Peter Zelinski has been a writer and editor for Modern Machine Shop for more than a decade. One of the aspects of this work that he enjoys the most is visiting machining facilities to learn about the manufacturing technology, systems and strategies they have adopted, and the successes they’ve realized as a result. Pete earned his degree in mechanical engineering from the University of Cincinnati, and he first learned about machining by running and programming machine tools in a metalworking laboratory within GE Aircraft Engines. Follow Pete on Twitter at Z_Axis_MMS.
Machined parts often have more material than necessary. This is true even after all of the cutting is finished. In fact, it might be that most machined parts have more material than necessary. This is true because the part, in general, only has to mate with its required connections and carry its required stresses. Any material not necessary for these purposes is superfluous.
Still, we don’t usually know what that unneeded material is. We don’t typically model a part’s precise pattern of stresses to find out, because the information would have no practical use. A part tailored to the stresses it actually carries might look like the nearer of the two parts in this photo. Machining offers no practical way to make such an odd shape. However, additive manufacturing does.
This part, in both of the versions seen here, is a component of a hinge for a maintenance access hatch on an aircraft. The farther version is the traditional form of this part, produced through casting and machining. By contrast, the nearer version was optimized for its function using software from Altair then built additively using a direct metal laser sintering machine from EOS. Producing an optimal design in this way resulted in a part that weighs less and requires less material, even though it is still every bit as functional as the part that was machined. For much more on the redesign of this part for additive manufacturing, see this paper.
It was about a year ago that 3D printer makers Stratasys and Objet announced their plan to merge. This video from the now-united company shows a 3D-printed part made with both of the machine lines.
The orange half of the interlocking part was produced through Stratasys’s fused deposition modeling (FDM). This process makes plastic parts strong enough to be used as functional components.
Meanwhile, the black half was produced through Objet’s inkjet-based process. This 3D printing method offers greater control over appearance, but generally makes components used for design prototypes rather than functional parts. (Though here is an exception—an Objet-printed part as functional tooling.)
Part of what this video shows is how 3D printing processes differ. The different outputs of these two different processes can be seen even in this one pair of components, even in a quick film.
But at the same time, the video also shows what these two processes have in common. Both are capable of producing components accurate enough to snugly fit together.
Additive Manufacturing, the quarterly supplement to both Modern Machine Shop and MoldMaking Technology, now has its own website. Like the supplement, this site will focus specifically on the use of additive processes to manufacture functional components. That includes tooling, fixturing, functional prototypes and end-use production parts. Learn more at additivemanufacturinginsight.com.
I often advocate evaluating new cutting tools, but finding the time and resources to do this testing is not easy. The machine tools are busy. The workpieces are expensive.
For GKN Aerospace, the opportunity to test cutting tools recently came in the form of a sustainability-related research project. A much smaller facility, G&G Precision, found its opportunity in a pre-production order for a new part number. In both cases, seizing upon the opportunity to test cutters dramatically improved the shop’s knowledge of the best tools and parameters to use.
Shops that have additive manufacturing capability in-house can sometimes use this capability to quickly make replacement components for vital equipment. In some cases, that equipment might not actually be in-house itself. John Danko, president of Danko Arlington—a 92-year-old pattern maker, foundry and machine shop—recently shared the story of 3D printing fixing his daughter’s tricycle. While the component produced in this incident arguably was not critical (one girl might have disagreed), the story illustrates the kind of responsiveness to maintenance needs that additive manufacturing makes possible. For example, just consider the extent to which a 3D printer might be able to take the place of having to order or inventory legacy spare parts.
