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FIG 1 Studies with SABIC’s Valox 420 PBT show that the molecules break down and viscosity properties of the material are lost when it is subjected to a temperature of 500 F for 6 min.

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.

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.

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

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.

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

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

Here also, residence time is calculated by multiplying the number of shots in the barrel by the cycle time. This formula works well for the most part but as we now know is not 100% accurate.

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.

This should never be the case, but let’s say the shot weight is 100 g; in other words, 100% of the maximum shot capacity is being used to mold the parts. If the screw is retracted all the way back to its maximum-shot-size position, then there are 100 g of plastic in front of the screw tip (Fig. 2). In addition to this material, there is plastic on the screw. All the plastic in the metering section of the screw is molten; the plastic in the compression section is partially molten; and the plastic in the feed section is in the process of softening and will be melted soon.

To keep things simple, let’s say the parts we’re concerned with are molded in PS, the standard material that machine shot capacity is specified in. Consider the maximum shot capacity of this machine to be 100 g. Shot weight is defined as the total weight of the parts and runners. For the discussion below, let us also ignore the small amount of cushion that must be present at the end of the compensation—pack and hold—phase.

An example of this experiment is shown in Fig. 4, where the color showed up in the third shot. These set of parts will be used to continue this topic in Part 2 of this column, which will focus on residence-time distribution.

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

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.

It's worth noting that the LDPE didn't stick to the molds, i.e. they didn't require any release agents. They did, however, get a little flash. And they report that the cycle time was three minutes per shot.

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

If the color showed up on the eighth shot, then there are at least seven shots in the barrel. The eighth shot has some color. To be on the safe side, you could say there are eight shots in the barrel. Multiply eight by the cycle time to get the residence time of the plastic in the barrel. As an example, if the cycle time is 40 sec then the residence time would be 8 × 40 = 320 sec or 5.4 min. If the maximum residence time for this plastic is say 6 min, then the parts do not have any degraded plastic. However, if the maximum residence time for this material is 4 min, then degradation is a definite concern.

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.

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

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.

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.

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.

FIG 4 To help determine the number of shots in the barrel, start molding parts; move the hopper away from the feedthroat and use a mirror or a phone camera to observe the plastic being fed onto the screw. When you see the bare screw, drop one or two pellets of any dark compatible color into the feed throat and pull the material hopper back in place. Let the mold open and eject the shot. Now start counting the number of shots (three, in this case) until you see the color show up on the parts.

In such a situation, the maximum amount of molten plastic is more than 100 g. It is clear here that screw-design factors—L/D ratio, compression ratio, ratio of the length of the feed section to compression to metering, and the screw type—will play a role in determining the amount of molten plastic on the screw.

There is a very easy and practical method to determine the number of shots in the barrel, however, it does not work well on dark-colored parts. In such cases, if possible, running the same mold with a lighter color or natural material will help. In this method, start molding the parts, move the hopper away from the feed throat and, using a mirror or a phone camera, observe the plastic being fed onto the screw. Please observe safety and never look directly into the hopper.

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.

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.

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

For the mold material they used both clear and high-temperature resin. Obviously you need something that can withstand a higher temperature than the plastic that's going to be squirted into it.

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

Understanding the concepts of pack and hold and applying them during process development is critical for molders to achieve consistent part quality.

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

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.

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.

Experiments reveal the relationship between vent depths and part thickness, allowing molders and moldmakers to more precisely determine vent dimensions.

Clearly, this is not easy or practical to perform in a day-to-day operation. To keep things simpler, there is a widely used formula to calculate the number of shots in the barrel:

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.

Now that desktop 3D printing has become widespread, there's another production method crossing over into the DIY realm: Desktop injection molding. It's now possible "to create molds in-house to produce small, functional parts in production plastics," writes Formlabs.

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

It is clear that estimating the amount of plastic inside the barrel is a function of several factors. Not mentioned so far is the effect of processing parameters, especially backpressure. To truly calculate the maximum amount of molten plastic in the barrel, a molder must add the amount of plastic in front of the screw to the amount of molten plastic on the screw in each of the sections.

For example, if the amount of the plastic on the screw and a built-up shot is 150 g and the shot weight is 25 g, then we can calculate that the number of shots in the barrel is six. If the cycle time for these parts is 30 sec, then we multiple that cycle time by the number of shots to determine it will take 180 sec (3 min) for the plastic to be conveyed from the location where it melts to the nozzle tip. Again, this does not include the material that has not yet reached the melt temperature, and so some portion of the plastic in the feed zone is not considered.

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.

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

Failing to calculate and accurately account for residence time can compromise material integrity before it’s even injected.

Addressing hot-runner benefits, improvements, and everyday issues from the perspective of decades of experience with probably every brand on the market. Part 1 of 2.

