Micro Extruder for 3D Printing Could Debut Early Next Year

A newly developed micro extruder that could be a game changer for the 3D printing business could be on the market early next year, inventor and veteran screw designer Tim Womer said in an interview this morning with The Molding Blog.

A prototype machine is now being built for an undisclosed 3D printing manufacturer and if testing progresses as planned, the machines could be offered on the market as part of a 3D printing package very soon, Womer said.

The invention overcomes inefficiencies of filament-based 3D printing that have kept the much-hyped technology from achieving its potential as a tool for series industrial production. The process is slow and expensive because of the cost of preparing the filaments.

In Womer’s invention, standard plastic pellets are fed into the micro extruder, which continuously feeds a filament-like stream into a printing head at a rate up to 20 pounds per hour. The micro extruder can be operated off a wall outlet and could find a role with hobbyists as well as industrial users.

It’s the first of its kind.

“We did a really thorough patent search and we were really surprised that no one has done this before,” Womer said in the interview. Arburg, a builder of injection molding machinery, developed a 3D printer using standard pellets called the FreeFormer. Its 3D printer, which is unique, is fed by an injection barrel and is not continuous. The FreeFormer is very expensive and is for high-end users.

The promise of Womer’s invention is that it brings the economics of extrusion to the standard 3D printing process. Womer has been designing screws and working on the extrusion process since the 1970s and has had top technical position at some of the leading companies in the business.

He is also no stranger to 3D printing. He developed the extruders that Cincinnati Inc. uses for its Big Area Additive Manufacturing (BAAM) machinery.

Womer feels the sweet spot for his machine will be production of parts that are up to a cubic yard in size—and that takes in a big chunk of industrial manufacturing. Targets will be parts that require intricate detail and tight tolerances. Even internal geometries can be easily made with 3D printers.

Speeds of 3D printers still have limitations, but research is underway to significantly improve speeds. Womer’s machine means the plastic supply can easily keep up with the printer. Plus the resin economics are much better and the plastic will not have the additional heat history of filaments.

He hopes to have at least a couple of the micro extruders on display at NPE2018 in Orlando, Florida.  

Additive manufacturing

China Exit Crushes American Recycled Plastics Markets

Prices for recycled plastic have caved because of China’s planned exit from the marketplace. Prices for bulk rigid scrap have plunged this year from 9 cents per pound to 2.5 cents per pound, according to plasticsmarkets.org, an online marketplace for recycled plastics.

China published plans to end scrap imports by the end of this year. Licenses of plastics scrap importers were already being pulled at the time of the announcement. According to an article in the Wall Street Journal, China wants to force its plastics scrap buyers to use domestic supplies, which are growing. Close to half of America plastic scrap had been consumed by China until this year.

The screws began to tighten in four years ago when the Chinese government began to strictly enforce regulations on non-conforming materials in imported recycled paper and plastics as well as restricting the import of certain other plastic recyclables.

The situation creates a conundrum for environmental movements in the United States.

Recycling by American municipalities has  tripled in the last 25 years. The commercial value of post-consumer plastic, considering cleaning and logistics costs, is moving closer to null. It could be diverted to waste-to-energy plants, but that approach is not popular with environmentalists. Landfilling is no longer an option in most areas. Increased use of recycled content in American manufactured goods is an option, but a very slow process.



Asia, Green, North America, Post-Consumer Plastic

New Womer Extruder Targets Inefficiencies of 3D Printing

Veteran screw designed Tim Womer has developed a single-screw micro extruder to improve the cost effectiveness of 3D printing. A U.S. patent application for the technology was published today.

In Womer’s invention, a rotatable screw is attached to a torque drive of the printer, and extends through the feed chamber and conical bore of the barrel. The channel root depth at the exit opening of the extrusion barrel is about 0.025 to 0.075 inches.

Womer said the design uses standard pellets and specifically addresses challenges of 3D printers, which currently use filaments of plastic made from pellets. One immediate advantage is that the plastic won’t have the additional heat history in Womer’s concept.

