 6 ultrasonic eco and the teco cs 90t 9.1 TCUs.
Shibaura discusses the upcoming Plastics Technology Expo (PTXPO) March 28-30
The 101-year-old German company will continue to manufacture machines from its sprawling operation in the Black Forest, but for the first time it will add assembly outside of the country.
Manufacture of several core products, including specific models and sizes of injection molding machines, automation and auxiliaries have shifted out of Austria and into Hungary, Bulgaria and Turkey.
NPE2024: The competition is a collaboration between Hillenbrand, Net Impact and Coca Cola.
The Austrian maker of injection molding machines and automation announced at NPE2024 that it will establish optimized sales, logistics and production structures for its three major regions: Europe, Asia and America.
The Miami-based supplier of various plastics technologies also featured a melt-temperature testing system, closed-loop cooling manifolds and its successful mold crane offering.
The Korean maker of injection molding machines featured eight machines in its nearly 14,000-square-foot booth with additional presses at Yushin and Incoe’s booths, as it targets 20% market share.
Mixed in among thought leaders from leading suppliers to injection molders and mold makers at the 2023 Molding and MoldMaking conferences will be molders and toolmakers themselves.
After successfully introducing a combined conference for moldmakers and injection molders in 2022, Plastics Technology and MoldMaking Technology are once again joining forces for a tooling/molding two-for-one.
Multiple speakers at Molding 2023 will address the ways simulation can impact material substitution decisions, process profitability and simplification of mold design.
When, how, what and why to automate — leading robotics suppliers and forward-thinking moldmakers will share their insights on automating manufacturing at collocated event.
As self-imposed and government-issued sustainability mandates approach, injection molders reimagine their operations.
August 29-30 in Minneapolis all things injection molding and moldmaking will be happening at the Hyatt Regency — check out who’s speaking on what topics today.
Get your clicking finger in shape and sign up for all that we have in store for you in 2023.
Molding 2023 to take place Aug. 29-30 in Minnesota; Extrusion 2023 slated for Oct. 10-12 in Indiana.
You likely either know a company who uses dry ice to clean or perhaps you are considering investing in the process. This webinar is your opportunity to gain insight into the science and data behind the process. Cold Jet will share independent testing studies; customer studies, testimonials and case studies; and governmental position statements. It will also review the most common application in plastics — cleaning various types of molds — and why utilizing microparticle dry ice is so popular. Agenda: Dry ice blasting and how to adapt to various applications Insight to the non-abrasive claims of dry ice blasting Where in plastics it is most used: videos and case studies Monitoring the process for data-driven decisions
Cooling time is typically the longest step of the molding process. How can you make it more productive? Learn how cooling time can be turned into production time by running two molding processes simultaneously on a single molding machine. For longer cycles, this can mean twice the productivity. In this webinar, you'll learn more about the Shuttle Mold System and how to calculate its potential productivity impacts for your application. Agenda: Learn how the Shuttle Mold System can deliver value to your business See the recent technical updates made to the system Calculate the potential impact on productivity
Discover possible applications in large format printing including layup tools, transport modules, film fixation devices, design components and enclosures. These are used in various industries such as automotive, aerospace, architecture and many others. Agenda: Possible applications in large format printing: layup tools, transport modules, film fixing devices, design components and enclosures. Process reliability and component quality in component production Pros and cons of the technology Sneak peek into current development projects—What will the large format printing of tomorrow look like?
