How common is this, really? Bozzelli answers, “As I remember, nearly all of the TEMs that I had done at Dow showed an air gap, whether the resin was filled or unfilled, filled being a bit worse. Since I left Dow, I try to break the part at the weld line and look at the surface of the break on both sides under a simple magnifying glass. Sometimes the areas on both sides of the weld line are glossy and cupped inward, an indication of a bubble or air. Also, often they do not match or mate, so to me that is an indication that the flow fronts were separated by an air gap. Filled or unfilled, I see this about 65% of the time. Now, I just assume it is there and do what I can to eliminate or reduce the weld line. Installing vents near the area often helps, But once you put in a vent on the parting line near the weld line, the weld line often moves and then you have to put in another vent. Vacuum on the mold does help and many times eliminates the weld line.”

Across all process types, sustainability was a big theme at NPE2024. But there was plenty to see in automation and artificial intelligence as well.

When, how, what and why to automate — leading robotics suppliers and forward-thinking moldmakers will share their insights on automating manufacturing at collocated event.

Exhibitors and presenters at the plastics show emphasized 3D printing as a complement and aid to more traditional production processes.

Image used by John Bozzelli in his training seminars shows a short shot with a weld line forming around a square hole. In his experience, a microscopic air gap is apt to remain between the flow fronts even after the part is fully packed. (The training tool was designed by consultant Glenn Beall to illustrate design and molding problems.)

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.

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.

And where would we be without the handful of uber-experienced plastics veterans who generously share their hard-earned knowledge about industry-wide problems like this?

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.

As everyone knows, weld lines are weak points. What’s less well known is just what’s going on inside that weld line on a microstructural level. Here’s a close-up look at some nasty little secrets.

The Plastics Industry Association (PLASTICS) has released final figures for NPE2024: The Plastics Show (May 6-10; Orlando) that officially make it the largest ever NPE in several key metrics.

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.

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.

Join KraussMaffei for an insightful webinar designed for industry professionals, engineers and anyone interested in the manufacturing processes of PVC pipes. This session will provide a comprehensive understanding of the technology behind the production of high-quality PVC pipes: from raw material preparation to final product testing. Agenda: Introduction to PVC extrusion: overview of the basic principles of PVC pipe extrusion — including the process of melting and shaping PVC resin into pipe forms Equipment and machinery: detailed explanation of the key equipment involved — such as extruders, dies and cooling systems — and their roles in the extrusion process Process parameters: insight into the critical process parameters like temperature, pressure and cooling rates that influence the quality and consistency of the final PVC pipes Energy efficiency: examination of ways to save material and energy use when extruding PVC pipe products

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.

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.

(From left) Uwe Telinde (managing director NETSTAL Deutschland GmbH), Thomas Fischer (senior trainer Injection Moulding SKZ Horb am Neckar), Peter Schmid (head of Application & Training NETSTAL Maschinen AG), André Liebscher (area sales manager South, NETSTAL Deutschland GmbH) and Jürgen Kern (site manager SKZ Horb am Neckar) at the handover of the new injection moulding machine in Horb am Neckar on June 25, 2024.

A homogenous melt is required for consistent part quality, but achieving it requires balancing a number of factors, including barrel usage and temperature as well as screw speed, backpressure and residence time. Learn how to prepare your melt for molding success in this two-part series.

This month’s resin pricing report includes PT’s quarterly check-in on select engineering resins, including nylon 6 and 66.

Injection moulding machine manufacturer Netstal is providing the SKZ Plastics Center in Horb am Neckar with an Elion 1200-510 injection moulding machine. The official machine handover took place on June 25, 2024. The Elion 1200-510 with a clamping force of 1,200 kN will be used in future for the extensive training activities in injection moulding at the Horb am Neckar site.

Core Technology Molding turned to Mold-Masters E-Multi auxiliary injection unit to help it win a job and dramatically change its process.

In many part designs, flow fronts will inevitably be split, but how and where they come back together is hugely important to the molded part’s finished strength.

"We are very pleased about our first injection moulding machine from Netstal at SKZ. Especially in times of a shortage of skilled workers, it is important to keep the machinery up to date in order to work with the latest technology. We would like to thank Netstal for their support and are pleased to be able to offer our participants courses at a very high technical level," said Jürgen Kern, site manager of the SKZ in Horb am Neckar.

Successfully starting or restarting an injection molding machine is less about ticking boxes on a rote checklist and more about individually assessing each processing scenario and its unique variables.

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.

This Knowledge Center provides an overview of the considerations needed to understand the purchase, operation, and maintenance of a process cooling system.

It’s widely known that when flow fronts converge at a weld line, the polymer chains (like fiber reinforcements) tend not to intermingle across the boundary. As Bozzelli puts it, “Weld lines are weak because you do not have any polymer chain bridging the weld line.” But his TEM photo (not available for publication) shows that’s not just a matter of polymer chains butting up against each other without intermingling. In some, or perhaps many, areas of the weld line, the polymer chains do not even meet!

