Last December we counted down our top five blog posts of the year. This was such a big hit, we’ve brought it back! Some of these blogs were written in 2020 and 2019, but they continue to capture your attention; landing in our 2021 count-down. Your readership and feedback is appreciated – thank you! Without further adieu…here are the top five most-read blogs of 2021.

Coming in at number five is a popular post in our blown film series, which outlines factors for consideration when selecting the right air ring for your process. This includes an overview of air ring options based on the type of film and degree of desired flexibility, resins used, optimal outputs, and more. Check it out.

https://davis-standard.com/custom_blog/what-to-look-for-in-an-air-ring-blown-film-series-part-iv/

At number four is our ever-popular blog about emergency feedscrew removal. Feedscrew removal can be daunting, but this blog helps alleviate your fears by summarizing 10 steps for safely removing your feedscrew. It also includes information on using a feedscrew jack to assist in this process.

https://davis-standard.com/custom_blog/the-911-for-feedscrew-removal/

Taking the spot at number three, as part one of a series on maintaining your feedscrew and barrel, we cover the process of feedscrew measurement. Achieving the right clearance between the barrel and feedscrew is essential for attaining operational excellence while avoiding processing issues. Learn more about the bottom line impact of feedscrew and barrel maintenance.

https://davis-standard.com/custom_blog/essential-feedscrew-and-barrel-maintenance-part-i/

In second place, many appreciate this step-by-step visual demonstration of purging flexible PVC from your extruder and die head. Valuable guidance on required tools, safety practices, equipment disassembly, and cleaning procedures is provided.

https://davis-standard.com/custom_blog/purge-and-feedscrew-cleaning-video-tutorial/

Topping our list 🏆  for most views in 2021 is…drum roll please 🥁 …Troubleshooting Common Blown Film Issues. 👏🏼  👏🏼  👏🏼

This blog summarizes various blown film defects, the causes and solutions, in order to facilitate uniform films with high tensile strength and reliable barrier properties.

https://davis-standard.com/custom_blog/troubleshooting-common-blown-film-issues/

Thank you for your continued support of the D-S Connect Blog. We look forward to giving you more valuable content in 2022, so stay tuned. We invite you to share the D-S Connect blog with your colleagues. Simply share this QR code:

Also, don’t forget to rate this blog post and comment! Your rating and engagement help us provide the content you want to read.

Happy holidays!  🎄  We wish you a healthy and profitable year ahead! 💫

For any other questions, feel free to e-mail marketing.

Cheers,
The D-S Connect Blog Team

Smarter processing and a healthier bottom line depend on our ability to use available technology to our advantage! When it comes to HDPE product applications such as pipe extrusion, we have found that groove feed extruders offer significant advantages over smooth bore extruders. These benefits include increased output, reduced melt temperature, improved mixing quality, and linear consistency. In terms of environmental and economic benefits, you can enjoy a smaller footprint, reduced operating costs, and improved energy efficiency. All of these factors can add up quickly! So, what is it about a groove feed extruder that makes these gains possible, and what are the criteria you should consider before opting for this technology?

First, let’s compare the operating principles of a smooth bore feed section versus a groove feed section. The frictional forces in an extruder exist between the barrel and solid bed to create forward conveying. A higher frictional force provides more efficient solids transport and vice versa. Due to the nature of groove feed design, frictional forces are higher, thus moving solids forward faster than a smooth bore extruder. This also enables higher processing rates with a lower melt temperature.

We conducted two case studies to illustrate the advantages offered by a groove feed extruder when compared to a smooth bore extruder while processing high-viscosity HDPE materials. Both case studies compare a 3.5-inch (90mm) 42:1 L/D groove feed extruder versus a 4.5-inch (114mm) 30:1 L/D smooth bore extruder. The first case study compares grooved and smooth bore performance while processing a 0.2 MI (Melt Index) HDPE, and the second uses an 8 HLMI, ( High Load Melt Index),  bi-modal HDPE. Both case studies compare the performance of the extruders at 1100 pounds per hour. The performance data summarized in the charts highlight the advantages of using a high-performance groove feed extruder. In addition, these charts provide a screw performance comparison with groove feed represented in green or “GF” and smooth bore represented in blue or “SB.”