In this webinar, Cold Jet will discuss some of the ways processors use dry ice such as in-machine mold cleaning at operating temperatures, de-flashing or de-burring parts, improving OEE scores, extending mold life, cleaning parts before painting, post-processing 3D printed parts, lowering GHG emissions, and monitoring and reporting the process. Agenda: Cold Jet Overview & Dry Ice 101 Understanding the Process and Fine-Tuning Techniques Case Studies: Applications in Plastics Monitoring the Process Exploring the Importance of Dry Ice Cleaning in an ESG Era
Finding it hard to get technical talent? Experiencing the pain of a knowledgeable, long-term employee's retirement? Learn how plastics processors are training generative AIs on their operations and unlocking the value from their tribal knowledge. Plastics processors are training generative AI models on their operations — from machine manuals to tools, polymers, procedures, maintenance records and engineering projects. Applying generative AI in the right ways can lower plastics processors' costs, improve overall equipment effectiveness (OEE) and upskill teams. In this webinar, you'll learn how to deploy AI technical assistants to your teams, what works and what doesn't, and how to use AI to build an organization that never loses tribal knowledge and fosters inter-team collaboration. Agenda: What is generative AI and how can its cognitive abilities be applied to plastics? Case study: how an injection molder trained a large language model on manuals and maintenance records to reduce downtime Case study: using generative AI in engineering teams to improve product development Live demonstration of a generative AI deep-trained on plastics knowledge Looking to the future: five predictions for an AI-augmented workforce in plastics
Turnaround time can be as low as 24 hours, although two or three days might be more typical. Rapid prototyping like this is especially useful to quickly identify critical end-use part geometries that will work in the molding process. Key components include material choice, 3D printing technology selected, use of adaptable mold bases for the mold inserts and implementation of appropriate injection molding process conditions. This presentation will review work conducted toward the assessment of a high-stiffness, high-temperature-resistant ceramic modified urethane acrylate for injection molding inserts. Agenda: Guide for 3D-printed injection mold inserts Optimization of digital light processing (DLP) printing Compatibility with various thermoplastics Real-world application success stories
As an annual conference and supportive community, Moms in MFG is designed exclusively to support working parents and caregivers in manufacturing. Moms in MFG is dedicated to empowering and connecting moms and caregivers in manufacturing. In addition, it aims to assist manufacturing companies in discovering how they can provide the necessary support and create a nurturing environment for caregivers in manufacturing. Through valuable content, networking opportunities, and collaboration with fellow industry professionals, Moms in MFG celebrates the unique journey of moms and caregivers in manufacturing.
The Society Plastics Engineers (SPE) Extrusion Division and the SPE Eastern New England Section will co-host the Screw Design Conference-Topcon on June 19-20, 2024 @ UMass Lowell in Lowell, MA. This highly technical program will focus upon screw design principles for single and twin screw extruders with wide ranging topics relating to screw designs for feeding, melting, mixing, venting and pumping plastics products and parts. Areas of focus will include screw designs for melt temperature and gel management, gel minimization, bioplastics, recycled materials and foaming. In addition to the technical sessions, a tour of the UMass Lowel Plastics Processing Laboratories will be integrated into Day 2 of the event. This program is not just for screw designers, but to help anyone responsible for any type of extrusion operation to evaluate existing extrusion equipment; and also to prepare for future projects. Price to attend: Less than $1000! Registrations will be accepted in early 2024. Call for papers – To be considered to give a presentation, please submit a talk title and abstract on or before December 15 to: Technical Chair: Eldridge M. Mount III, e-mail emmount@msn.com Corporate sponsorships - A limited # of corporate sponsorships (15) are available on a 1st come basis. Included is a 6’ tabletop display (must fit on table), denotation in all promotional activities, and 1 no charge registration. To become a sponsor contact: Charlie Martin, Leistritz Extrusion, e-mail cmartin@leistritz-extrusion.com, cell 973-650 3137 General information: A reception on Day 1 and a tabletop display area will allow the attendees to meet and discuss state-of-the-art screw technologies with industry experts. The SPE Extrusion Division will issue a “Screw Design Certificate” to all participants who have attended the program. Students are encouraged to attend and will receive a discounted rate. For additional information contact: Program Chair: Karen Xiao, Macro Engineering, KXiao@macroeng.com
Debuting in 2010, the Parts Cleaning Conference is the leading and most trusted manufacturing and industrial parts cleaning forum focused solely on delivering quality technical information in the specialized field of machined parts cleansing. Providing guidance and training to understand the recognized sets of standards for industrial cleaning, every year the Conference showcases industry experts who present educational sessions on the latest and most pressing topics affecting manufacturing facilities today. Discover all that the 2022 Parts Cleaning Conference has to offer!
Presented by Additive Manufacturing Media, Plastics Technology and MoldMaking Technology, the 3D Printing Workshop at IMTS 2024 is a chance for job shops to learn the emerging possibilities for part production via 3D printing and additive manufacturing. First introduced at IMTS 2014, this workshop has helped hundreds of manufacturing professionals expand their additive capabilities.
Formnext Chicago is an industrial additive manufacturing expo taking place April 8-10, 2025 at McCormick Place in Chicago, Illinois. Formnext Chicago is the second in a series of Formnext events in the U.S. being produced by Mesago Messe Frankfurt, AMT – The Association For Manufacturing Technology, and Gardner Business Media (our publisher).
