How to choose the right plastic prototyping method

January 16, 2020 • 3D Printing, Blow Molding, Extrusion: Pipe & Profile, Injection Molding, Materials, Medical, PLASTEC West, Science, Technology, Thermoforming

What is the best prototyping method for a plastic product? Well, that depends. A panel discussion at Medical Design & Manufacturing (MD&M) West in Anaheim, CA, next month will explore the various options and discuss the advantages and limitations of each. In advance of that Tech Talk session, panelist Michael Paloian, President of Integrated Design Systems Inc., shared his insights with PlasticsToday. An industrial designer and plastics engineer with hundreds of products under his belt, Paloian will be joined at the session, scheduled for Feb. 12 at 8:30 AM, by panelists Rick Puglielli, President, Promold Plastics; Albert McGovern, Director of Mechanical Engineering, Shure Inc.; and George Wilson, Senior Program Manager, ARRK Product Development Group USA. MD&M West, co-located with PLASTEC West, comes to the Anaheim Convention Center from Feb. 11 to 13, 2020.

young engineer

The panelists will discuss the use of 3D printing for prototyping, of course, but they will also delve into CNC machining, polyurethane casting, limited production runs of injection molded prototyping and other technologies, said Paloian. The best process ultimately depends on the designer’s objectives. He or she should ask the following questions before settling on a prototyping process, recommends Paloian.

What’s the purpose of the prototype—if it’s for show and tell, don’t bother spending a lot of money replicating details.
What’s the lead time? If you need something really fast, that will dictate the optimal process.
How large (or small) is the part?
What manufacturing process—injection or blow molding, thermoforming, extrusion—are you trying to replicate? That will have some effect on the prototyping process you select.
What are the tolerances, material properties, level of detail, quantities?
What are you intending to test or evaluate?

“If properties are a critical aspect of your evaluation and testing, CNC machining the part from a particular resin will give you a better indication of how the product will perform than 3D printing,” said Paloian. Don’t be misled by claims of material similarity. “If they tell you it’s similar to ABS or similar to PE, that leaves a lot of gray area. ‘Similar to’ means nothing,” stressed Paloian.

If you’re more interested in the structural behavior of a detail on a part—say, the front bezel of an ultrasound scanner—you could 3D print or machine that portion of the part and subject it to the loads to which it might be exposed, said Paloian. “But if you’re trying to evaluate the wear resistance of a material, for example, you really have to use the material in question, or your evaluations will be erroneous.”

But if your key goal is the best design replication at the lowest cost, it’s hard to beat 3D printing. Then the question becomes, which type of 3D printing?

The three most common platforms are selective laser sintering (SLS), stereolithography (SLA) and fused deposition modeling (FDM), according to Paloian, but SLS is fast becoming the preferred platform. “According to one survey, its market share in prototyping will almost triple over the next 10 years, from about 13% to 33%, while SLA and FDM will shrink.” Materials are playing a big role in that.

“SLA typically is based on a UV-cured acrylic or epoxy, and your properties are limited. There’s no way you’re going to replicate PP or PE with an SLA part,” said Paloian. “With SLS, you’re basically fusing together a powder, so you can use the actual resin, similar to FDM, for testing.” FDM, which Paloian likens to stacking Lincoln logs on top of each other to create the part, lacks resolution. “SLS gives you the best of both worlds—the fine resolution of SLA and the material selection of FDM,” said Paloian.

At the end of the day, understanding the pros and cons of each prototyping process will steer design engineers toward the best option for achieving their objectives. And that won’t always be 3D printing, added Paloian.

Image: Yakobchuk Olena/Adobe Stock

New Polymers Bend, Twist, And Grab

January 3, 2020 • Materials & Assembly, Science, Technology, Thermoforming

In the past materials tended to remain static. More and more, researchers are developing dynamic materials that can change their shape on the fly.

One of the latest breakthroughs in this type of technology comes from researchers at Georgia Institute of Technology (Georgia Tech) and Ohio State University who have developed a magnetic shape memory polymer that can transform into a variety of shapes. Researchers believe the material can be used to create new capabilities in robotics and electronic applications.

shape memory polymer, robotics or electronics applications, Georgia Institute of Technology, Georgia Tech, Ohio State University

Researchers from the Georgia Institute of Technology (Georgia Tech) and The Ohio State University have developed a magnetic shape memory polymer that can transform into a variety of shapes, paving the way for new capabilities in robotics and electronics, they said. (Source: Georgia Tech)

The material—a mixture of three ingredients, each of which contribute unique properties that are integral to its behavior—uses magnetic fields to transform itself, said Jerry Qi, a professor of mechanical engineering at Georgia Tech. The material is comprised of two types of magnetic particles—one that provides inductive heat and one with strong magnetic attraction—as well as shape-memory polymers that lock the shape changes in place, he said. This combination of materials is what provided researchers their unique result.

“This is the first material that combines the strengths of all of these individual components into a single system capable of rapid and reprogrammable shape changes that are lockable and reversible,” Qi said.

Creating freedom of movement

The new material builds on earlier research the team conducted that outlined actuation mechanisms for soft robotics and active materials, assessing the limitations in current technologies, said Ruike (Renee) Zhao, an assistant professor in the Department of Mechanical and Aerospace Engineering at Ohio State. “The degree of freedom is limited in conventional robotics,” she said. “With soft materials, that degree of freedom is unlimited.”

To create the material, researchers first distributed particles of neodymium iron boron and iron oxide into a mixture of shape memory polymers. Once the particles were fully integrated, they then create various objects from this mixture to test how the material would perform in various scenarios.