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

Assuming that all processing parameters other than the shot size are identical in both scenarios, you can see that the amount of plastic in the metering section and in the compression section of the screw is identical (Fig. 3). However, the amount of plastic in the feed section will be higher in the second scenario, where 20% of the shot size is used compared to the 100%.

While it's free to download, there is a catch--you need to enter your e-mail address, and they openly state "We will also opt you into other relevant marketing communication," so you can presumably expect some spam.

For our next example, let’s say the shot weight is 20 g, meaning 20% of the maximum shot capacity is being used. Similar to the discussion in Scenario 1, the total amount of molten plastic in the barrel will be 20 g in addition to the molten plastic on the screw.

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

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.

Most thermoplastics are organic materials, and their chemistry is such that they are not able to withstand melt-processing temperatures beyond a certain time. Data from studies with Valox 420, a commonly available PBT from SABIC, show that when it is subjected to a temperature of 500 F for 6 min, the molecules will have broken down and the properties of the plastic are lost (Fig. 1).

Residence time is the time that the plastic spends in the molding barrel. To be precise, it is the time from when the plastic pellet is at the bottom of the hopper and on the screw ready to be conveyed until the time it reaches the tip of the nozzle. It can be calculated with a very simple formula, but that formula is really just an estimate. To understand this, let us first understand the calculation for the maximum amount of plastic inside the barrel. Many molders would just use the published value of the maximum shot capacity of the machine. This is acceptable, but not entirely accurate.

FIG 2 Here, if the shot weight is 100 g, 100% of the maximum shot capacity is being used to mold the parts. If the screw is retracted all the way back to its maximum-shot position, then there are 100 g of plastic in front of the screw tip.

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.

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.

With a stereolithography (SLA) 3D printer, you can produce molds that are smooth and strong enough--at least with a little help--to use for injection-molding small runs (10 to 100 parts, Formlabs reckons). What they've done in their testing is placed the molds--which have cavities, gates and sprues, they're the real deal--into aluminum frames, which prevent the mold from warping. You can work with standardized aluminum frames from injection molder manufacturers, or spend the bread to have something custom fabricated at a machine shop.

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.

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.

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

ABOUT THE AUTHOR: Suhas Kulkarni is president of Fimmtech Inc., which specializes in services and training related to plastic injection molding. He earned his Masters in Plastics Engineering from the University of Massachusetts, Lowell, as well as a Bachelors in Polymer Engineering from the University of Poona, India. He has 27 years’ experience as a process engineer and is the author of Robust Process Development and Scientific Molding, published by Hanser Publications, now in its second edition. He also works as a contract faculty member at U.Mass.-Lowell. Contact: suhas@fimmtech.com; fimmtech.com.

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

As soon as you see the bare screw, drop one or two pellets of any dark compatible color into the feed throat and pull the material hopper back in place. Let the mold open and eject the shot. Now start counting the number of shots until you see the color show up on the parts.

"For low-volume production (approximately 10-100 parts), 3D-printed molds save time and money. They also enable a more agile manufacturing approach, allowing engineers and designers to easily modify molds and continue to iterate on their designs with low lead times and cost."

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).

FIG 3 Here, assuming that all processing parameters other than shot size are identical to the Fig. 1 scenario, you can see that the amount of plastic in the metering section and in the compression section of the screw is identical. However, the amount of plastic in the feed section will be higher here, where 20% of the shot size is used, vs. 100% used in Fig 2.

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.

The property studied here is viscosity. We conclude that the maximum residence time for this PBT at 500 F is 6 min. However, I’d consider this to be too broad a definition of the maximum residence time for a given material, since there is no mention anywhere of any absolute or percentage drop in any specific property. An over-designed part, or a part that is not subjected to a load, could probably function even if it is molded with some number of molecules that are degraded and have a lower molecular weight. There are also additives that can degrade base resins, adding another layer of complexity.

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

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.

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

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.

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.

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

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.

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

In a case where the percentage usage of the maximum shot size is high—say 70% of the maximum—the resin may be subjected to the processing melting temperatures even in the feed zone. The amount of plastic that we talk about here is the melt-processable plastic, and it is difficult to estimate where on the screw the plastic has reached the melt-processable temperature. Surely, screw-design information from the manufacturer can provide insights about the volume of the plastic in each of the sections, and this can be used for calculations.

RainIs this the White Paper you referred to?https://archive-media.formlabs.com/upload/injection-molding-from-3d-printed-molds.pdf

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

Once we know the amount of plastic in the barrel, we can divide this number by the shot weight and that will be equal to the number of shots in the barrel. Multiplying the number of shots by the cycle time will give the total time the plastic spends in the barrel.

Next they used a desktop (okay, benchtop) Galomb Model B-100 Injection Molder, which is relatively affordable at about four grand. They squirted low-density polyethylene into the mold--LDPE was specifically chosen for its low-melt temperature--and were successfully able to produce these parts: