Borstar technology delivers unique advantages to greenhouse film applications due to its unique molecular architecture. Borstar technology relies on a broad bimodal molecular weight distribution of polyethylene copolymers to enhance performance and processability of material, making a film that is readily processed on film equipment and mechanically strong and tough to provide enhanced crop protection. These variables grant engineers and product development technicians significant design freedom to create products over a wide density and molecular weight range, allowing for precise performance of the material for a particular application. Borstar resin provides better durability with increased toughness, environmental stress crack resistance (ESCR) and weatherability.  Because of the improved processability and mechanical properties of Borstar resins, demanding agricultural applications can gain from a longer service life of the film, reducing the total carbon footprint of the entire agricultural operation. 

Additionally, the unique optical properties of Borstar, which are also derived from its molecular design, bring a natural ability to diffuse light while maintaining high transmission rates. The matte appearance of the film naturally diffuses sunlight across the interior of the greenhouse and does not tend to reflect light the way a clear film would.

This performance is achieved without the use of additional fillers or other additives to diffuse or absorb the light. This design allows the maximum use of sunlight for the plants in the greenhouse without overexposing them and keeping the climate within control limits to improve crop yield and quality.  Good light distribution in the greenhouse allows the crops better conditions for photosynthesis and microclimate development.  Additionally, the PE film and greenhouse structure protect from too much direct sunlight, high winds, extreme temperatures and variable rainfall. These types of greenhouse films are suitable for crops such as vegetables (including non-native varieties- tomatoes, cucumbers, peppers), lettuce, melons, flowers and other crops that thrive under consistent conditions. 

This design allows the maximum use of sunlight for the plants in the greenhouse without overexposing them and keeping the climate within control limits to improve crop yield and quality.

Borstar FB2230 was evaluated for the agricultural film greenhouse application owing to its physical and optical properties. Because of the unique molecular structure, a naturally matte surface finish occurs when making blown film (Figure 1).

Figure 1: Unique molecular structure creates naturally matte surface finish.

This matte surface finish is what allows even distribution of the light which was shown to improve crop yields in a study of tomato growth in the Netherlands¹. Compared to a clear control film, a moderately hazy film (45% haze) showed an 8% increase in crop yield. When the haze value was increased from 45% to 71%, a further 3% increase in crop yield was seen (Figure 2). 

Figure 2: Increase in crop yield based on haziness of film.

While the production advantage of crops is clear from the use of Borstar film, it is also essential that the film be able to hold up mechanically to use in the field. While durability can be improved by using thicker films, 3-4 mil film is typical for single-season growing while 6-10 mil film is more common for multiseason use, the addition of UV stabilizers can also bring increased longevity and durability to the film as well. By including a UV stabilizer in the Borstar FB2230 film, the retained elongation over 30 months was improved from just 10% in the MD reference, to over 70% in the modified film examples (Figure 3)². 

Figure 3

In other studies, growth acceleration and production increases were also measured. By using a film that diffuses light, the time to harvest for different plants was reduced by about 25% while increasing the total weight of finished product by about 6% (Figure 4). These kinds of improvements in agricultural operation allow for increasing the value per square foot of farmland and bringing better, more reliable production methods to the market.

 

It is clear that these kinds of improvements in agricultural operation allow for increasing the value per square foot of farmland and bringing better, more reliable production methods to the market.

Figure 4

 

 

 

 

 

 

 

Conclusion:

Several case studies have shown how the advanced optical and mechanical properties of Borstar films can significantly benefit agricultural and greenhouse applications. Increases in yields, decreases in production time and ease of use and durability are all inherent advantages of this technology.

Products like Borstar FB2230 are well positioned to serve this growing market segment and to continue to bring performance to a demanding application that is critical to our modern supply chain infrastructure. PE resins with unique and tailorable molecular designs for demanding applications continue to push the boundaries of what is possible and help deliver efficient and effective solutions to the market.

 

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[1] Diffuus licht bij tomaat, Wageningen University and Research Glastuinbouw, 2012 (Rapporten GTB 1158)

[2] "Effect of a Diffuse Glass Greenhouse Cover on Rose Production and Quality" N. García Victoria, F.L.K. Kempkes, P. Van Weel, C. Stanghellini, T.A. Dueck and M. Bruins, Wageningen UR Proceedings of the International Symposium on Advanced Technology

Susan Zhang is Senior Technical Service and Development Advisor. Peter Malmros is the Business Development Manager. Kyle Anderson, Ph.D, is Application Development Supervisor. 

Photo Credit: Siemens Industry Inc.