First, is the performance comparison when processing a 0.2 MI HDPE at 1100 pounds per hour:

Second is the performance comparison when processing 8 HLMI bi-modal HDPE at 1100 pounds per hour:

The performance data summarized by these figures clearly defines the advantages of using a groove feed extruder. In each case study, the groove feed achieved a lower melt temperature and reduced power consumption for improved energy efficiency.

What does this mean for your bottom line?

Reduced energy consumption equates to tangible savings for your operation. Using an 8000 per hour operating year at a cost of 10 cents/kW-hr, the first case study results in savings of 268,000 kW-hr and the second, a savings of 388,000kW-hr. This adds up to a cost reduction of $26,800 and $38,800 per year. From a sustainability perspective, using a modest figure of 0.85 pounds per kW-hr for electricity generation, the groove feed extruder would cut CO2 emissions by 227,800 and 329,800 pounds, respectively. In other words, groove feed extrusion has the capacity to improve your triple bottom line, offering social, environmental, and financial benefits.

Want to learn more about this topic? We have an on-demand webinar available – click here.

If you believe making the transition from smooth bore to groove feed would benefit your process, do not hesitate to contact us to discuss your options.

For any other questions, please don’t hesitate to reach out – email marketing.

Cheers,
The D-S Connect Blog Team

Is alignment important in order to optimize your extruder investment? You bet it is! And the longer the extruder barrel, the more significant alignment becomes. A poorly aligned extruder causes excessive wear and tear on both the screw and barrel. We’ve seen misalignment cause costly and unnecessary damage including premature wear, bent and broken screws, unstable barrels, heater crawl, thermocouple shearing, additional drive load, and die movement. In this blog, we’ll discuss the value of extruder alignment and why using a barrel support system is important to protect your investment. We have also included a boroscoping video at the end.

First, the barrel must be aligned to the driving mechanism, which is the drive quill of the gearbox. No exceptions. Trying to determine alignment by leveling is inaccurate as it is not indicative of the drive quill and only measures the vertical plane. The correct procedure involves using an optical or laser alignment scope inside the drive quill to align the barrel to a fixed center line by rotating the drive quill. The barrel and feed throat are then aligned to that center line by adjusting the barrel supports, or the mounting faces of the feed throat.

There are a number of quality support system designs available, but take note of the following considerations during selection. First, the barrel must be able to freely expand through the support(s) as it is heated without distortion. The barrel should never be locked down by a support that completely surrounds it. This prevents the barrel from having the necessary room to slide when expanding. Secondly, the support joints need to be made from non-corrosive materials, such as brass, which will prevent “freezing” of the support. Finally, the entire barrel support must be rigid enough to maintain its position rather than tipping over as the barrel expands. Steel expands at 0.000006 in./in.-°F, so a 4.5-inch 36:1 barrel at a uniform operating temperature of 450 °F grows 0.320 inches longer when heated from room temperature. If the steel can’t expand in a straight line, it will bend. This diagram shows how a two-point barrel support system allows for this expansion.

To see if your supports are working properly, open the covers and observe where the fresh mark on the barrel is relative to where the barrel slides through the support. If these do not closely correspond to the calculated expansion, there is an issue with your support system. It is also important to make some checks after the initial heat-up to ensure alignment. This can be done by placing dial indicators at 90-degree angles on the discharge flange to see if the barrel has significant deflection when heat is applied. Noticeable deflection can be caused by a support that is not functioning properly, unbalanced heating due to burned-out heater valves, half heaters around a vent, or structural weakness.

In general, the importance of aligning extruders 3.5 inches (90mm) or smaller is often considered redundant from the manufacturer’s original alignment; unless the L/D is exceptionally long. For larger or lengthier extruders, the bases are seldom rigid enough to hold the manufacturer’s alignment for a long period of time. We recommend using certified extruder alignment technicians to perform the service. Davis-Standard also offers barrel alignment services. The money spent on alignment will provide significant cost savings by helping you get the most out of your barrel and screw investment while ensuring peak extruder performance.

Now that you understand the importance of alignment, check out how to borescope your extruder in this Davis-Standard video and don’t forget to turn up your volume.

We hope you enjoyed the borescoping video. Happy extruder aligning!

Do not hesitate to contact us if you need additional help aligning your extruder (select service in the Project Type drop-down menu).

