3D Printing Design Fundamentals

Download “Design Essentials for 3D Printing”

3D printing opens up new design possibilities like hollow parts and complex organic geometries, but it’s still important to keep a few fundamentals in mind to take full advantage of 3D printing’s capabilities.

Understanding materials and processes as well as considerations like support structures and feature resolution are crucial for success. These design essentials will help you make the most out of your 3D-printed parts and accelerate your product development efforts.

In the following guide to 3D printing we focus on these topics:

  • 3D printing prototypes and fully functional, end-use parts
  • Designing for metal 3D printing
  • Comparing additive manufacturing processes
  • Material properties and selection

Click here to download Design Essentials for 3D Printing.

3D Printing’s Next Dimension? 7 Questions for Industry Experts

Rob Connelly

Patrick Dunne

A higher profile for industrial-grade 3D printing over the past decade has led to notable technology developments and potential new applications. The buzz over 3D printing, or additive manufacturing, has also created a lot of speculation in the trade press about whether this technology, which has been around for more than 30 years, is poised to make a giant leap forward in capabilities.

“We are just now starting to see the fruits of these developments,” said Rob Connelly, vice president of additive manufacturing for Proto Labs, referring to a spate of recent announcements about advancements in new machines, materials, and software.

We recently interviewed three leaders from the 3D printing industry for insight into the current and future state of 3D printing:

John Murray

  • Rob Connelly, Vice President, Additive Manufacturing, Proto Labs
  • Patrick Dunne, Vice President, Advanced Application Development, 3D Systems, which manufactures and sells 3D printers
  • John Murray, President and CEO, U.S., Concept Laser, a global provider of 3D metal printing systems

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How to Design 4 Common Metal 3D Printing Features

Click to watch an on-demand webinar on how to design for direct metal laser sintering (DMLS).

Direct metal laser sintering (DMLS) is not intended to replace traditional metal manufacturing like casting, metal injection molding, or machining. Rather, it’s a product development tool that opens up new design possibilities. Product designers and engineers commonly rely on metal 3D printing to manufacture complex geometries, reduce the number of components in an assembly, or even lightweight objects.

Here’s a look at how to design 4 common features found in metal 3D-printed parts.

1. Self-Supporting Angles
A self-supporting angle describes the feature’s angle relative to the build plate. The lower the angle, the less the likely it is to support itself.

Support angles built with direct metal laser sintering

Designing support angles no less than 45 degrees will ensure a quality surface finish and detail.

Each material will perform slightly different, but the general rule of thumb is to avoid designing a self-supporting feature that is less than 45 degrees. This tip will serve you well across all available materials. As you can see in the picture above, as the angle decreases, the part’s surface finish becomes rougher and eventually the part will fail if the angle is reduced too far. Continue reading

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.