Machining can be an obstacle in the quest for “first-time right” 3D printing — designers need to ensure parts can be held in the machine tool, and that machines can access the features and critical surfaces that need to be machined. The digital thread can aid in this by connecting designers with machining simulations, so they can adjust the part accordingly.

Adam Hiller, additive manufacturing and Siemens Xcelerator portfolio solutions consultant at Siemens Digital Industries Software, designed this 3D printed steering knuckle for an eRod (electric dune buggy) from Kyburz using Siemens software solutions connected by the digital thread. “We’re thinking of the entire lifecycle now instead of just saying, ‘Oh, the part looks cool, it does what we want and it will satisfy all our criteria,’” he explains. “We're saying, ‘Let's also make sure that everybody else downstream is able to do as automated of a process as possible.’” Here are several features on the as-printed part that were designed with machining in mind:

1. Triangular mounting feature in center spindle hole. This triangle within what eventually became the spindle hole served as a mounting feature, and was eventually milled out.
2. Extra stock in bolt holes. The four bolt holes were also machined (instead of printed) to ensure quality and precision at the points where the part attaches to the vehicle.
3. Extra stock on critical surfaces. Designers added extra stock to the sections of the part that make contact with the vehicle. These areas were machined to ensure a flush fit.
4. Machinable support structures. Support structures in metal 3D printed parts serve the important functions of holding up overhanging features and distributing heat away from the part to prevent warpage. Once the part is out of the printer and support structures are no longer necessary, they are typically removed by hand or machine tool. Hiller wanted postprocessing for the steering knuckles to be as automated as possible, so he ensured that the machine tool could access all of the support structures for removal.
5. Trumpet mounting feature. While simulating the machining process, machinists realized the parts were at risk of being ripped off the build plate due to vibration. Hiller worked with the machinists to create a trumpet-shaped structure in the middle of the build plate to securely mount the parts for machining.

To learn more about how Hiller and his team used the digital thread in this application, read “Digital Thread Enables First-Time Right 3D Printing.”

More From This Author

Julia Hider is a senior editor for Modern Machine Shop, where she writes about the metalworking industry. She also serves as the robotics and autonomy correspondent for parent company Gardner Business Media. To find more of her content, SUBSCRIBE HERE.

Dr. Chris Rauwendaal, Rauwendaal Extrusion Engineering, Inc., (EE.UU.) Source: Plastics Hall of Fame

Dr. Chris Rauwendaal's legacy is synonymous with groundbreaking advancements in plastic extrusion. From his pioneering screw designs to his seminal work in extrusion theory, his contributions have empowered professionals worldwide and propelled the industry forward.

A graduate of Delft University of Technology in the Netherlands, Rauwendaal earned his postgraduate degree in mechanical engineering in 1973, followed by a doctorate from Twente University of Technology in 1988.

Rauwendaal's professional journey began at American Enka Co., where he served as a development engineer. His groundbreaking work on a patented screw design earned him the prestigious President's Award. Over the years, he continued to innovate, developing patented screw designs, mixing elements and extruder components that revolutionized extrusion and injection molding processes.

In 1977, Rauwendaal's quest for innovation led him to Raychem Corp. in California, where he assumed the role of manager of process engineering in Corporate R&D. Here, he spearheaded a myriad of activities, including sheet extrusion, wire coating, tubing extrusion, blown film extrusion and coextrusion activities. He was also an internal consultant on process-related problems and activities.

A prolific author and educator, Rauwendaal's contributions extend far beyond the laboratory. His impressive publication record includes over 300 papers, books and video training courses. Notably, his book “Polymer Extrusion,” first published in 1986, remains a cornerstone in the field.

Reflecting on the journey of writing his first book, “Polymer Extrusion,” Rauwendaal recalls the arduous yet fulfilling process that spanned several years. Balancing the demands of full-time employment and parenthood, he poured countless hours into the project, often working upwards of 60 to 80 hours per week. Despite the initial challenges and uncertainties, his optimism and determination drove him forward. Initially envisioning completing the book in six months, Rauwendaal ultimately dedicated two years to the writing process. The culmination of his efforts proved immensely gratifying as “Polymer Extrusion” garnered widespread popularity within the industry.

Indeed, the enduring success of "Polymer Extrusion" is a testament to its significance within the field. Widely regarded as essential reading for process engineers working with extrusion, the book has achieved remarkable sales figures over the past three decades. Published by Hanser, the book's enduring appeal has led to multiple new editions, with the latest being the fifth edition. Rauwendaal takes pride in the book’s enduring legacy, recognizing its pivotal role in shaping his career trajectory and establishing him as a leading authority in the realm of plastic extrusion.