In the hyper-competitive stretch-film market, more layers often mean more market share. Moving from five layers to seven or nine can give an edge through higher performance or reduced cost.
Downgauging and sophisticated structures make today's stretch film go farther. Pliant's newest seven layer line puts 9,000 ft of 51-gauge stretch film on a foll, vs. only 5000 ft of conventional 80-gauge film.
Making seven-layer film with high mLLDPE content at high output rates requires North America's largest-diameter cast chill roll. (Photo: Pliant)
Pinnacle Films makes only seven-layer, high-performance stretch films using mLLDPE. Last year it added a second seven-layer line.
High-performance seven-layer films can stretch farther than most wrapping machines can pull them, even on a load like this with protruding corners. (Photo: Highlight Industries)
The world's first nine-layer stretch-film line at Sigma Stretch Films doesn't use mLLDPE. Its extra layers create a commodity film less expensively.
Automatic core loading, roll unloading, and boxing is more prevalent in Europe, where labor costs are higher. (Photo: SML)
Stretch-film processors were used to a market that doubled every five years. Between 1985 and ’90, demand grew from 250 million lb/yr to 500 million lb, and from 1990 to ’95 it swelled to 1 billion lb. Even as recently as five years ago when five-layer stretch film swept the market, resin demand still grew in double digits. But for the past couple of years, stretch-film resin demand stalled at around 1.4 billion lb. Stretch film is 65% to 70% cast film, mostly for machine wrapping, and 30% to 35% blown film, mostly for commodity hand wrap and a few highly puncture-resistant specialty films.
Competition in this film sector is a cutthroat fight for market share. Processors’ profits are often in fractions of a cent per lb, and the rate of new machine installations is down to only a couple a year. The only North American processors who appear to be growing and reinvesting are those making the new highly layered films.
When five-layer stretch film was introduced in the mid ’90s, it replaced a lot of one- and three-layer films composed of hexene and/or octene LLDPE. It required a fourth extruder and a five-layer feedblock and allowed use of less-expensive butene LLDPE reinforced with thin support layers of then-new metallocene LLDPE. A typical five-layer structure could be A-B-C-B-A with 10% hexene LLDPE surface skins, 20% mLLDPE subsurface layers, and a 40% butene LLDPE core.
Stretch-film machines grew larger and output rates rose along with the number of layers. The standard five years ago was five 20-in. rolls up and three layers. Now it’s six rolls up and five layers. Five-layer stretch now accounts for 40% of all stretch film made in North America, and metallocene resin use has grown from nothing in 1995 to 12% of all LLDPE used in stretch film.
But mLLDPE is pricey, so processors went to seven and nine layers mostly to enable use of more wide-spec or butene LLDPE and less mLLDPE—and, in a few instances, to create higher-performing films. For example, all makers of seven-layer stretch film say they can replace thicker films having fewer layers without sacrificing load-retention capacity.
For the past few years, all the cast stretch-film lines installed in North America have been designed for five or more layers. They set new records for numbers of layers—first seven, then nine. Now processors and machine builders are talking about 11, 14, and even 70 layers.
“We commercialized microlayer feedblock technology for barrier properties, but stretch film could also be an application. We can produce layers at the angstrom thickness level [1 angstrom = 0.0001 micron] or tenths of a percent of film thickness,” says Gary Oliver, senior corporate scientist at Cloeren Inc. “Processors are interested, but nobody is testing it yet.”
Most of the new highly layered lines went to new players in the stretch film business, bringing shifts in market share. Chaparral Films in Mauriceville, Texas, was the first to come out with five-layer stretch film in 1994 and reportedly was the first with seven layers in ’96, though this was never publicly announced. Chaparral made even higher numbers of layers on a developmental basis, according to sources at Cloeren, which built the dies and feedblocks and was an investor in Chapparal. (ITW Stretch Packaging Systems in Glenview, Ill., bought Chaparral in 1996 but makes only five-layer films.)
Poly Rafia in Atlacomulco, Mexico, was next in line with seven-layer capability in 1996 and added a second line in 2001. When Quintec Films Corp. in Shelbyville, Tenn., and Pinnacle Films Inc. in Charlotte, N.C., started up in the fall of ’98, both new firms made nothing but seven-layer stretch film. Quintec was awarded U.S. Patent #6,265,055 in July 2001 for stretch films with “two outer layers and at least five inner layers.”