One example the team created to demonstrate their material was a gripper claw, which they fabricated from a t-shaped mold, researchers said. They applied a high-frequency, oscillating magnetic field to the gripper to cause the iron oxide particles to heat up through induction and warm the entire object. This rise in temperature than caused the material to soften, which made it pliable.

Researchers then applied a second magnetic field to the gripper to make its claws open and close, they said. Then, once the gripper cooled back down, whichever position it was in at the time remained locked.

Locking in the shape

The shape-changing process takes only a few seconds from start to finish, and the strength of the material at its locked state allowed the gripper to lift objects up to 1,000 times its own weight. “This process requires us to use of magnetic fields only during the actuation phase,” said Zhao. “So, once an object has reached its new shape, it can be locked there without constantly consuming energy.”

Researchers published a paper on their work in the journal Advanced Materials.

The team also tested other applications for the material, making coil-shaped objects that can expand and retract. This particular function simulates how an antenna could potentially change frequencies when actuated by the magnetic fields.

Other uses for the material are in robotics, Qi said, particularly for scenarios in which machines need to manipulate delicate objects, such as in the food industry or for chemical or biomedical applications.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

January 28-30: North America’s largest chip, board, and systems event, DesignCon, returns to Silicon Valley for its 25th year! The premier educational conference and technology exhibition, this three-day event brings together the brightest minds across the high-speed communications and semiconductor industries, who are looking to engineer the technology of tomorrow. DesignCon is your rocket to the future. Ready to come aboard? Register to attend!

Ford has a McDonald's caffeine fix for plastic parts

December 18, 2019 • Automotive, Automotive and Mobility, Compounding, Injection Molding, Materials, Materials & Assembly, Recycling, Science, Sustainability, Technology, Thermoforming

Image souce: Ford Motor Co.

Like many commuters, Ford Motor Co. is making a morning stop by Mickey Dee’s for coffee. Only Ford’s coffee run is for the chaff of the dried skin that comes off the beans when roasting them.

McDonald’s USA produces millions of pounds of coffee chaff every year, and now Ford is incorporating some of that waste stream into the creation of injection-molded plastic parts like F-150 pickup truck headlamp housings.

An F-150 headlamp housing. Image source: Ford Motor Co.

Ford’s Sustainability Projects

2007: Soybean-based foam for seats and headliners

2008: Recycled plastic bottles for carpets, wheel liners and fabrics

2009: Wheat straw for storage bins and cup holders

2010: Post-consumer recycled cotton for door and trunk sound-dampening

2011: Recycled tires for seals and gaskets and dandelions for floor mats, cupholders and interior trim pieces

2012: Recycled/shredded US currency for small bins and coin holders and kenaf plant into door bolsters

2013: Rice hulls for electrical harnesses

2014: Tomato skins for wiring brackets and storage bins

2015: Cellulose tree bark for underhood applications

2016: Agave fiber for cup holders and storage bins

2017: Captured CO2 to convert into foams and padding

2018: Bamboo for interior and underhood plastic composite parts

2019: Coffee chaff for headlamp housings and underhood components

The chaff serves as a filler in place of talc, which is normally used to help reduce the weight, increase the strength and improve the heat resistance of plastic parts by blending it into the mixture that is used to make parts

The coffee chaff doesn’t just turn out to be a sustainable alternative to talc, it actually performs even better than the regular material. Of course, if you could just grind up coffee chaff and stir it into plastic materials, suppliers would likely have been doing so already.

Ford’s Research and Innovation Center has developed a process that heats the chaff to high temperatures under low oxygen and then mixes it along with other additives into plastic to create the pellets that plastic manufacturers use to create the end product.

Ford and McDonald’s partner with Competitive Green Technologies, which processes the coffee chaff and with Varroc Lighting Systems, which supplies the F-150’s headlamps to Ford. Together, they create parts that are about 20 percent lighter than before and use 25 percent less energy during the molding process, but which have significantly better heat properties than headlight housings made with talc.

“The coffee chaff is even better than the talc material we are replacing,” said Debbie Mielewski, Ford senior technical leader, sustainability and emerging materials research team. “It is better for the environment, lighter weight and it even has better heat properties.”

While McDonald’s produces millions of pounds of chaff annually, the project with Ford is starting off using 75,000 lbs. “Which really is a lot, but it is just the tip of the iceberg,” said Ian Olson, senior director of global sustainability for McDonald’s. “The potential is unlimited,” he enthused.

Indeed, Ford doesn’t plan to stop with just this one part for one vehicle. “We don’t want to put it on just one car line,” said Mielewski. “We start there and grow it until we do sustainability everywhere we can.”

Ford has a record of using recycled and sustainable materials in its vehicles dating to 2007, when the company employed soybean-based foam for seats and headliners. “This has been a priority for Ford for over 20 years, and this is an example of jump starting the closed-loop economy, where different industries work together and exchange materials that otherwise would be side or waste products,” Mielewski explained.

McDonald’s is planning to have all of its coffee beans be sustainably sourced by 2020, which will further improve the benefits of the project. “Like McDonald’s, Ford is committed to minimizing waste and we’re always looking for innovative ways to further that goal,” said Olson. “By finding a way to use coffee chaff as a resource, we are elevating how companies together can increase participation in the closed-loop economy.”

Dan Carney is a Design News senior editor, covering automotive technology, engineering and design, especially emerging electric vehicle and autonomous technologies.