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3D Printing of “Porous” Tools Awarded Walmart Research Grant

By: Tony Deligio 9. September 2014

Additive manufacturing has long been used to add conformal cooling channels to injection molds, maximizing heat transfer efficiency, but what if it could be taken further, using just the amount of material needed in just the right place to create a porous tool sub-structure that would lessen the tool’s cost and weight while boosting its efficiency?

 

That’s exactly the goal of a team of researchers at the Purdue School of Engineering & Technology at Indiana University–Purdue University Indianapolis (IUPUI) who received a  grant from retailer Walmart’s U.S. Manufacturing Innovation Fund and the United States Conference of Mayors.

 

The two-year $291,202 grant will fund IUPUI’s research project: “Optimal Plastic Injection Molding Tooling Design and Production through Advanced Additive Manufacturing.” The project’s goal is to reduce the cost and increase the performance of U.S.-made tooling through what it calls “multiscale, thermo-mechanical topology optimization methods and metal additive manufacturing.”

 

Andrés Tovar, an assistant professor in IUPUI’S Department of Mechanical Engineering, said the goal is to create a “free-form, lightweight, innovative structure of maximum performance….a lightweight structure of maximum mechanical stiffness and maximum heat dissipation.”

 

IUPUI is working with Hewitt Molding Company (Oakford, Indiana) and 3D Parts Manufacturing (Indianapolis) on the project, with 3D Part Manufacturing using its EOS EOSINT M 280 direct metal laser sintering system to build the porous tools.

 

A sample product confirmed the potential benefits, according to Tovar. He estimates that “conservatively” the optimized porous tool would allow 30% cost reduction, derived directly from material saving, as well as a 20% performance increase based on greater cooling efficiency and a shorter cycle time.

 

In addition, Tovar’s team expects to see tool life increase of at least 10% compared to conventional cavity molds, with a lower cost per plastic part (from $0.62/piece to $0.58/piece for a given industrial test case), and increased part quality by eliminating imperfections resulting from non-uniform cooling.

 

“The cost of 3D printing is proportional to the weight,” Tovar said, “so, what we propose is: we can take those designs of molds and redesign them by changing the solid fill material with porous material. So we can have complex molds with conformal cooling in a porous structure.”

 

Done correctly, Tovar notes the novel design will have no deleterious impact on the tool’s integrity. “Mechanically it’s going to maintain the structural stability; it doesn’t compromise any structural performance; it’s not going to deform; it’s not going to change over time, due to deformation. Wherever it needs to have the material, it will put the material in there.”

 

Over the next two years, Tovar said his team, in conjunction with Hewitt and 3D Parts, will create production tools to further test the technology, and fine tune the predictive models and algorithms that determine the tool’s cellular structure. In addition, molding trials will allow the researchers to incorporate processing parameters into the algorithm. Above all, the trials will create data, something currently lacking in the additive manufacturing field.

 

“There is very little data out there available about the thermal and mechanical properties of layered materials using additive manufacturing,” Tovar explained, “so we want to populate that data base.” Better data = better algorithm.

 

If the predicted results are proven out, Tovar believes that additive manufacturing could encroach on long-held subtractive manufacturing techniques.

 

“We believe porous structures are going to be more and more common in many thermo mechanical components,” Tovar said. “If you put the holes in in the right way then the mechanical performance is not going to be decreased and the thermal performance is going to be higher. We believe it will be cheaper for the manufacturer.”

 

Oregon State partners with Arburg
Given how many of the products it sells are made from plastics, with all of those requiring a tool or die, Walmart is keenly aware how important advances in mold and die production could be as it works to ramp up U.S. sourcing.

 

In addition to Tovar and IUPUI, Sundar V. Atre and Rajiv Malhotra, researchers at Oregon State University, were awarded a $590,000 grant from the Walmart Foundation. Their research project involves “novel metal additive manufacturing processes for fabricating low cost plastic injection molds.”

 

Oregon State will partner with MTI Albany (direct laser sintering), North American Höganäs (tailoring metal powders)  and injection molding machine supplier Arburg (testing mold performance).

 

Atre told Plastics Technology that his team is developing two additive manufacturing approaches to create molds, with tool steel as the base material. In an Oregon State release, Atre estimated their technique could reduce mold-making costs by 40-50% noting:

 

“Current practices for fabricating these molds are labor-intensive and costly, and much of the mold material is wasted as metal chips. [Additive manufacturing] will give U.S. manufacturing an edge.”