“With enough extruders and layers, you can make a cost-effective, high-performance film with metallocenes. That’s the market opportunity we saw,” says William Rice, president of Pinnacle, which installed a second seven-layer line last April. “Most old established players in this field can’t afford to add new higher-tech capacity. They aren’t reinvesting in new seven-layer lines.”
However, two longer-established processors have added seven-layer stretch-film capacity since then: Pliant Corp. of Schaumburg, Ill., and AEP Industries Inc. of S. Hackensack, N.J.
Meanwhile, Sigma Plastics Group, a major bag-film maker that has been in the stretch-film market since ’94, installed the world’s first nine-layer stretch line in Belleville, Ont., in 2000. “We’ve gone from nothing to 15% market share in eight years. We’re pretty proud of that,” says Per Nylen, executive v.p. of Sigma Stretch Film, based in Lyndhurst, N.J. Most recently, AmTopp in Livingston, N.J., one of Inteplast Group's three divisions, ordered a nine-layer Battenfeld Gloucester line for delivery later this year to its plant in Lolita, Texas. .
One reason resin poundage for stretch film isn’t growing much right now is that film has thinned down. In 1985, the standard was 90 gauge (0.0009 in.). Today it’s 65 to 80 gauge. One major impact of downgauging is that it has made older lines less efficient. “Equipment that used to make 1-mil film at 3000 lb/hr is making 70 gauge today, so they have lost 30% of their machine capacity,” notes Andrew Christie, president of Optex Process Solutions LLC in Fulton, N.Y., a consultant on stretch films. The only way an older line could keep up is with a brand-new winder, but processors have tended to make such a large investment only for new lines.
Even if the film poundage is static, the number of pallet units wrapped in stretch film is still growing healthily. Not only is today’s film thinner to start with, but it can stretch farther. In 1985, it took 12 oz of film to wrap an average pallet. That number dropped to 5 oz in. ’95 and to 4 oz in 2000, a threefold increase in units wrapped for the same pound of plastic.
Pinnacle (the only stretch-film maker that would provide concrete performance data for this article) reports that its 63-gauge, seven-layer Apex film shows 360% to 370% ultimate stretch on a standard test device from Highlight Industries, a maker of stretch-wrapping machines.
That means there’s still plenty of room to downgauge further, especially in the highly layered films. “We test films and find that most have an ultimate level of stretch over 350%, but the average actually applied to pallets is probably only 165% to 180%,” says Kurt Riemenschneider, president of Highlight Industries. “In many cases. the stretch films are better today than the stretch-wrapping equipment.” Film already on the market could wrap many more pallets than it does, potentially creating even more overcapacity.
Further development in this vein was reported by Pliant at the Flexpo 2002 Conference in September in Houston (sponsored by Chemical Market Resources in Houston). Pliant said it made 1-mil monolayer blown film with up to 500% stretch in R&D to evaluate three different mLLDPEs.
Highly layered films apply only to cast stretch film for machine wrap. Blown stretch film for hand wrap has one to three layers of hexene/octene LLDPE blends with expensive cling additives that are not used in cast films.
Film with more layers doesn’t usually have more different materials. Rather, the additional layers are created in the feedblock by splitting one resin stream into thin slices stacked together or alternated with layers from a different resin stream. The technique is commonly used in sheet extrusion to get a more uniform resin distribution.
“Coextrusion of thin alternating layers can improve puncture strength,” says Cloeren’s Oliver. “Extruding metallocene resins thinner actually makes them less splitty—the same way glass, if it’s thin enough, is flexible.”
“Look at nine layers as like plywood,” says Sigma’s Nylen. “We get higher pre-stretch, puncture, and tear resistance with nine layers than with five.”
Alternating thin layers of mLLDPE also allow greater use of low-cost wide-spec or butene LLDPE and reduce the amount of mLLDPE needed. In a seven-layer film with three mLLDPE layers, the metallocene content might drop to 33% versus as much as 40% mLLDPE spread over two layers of a typical five-layer stretch film.
While there are thus good reasons for letting the feedblock create multiple layers from one resin stream, there are also arguments to be made for using more extruders. “Coextruding layers of a single resin with two extruders increases throughput of a line but doesn’t affect film properties,” explains Oliver. “A high-output line with two 4.5-in. ex truders instead of one 6-in. extruder also gives the flexibility to do complex or simple products, and temperature control is a lot easier on a 4.5-in. extruder than on a 6-in. extruder.”