In his current role as president of REE Inc., Rauwendaal remains at the forefront of advancing extrusion technology. Through REE, he provides a comprehensive suite of services tailored to the polymer processing industry. Additionally, REE serves as a focal point for training and professional development initiatives, with Rauwendaal leading the charge.

About his extensive experience as an educator, Rauwendaal underscores the value he finds in sharing knowledge and expertise. Over the span of four decades, he has conducted numerous seminars and taught thousands of individuals, imparting invaluable insights to the next generation of professionals. The opportunity to witness the impact of his teachings firsthand brings him a profound sense of fulfillment and purpose.

Among his many accomplishments, Rauwendaal's development of a groundbreaking theory for predicting shape changes in noncircular extrusions stands out as a significant milestone. This theory revolutionized die design, providing invaluable insights for the industry. Additionally, his invention of the patent-pending super degassing screw (SDS) represents a major leap forward in extrusion technology.

With nine patents to his name and esteemed recognition as a fellow of the Society of Plastics Engineers, his innovative spirit continues to shape the future of plastic extrusion. Currently collaborating with his colleague Giuseppe Poncelli in Italy, Rauwendaal is engaged in pioneering work to enhance degassing capabilities. Together, they are developing a cutting-edge system, designed for high-level degassing for single-screw extruders. Anticipation runs high as they await the outcome of their research in a couple of months, with the potential for these innovations to revolutionize the industry.

Talking about his induction into the Plastics Hall of Fame, Rauwendaal expresses a profound sense of fulfillment and enthusiasm for the industry. With 51 years of experience under his belt, he remains deeply passionate about his work, finding excitement and inspiration in the ever-evolving landscape of plastic extrusion. Looking ahead, he harbors hopes of continuing to contribute to the field for many more years to come, driven by his unwavering dedication and enthusiasm for innovation.

La incorporación se ha dado en un momento de expansión de la empresa italiana, experta de soluciones de filtración para recicladores, donde Teresa Márquez aportará su experiencia.   
Fuente: Fimic.

Fimic, compañía italiana especializada en soluciones de filtración para reciclaje, ha incorporado a su equipo de ventas a María Teresa Márquez Gradis como nueva responsable de ventas en Centroamérica, México y España.

Se trata de una decisión estratégica en un momento de expansión de la empresa y cumplimiento de objetivos como proporcionar soluciones de vanguardia y un soporte integral a clientes globales, impulsando la innovación y la eficiencia operativa durante el proceso de reciclado de plásticos.

Antes de Fimic, Teresa Márquez dirigía su propia empresa representando productos que contribuyen a incrementar la eficiencia y sostenibilidad de los procesos industriales, una experiencia que aplica en su nuevo rol desde marzo.

“Es un privilegio tener la oportunidad de ser parte de una empresa que tiene un impacto tan grande en la comunidad del reciclaje del plástico. Nuestro objetivo es seguir expandiendo nuestro servicio, centrar nuestros esfuerzos en el cliente, introduciendo tecnología innovadora y asegurando nuestra posición de líder en el sector. Nos esperan muchas actividades emocionantes”, señaló Teresa Márquez.

Con esta incorporación, Fimic reitera su compromiso de ofrecer valor a clientes, anticipándose a las necesidades del mercado, aportando colaboración, innovación y crecimiento en la región.

Over the last 13 years, General Atomics Aeronautical Systems Inc. (GA-ASI) has explored the use of polymer/composite and metal additive manufacturing (AM) as a cost- and time-saving alternative to conventional manufacturing, not only for tooling to produce advanced composite parts, but also for flight-qualified parts themselves via the company’s unmanned aerial systems (UAS). Photo Credit, all images: General Atomics Aeronautical Systems Inc.

When unmanned aircraft systems (UAS) company General Atomics Aeronautical Systems Inc. (GA-ASI, Poway, Calif., U.S.) began experimenting with polymer additive manufacturing (AM) circa 2011, a small team used the technology to rapidly prototype parts that would subsequently be produced in advanced composites. Since it was so much faster to print than hand layup and cure parts, this approach provided a quicker and less costly method to rapidly move through multiple design iterations, focus on the best option, then produce tooling and trial actual molded parts.

Over the next few years as it added more printers — including polymer, and later, metal printers representing multiple additive technologies — GA-ASI envisioned further uses for AM technology and began a program to explore production ramp-up and commercial adoption. By 2018, the first flight-qualified polymer AM part was flying on the company’s UAS and by 2019 its first flight-qualified metal additive part was in use. In 2021, the company opened a 700-square-meter Additive Designs & Manufacturing Center of Excellence in Poway, staffed by a team of 14 AM subject matter experts (SMEs) who focus on AM-related production, new application development and R&D projects. By 2026, that facility is expected to expand to 1,858 square meters with a concurrent increase in staff.