Recipients of Walmart's 2014 Manufacturing Research Grants

VW Explores Thermoplastic RTM

By: Matthew H. Naitove 5. September 2014

I recently posted news that BMW in Germany had installed a large vertical press from Engel to mold composite parts with liquid reactive thermoset resins. Now, it appears that Volkswagen in Germany is also pursuing liquid reactive molding of composites, but in this case with thermoplastics.

KraussMaffei (U.S. office in Florence, Ky.) is developing equipment systems for thermoplastic RTM, involving conversion of liquid caprolactam monomer into nylon 6. Because of the low-viscosity of molten caprolactam, it can impregnate dry fabric reinforcements in a mold, which would be impossible with viscous nylon in its polymerized state. KM has pursued what it has dubbed “T-RTM” using one of its own PUR metering machines paired with a vertical-clamp, tilting mold carrier (introduced at K 2013). This equipment comes from the Composites/Surfaces Business Unit of the Reaction Process Machinery Div. at KM.

The first products made with KM’s T-RTM process are B-pillar reinforcement prototypes made at the FRP TechCenter of the Volkswagen Group Research Center in Wolfsburg, Germany. The project utilized caprolactam supplied by BASF SE (U.S. office in Wyandotte, Mich.). A special RimStar series metering machine was adapted specifically to the extremely low viscosity of caprolactam and was fitted with a special mixhead, high-performance axial pumps, and a fully electric temperature-control system.

A True Pioneer Passes

By: James Callari 29. August 2014

 

I was saddened earlier this week to learn of the passing of Frank Nissel, who revolutionized the sheet extrusion business when he co-founded Welex in 1966, and was elected to The Plastics Hall of Fame in 2000 during NPE.  Frank passed away Thursday, Aug. 28. He was 89.

 

I remember the first time I met Frank. It was in 1988. I had just joined the now-defunct Plastics World Magazine as senior editor in charge of reporting on extrusion. I didn’t even know what extrusion was at the time. My boss back then, current plastics blogger Doug Smock, explained it to me this way, to my recollection: “In extrusion, plastic pellets are melted and conveyed by a rotating screw through a die to form a part.” A light bulb went on over my head that would soon be extinguished. I replied, “Oh I get it, so the plastic is somehow colored?” “No,” Doug said. “It’s not d-y-e, it’s d-i-e.” I’m not sure if learning that made matters better or worse in my mind. Was extrusion a process where plastic pellets went to die?

 

So with that “background,” I was soon off to Blue Bell, Pa. to meet this regal, larger-than-life figure that I had heard a little bit about beforehand. I don't know how tall Frank was. Maybe 6 ft or a bit more? But he seemed a lot bigger. When he stood up his back was perfectly straight, his shoulders were thrust back, his shirt was crisp and his suit immaculate. I remember thinking, "This guy is a giant."

 

I was not working on an article about sheet when we met, as I recall; I just wanted to sit down and talk with someone who knew stuff and pick his brain. Pick his brain? Who was I kidding?  I was scared. I knew nothing, didn't even know what questions to ask, and realized I wouldn't understand the answers anyway. And I had heard that Frank, well, could be a bit intimidating and didn't suffer fools gladly.

 

But Frank could not have been more accommodating. He was pleasant, charming, friendly, and funny. Very funny. He called me Mr. Callari, which was disarming and immediately put me at ease. And he was patient. (I came to discover later that he wasn't always patient!) I learned more about his personal trials and tribulations, his outside hobbies and interests, and his opinions about this and that (including plastics magazines and editors) during that meeting than I did about the nuts and bolts of sheet extrusion. But that was more because a lot of the technical stuff he told me went over my head. Somehow he realized that (I guess it was the glazed look in my eyes), teased me about it, waved his hand and suggested that I close my notebook, told me to relax and assured me that at some point sooner or later some of this extrusion mumbo-jumbo would make sense to me (later, as it happens) if I kept at it.

 

One thing I found out soon enough was that a lot of people in a lot of places all over the world had his equipment. "That article you wrote about (so and so)...100% Welex," he'd quip.