Bozzelli explains, “It’s a huge issue in the industry that few know about. Many resin suppliers actually make thing worse by putting in too much lube, wax or flow aids. The black line of material is not ABS, but a wax, oil or other additive that phase-separated. It is much lower in molecular weight and rushes to the flow front because it is much easier flowing than the plastic and forms a barrier preventing the two flow fronts from melding together. Again, no wonder weld lines are weak—this is not a junction of plastic to plastic, but of plastic to wax. Most plastics have some additive that is low in molecular weight and has the potential to phase-separate. Make a guess how many plastics people even have a hint about this issue.”

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Who knows what evil lurks within weld lines? One who does know is molding expert, trainer and technical guru John Bozzelli, a prolific contributor to this magazine. When he worked in R&D at Dow Chemical, Bozzelli had access to an electron microscopy lab. He recalls the case of an unfilled ABS computer keycap back in 1987: The weld line where three flow fronts came together was “barely visible—barely a scratch to the human eye.” Under a transmission electron microscope (TEM), the ABS flow fronts appeared as a gray “soup,” larded with darker blobs of the rubber phase; but between the flow fronts, the scan was pure white. “Nobody could believe there was nothing between the flow fronts,” Bozzelli states. That was a revelation of the true nature of weld lines.

If all this isn’t enough to inspire a righteous fear of the harm that weld lines can cause if placed in critical locations, Bozzelli knows of one more “evil” that lurks within those weld lines: “Take another look at the TEM photo of the ABS keycap. First is the air gap; but on one side, note the black line separating two flow fronts. That’s not supposed to be there. Yet another problem!”

While prices moved up for three of the five commodity resins, there was potential for a flat trajectory for the rest of the third quarter.

Discover how artifical intelligence is revolutionizing plastics processing. Hear from industry experts on the future impact of AI on your operations and envision a fully interconnected plant.

Determining the source of streaking or contamination in your molded parts is a critical step in perfecting your purging procedures ultimately saving you time and money.

When determining the best ejection option for a tool, molders must consider the ejector’s surface area, location and style.

Join Wittmann for an engaging webinar on the transformative impact of manufacturing execution systems (MES) in the plastic injection molding industry. Discover how MES enhances production efficiency, quality control and real-time monitoring while also reducing downtime. It will explore the integration of MES with existing systems, emphasizing compliance and traceability for automotive and medical sectors. Learn about the latest advancements in IoT and AI technologies and how they drive innovation and continuous improvement in MES. Agenda: Overview of MES benefits What is MES? Definition, role and brief history Historical perspective and evolution Longevity and analytics Connectivity: importance, standards and integration Advantages of MES: efficiency, real-time data, traceability and cost savings Emerging technologies: IoT and AI in MES

Plastics Technology covers technical and business Information for Plastics Processors in Injection Molding, Extrusion, Blow Molding, Plastic Additives, Compounding, Plastic Materials, and Resin Pricing. About Us

The machine will enhance the existing range of training courses in Horb - including "Machine Operator" or "Certified Setter", as well as courses on injection moulding defects or sampling of injection moulds. The course program includes course options for career changers and specialists. The injection moulding unit from the Elion series is characterized by low noise emissions and optimum energy efficiency. With injection compression moulding (ICM), new fields of application can also be opened up.

Join this webinar to explore the transformative benefits of retrofitting your existing injection molding machines (IMMs). Engel will guide you through upgrading your equipment to enhance monitoring, control and adaptability — all while integrating digital technologies. You'll learn about the latest trends in IMM retrofitting (including Euromap interfaces and plasticizing retrofits) and discover how to future-proof your machines for a competitive edge. With insights from industry experts, it'll walk you through the decision-making process, ensuring you make informed choices that drive your business forward. Agenda: Maximize the value of your current IMMs through strategic retrofitting Learn how to integrate digital technologies to enhance monitoring and control Explore the benefits of Euromap interfaces and plasticizing retrofits Understand how retrofitting can help meet new product demands and improve adaptability Discover how Engel can support your retrofitting needs, from free consultations to execution

While the major correction in PP prices was finally underway, generally stable pricing was anticipated for the other four commodity resins.

I asked Bozzelli what he thinks of this approach. He responds, “Adding the overflow channel to improve weld-line strength is not common, but I have seen it done a number of times. Yes, it does help, for two reasons: Often the weld line traps air and the ‘dump’ acts as a vent to allow the air to escape. That helps. Second, depending on the size of the overflow well, you get a little bit of flow melding together, and that helps strength so that you have some intertwining of the polymer chains. This is similar to putting whatever is causing the weld line, like a hole in a part, away from the end of fill. Plastic then has a chance to flow around the hole and re-meld as it continues to fill the part. That really helps to improve strength.”