To date, GA-ASI says it has developed more than 350 flight-qualified AM parts and produces more than 7,500 production AM parts annually that have successfully completed over 300,000 hours of cumulative flight. The company forecasts growth rates to rise from 25% to 35% per year. How did GA-ASI move from prototyping to industrial adoption of AM tools and parts in the demanding aerospace/defense sector in roughly a decade?

“First we demonstrated to ourselves, then to our management, and later to key customers, the many, often compounding, benefits that additive technology can bring to programs — not just during the prototyping phase but also as low-rate initial production [LRIP] gets underway,” explains Steve Fournier, GA-ASI senior manager, Additive Designs & Manufacturing Center of Excellence and department. He says it’s vital to differentiate between prototype projects (doing it right once) versus production projects (doing it right 100+ times in a row) and to find the right applications early on to drive establishment of the elements of an AM ecosystem for application families that have a good chance of success. It’s also important to ensure that proper business case assessments are performed before technical development gets underway.

“Another critical aspect is to ensure you’re using the correct material, process and design for each application — and it does take time to develop guidelines to design for additive manufacturing,” Fournier continues. “For GA-ASI, buying printers so we could have a fast learning curve was important to our success and brought benefits at the aircraft level that wouldn’t have been possible if we hadn’t strategically built a centralized, consolidated AM infrastructure near where we build our UAS. However, we didn’t operate in a vacuum when building our expertise. Instead, we worked with other GA divisions, as well as strategic suppliers and customers. That helped us grow in competence without needing large CAPEX investments before we proved out the technology and achieved ROI.”

Early challenges

Moving from prototyping to industrial implementation was neither simple nor straightforward. The team at GA-ASI faced many challenges, including learning to navigate the differences between conventional engineering design and design for AM (DfAM), dealing with the higher cost of AM materials and the time and cost required to qualify them, plus the high, nonrecurring engineering (NRE) costs to develop and qualify new AM applications. It also took time to build adoption confidence within engineering, manufacturing and quality stakeholders, to secure funding to support increased staffing, equipment and R&D allowances, and to recruit and train staff.

“You need a coherent strategy to reduce risk and successfully implement and grow AM opportunities,” continues Fournier. “Start with established use cases, find the right AM applications and then application families with lower requirements and levels of control to build the use case and establish ROI.” He adds that in a high-mix/low-volume business model, it’s critical to approach AM by qualifying component families to spread the impact of initial NRE costs to develop the required AM ecosystem and to find mature users and willing partners to build your pathway to success. Additionally, communication is key, so constantly promoting AM’s capabilities internally and externally while building depth within your SME team are necessary. “It’s also important to find internal executive champions so top management supports what you’re trying to achieve and gives you the resources you need to be successful,” says Fournier. He also suggests prioritizing in-house capacity (what he calls “the brains of additive”) so internal teams can react rapidly to development efforts and stay sharp but outsource overflow and forecastable production to qualified AM partners (“the muscles of additive”) to manage CAPEX and ensure you can grow quickly when opportunities present themselves.

Among the AM ecosystem resources Fournier and his team ended up developing were material allowances and equivalencies, process and materials specifications, training programs and engineering design guides, production-/development-ready hardware, industrialization and qualification methodologies, and a qualified supply chain. Additionally, they had to develop and manage the digital thread and the technical data package, as well as develop a custom layer of software to tie commercial software packages together (including structural analysis, DfAM and manufacturing simulations) to analyze AM parts. They also developed an application library and assembled centralized resources, built knowledge and experience within the SME team, managed printing infrastructure (including design, prototyping and production), and ensured sufficient R&D and CAPEX funding (with concurrent technology readiness level improvement, application development and equipment, etc.).

AM success stories

As GA-ASI’s team gained experience and broadened the types of applications for which AM was seen as a viable manufacturing alternative, many interesting tooling and later flight-qualified parts were developed. Some of the most successful part and tooling cases are described below.

Vacuum mill fixture tools

Above are left and right sides of a fairing trim fixture used to finish a small section of a UAS wing. Tooling was produced in ABS on a big area additive manufacturing (BAAM) printer. Different sections/colors in the tools represent areas that were modified from the original build, demonstrating how easily AM tooling can be altered at minimal cost.

An especially successful application area at GA-ASI is printing both small and large mill fixture tools used to verify dimensionality and hold cured composite parts at room temperature as they are drilled and trimmed to final specifications. Tooling is typically printed on large-format AM (LFAM) printers such as the large-scale additive manufacturing (LSAM) printers from Thermwood Corp. (Dale, Indiana, U.S.) or the big area additive manufacturing (BAAM) printers from Cincinnati Inc. (Harrison, Ohio, U.S.) in discontinuous carbon fiber-reinforced acrylonitrile butadiene styrene (ABS). Versus producing tooling conventionally in composite or metal, printing is 2-3 times less costly yet can be completed 3-4 times faster.