Stay safe and healthy! For any other questions, e-mail marketing.

Cheers,

The D-S Connect Blog Team

“Safety isn’t expensive; it’s priceless.” – Author Unknown

Creating a culture that values safety in the workplace is a key driver of quality, performance, and profitability. This blog will discuss the value of implementing a safety program that merges employer responsibilities with employee responsibility to achieve consistent results that make employers and employees happy.

First, let’s start with employer responsibilities. Per OSHA guidelines, employers have an obligation to provide a safe workplace. Here is a modified list of some employer responsibilities taken from the OSHA website:

• Provide a workplace free from seriously recognized hazards and comply with standards, rules, and regulations issued under the OSH Act.
• Examine workplace conditions to make sure they conform to applicable OSHA standards.
• Make certain employees have and use safe tools and equipment and properly maintain this equipment.
• Use color codes, posters, labels, or signs to warn employees of potential hazards.
• Establish or update operating procedures and communicate them so that employees follow safety and health requirements
• Employers must provide safety training in a language, and vocabulary workers can understand.
• Employers with hazardous chemicals in the workplace must develop and implement a written hazard communication program and train employees on the hazards they are exposed to and proper precautions (and a copy of safety data sheets must be readily available). See the OSHA page on Hazard Communication.
• Provide medical examinations and training when required by OSHA standards.
• Post the OSHA poster (or the state-plan equivalent) informing employees of their rights and responsibilities at a prominent location within the workplace.
• Report to the nearest OSHA office all work-related fatalities within 8 hours, and all work-related inpatient hospitalizations, all amputations, and all losses of an eye within 24 hours.
• Keep records of work-related injuries and illnesses.
• OSHA encourages all employers to adopt a safety and health program. Safety and health programs, known by various names, are universal interventions that can substantially reduce the number and severity of workplace injuries and alleviate the associated financial burdens on U.S. workplaces.

The last bullet of adopting a safety and health program is essential for promoting personal responsibility and empowering your work teams to have a vested interest in safety protocol. The only way an effective safety program works is if each employee commits to daily safety practices that protect themselves and their colleagues. At Davis-Standard, we focus on leading indicators such as inspections, risk assessments, and action logs rather than lagging indicators such as injury rates. We believe this is the most proactive way to prevent accidents and promote consistent safety practices. Here are eight basic steps we use in our safety program.

1) Establish a safety committee with representation from all areas of manufacturing.
2) Set up regularly scheduled meetings to track progress and action items.
3) Understand and map out the financial impact of safety measures.
4) Make sure your goals are realistic and measurable.
5) Develop a calendar plan to correct unsafe or hazardous areas in your workplace.
6) Host a meeting with all employees to roll-out the plan.
7) Report on wins and lessons learned on a regular basis (see below).
8) Reward outstanding employee safety based on established metrics.

To keep employees involved and motivated, we suggest weekly safety updates. These do not have to be overly involved or time-consuming. Just an opportunity to share how things are going, recognize successes, and offer helpful suggestions. Some ideas include:

• Year-to-date KPI wins such as safety actions opened and closed, awards rewarded, days since last lost-time incidents, completed risk assessments, etc.
• Weekly accomplishments, highlighting what your safety team has done to promote a safer work environment
• Safety tips on various topics (electric tool safety, lockout safety, proper eye, glove and mask protection, forklift safety, entrance safety)
• Lessons learned for any incidents that occurred that week (what went right, what went wrong, how to avoid for next time)
• Links to safety resources or articles
• Visuals and photographs to support progress

The best part is, you have the flexibility to customize your safety program so that it aligns with your operational objectives. By prioritizing safety, we believe you will discover tangible and intangible benefits that lead to better manufacturing, improved productivity, and a better workplace.

Aside from what’s mentioned above, what do you do at your facility to promote workplace safety? Do you have a safety program in place and do you provide updates to your employees? What else can be included?Comment below!

If you have any questions you can comment below or e-mail marketing at marketing@davis-standard.com.

Cheers,
The D-S Connect Blog Team

What is the value of digital transformation to your operation? The answer lies in the multitude of benefits realized through increased situational awareness.

Situational awareness is defined as developing and maintaining a dynamic awareness of the situation and the risks present in an activity. This is based on gathering information from multiple sources from the task environment, understanding what the information means, and using it to think ahead about what may happen next.