In Part 1 of this series, we address long-fiber processing fundamentals and best practices, including practical tips and guidance on maintaining fiber length and deriving maximum advantages for demanding end applications. Part 2 will provide the same information for short-fiber materials.

Say “manufacturing automation” and thoughts immediately go to the shop floor and specialized production equipment, robotics and material handling systems. But there is another realm of possible automation — the front office.

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.

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.

I’ve been thinking about weld lines lately. We published in Plastics Technology a two-part series from Avient on molding long- and short-fiber reinforced thermoplastics; Part 2 comes out in March. Both parts note that fiber-reinforced plastics lose much of their robustness at weld lines, because the fibers tend to line up side by side, rather than “reach across” the point where flow fronts meet. It’s not just a problem for reinforced plastics.

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.

Second quarter started with price hikes in PE and the four volume engineering resins, but relatively stable pricing was largely expected by the quarter’s end.

What else can you do about weld lines—besides redesigning the mold or gate locations or adjust the flow pattern during fill with sequential valve gating? I recently saw a report on this issue from Moldex3D, the maker of molding simulation software. It explored the use of an overflow well (see illustration) that is designed to fill after the weld line forms, such that filling the well causes melt flow across the weld line. Simulations of 35% glass-reinforced nylon 66 indicated that higher mechanical properties should result from use of the overflow well.

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.

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.

Following on a similar guide for long-fiber reinforced compounds, here are practical tips on designing and injection molding parts utilizing short-fiber reinforcements.

In a time where sustainability is no longer just a buzzword, the food and beverage packaging industry is required to be at the forefront of this innovation. By adopting circular packaging processes and solutions, producers can meet regulatory requirements while also satisfying consumer demand and enhancing brand reputation. Join Husky to learn more about the broader implications of the circular economy — as well as how leading brands are leveraging this opportunity to reduce costs, increase design flexibility and boost product differentiation. Agenda: The cost and operational benefits of embracing circularity Key materials in circular packaging — including rPET and emerging bioplastics How to design a circular food and beverage package Strategies for selecting sustainable closures to future-proof packaging solutions Optimization and streamlining of production processes for enhanced efficiency How Husky Technologies can enable your sustainable success

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.

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.

Under a microscope, air gap is visible between flow fronts of a fully packed ABS part. Striations are due to incomplete color mixing. (Photo: John Bozzelli)

Multiple speakers at Molding 2023 will address the ways simulation can impact material substitution decisions, process profitability and simplification of mold design.

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.

Additive technology creates air pockets in film during orientation, cutting down on the amount of resin needed while boosting opacity, mechanical properties and recyclability.

The aim of this presentation is to guide you through the factors and the numbers that will help you determine if a robot is a smart investment for your application. Agenda:  Why are you considering automation? What problems are you trying to solve? How and why automation can help Crunch the numbers and determine the ROI

Ultradent's entry of its Umbrella cheek retractor took home the awards for Technical Sophistication and Achievement in Economics and Efficiency at PTXPO.

"We are proud to provide the SKZ with a machine and thus support training and further education in the plastics industry here in Germany. It is crucial that skilled workers have access to advanced machines to develop their skills in plastics processing," explained Uwe Telinde, managing director of Netstal Deutschland GmbH, at the handover of the machine.

While prices moved up for three of the five commodity resins, there was potential for a flat trajectory for the rest of the third quarter.

While the melting process does not provide perfect mixing, this study shows that mixing is indeed initiated during melting.

Sustainability continues to dominate new additives technology, but upping performance is also evident. Most of the new additives have been targeted to commodity resins and particularly polyolefins.

Plastics Technology’s Tech Days is back! Every Tuesday in October, a series of five online presentations will be given by industry supplier around the following topics:  Injection Molding — New Technologies, Efficiencies Film Extrusion — New Technologies, Efficiencies Upstream/Downstream Operations Injection Molding — Sustainability Extrusion — Compounding Coming out of NPE2024, PT identified a variety of topics, technologies and trends that are driving and shaping the evolution of plastic products manufacturing — from recycling/recyclability and energy optimization to AI-based process control and automation implementation. PT Tech Days is designed to provide a robust, curated, accessible platform through which plastics professionals can explore these trends, have direct access to subject-matter experts and develop strategies for applying solutions in their operations.

Processors with sustainability goals or mandates have a number of ways to reach their goals. Biopolymers are among them.

Join Engel in exploring the future of battery molding technology. Discover advancements in thermoplastic composites for battery housings, innovative automation solutions and the latest in large-tonnage equipment designed for e-mobility — all with a focus on cost-efficient solutions. Agenda: Learn about cutting-edge thermoplastic composites for durable, sustainable and cost-efficient battery housings Explore advanced automation concepts for efficient and scalable production See the latest large-tonnage equipment and technology innovations for e-mobility solutions

Across the show, sustainability ruled in new materials technology, from polyolefins and engineering resins to biobased materials.

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).