This large carbon fiber/ABS composite mill tool for an engine cowl/skin is 2.4 meters long and 1.5-1.8 meters wide. It features complex vent channels used to pull a vacuum and hold cured parts in the correct position when drilling and milling. Vent channels were CNC’d after the part was printed on the BAAM and surface finished to smooth out the bumpy surface typical of LFAM prints.

In addition to using polymer LFAM technology to print mill fixtures for composite laminate parts, GA-ASI also uses the technology to produce full-scale wind tunnel models, as well as large-scale (3.1- to 4.6-meter) end-use assemblies and medium-scale models of UAS for ground-based testing. More recently, the company qualified a low-temperature-cure lamination mold to form shallow composite facesheet parts that are planned for production in early 2024. Further out, the company expects to expand use to even larger (6.1- to 12-meter) structures to support qualified applications. One GA-ASI workaround to limitations in the build envelope with many AM technologies is a series of techniques to bond/join/weld printed metal and composite components into much larger assemblies.

Propulsion ducting and tools

Another interesting success with composite LFAM involved printing sizable tubular ducts (4.6 meters long and 1.5-1.8 meters in diameter) that were used early during propulsion system development. That early in the design process, when the propulsion system was still evolving, it didn’t make sense to lock down tooling or part designs — an approach that is both time-consuming and costly. Instead, by printing designs, the team was able to iterate faster and more freely while ensuring costs stayed low. Now that product development work is complete, an advanced composite version of the ducts is planned for 2024. The last printed duct design will be converted to a trim tool, thereby giving it a second life.

Composite LFAM has also been used early in the design process to produce ground-based propulsion system ducting. The final printed duct is planned to be reused as a trim tool for advanced composite parts.  

Lamination molds

This qualified high-temperature lamination mold produced in Invar via WAAM will be used to produce composite parts for a next-generation UAS platform at GA-ASI.

Building on success with room temperature mill fixture tools, GA-ASI explored lamination molds requiring vacuum tightness and the ability to maintain tight tolerances at elevated autoclave temperatures and pressures. Metal LFAM technologies, primarily from the directed energy deposition (DED) family (including wire-arc additive manufacturing (WAAM) from Lincoln Electric Co. (Cleveland, Ohio, U.S.)), with various alloys were successfully used. (Read “Metal AM advances in composite tooling, Part 1.”)

A WAAM-printed mild-steel winglet lamination tool with challenging geometry passed all program qualifications at 30-40% less cost and 20-30% shorter lead times.  

Perhaps more significant is GA-ASI’s use of composite LFAM to produce autoclave-capable lamination tooling. Polymer/composite LFAM is of interest, owing to its lower cost and lighter parts. Discontinuous fiber is typically used in polymer LFAM prints to control slumping while the thermoplastic cools and solidifies. However, that also compounds anisotropy from the printing direction. While this isn’t an issue with room temperature tooling like vacuum mill fixtures, it’s a big concern at autoclave temperatures, especially when curing large parts requiring tight tolerances. By definition, the tool expands/contracts at different ratios in X, Y and Z axes as temperature changes. Despite these challenges, GA-ASI has been successful using two different composite AM technologies.

The team printed a 4.6-meter-long composite lamination tool on the BAAM machine.  Similar to the way injection moldmakers reverse engineer steel molds to solve warpage issues in thermoplastic parts — a technique called Kentucky windage — GA-ASI undersized certain tool dimensions during printing so that as the thermoplastic composite tool “grows” during autoclave ramp-up, it achieves the correct dimensions once at temperature. Fournier notes that it’s critical to use this technology for the right kind of part — ideally those with shallow curvatures and no interlocking features — and to preferentially design/print the tool so the axis with the lowest coefficient of linear thermal expansion (CLTE) coincides with the direction whose dimensions must be most tightly controlled in the final composite part.

Low-temperature composite BAAM lamination tool for a production application at GA-ASI.

Additionally, for use on LRIP tooling, GA-ASI has tested (up to 50 cycles) a ceramic matrix composite (CMC) technology widely used in the foundry industry for investment casting. Such tools are fragile in their as-printed “green state.” However, after controlled post-print infiltration (applying a chemical binder to silica sand during binder jet printing) and surface treatments, they can be densified and rendered vacuum tight. After a few curing cycles, the tool remains stable and exhibits easy surface maintenance and even a repair strategy.

GA-ASI has developed and qualified a variety of infiltration and surface processing methods to adapt the technology to high-temperature autoclave lamination tooling for aerospace. To date, more than seven infiltration and 10 surfacing processes have been tested, each with its own set of pros/cons and applicability. Of interest, the technology can produce large isotropic tools that can handle autoclave temperatures and pressures. More research is underway on this GA-ASI-developed printing technology.

Multiple examples of binder jet printed lamination molds using sand and epoxy. Autoclave-capable lamination tools ranging from 1 to 4 meters in length are used at GA-ASI for LRIP production. Advantages are significant lead time and cost savings — from months to days — using in-house printers. 

Additive takeaways

Given GA-ASI’s track record of industrializing AM technology, what advice can it offer companies considering the option?

“Before investing, ensure you understand the benefits AM can offer your business,” explains Fournier. “Recognize that AM technologies are expensive, so don’t rush into capital expenditures or try to squeeze an AM square peg into an application round hole and vice versa. Instead, establish strategic supply chain partnerships to build your ROI. Win/win partnerships with suppliers and customers are key to speeding up AM growth and adoption. Also, invest in additive manufacturing SMEs to drive your strategy and intentionally develop AM executive champions.” He notes that the faster companies focus on taking advantage of parts consolidation, complex designs and moving beyond the component level, the better the total AM value proposition becomes. He also suggests concentrating on applications featuring tight curves and conformal shapes that are costly or laborious to produce conventionally.

“If additive doesn’t bring value, it doesn’t belong there,” Fournier adds. “Start by establishing an AM ecosystem with low-criticality application families that have the highest business case to gain traction. Also, establish a centralized AM organizational structure, which for us proved to be a strong catalyst for AM adoption. After all, if no one knows about a technology, then nobody develops things for it.” He adds that industrial production AM for defense and civilian UAS is possible and it’s important to recognize that different and compounded AM benefits can be gained depending on the stage of the UAS lifecycle (see sidebar).

“However, one thing to also keep in mind is that despite its many potential benefits, AM is not the end goal,” he concludes. “Rather, AM is an enabling suite of technologies supporting full digital design and manufacturing process flows to realize significant total cost and lead time value propositions.”

Kyocera SGS Precision Tools’ MB45 Milling Series for general purpose milling features economical eight-edge inserts and a new helical body design, giving users a more durable and versatile cutter with better finish capabilities over conventional mills.

The MB45 series of milling cutters provide durable, reliable performance when used in general machining applications or for more specialized solutions. The MB45 series delivers the low cutting force benefits of positive inserts and the fracture resistance of negative inserts, providing an optimal surface finish, while making it well suited for smaller machining centers. The series is designed to cater to a broad spectrum of machining applications, giving customers a cost-effective solution for a wider range of possibilities.

The MB45 series is enhanced by Kyocera’s new PR18 Series physical vapor deposition (PVD) coating, which extends tool life. These grades incorporate Megacoat Nano EX coating technology, which, in some cases, double the resistance and durability, according to the company. By using a specialized double-lamination technique with special nano multi-layers for abrasion, wear and heat resistance, this coating surpasses conventional grades, delivering superior performance and extending the lifespan of the tools.

A walk through the two plants would reveal some fundamental differences in the way these two classes of materials are processed. Molding of thermoplastic materials is comparatively straightforward in that there is no difference between the chemistry of the raw material and that of the resulting molded part. The raw material delivered to the molding plant is chemically complete; a fully formed polymer of a desired molecular weight with the appropriate additives. If desired, certain fillers and colorants may be incorporated into the pelletized product.

The process then involves heating the material to an appropriate temperature so that a viscosity can be achieved that enables the mold cavity or cavities to be filled and packed, after which the material is allowed to cool before the mold is opened and the parts are ejected.

Sometimes this process is preceded by drying the raw material. If all goes well, the composition and molecular weight of the polymer in the raw material and the molded part will be comparable. In our facility, the process of choice was injection molding. But melt processing can also involve extrusion, blow molding and a variety of other approaches.

Shear rate is a function of flow rate and the size of the flow path, and higher shear rates produce a substantial reduction in melt viscosity, as depicted here. 

The thermoset plant looks very different. First, most of the presses, especially in the early days, were not injection molding machines. Instead, they were vertical platen systems without an injection unit — compression molding machines, where raw material is placed into the stationery bottom half of the mold and the closing of the mold then distributed the material into the cavity or cavities. Alternatively, the machines were hybrids that employed a “pot” that holds raw material that is then injected into a closed mold using a plunger, a process known as transfer molding. In addition, these raw materials were not pelletized. Instead, they were powders consolidated into pucks or they were soft, pliable materials, supplied in bulk or in sheet form.

