MMS Blog

One article in the latest issue of Additive Manufacturing (sister publication to Modern Machine Shop) tells the story of a 3D-printed bracket. This particular bracket is significant because of what it illustrates about the potential for topology optimization and metal 3D printing to transform the appearance of the objects around us. But it is also significant because of what it suggests about the collaborative nature of additive manufacturing (AM). This bracket was created for the U.S. Army Aviation and Missile Research Development and Engineering Center (AMRDEC); it was redesigned for AM by Materials Science Corp.; and finally, 3D printed at the Center for Innovative Materials Processing (CIMP-3D). Without these organizations working together in collaboration, the bracket might never have been printed.

Many 3D-printed parts have a story like this. Many 3D-printed parts might not exist if not for multiple parties coming together, each bringing their particular needs and expertise. The same might be said for AM technology, materials and applications at large. AM works best through collaboration, an idea that the editors of Additive Manufacturing sought to illustrate in the most recent issue of our print magazine. Stories in this issue highlight how different parties are coming together to share AM knowledge and advance the use of this technology:

If you are a regular reader of our magazine and blog, then you likely are aware of Cardinal Manufacturing, the student-run manufacturing business within Elva-Strum High School in Strum, Wisconsin. The concept was the brainchild of teacher Craig Cegielski, who sought a solution to the age-old problem of limited funding and support for school vocational programs here in the United States. His idea was to set up a vocational program to function like a manufacturing business and have his students run it. The program would then become financially self-sustaining, because students would be performing real production work for real customers. In addition to the technical training they’d receive, students would also get profit-sharing checks at the end of the year based on their participation. Cardinal Manufacturing launched in 2005, and 110 students have since graduated from this successful program. (Read the original story as well as update articles and video.)

We have covered other such subsequently created student-run manufacturing businesses, too. What you might not be aware of, though, is that a nonprofit organization—the American Center for Student Run Manufacturing Businesses—was established last year to help schools set up their own in-house manufacturing businesses. Industry veteran John Silveria is its executive director. Mr. Silveria says the ACSMB seeks to replicate the Cardinal Manufacturing model in other schools across the country, effectively providing a program template and speeding its implementation so those manufacturing businesses can be running and making money within a couple years.

By: Timothy W. Simpson 9. December 2018

Additive Manufacturing for Large Parts

For most of my columns, I focus on additive manufacturing (AM) using laser powder-bed fusion (PBF). This AM process is what is driving much of the hype given PBF’s ability to build complex and intricate shapes as well as organic structures that were previously too expensive or impossible to make via traditional manufacturing operations. For example, the design freedoms enabled by laser PBF can be exploited to lightweight components, to build intricate lattice structures for more efficient material usage, to consolidate multi-component assemblies and to optimize a part’s shape for functionality. Of course, laser PBF also has its drawbacks including difficult-to-remove support structures, thin-walled/high-aspect-ratio parts that might fail during a build, layering effects on surface roughness and different process parameter settings (e.g., laser settings for up-skin versus down-skin surfaces).

Despite PBF’s many advantages, its big limitation is the size of the part that can be printed in the build envelope. For a variety of reasons, most commercial laser PBF systems offer a build envelope measuring 250 by 250 by 325 mm (roughly 10 by 10 by 12 inches), though some laser PBF systems can accommodate taller parts, and larger systems are in development. For instance, GE’s Concept Laser X Line 2000R boasts an 800 by 400 by 500 mm build envelope, and the company plans to build a system that starts at 1.1 by 1.1 by 0.3 meters.

By: Timothy W. Simpson 8. December 2018

Smoothing out the Rough Edges

So, is machining the only way to finish your metal part after additive manufacturing (AM)? You might think so from everything you see and read, but there are countless other post-processing techniques to improve the surface finish and dimensional integrity of your part. Besides, if you have to machine your AM part, you will likely need fixtures and jigs to orient and hold your part, especially if it is a complex organic shape. You will also need to establish datums and references on the part once it is removed from the build plate so that you know how to orient and align it. In short, doing all of this extra work to machine your AM part will quickly undermine all of the benefits and advantages of using AM in the first place.

The big challenge with metal AM parts is that they are not “smooth” when they come off the build plate. The close-up of the lattice structure in Figure 1 is a great example of this. Partially melted powder particles adhered to the part, stair-stepping effects of the layer-by-layer process, tessellation of the 3D solid model and differences in up-skin and down-skin surfaces all contribute to surface roughness as I discussed in my October column. Smoothing out these rough edges and surfaces adds time and cost for post processing too and is critical for meeting specifications and tolerances, especially mechanical properties and fatigue life.

Imagine voice-recognition technology as the star of your machine shop. Imagine a hands-free way to execute a number of control and information functions on every piece of digitally connected equipment. Imagine getting instant access to CNC machine info that otherwise would require wading through the interface to find things such as machine settings or maintenance history.

Too good to be true? All the components of this technology already exist, and now it’s a matter of integrating them with more production equipment and software applications that control the shop.

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