“With the growth of 3D printing, an opportunity has been created to invent and develop a relatively small extruder, appropriately scaled to size that can deliver a consistently uniform and repeatable flow of molten plastic to a printer head at a rate of 20 lbs per hour or less,” Womer states in the patent application.

In 3D printing, the extruder must be able to operate at screw speeds from 0 to 400 rpm. Different screw designed are used for different plastics.

Womer’s invention overcomes many limitations of the filaments used in 3D printers. First filaments must have uniform composition and dimension or deposit rates will vary from spool to spool. Filaments may also break, slowing production. Spool costs are high and not all thermoplastic resins are available in filament form. Womer sates: “In summary, spool driven 3D printers are slow, failure prone, labor intensive, expensive to operate, and limited to particular polymer resins.”

Womer’s invention is part of a trend to make 3D printing more production friendly. 3D printing was developed as a way to make prototypes rapidly.  

 A former president of the Society of Plastics Engineers, Womer was the Global Corporate Technical Advisor for Xaloy, and has also served in leadership positions in engineering, research and development at Spirex, Conair, and NRM. He started a consulting business in Edinburg, Pennsylvania in 2011.

Womer’s micro extruder concept. (USPTO)

Additive manufacturing

Coke Invents On-The-Fly System to Measure Bioplastic Content

Coca-Cola, arguably the largest global user of renewably sourced plastics, is developing a method to measure bio-source content on the fly.

Currently used methods can be very time-consuming, expensive or inaccurate. Accelerator Mass Spectrometry (AMS) iis precise, but expensive and is done by third parties that can be slow. Liquid Scintillation Counters (LSC) are generally considered low precision and can take weeks.

In the new Coke method, carbon content in renewable bioplastic resins is measured by correlating production samples measured by Cavity Ring-Down Spectrometry (CRDS) with actual renewable bio-source carbon content measurements (AMS or LSC) via a linear regression.

A PET resin made of bio-derived monoethylene glycol and non-renewable petroleum-derived terephthalic acid may contain up to about 30 percent  renewable bio-content.

Renewable biomass contains carbon-14 that is easily differentiated from other materials, such as fossil fuels, that do not contain any carbon-14.

Eight years ago, Coca-Cola introduced the PlantBottle, described as the first-ever fully recyclable PET plastic beverage bottle made partially from plants. Today, PlantBottle packaging accounts for 30 percent of Coke’s packaging volume in North America and 7 percent globally. That’s seven billion bottles annually. Coke’s goal is to eliminate fossil fuel based plastic bottles.  Coke’s bioplastic is produced from sugar in Brazil. 

Coke says it has a particular need to measure bio content during transition periods in the process where non-renewable petroleum-derived plastic starting materials are swapped out for renewable bio-derived plastic starting materials.


Bioplastics, Green, Packaging

CFRP Roof Cuts Weight On New BMW M5

BMW is showing extended use of its carbon fiber roof technology at this week’s Frankfurt Auto Show.  First introduced on the E92 M3, the carbon fiber roof is now also used on the M5. Weight of the roof is around 11 pounds, or about half of a steel roof. Weight savings compared to an aluminum roof is about 25 percent.  

The epoxy-based system is manufactured at BMW’s plant in Landshut, Germany, which specializes in CFK/CFRP production. The M5 uses the technology and the manufacturing process from the F13 M6.

The M5 is 11 pounds lighter than its predecessor.

BMW’s new M5 (BMW)

Automotive, Carbon Composites, Europe

Apple Invention Combines Ceramics and Plastics

Apple is developing a comolded plastic and ceramic phone housing that combines the benefits of both materials.

Traditionally phone housings have been molded plastic, but ceramics and glass are being used increasingly because of their superior strength, aesthetics and optical properties. “However, such materials present drawbacks of their own,” a new Apple patent states. “For example, small retaining features for coupling housing components together (e.g., clips, arms, detents, grooves) may be relatively simple to mold into a plastic piece, but may be difficult or impossible to form out of glass or ceramics.”

The visible part of the ceramic would be polished while the part next to the molten plastic would be sanded or etched to promote adhesion. Posts or pegs may be added to increase the strength of the comolding. A fixture may be used to hold the ceramic insert in place before plastic is injected under high pressur

Design, Electronics, Insert Molding, North America , ,

DuPont Takes Historic Exit From Plastics

For more than 80 years, The name DuPont was almost synonymous with plastics. Some of the industry’s greatest innovations emerged from the company’s famous labs in Delaware. Nylon, DuPont’s name for polyamide, was the first commercially successful synthetic thermoplastic. Until then, the industry was dominated by hard-to-process thermosets resins such as phenolic. DuPont later made significant advances in acetals, elastomers, and polyesters, and more recently in bioplastics that have made big headway in fiber.

Those plastics will definitely survive, but the attachment of DuPont is in name only. And even that will end soon. They are now part of a company in Midland, Michigan that clearly is placing its emphasis elsewhere, including  on a newly acquired silicone business.

It will be interesting to see how well DuPont’s engineering and renewable plastics fit into the new DowDuPont Materials Science Division, which became a legal entity on Sept. 1 and is scheduled to be spun out as a standalone company no later than March, 2019.

The new operation is very Dow-dominated. It will be headed by Andrew Liveris, the former CEO of Dow. The only DuPont member of the advisory committee (a kind of board in waiting) is former CEO Edward Breen, a cost-cutter who earned his stripes at Tyco, not DuPont.

A fact sheet distributed by the new entity says it will be focused on three molecules: ethylene, propylene and silicone. The key chemistries in the DuPont Performance Plastics business are polyamides, polyacetal and PBT-type polyester. Dow assets dwarf those of DuPont, which had long ago divested commodity-type polyethylene assets. A $100 million Innovation Center in Midland, Michigan is being built to drive growth in the silicone sciences and organic chemistry from new acquisition Dow Corning Corp. Interestingly, Dow divested its stake in engineering plastics (Calibre polycarbonate) seven years ago. In another footnote, Dow had tried to largely exit the ethylene and propylene businesses 10 years ago. The 2008 financial meltdown derailed a plan to create  K-Dow with Kuwait Petroleum Corp. For $9.5 billion, Dow agreed to give up 50 percent of its interest in five global businesses: polyethylene, polypropylene and polycarbonate plastics, and ethylenamines and ethanolamines.

Sure, the global  plastics business has looked something like “As the World Turns” as investors pushed global giants to emphasize high-return businesses such as pharmaceuticals. GE and Bayer–two other historical giants in plastics –also set new courses.

It wouldn’t be a stretch, at least in my view, to see much of the DuPont performance plastics assets divested before the new materials company is formed. Not surprisingly, BASF—a global giant in polyamides—was rumored to have had interest. That obviously would make no sense from a competitive aspect. But the DuPont assets would be a good fit for several other companies.

DuPont’s global-leading effort to find new, renewable ways to make chemical feedstocks looks to me like an unfortunate loser in the new DowDuPont. Under investor pressure, DuPont had already begun cutting overall R&D, except in ag seeds–an investor sweet spot. The industrial bioscience business looks like an orphan in the new Specialties group.

DuPont’s “performance” chemicals business is now owned by an entity called Chemours, which took over the DuPont building in Wilmington, Delaware. DuPont donated significant art collections to local museums and charities and sold the DuPont Hotel.

The new DowDuPont companies centered on agriculture and specialties will be based in DuPont’s new home at Chestnut Run, a suburban research site in Delaware.

It’s possible that the new ag business will retain the DuPont name, and maybe even some of its culture of innovation. From gunpowder to seeds in 200 years. Performance plastics? Didn’t make the cut.

Management, Phenolics, Polyacetal, Polyamides

Invention Targets Mechanical Weakness of Molded-In Antennas

Mitsubishi Engineering-Plastics Corp., Tokyo, says it has developed a superior compound for making three-dimensional antennas in cellphones.

The glass-reinforced alloy of polycarbonate and ABS contains as much as 30 parts per weight of a laser direct structuring (LDS) additive comprising antimony and tin.