A closer look reveals additional differences. For thermoplastic molding, the barrel that is used to deliver the material to the mold is heated and the mold is plumbed with water lines that remove the heat from the injected material and enable the solidification of the polymer in the mold. In the thermoset plant, the raw material is kept at a relatively low temperature until it reaches the mold and the mold is heated to a very high temperature, usually with steam, hot oil or electric cartridges.

This difference in material handling is fundamental to the processing requirements for thermoset materials. The raw materials, as provided to the molder, consist of a low molecular weight prepolymer, the appropriate fillers and additives, and a catalyst that is designed to initiate a chemical reaction which crosslinks the material into the three-dimensional network that, once formed, cannot be remelted. These catalysts are activated by heat, therefore the exposure to elevated temperatures should not happen until the material reaches the heated mold. Therefore, the thermoset molding process includes a chemical reaction that changes the structure of the material while the part is being molded.

How Thermosets and Thermoplastics Differ

This difference in the behavior of thermosets and thermoplastics during processing is fundamental to the approach of managing process control for the two classes of materials, particularly as it relates to viscosity.

Thermoplastics follow the familiar rules of non-Newtonian fluids. Viscosity declines with increasing temperature once the material is in the molten state, and it is also influenced by the effects of the shear rate applied to the material. Shear rate is a function of flow rate and the size of the flow path, and higher shear rates produce a substantial reduction in melt viscosity, as shown in Figure 1. The viscosity remains relatively low for most of the mold filling process and then, as solidification begins in the cavity, the viscosity will begin to increase. But ideally, most of the solidification process occurs after the mold cavity is full and, once the cycle is complete, the polymer has simply returned to the state represented by the raw material.

This difference in material handling is fundamental to the processing requirements for thermoset materials. 

The process of viscosity development is more complex in thermosets as shown in Figure 2. In this graph, the viscosity is measured in a torque rheometer in terms of the load on the instrument. The material enters the process as a low-viscosity thermoplastic and, in the early stages of processing, there is a small decline associated with mild heating of the material. However, as the elevated temperature of the mold initiates the crosslinking process, the viscosity increases rapidly. At some point, the viscosity rises to a point where the material will no longer flow. This is often referred to as the gel point, and is approximately indicated in Figure 2 by the point denoted as Tc10.

Here, the viscosity is measured in a torque rheometer in terms of the load on the instrument. The material enters the process as a low-viscosity thermoplastic and in the early stages of processing there is a small decline associated with mild heating of the material. However, as the elevated temperature of the mold initiates the crosslinking process, the viscosity increases rapidly. At some point, the viscosity rises to the gel point where the material will no longer flow (denoted as Tc10).

There are different methods for identifying this point quantitatively, but the practical significance of this event is that the mold cavity should be filled before this point is reached, because continued mold filling will be difficult if not impossible beyond this point regardless of how much pressure is applied to the material. The final viscosity of the properly crosslinked material can be 10 to 100 times higher than the viscosity of the material that entered the process.

Often, a crosslink density that constitutes 90% of what is theoretically achievable is considered to be a desirable condition that ensures good performance of the molded part and is indicated by the point identified as Tc90. The profile of this cure development is dependent upon both time and temperature. Higher temperatures will produce a lower minimum viscosity and a faster cure time.

If the cure time is shorter than the time required to fill the mold, this can result in impeded flow, poor weld line strength and cosmetic defects. While elevated viscosity is the cause for these defects in both thermoplastics and thermosets, the remedies can be very different. For thermoplastics, the premature development of an unmanageably high viscosity typically requires an increase in melt or mold temperature. In thermosets, the same strategy can simply make the problem worse by producing a more rapid increase in viscosity.

In our next installment we will look more closely at the cure process and how it can be measured with tools that provide greater insight into the crosslinking process.

ABOUT THE AUTHOR: Michael Sepe is an independent materials and processing consultant based in Sedona, Arizona, with clients throughout North America, Europe and Asia. He has more than 45 years of experience in the plastics industry and assists clients with material selection, designing for manufacturability, process optimization, troubleshooting and failure analysis. Contact: 928-203-0408 • mike@thematerialanalyst.com

The descendants of that original product are still part of the company’s portfolio, along with vacuum systems for material conveying, which usually function to deliver powders from the ingredient supply to a twin-screw extruder, either directly or through a feeder system.

Vac-U-Max Signature Series conveying systems. Source: Vac-U-Max

The historical trends that impact powder conveying have only accelerated in recent years. The rise of ever more specialized materials have necessitated greater accuracy. “Compounding has become more sophisticated,” Kennedy says. “There are new kinds of functional recipes for fire resistance, for health care, for biodegradable and new hybrid products mixing plastics with other materials. There is much more need for accuracy and quality control.”

