Nov 9, 2015 | By Kira

We already know that additive manufacturing can save up to 60% or more in terms of time, cost and material waste when compared to traditional manufacturing, since not only can parts be produced in small-batches and on-demand, but the technique uses only the exact amount of material required (rather than subtractive manufacturing, which starts with a block and whittles away what isn’t needed.) But still, 3D printing isn’t exactly ‘green.’ The majority of desktop 3D printing and industrial prototyping is done with cheap, non-recycled plastics, and even the most experienced designers end up with failed prints or outdated prototypes that more often than not end up in the garbage. Not to mention the fact that a recent Riverside study found certain 3D printing materials to be alarmingly toxic. 3D printing is on the verge of becoming mainstream, meaning it is more important now than ever to implement responsible, sustainable and green 3D printing practices for future generations to implement.

There have been some great developments in this area, including recycled or recyclable 3D printing filaments. However a modified 3D printer created by students in Germany goes beyond recycled filaments by ensuring that less material will be used and/or recycled/wasted in the first place. In the case of failed prints, iterations that need to be updated, or even old broken objects, the Patching Physical Objects system allows users to simply scan the defect, remove parts if necessary, and then 3D print a usable patch directly where it is needed. The same ecnomic concept can be applied to almost any area of our lives—the same way mom sewed on mismatched buttons or mended pocket holes rather than buying a brand new pair of jeans. “Being able to patch an existing object allows for what we call life-long design and effectively reduces material consumption and waste.”

(a) First, our software calculates which part changed, then (b) a mill removes outdated geometry, followed by a print head that prints the new geometry.

Devised by students at the Hasso Plattner Institute in Potsdam, Germany, the system combines subtractive and additive fabrication in a single integrated process to remove and add geometry to an object.  The developers created an add-on for their MakerBot Replicator 2 3D modified-3D-printer, with a mill with suction for removing geometry, a  5-axis rotating platform for additional degrees of freedom (generally 3D printers have only 3 axes), and a depth-camera, the Creative Senz3D, for scanning and alignment. They also developed their own software with an algorithm that can determine which parts need to be removed and which need to be reprinted.

The process is simple: “Users mount the existing object into the 3D printer, then load both the original and the modified 3D model into our software, which in turn calculates how to patch the object,” write the developers. After the software identifies what needs to be removed and then added to make the object functional again, it calibrates the orientation so that the mill removes the outdated geometry, and the print head prints the new geometry in place. “Since only a fraction of the entire object is re-fabricated, our approach reduces material consumption and plastic waste,” they said, adding that in their example demonstrated material savings between 82 and 93%. “Our approach not only saves material, but also reduces plastic waste—making 3D printing more sustainable.”

The developers note that there are several instances over an objects’ life in which it could require a patch: immediately, because of a failed 3D print; minutes to hours later because of a new design iteration; days to months later because the object breaks; or even months to years later because of changing requirements. This is precisely what they mean by ‘life-long design.’

As an example, the team demonstrated the case of a 3D printed smartphone mount. Assuming the 3D printer failed halfway through, rather than starting from scratch, the user can upload the 3D model into the software and calibrate the software to remove the failed upper layers and then resume 3D printing. In this example, 39% of material was saved compared to reprinting from scratch.

Let’s say a few hours later, the same maker of the smartphone mount realizes that the home button is half-way covered making it hard to use. Again, rather than starting from scratch, he can add a cutout to the design, mount the existing phone dock to the 3D printer, and have the mill remove the outdated geometry. In this case, 96% of material was saved compared to reprinting from scratch.

(a,b) Our system finds the optimal orientation to minimize printing material and waste. (d) Milling.

(a) The user accidentally broke the object. (b) The user marks the parts that need repair. (c) Our system then repairs the object using mill and print head.

Taking the same idea even further, they demonstrate how the system could be used to repair the smartphone mount days later if it was dropped and broken, or even years later, if the user upgrades to a larger phone, and just needs to patch on extra material to get it to fit.

The Patching Physical Objects system assumes that personal fabrication does not have to be a one-way process of trial -> error -> wastage. “The problem is that this approach ignores the nature of design iteration, i.e. that in subsequent iterations large parts of an object stay the same and only small parts change,” said the developers.

Though there are still some limitations to work out, such as how support materials will be handled to reduce wastage, physical constraints due to the size of the print head, and some issues with the suction, the overall project is extremely promising and contributes towards the immediate need for responsible, sustainable and green 3D printing. Moreover, it is a philosophy we can start to apply in all areas of our lives. Perhaps the saying should be “If it ain’t broke, don’t fix it…and if you can fix it, don’t buy another.’

The process and results of the Patching Physical Objects were published in a paper authored by Alexander Teibrich, Stefanie Mueller, François Guimbretière, Robert Kovacs, Stefan Neubert, and Patrick Baudisch. They will presenting their findings to the public next week at the Symposium on User Interface Software and Technology (UIST) in Charlotte, North Carolina.



Posted in 3D Printer Accessories



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Mindaugas wrote at 11/9/2015 10:42:39 AM:

I think we are months away from commercial 6-axis FDM 3d printer!

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