LDS, developed by a German company called LPKF, has become an important approach to manufacturing molded-in cellphone antennas that conform to the shape of the part, allowing significant space savings. Addition of the metals that allow plating, however, has negatively impacted the mechanical properties of the molding.

The patent states: “As a result of intensive studies by the present inventors, it has been found that when the amount of glass filler is increased, although the mechanical properties are enhanced, the LDS activity is lowered.”

The Mitsubishi invention is an effort to overcome that problem. In one aspect of the invention, talc surface-treated with organopolysiloxanes is used to replace some of the glass fiber. In another aspect, some of the glass fiber is replaced with glass flake or a plate-like glass. Elastomers may be added to improve resistance to shattering. White pigment is also used in the compound for coloring.

Recycled polycarbonate can be used.

Mitsubishi is one of 19 materials companies that have developed proprietary compounds for the LDS process.

ABS, Asia, Electronics, Filler, Injection Molding, Laser Structuring, Polycarbonate, Polystyrene, Reinforcing Material , , ,

Unique Micro Molder Makes Internal Threads

Successful micro molding machines are highly customized. Some players such as Accumold build their own machines to meet demands of specific molds.

Franz Hirt

A relatively new German micro molder is working with Wittmann Battenfeld to develop new molding technology. microtechnik HIRT (abbreviated MTH), a specialist in hybrid parts based in Schramberg, Germany, helped developed the 5-axis MicroPower into a 6-axis production cell to facilitate manufacturing of parts  with unscrewing functions, helical micro cogwheels and shafts with inclination profiles.

Following mold opening, the mold cavity is driven by a toothed belt installed on the side of the mold to release the molded part for ejection. The ejector subsequently demolds the part with a servo-electric drive, and a new cycle starts as soon as the contour element has been returned to its original position.

It’s also possible to drive thread cores inside the mold to produce high-precision internal threads on molded parts. One example is a focusing device used in cameras to hold lenses in place and/or focus them, or in medical measuring devices to focus optical measurement systems.

The unscrewing unit is integrated into the machine’s Unilog B6 control system

MTH is itself a tiny company with a staff of just three. Founder  Franz Hirt sees rapid growth coming for micro hybrid parts in medical technology, electronics, communication and satellite technology, as well as in the automotive industry.

Mold with integrated unscrewing unit (mikrotechnik HIRT)

Focusing device with an internal thread.

Automation/Robots, Electronics, Europe, Medical, Micro Molding, Molds & Moldmaking ,

Research Shows Path To Improved Thermal Properties

Researchers at the University of Michigan have invented a specific plastic compound that releases heat 10 times faster than a typical plastic compound. The invention has no short-term commercial implications, but shows the potential to design compounds that could create more powerful electronics packages, while saving weight and cost.  

Gun-Ho Kim, a research fellow in Jinsang Kim’s research group, holds a sample of a polymer. (University of Michigan)

The researchers linked chains of polyacrylic acid (PAA) with short strands of polyacryloyl piperidine (PAP) to form hydrogen bonds that are described as 10 to 100 stronger than the van der Waals forces in most other plastics.

“People have spent a lot of time designing polymers that conduct electricity for organic LEDs or solar cells, but no one has looked at how to engineer the thermal properties and we need polymers that conduct heat a lot better than the ones we have today,” said Kevin Pipe, an associate professor of mechanical engineering and corresponding author of a paper.

Jinsang Kim, an associate professor of materials science and engineering and another corresponding author of the paper, said: “There’s still a long way to go, but this is a very important step we made to understand how to engineer plastics in this way. Ten times better is still a lot lower heat conductivity than metals, but we’ve opened the door to continue improving.”

Usually metal or ceramics are added to plastics compounds to improve their thermal properties. The new approach could improve overall properties of the compound, while maintaining a lower mass. Obviously getting the right polymers to work with good thermal characteristics will be the real challenge.

The paper is titled “High thermal conductivity in amorphous polymer blends by engineered interchain interactions.” The research was funded by the U.S. Department of Energy, Office of Basic Energy Sciences as part of the Center for Solar and Thermal Energy Conversion in Complex Materials, an Energy Frontier Research Center.