At NPE2024, Vac-U-Max will also seek to connect with businesses that are using recycled material in their products, a change from past shows where the focus would have been squarely on users of powdered ingredients.

The irregular shape and properties of recycled plastic flakes present their own challenges, and these materials are often being mixed with wood flour, fiberglass or abrasives to make composite materials. Vac-U-Max considers non-free-flowing materials such as recycled plastic waste to be its specialty. “Recycled plastics are the epitome of non-free-flowing,” Kennedy says.

As health information and labor agency have raised the bar for worker safety, minimizing exposure has become a priority for facilities. Loose dust from manual dumping and refilling can be both an inhalation and combustible hazard, and vacuum conveying can serve to minimize those issues. “Dust can build up on rafters, on top of machinery — and some of the ingredients in compounding can be an immediate health hazard,” Kennedy explains. “When you move things by vacuum conveying, even if you do have a leak, it is less of a problem.” This is because the pressure differential tends to pull dust toward the equipment rather than disperse it out into the surrounding area. 

Vac-U-Max conveying systems for powders and granules can work with scales from the handful size up to 25,000 lbs/hr. 

Rösler’s compact RWK 6/12-2 swing chamber shot blast machine is equipped with automated workpiece handling and can easily be integrated into linked manufacturing lines, requiring very little space. In addition, the furnished digitization software package from Rösler Smart Solutions provides complete process and cost transparency and minimizes the overall personnel requirements.

The swing chamber shot blast machine can be used for all kinds of shot blast applications such as surface cleaning, de-sanding and descaling, surface homogenization and sophisticated shot peening operations. The workpieces treated in this machine include all kinds of castings and forgings, machined components, welded sheet metal parts and technical springs.

With its surprisingly small footprint, the compact shot blast machine requires little space when integrated into linked manufacturing lines. Specially prepared interfaces in the machine controls facilitate the quick connection to higher-level production control systems. A standard industrial robot handles the workpieces by placing them into the blast chamber and removing them after completion of the blast cycle. This task requires very little programming effort. A special clamping mechanism in the blast chamber holds the workpieces in place during the shot blast process.

In its standard version, the RWK 6/12-2 can handle workpieces with diameters of up to 600 mm and lengths of up to 1,200 mm. The clever dual chamber design enables the workpiece loading/unloading in one chamber, while the shot blast process takes place in the second chamber. This can almost eliminate unproductive times. The machine is equipped with two Gamma G turbines, which guarantee short cycle times and energy-saving operation. The installed power of the turbines and their placement on the blast chamber is always adapted to the respective shot blasting task. These turbines are equipped with curved throwing blades in “Y” design.

Compared to conventional turbines, the special blade form produces a significantly higher media throwing speed. This results in a 20% higher shot blast performance with a significantly lower energy consumption. Overall, cost savings of up to 25% can be achieved producing overall excellent efficiency of the entire shot blasting operation.

Another benefit of the “Y” shaped blade design is that both sides of the throwing blades can be used. This practically doubles their usable life. With a quick-change system, the throwing blades can be easily replaced without having to remove the turbine from its housing. Idle equipment times are, therefore, minimized.

The machine also has a wear-resistant design: The blast chamber is made from manganese steel and is additionally lined with easily replaceable wear plates made from a low-wearing material.

Digitization modules from Rösler Smart Solutions software package is designed to lower the operational costs and personnel requirements through intelligent process and equipment controls. At its center is the active monitoring and analysis of various machine components and process parameters. 

Industries such as automotive, aerospace and medical engineering frequently demand complete documentation of the operational data to control the compliance with precisely defined and validated process parameters. With the Smart Solutions modules Rösler also helps optimize the preventive maintenance of the equipment by keeping track of the operating hours, recorded uptime statistics and the automatic release of spare parts orders. 

Modern Machine Shop has launched a new online home for its Top Shops program. Shop leaders can find information about the program, explore the practices and stories of past Top Shops Honorees and find a link to the newly streamlined survey.

Modern Machine Shop’s Top Shops benchmarking program provides job shops with a free custom report that details how they are performing against their peers across a wide array of variables. Shops can use this information to better assess their strengths and weaknesses and explore options for future growth and improvement. Standout shops in machining technology, business strategies, shopfloor practices and human resources also feature as the subjects of an issue of Modern Machine Shop.

Modern Machine Shop has streamlined this year’s survey, dividing questions into smaller categories so users can focus their time and energy on their business priorities. Visit the Top Shops homepage to learn more about the program and find out how your shop compares to others by taking the free survey, open through April 30.