The three aspects of information processing include perception, understanding/interpretation, and prediction.

Perception or gathering of information directly using our senses of vision, hearing, and touch, or indirectly through a complex control system involving HMI displays and interfaces.

Understanding information by combining this data from the production process or equipment with existing knowledge and experience from memory. Information gathered is given meaning. This includes developing an accurate and complete picture of the operation, better informing our decisions.

Prediction and projection into the future, which includes thinking ahead. This involves predicting what to expect as well as what not to expect.

• • What happened? (perception)
  • What is happening? (comprehension)
  • What might happen in the near future? (projection or what to expect in the near future)

Situational awareness provides context to the complex data that your team receives from your production environment. It helps your team interpret data to make informed decisions that result in positive projected outcomes. Using post-failure analysis makes it possible to transition from a historical perspective of “running to failure” to a preventative and forward-looking system using real-time information from your process and equipment.

Perception –What has happened/is happening on my process and equipment?

DS Activ-Check™ uses visuals to summarize and present current process conditions and equipment performance. This enables your team of process technicians, maintenance, engineering, and management to understand the current state of the operation at-a-glance.

Team members do not have to download files or create graphs to gain insight. Instead, the information is presented logically in the form of informational dashboards. This allows for precious time to be spent resolving the issues and not hunting for them. In addition, users can gain access to their data anytime and anywhere via browser or mobile application. Accessibility can be tailored to each user, allowing system administrators to fully control the level of access and what data is visible to each user.

Here is an example of an extruder overview dashboard:

Comprehension – How is the system operating? Evaluation of the current quality parameters and trends.

Dashboards like the one above are designed to keep you aware of current line conditions and add context to data, so your team has a complete understanding of how system components interact and affect product quality.

An aggregate analytic continuously monitors important KPI during production runs and displays the degree of variation and overall average. It is a tool that visualizes variation of process and equipment performance. Again, system performance can be understood by just glancing at the dashboard.

Projection – Helping your team use information effectively to predict future outcomes.

Trends of production system analytics are continuously monitored, tracked, and visually displayed using an activity map. This determines the direction of your process and equipment. Categories include: good trending better, good trending worse, bad trending better, and bad trending worse. Proactive steps can be taken to improve performance using this information. The team can clearly see how recent actions impact system performance in real-time.

Taking this a step further, you can put your production data to work. An optimization toolbox uses production run information, including analytical performance parameters and KPIs, to select the best conditions for your process and equipment. This guides your team to select the most desirable line conditions to achieve the best performance for future production runs. The figure below shows a comparison of quality performance data from several production runs.

In summary, the advantages of digital transformation are threefold and interconnected.

By taking advantage of cloud-based platforms, you have a digital toolbox at your fingertips, enabling you to use the most up-to-date technology to enhance the performance of your extrusion line equipment. By improving situational awareness through technology such as the DS Activ-Check™, you will have greater control of operational variables that influence value, profitability, and better processing for you and your team. The possibilities are endless!

Have questions about this blog or the digital transformation series? Comment below!

Learn more about digital transformation and DS Activ-Check™ in the upcoming webinar – click the “Sign Me Up” button to register. And if you miss this webinar, you can still obtain the recording on-demand, just click below.

Want to inquire about the DS Activ-Check™ system? Contact us today.

Cheers,
The D-S Connect Blog Team

In this second blog of our digital transformation blog series, we’ll explain the digital architecture of a cloud-based system using DS Activ-Check™ as an example and review its advantages.

DS Activ-Check™ is a custom-designed, cloud-based platform that improves your team’s situational awareness to enhance extrusion production line performance and productivity.

DS Activ-Check™ leverages systems and strategies offered by the IIoT to increase operator effectiveness, leading to reduced downtime, better product quality, and reinforced operator safety. The configurable platform engine uses analytical tools based on long-term cloud data storage along with process and equipment technology algorithms to help management and production teams identify issues before problems occur and improve product quality and line efficiency.

The digital architecture of the system is shown in the figure below. The production line equipment on the left is continuously monitored by the cloud-based DS Activ-Check™ system. The real-time operating data, including KPI (Key Performance Indicators) from the production line PLC or SCADA system historian, is sent to an edge server inside the plant. The edge server collects, buffers, and encrypts the data before sending the information on a secure Port 443 through a secure firewall. The server is located behind a secure firewall to prevent unwanted access.

The data moving on the secure Port 443 travels over the internet and is stored on the cloud. The cloud refers to servers or computers accessed over the internet and the software and databases that run on those servers. This is where cloud computing giants such as Amazon, Netflix, Google Maps, Google Earth, and the DS Activ-Check™ system reside, among many others. The right side of the image shows how the information from the cloud-based system can be securely accessed remotely from anywhere using your smartphone, tablet, or PC with a secure internet connection.

The logical question to ask is, why use the cloud for a continuous monitoring system? What advantages does this technology offer?

Information storage and access

Data collection and storage capacity is unlimited. Your valuable production data is securely stored and can be used in the future for comparing production performance between lines and plants, optimizing production processes, and more.

Connectivity

You can securely monitor your production process from anywhere at any time. This is a force multiplier for your process, maintenance, and operations teams. First, they will be able to address issues before failure, eliminating lost production. They will be able to identify a specific issue and take corrective action quickly versus spending countless hours trying to determine a root cause. Second, they can deploy maintenance tasks with all records of completion stored for future reference. Finally, they can collaborate and troubleshoot issues in real-time to prevent costly production downtime.

The data storage capacity for a typical SCADA system is limited to 180 days. After 180 days, the data is lost. A cloud-based system ensures your data is never lost.

Scalability

Production equipment can be easily added to the system starting from one line. In addition, production lines in the plant and from other locations, both domestically and internationally, can be included. This is a critical feature for digitally transforming multiple locations.

Analytics Running in Real-Time

The cloud platform provides the capability to run software that analyzes equipment performance continuously. This feature is known as analytics. Using real-time data from your production process, software programs continually monitor the performance of your operation and provide critical information. This reduces or eliminates unwanted downtime and guides your decision-making with regard to preventative and predictive maintenance items.

Using the advantages listed above, a cloud-based system like DS Activ-Check™ performs a detailed analysis of data coming from your extrusion system. It simplifies your extrusion system’s multiple and complex dependencies using built-in analytics, which is based on performance data. These features translate into informed decisions and expanded situational awareness for your team.

The next blog, we’ll discuss how digital transformation provides value to your operation through improved situational awareness. Have any questions on digital architecture? Write in the comments below.

For any other questions, contact marketing.

Cheers,
The D-S Connect Blog Team

Over the last three decades, the world has undergone a far-reaching digital transformation. The infrastructure making this possible is built on the Internet and World Wide Web (WWW), transforming our daily lives and activities with convenience, greater connectivity, and instant access to information. Examples include everything from multiple cell phone features to navigational systems in our cars, live streaming of movies and media into our homes, instant access to information, reservations, and more. The list goes on and on. This technology is referred to as the Internet of Things or IoT, which has changed how we live and do business today.

Manufacturing operations are extremely complex, which is why digital infrastructure has been slower to occupy this space. The industry looked inward to strengthen the efficiency and profitability of operations. Improvements focused on control systems for the factory floor through automated control systems that improve safety, reduce human interaction, strengthen local data collection using improved SCADA systems (Supervisory Control and Data Acquisition), and accessing equipment via the internet. These steps served as the initial building blocks for digital transformation within operations.

This movement further accelerated as digital technology proved to be more reliable. Our industry realized the potential and initiatives gained traction. The fourth Industrial Revolution, known as Industry 4.0 or I 4.0, quickly gained popularity. The possibilities and advantages of Industry 4.0 spread around the globe, and today we have the Industrial Internet of Things or IIoT.

The IIoT platform is enabling the development of new technology by leveraging information from existing control capabilities. Currently, line control systems can display and collect performance information, providing an interface for operating equipment. However, this presents disparate information that is difficult for operators to translate. New digital technology expands this platform by introducing a “human factors” concept of situational awareness to improve performance while incorporating preventative and predictive tools into our operations.

What does this mean for your operation? In this blog series, we’ll summarize important features of this technology and identify ways you can take advantage to realize the maximum impact. We’ll use the example of Davis-Standard’s DS Activ-Check™ to describe the architecture of a cloud-based system, review relevant terminology, and discuss how improved situational awareness can add value to your process.

Stay tuned on September 28^th for the second part of this exciting series! We look forward to sharing what we know about this exciting topic.

Have any questions about the first part of this series? Comment below.

For any other questions e-mail marketing.

Cheers,
The D-S Connect Blog Team

Purging flexible PVC from your Davis-Standard extruder and die head after each use is essential to maintain optimal equipment operation, avoid contamination and corrosion, and ensure product quality. In this seven-minute video, we provide a step-by-step demonstration of this important process. This includes the required tools, safety practices, equipment disassembly, and cleaning procedures for removing excess PVC from your flange, die head, mandrel, and feedscrew. Even if you’ve done this many times before, this video is an excellent refresher to achieve the best results.

Feedscrew maintenance is so important we have written 8 other blog posts on this subject. Check out the below:

Feedscrew and Design Truths for Improved Longevity, Part I

Feedscrew and Design Truths for Improved Longevity, Part II

Feedscrew and Design Truths for Improved Longevity, Part III

Essential Feedscrew and Barrel Maintenance Part I

Essential Feedscrew and Barrel Maintenance Part II

Essential Feedscrew and Barrel Maintenance III, Purging – Part 1 of 3

Essential Feedscrew and Barrel Maintenance Series Part III – Effective Shutdown and Restart Procedures – Purging 2 of 3

Essential Feedscrew and Barrel Maintenance Series Part III – Effective Purging for Scheduled Maintenance & Disassembly – Purging 3 of 3

With these 8 blogs and the video tutorial in your maintenance toolkit, we hope it helps you achieve better quality products, keeps your machine running in tip-top shape, and your feedscrew as good as new for many years to come.

Have comments or questions about this video? Comments below!

Don’t forget to rate this blog post so we can provide more of the subjects you like!

If you need service assistance, please contact us.

Cheers,
D-S Connect Blog Team

In the previous blog, we covered basic characteristics of low bulk density materials and common single screw extruder designs used in reclaim processes. This blog takes that a step further by delving into the benefits of feed-assisted single screw extruders, including a crammer feeder, ram stuffer and cutter compactor. Feed-assisted single screw options are a game-changer when bulk density is too low for gravity feeding or when dealing with problematic feeding material.

Crammer Feeder: This is the most basic of the feed-assisted single screw options. The crammer feeder has a unique hopper with a vertical auger to convey materials into the feed section. The hopper and feed auger are designed based on your specific material characteristics to ensure that the materials can be compressed and fed into the extruder. The downsides are that the feed opening is smaller, bulk density and feed geometry need to be in a narrow range, and the crammer is difficult to remove. However, this is an economical option for feeding a range of reclaimed materials.

Ram Stuffer: This machine is engineered with a pneumatic ram assembly to push recycled material into the feedscrew. Grooves in the feed section enhance operation, and this design works with low or high bulk density materials. Advantages include low energy usage, simple device control, versatility to run just about any scrap material, and the ability to retrofit onto existing extruders with minimal rework.

The ram stuffer has a feed opening that is 12 to 14 times larger than a crammer. The pneumatically actuated ram does not have to be connected to extruder speed, can be retracted for high bulk density material, and can generate high pressure. When using the ram stuffer, remember that bulk density will affect the rate. For example, changing from a ground film to a uniformly shredded film can result in an output increase of 10 to 15 percent. Ram stuffers are also necessary when working with non-compressible reclaim materials like nylon fiber. Moisture content must be controlled to less than one percent for proper operation.

Cutter Compactor: As with the ram stuffer, this machine works well with low bulk density materials. In the case of higher bulk density infeed materials, accessory components may need to be added. Some size reduction can be achieved in the drum and shredded material from 2 to 4 inches in size can be fed. A significant bonus of this feeder is that it can accept feedstock with residual moisture up to eight percent. It is also PLC controlled to maintain consistent feeding, which minimizes product variation. The downside is that the drum requires relatively high power consumption.

With this design, material is fed directly into the cutting chamber via a conveyor. Slabbed or loose waste can be size-reduced by an adjacent shredder and conveyed to the drum automatically using logic to maintain consistent feeding. It can also be fed directly from an off-spec roll using a driven nip roll. Moisture is removed from the material in the compactor drum using mechanical energy and a blower. Temperature is regulated within the drum to ensure stable operation. Residence time is managed to optimize this process, and an auger feeds the densified material into the extruder at consistent rates. Higher moisture content will result in lower overall extrusion rates as the residence time in the drum is increased to ensure that moisture is controlled prior to entering the extruder.

