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.”

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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:

 

3D Printing Experts Discuss Technology’s Future

3D printing is the topic of conversation in our latest Journal issue, which focuses on the technology’s next dimension—how additive manufacturing is poised to make a giant leap forward in capabilities.3D printing

The cover story includes interviews with three leaders from the 3D printing industry who offer insight on a variety of topics, such as advancements in new machines and materials, a growing demand for 3D printing for production parts, and notable trends in software.

Another feature, “A Cloud-Based Future for CAD,” explores how 3D CAD design software is increasingly moving to cloud-based models, a trend with benefits for both product developers and manufacturers.

Elsewhere in the Journal, our Eye on Innovation column features a driverless bus, a 3D GoPro, and a DIY Bluetooth.

Read the entire Journal here.

We’re always on the hunt for though-provoking content, so send your cool project or article idea to our editor at angelo.gentile@protolabs.com.

Thanks and enjoy the issue!

Stereolithography: Sorting Out Surface Finishes

There are a number of factors—resolution, tolerance, material selection, surface finish—to consider when designing for the industrial 3D printing process of stereolithography (SL). For our latest tip, we’ll discuss the four stereolithography finishing options available at Proto Labs, and when it makes sense to use each.

Unfinished

Stereolithography (SL) technology uses a build platform that requires support structures for all features so they don’t float away or collapse during the build process. These support structures are removed after the build is complete, but they do leave visible markings on the part.

stereolithography proto labs

3D-printed parts are moved from the SL chamber after a build finishes. Supports are then removed, parts are UV cured, and a selected finish is applied.

In an unfinished state, after the support structures are removed, dots or nibs are noticeable where structures were attached to the part surfaces. So, when would leaving a part unfinished make the most sense?

  • When a clear part is desired with no custom finishing
  • If you have your own finishing capabilities, or have another shop that can perform post-build finishing
  • To achieve the best accuracy possible

Natural

A natural finish provides a surface finish that absent of dots or nibs, which leaves a more desirable cosmetic appearance. The surface is not as clear on the down-facing surfaces that had supporting structures, but the top surface would remain clear. When should you use a natural finish?

  • On small or delicate features that may be destroyed by additional finishing such as grit blasting
  • On clear parts where down-facing surfaces are not a cosmetic concern

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INDUSTRY SPOTLIGHT: 3D Printing for Production Parts Gains Credibility

Why are some engineers so hesitant to use 3D printing for more than just development?

Engineers are hardwired and trained to make calculated decisions based on facts. Traditional manufacturing processes such as casting and molding have been around a very, very long time—since the Bronze Age—and time has perfected these processes and brought them to what they are today. Both industry experts and novices alike can benefit from hundreds of years of this process evolution. 3D printing processes are relatively new, especially when compared to casting or injection molding.

Motor mounts are among a growing list of automotive parts that are now manufactured using commercial-grade 3D printing.

Modern, commercial-grade printing equipment and processes are capable of predictable results that will ease the mind of the most skeptical engineer. DMLS (direct metal laser sintering) can produce repeatable results for parts that can be manufactured in no other known method. Proto Labs’ 3DP facility is not only ISO 9001:2008, but also AS 9100. This is the supplemental requirement established by the aerospace industry to satisfy DOD, NASA, and FAA quality requirements. This certification should give any engineer a sense of security.

Understanding some basic quality parameters around the processes can help to lay a foundation of credibility. For example, limits are set to the number of times base material can be used, or only virgin powder could be specified. This is no different than controlling the amount of allowable regrind into a plastic injection-molded part.

Rolls-Royce is a notable automaker now using commercial-grade 3D printing for some production parts.

Testing parts to confirm material properties are extremely common in DMLS. Building a standard tensile bar with each build is a great way to confirm batches of production are producing the desired results. This way the first batch can have destructive testing on the tensile bar and parts to confirm the material and process are producing parts with the specified properties. The future batches can test the tensile bar for confirmation the predictable results were achieved.

The aerospace industry has been embracing advanced manufacturing methods for some time now and the automotive industry has also been making great strides in this area. For example, recent articles have been published around the Rolls-Royce Phantom’s printed parts and BMW’s leading spot in adopting printing technologies.