3D Printing Boosts Rocket Project for Engineering Students

University of Minnesota engineering students are readying a 3D-printed rocket engine for launch sometime later this year, with help from Proto Labs.

This cutaway view of the engine shows the cooling channel, which is one long tube that spirals down inside the wall.

David Deng, a senior aerospace engineering student at the U of M’s Twin Cities campus, is leading the extracurricular effort to design, build, and eventually fly a liquid-propellant rocket as project manager of LPRD Rocketry. The group’s name, pronounced “leopard,” is an acronym for Liquid Propellant Rocketry Design. The group includes aerospace engineering students and others studying electrical engineering, computer science, mechanical engineering, and materials science.

The primary design challenges the group faced included the small overall size of the engine itself, and the need to also somehow incorporate a cooling system inside the engine.

David Deng (right), and the University of Minnesota student group LPRD Rocketry (left).

“The manufacturing of [the rocket engine] is incredibly difficult using conventional methods, especially for a very small engine,” Deng said. “The struggle was how do we [add] a single cooling channel through this entire engine, coiling around the side of it? That’s where Proto Labs came in. 3D printing is essentially the only way to get regenerative cooling on an engine this small and have it be a single channel.”


EYE ON INNOVATION: Self-Driving Tractor Harvests Interest from Ag Industry

The latest innovation in tractors for the modern farm “features everything but the farmer,” muses a recent headline in a story from Bloomberg News about an autonomous tractor concept from CNH Industrial.

“As Detroit carmakers and Silicon Valley tech giants vie to bring driverless cars to U.S. roads, one of the world’s largest tractor makers is looking to do the same down on the farm,” Bloomberg reports.

This self-driving tractor, a Case IH Magnum prototype model from CNH Industrial, was revealed for the first time last month at a farm equipment show in Iowa.
Photo: Wall Street Journal

At a farm equipment show in Iowa in September, CNH Industrial (Case IH/New Holland) revealed its Autonomous Concept Vehicle, which drew strong interest from those in attendance.

The cabless, self-driving tractor—a Case IH Magnum prototype model—is equipped with cameras, radar, and GPS, enabling farmers to remotely monitor planting and harvesting via computer or tablet from their homes, barns, fields, or pickup trucks. A second concept model, the New Holland T8 NH, includes a cab, so that the tractor can be operated either by a driver or in autonomous mode.

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VIDEO: Lockheed Martin Drone Takes Flight with help from Proto Labs

The drone market in the U.S. is expected to soar to an $82-billion industry in the next decade, the New York Times recently reported. With that robust market in mind, Lockheed Martin, the aerospace, defense, and technology giant, developed a small, fold-up, lightweight drone, the Indago Quadcopter UAV (unmanned aerial vehicle), turning to Proto Labs for quick-turn prototyping and low-volume production.

Proto Labs’ automated design for manufacturability (DFM) and quoting system was especially helpful in taking the Indago from 3D-printed prototypes to injection-molded parts, and getting finished parts delivered in days and weeks. The video tells the story:


Rapid Overmolding: Consider These 3 Elements

Injection molding is a common, cost-effective method for manufacturing parts, but, sometimes, those parts need a little help. Low impact or vibration resistance, slippery surfaces, poor ergonomics, and cosmetic concerns are only a few of the reasons why a second molded part is often added as a grip, handle, cover, or sleeve.

Proto Labs now offers rapid overmolding for parts, including the three samples pictured here.

The process of rapid overmolding will get the job done. This method, which Proto Labs now offers, and is the focus of our October design tip, uses a mechanical or chemical bond (or both) to permanently marry two parts together.

This month’s tip discusses:

  • Bonding: A strong bond between the two materials is critical to overmolding.
  • Materials: This is a key consideration in overmolding.
  • Principles: Overmolding uses the same playbook as injection molding, but with a few quirks.


THE ENGINEERIST: Mitigating Production Risk with Prototypes

Editor’s Note: The Engineerist is a three-part blog series written by Michael Corr, founder of Los Angeles-based manufacturing consulting firm, DuroLabs. This is part one.

Startup companies have limited time and money, and, rightfully so, treat them as precious resources. There is constant pressure to get products out to the market fast, and when cash is limited, there is little margin for mistakes.

As an engineering manager, my responsibility is to ensure that the development processes being used by my team to bring parts to production are reliable, repeatable, and properly mitigate risk. For high-volume production, injection molding is the best option for plastic parts but it can be expensive and time consuming—two factors that can severely impact the success of a product launch if there are mistakes.

Waiting 12 to 16 weeks for first articles off a steel mold can be an eternity for a company pressured to get products into production in a shortened nine-month time frame. Any delays only compound the issue, adding pressure on myself, my team, and the company as a whole.

CAD model

Analysts at Proto Labs prepare CAD models for manufacturing.

Automated Quoting
When I was first introduced to Proto Labs almost 10 years ago, I was impressed with its commitment to leveraging modern technology. Its quoting process was simple and quick due to automated online tools. This allowed me to independently configure part options without having to go back and forth with a sales rep to update quotes and lead times. The automation saves hours, if not days, in evaluating various options. Additionally, the design for manufacturability feedback tools, which automatically highlight problems and areas of concern in the parts, save days to weeks of time and potentially hundreds to thousands of dollars by alleviating the risk of re-spinning due to an erroneous part. Again, with time being a limited commodity and a close watch on development dollars, these attentions to detail were very important to me.

The Case for Milled Prototypes
Prototyping before production is necessary to mitigate this risk but it can potentially cost money and take time to produce parts, so it’s important to choose your prototype runs wisely. One risk-mitigating technique I’ve incorporated into my mechanical engineering team’s process is to always produce a CNC-milled prototype of any part that is identified to be injection molded for production. This seems like trite advice, but I was amazed at how often engineering teams overlook the value of this step. Even 3D printing, another valuable prototyping tool, is often not as effective as a milled part if a move to molding is imminent. The advantage of the milled part is a closer approximation to the final molded material properties—not only in strength but also look, feel, and toughness when handled.

CNC machining

Proto Labs has hundreds of CNC machines, which enable quick-turn milling of functional prototypes and production parts.

I have now built several dozen parts with Proto Labs, so I can attest to the quality and expediency of the parts. In just a few days and not much investment, one can have several milled parts in-hand and ready for evaluation. Proto Labs’ extensive library of material options has also allowed me to select the same exact plastic to be used in the eventual injection-molded parts. This flexibility paired with comparable tolerances and resolution to final injection-molded parts, allows me to reliably use milled prototypes for a full form and fit check. In many cases, I can even use the parts for structural and environmental performance tests, so we can evaluate and make any final tweaks before cutting steel without having to cross our fingers that nothing goes wrong.

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