Once you determine the right feeding mechanism, all other standard screw processes need to be addressed to ensure the best performance. These include melting, mixing, devolatilization, and pumping. Screw design is critical to performance and should be based on your materials and the final product.

Additives such as antioxidants, fillers, and colors need to be considered along with devolatilization (single vent or multiple vents), and filtration based on contamination levels.

We are happy to work with you to determine the most feasible solution based on your materials and applications. Contact us today for an evaluation.

Cheers,
The D-S Connect Blog Team

Reclaim extrusion is a worthwhile pursuit for processors looking to achieve sustainable practices while taking advantage of cost savings from re-using available materials. What is the right machine for your reclaim objectives? In the first part of this blog series, we’ll cover the basic characteristics of low bulk density materials as well as various single screw extruder designs used in reclaim processes. In the second blog, we’ll discuss feed-assisted single screw extruders including a crammer feeder, ram stuffer and cutter compactor.

Due to the nature of plastics recycling, materials come in different forms and shapes. The most common include flake, fluff, pellets, chips, chunks and ribbons. The term bulk density refers to the weight per unit volume of the raw plastic material as it is purchased from the material supplier. In the world of plastic resins, bulk density is labeled in pounds per cubic foot (lbs/cu ft), grams per cubic centimeter (g/cc), or kilograms per liter (kg/l). Some of these materials are non-free-flowing due to irregular particle shapes, inconsistent bulk density, varying contamination levels, electrostatic charge, or moisture content. When conveying or feeding these materials, they may agglomerate into large masses that impede flow and create erratic throughputs or blockages. Thus, the need for reclaim technology that supports consistent materials conveying and processing.

When choosing a machine, it’s important to consider the feedstock form (particle size, material properties), the bulk density of the feedstock (in general the higher the bulk density, the higher the output rate), and the compressibility of the feedstock. Common reprocessing concerns include material contamination (soil, wood, paper, different types of plastics); contamination levels (by percentage); moisture content;  availability of a consistent material stream; and if the equipment is capable of processing varied bulk densities. Following are the reclaim pros and cons of some common extruder designs.

Smoothbore single screw extruder: This is the most fundamental extruder choice with the lowest capital cost and greatest versatility. However, bulk density is critical and typically needs to be greater than 15 pounds per cubic foot. In terms of particle size, the aspect ratio must be smaller than the available feed opening. Small extruders (under 4 ½-inches in diameter) are limited in feed depth because of mechanical constraints so particle size reduction is critical to proper feeding.

Groove feed extruder: With the type of intensive grooves often found in an extruder designed for PE pipe extrusion, this type of extruder is best for specific medium-to-heavy reclaim materials that do not involve thermally sensitive plastics. Axial grooves in the feed section increase friction in the feed zone to improve feeding. The grooves will increase output over a standard smoothbore extruder and impart less shear temperature into the material. The material exits the extruder at lower melt temperature and downstream cooling requirements are reduced.

Wide mouth scrap reclaim extruder: Ideal for light to medium bulk density material, wide mouth extruders feature a 3 L/D tangential feed throat with a 30-degree feedsection opening to one side of the extruder. A grooved horizontal liner creates positive material conveyance through the feed section. This type of machine can be used for bulk densities from five pounds per cubic foot upward, although at densities under 10-15 pounds per cubic foot a ram stuffer can enhance performance significantly.

Dual diameter extruder: This extruder is used for very low bulk density products, such as foam, ranging from two to five pounds per cubic foot. It is engineered with two different diameter sections; a large feed section and a small extrusion section. The feed section is typically two extruder sizes larger than the smaller diameter section to allow for a high-volume feed area for compressible low bulk density materials. The small diameter section is fed by the large-diameter via the transition section. The small diameter section acts as a standard extruder performing feed, melting, mixing, venting and pumping functions. The feedscrew can be a simple metering screw or a complex barrier design depending on application.

We look forward to talking about options for feed-assisted single screw machines in the next blog. In the meantime do not hesitate to contact us for support or additional questions  Stay safe and healthy!

Cheers,

The D-S Connect Blog Team