 

Over the years, meeting at his office, at trade shows, at SPI/SPE events, Frank and I became friendly. Oh, he'd poke me every now and then about this article or that, but Frank was one of those guys who once he decided he liked you…that was that.  He enjoyed pulling my leg. "What’s new?” he’d ponder, repeating my question. “We painted our machines a different color. Write about that.” But he was truly a font of information about anything related to polymers and processing, and not just extrusion either. "I read that article you wrote last month," he'd say. "That (whatever) that you reported was new is actually about 25 years' old. It didn't work then, it won't now."

 

Excuse the cliches, but Frank was in no uncertain terms an industry icon, a legend, a pioneer, a giant, an immortal. Frank was to the world of extrusion what Robert Schad has been to the world of injection molding. Now, if God has any questions about seven-layer sheet extrusion for thermoforming drinking cups, he knows who to ask. Heck, they might be stringing up a line now.

Plastic Pallets Manufacturer Gets Grant To Further Expansion Into Thermoplastic Composites

By: Lilli Manolis Sherman 28. August 2014

Indiana-based Jeco Plastics Products recently received a research grant from Purdue University under the IN-Mac program to study how thermoplastic composites with continuous internal fibers in either single or multiple directions develop wrinkles when being molded with multiple cavity thermoforming tools. The aim is to compete with thermoset composites used in applications such as aerospace and defense components. “Thermoplastic composites are lighter weight, less expensive and have fewer design limitations” says Jeco president and CEO Craig Carson.

 

Jeco was the first to receive a grant under this program which is tailored to assist companies extend existing technology. In Jeco’s case, the grant focuses on the company ability to design sophisticated multiple cavity thermoforming tools for molding complex structures that cannot be manufactured using other processing technologies. In fact, Carson points out that critical to his company’s selection for the grant is its unique thermoforming capabilities, which were recently used to develop a thermoformed door liner for a cryogenic container to be used by NASA on the International Space Station. In a recent interview, Carson told me that this cryogenic container is formed from a PP composite reinforced with continuous PP fibers which boasts significant durability even in thin gages at cryogenic temperatures of -195˚C (-319˚F).

 

Jeco’s mainstay has been the design and manufacture of  rotationallymolded, highly durable pallets and containers made of LLDPE and reinforced with steel or tension members for the worldwide printing and automotive industries, along with other industries handling heavy product that needs damage protection.

 

However, this forward-thinking company has developed capabilities that include the ability to produce large plastic structural components made with continuous carbon, fiberglass and PP fibers in a variety of thermoplastics including PP, nylons, PEEK, PEKK, and polysulfones. Carson told me they also have integrated custom woven cloth of various metals and other fibers into laminated thermoplastic structures to create materials with unique properties. “The IN-Mac grant has allowed us to discover how to predict the wrinkling of the fabric and optimize our tool design to minimize this problem.” He also notes that controlling the amount of wrinkling taking place is very difficult, as the necessary sheet control is too limited in existing thermoforming equipment. “It was necessary to develop and fabricate extensive modifications to address this shortcoming”, he notes. He also adds that tooling software currently available does not take into account the within the sheet. “So, after much trial and error, as well as simulation modification and validation, we are now capable of producing, for example, structural components with PEEK and PEKK with unidirectional carbon fibers and PP with bidirectional PP fibers.”  Be on the lookout for more extensive coverage on this innovator in an upcoming PT issue.

 

Want to find or compare materials data for different resins, grades, or suppliers? Check out Plastic Technology’s Plaspec Global materials database.

 

New Guide Offers Tips on Speeding Changeovers

By: James Callari 27. August 2014

 

Time, as the old adage goes, is money. This is certainly true for custom processors, who in large part are able to pay their bills based on how quickly they are able to transition from one job to the next. It makes no difference whether you are involved in injection molding, extrusion, blow molding or any other process; you don't make money if your not making parts.

 

There’s some help along the way. Check out  How to Reduce Changeover Time and Increase Throughput, available on line from Polymer Ohio and its subsidiary, OH!Manufacturing.

 

Does $1.8 million sound like a lot of cash. According to the guide, that's what it costs for a one-hour daily changeover on a fairly significant packaging project with the line running 240 days per year. Many manufacturers don’t even realize how much money is slipping out the door because they aren’t measuring properly. Maybe there are techniques where you can cut that time in half.

 

Can you improve your changeover procedures? Click here and download the PDF.




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