Pliant’s seven-layer stretch films can be made with three, four, five, or six extruders. Its first seven-layer line in Lewisburg, Tenn., has five extruders plus a small sixth machine that extrudes edge bead out of trim waste. Pliant’s newest seven-layer line, installed three months ago, has four extruders. Predefined plugs for the feedblock allow it to make seven layers with three or four different polymers. It also uses a chill roll believed to be North America’s largest for cast stretch film. The large roll quenches the film faster, further improving puncture strength and cling, Pliant reports.
Pliant’s first high-performance seven-layer film, designated R-122, was introduced in 2001 but not fully commercialized until 2002. It was developed to improve on the strength and reduce the noise level of Pliant’s OPTX five-layer film. R-122 is a premium product with Pliant’s highest mLLDPE content (over 50%), allowing both downgauging and high pre-stretch ratios. Nonetheless, it is one of Pliant’s best selling stretch films in 51- and 63-gauge versions.
R-122’s thinness gives customers more usable footage for the same roll weight: 9000 ft for a roll of 51 gauge R-122 film and 7250 ft for 63-gauge R-122, while a standard 80-gauge roll has only 5000 ft. The 51- and 63-gauge films can contain C pallet loads (irregular unboxed load with lots of protrusions) and beat the performance of some of the toughest 70- and 80-gauge films in the market, Pliant says.
R-122 took over a year to develop because initial production rates were too slow to be considered commercial. Throughput suffered and processing was more difficult with the higher mLLDPE content, so Pliant made processing and resin formulation changes.
Pinnacle’s Apex high-end stretch film, introduced in 2000, also uses seven layers and mLLDPE to achieve thinness. “We can replace a standard 80-gauge stretch film with 63-gauge film. For light loads we can go as thin as 55 gauge,” says Pinnacle’s Rice.
Black Clawson’s seven-layer stretch-film line at Quintec uses five extruders and an Ultraflow feedblock from Extrusion Dies Industries with selector spools to change layer sequence. Black Clawson says a typical seven-layer structure might be 5% to 15% skin tack layer, 5% to 10% sub-skin performance layer, 15% to 20% inner performance/refeed layer, 40% to 50% bulk/refeed core, 5% to 10% inner performance/refeed layer, 5% to 10% sub-skin performance layer, and 2% to 15% skin slip layer.
Not all highly layered stretch films use mLLDPE. Sigma doesn’t use any in its nine-layer films, noting that TD tear strength is lower with mLLDPE than with standard hexene/octene blends. AmTopp doesn’t plan to use mLLDPE in its nine-layer films, either. AEP Industries also avoids mLLDPE.
AEP rebuilt an existing four-extruder line and added a seven-layer feedblock. Its first seven-layer product was EXRW (Excaliber Roll Wrap)—heavy-gauge, 3-mil films for paper-roll wrap, a new market for one-sided cling wrap. Protecting giant rolls of paper requires surface toughness but little stretch.
AEP’s newest five- and seven-layer films, EXP (Excaliber Plus), are high-strength films designed for downgauging on high-speed automated stretch wrappers. EXP film can wrap at speeds of up to 60 rpm, whereas 20 rpm is typical for machine wrapping and 30 rpm is considered high, says Michael Hildreth, AEP’s technical manager.
Sigma focuses on less-expensive commodity films with its nine-layer line. Its Battenfeld Gloucester system uses four extruders and a Cloeren die and feedblock. The sub-skin B, core C, and sub-skin D are split into alternating layers: A-B-C-B-C-D-C-D-A.
Non-stop operation and high uptime efficiency are critical to eking out profits in stretch film. On-line width adjustment coupled with changeable flow paths in the feedblock are essential to changing layer sequences on the fly.
Stretch-film lines are also running faster and faster to beat the competition. “A couple of producers can sustain 1700 to 1800 ft/min at 4100 lb/hr,” says Robert Moeller, product manager for extrusion systems at Black Clawson. Higher production in turn requires faster winding and more automation.
The latest stretch-film winders run at up to 1400 ft/min vs. about 600 ft/min for conventional stretch-film winders. The newest winders produce a set of six to 10 hand-wrap rolls every 50 to 60 sec, and the same number of rolls of machine wrap (with larger diameters) every 3 to 5 min, depending on gauge. Such blazing speeds require automatic roll unloading and re-coring.
At least three U.S. processors have also invested in fully automated box loading of blown film for hand wrap. AEP was the first in the early 1990s, followed by Intertape Polymer Group’s Danville, Va., plant and at least one plant of Minneapolis-based Tyco Plastics. Machine wrap, which runs more slowly, typically uses partial automation. Fully automated box loading is more common in Europe, where labor costs are higher.
In the early ’90s, stretch-film lines also grew wider to increase throughput. To reduce neck-in from very wide dies, processors use a dual-chamber vacuum box and edge pinning to hold the film against the chill roll.
Winders have also grown wider. When Black Clawson builds winder rolls wider than 120 in., it uses a two-piece core shaft with a center support. This allows a single winder with 3-in.-diam. shafts to wind a wide web at high line speeds. On the other hand, the latest winders from Battenfeld Gloucester and Davis-Standard’s Egan Div. are designed as dual winding units, each with shorter shafts that reportedly provide more stability, though they cost more for equipment and maintenance.
Neither mLLDPE nor many layers are used so far in blown stretch film, though orientation developments could open opportunities for more layers and performance. Last fall, Battenfeld Gloucester introduced an in-line MD orienter that stretches film 200% to 300%. Blown stretch-film output is typically cooling limited, but this development allows an extruder pumping the same lb/hr to produce two to three times more linear ft/hr of stretch film.
Gloucester’s prototype MDO unit uses an S-wrap of two preheating rolls, one to heat each side of the film. It also has an S-wrap of two rubber pull rolls turning three to four times faster than the preheat rolls to stretch the film. Two heated annealing rolls recover some of the stretch. Finally, two cooling rolls lock in the residual stretch.
A question mark about oriented monolayer film is the effect that high levels of pre-stretch could have on additives “blooming” to the surface of the film. Research is being done now to characterize this effect, which is well understood for multi-layer film with a surface cling layer.
Stretch-wrapped silage and large cubes of garbage are relatively new niches for blown stretch film developed by AEP, Tyco, and Sigma within the past three years. Three-layer film is preferred for silage to prevent decomposition, and the biaxial stretch gives better puncture resistance against hay stalks.
Anti-corrosion stretch wrap, called VCI (vapor corrosion inhibitor) is a new niche product used to protect iron bars and other metal products from rust. VCI is difficult to make because the inhibitor additive is corrosive.
Downgauging and sophisticated structures make today’s stretch film go farther. Pliant’s newest seven-layer line puts 9000 ft of 51-gauge stretch film on a roll, vs. only 5000 ft of conventional 80-gauge film.
Making seven-layer film with high mLLDPE content at high output rates requires North America’s largest-diameter cast chill roll. (Photo: Pliant)
Pinnacle Films makes only seven-layer, high-performance stretch films using mLLDPE. Last year it added a second seven-layer line.
High-performance seven-layer films can stretch farther than most wrapping machines can pull them, even on a load like this with protruding corners. (Photo: Highlight Industries)
The world’s first nine-layer stretch-film line at Sigma Stretch Films doesn’t use mLLDPE. Its extra layers create a commodity film less expensively.
Automatic core loading, roll unloading, and boxing is more prevalent in Europe, where labor costs are higher. (Photo: SML)
As drying, blending and conveying technologies grow more sophisticated, they offer processors great opportunities to reduce cost through better energy efficiency, smaller equipment footprints, reduced scrap and quicker changeovers. Increased throughput and better utilization of primary processing equipment and manpower are the results.
Selecting of the correct purging compound can speed up material and color changeover time and reduce scrap. You’ll even save on material.
You rightfully worry about melt temperature, but don’t overlook head pressure, because the two are closely linked and will influence line performance.
Extruder screws and barrels will wear over time. If you are seeing a reduction in specific rate and higher discharge temperatures, wear is the likely culprit.
Implementing a production monitoring system as the foundation of a ‘smart factory’ is about integrating people with new technology as much as it is about integrating machines and computers. Here are tips from a company that has gone through the process.
Plastics processors are finding applications for 3D printing around the plant and across the supply chain. Here are 8 examples to look for at NPE2024.
Driven by brand owner demands and new worldwide legislation, the entire supply chain is working toward the shift to circularity, with some evidence the circular economy has already begun.
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