Chemical Melting Finishing Reduces Ribbing and Cost of 3D Printing
Colin Payne posted on March 29, 2017 |
Visual comparison of printed surface before smoothing (1), with smoothing by conventional methods (2) and by 3D-CMF (3). CMF result (a-3) is more uniform than polishing (a-2), and CMF (b-3) accurately preserves more desired surface detail than solvent vapor method (b-2). (Image courtesy of Waseda University.)
Visual comparison of printed surface before smoothing (1), with smoothing by conventional methods (2) and by 3D-CMF (3). CMF result (a-3) is more uniform than polishing (a-2), and CMF (b-3) accurately preserves more desired surface detail than solvent vapor method (b-2). (Image courtesy of Waseda University.)

In what could be a leap forward for 3D printing, two Japanese researchers have discovered a way to apply solvent selectively to rough areas of resin products using a special pen-like tool, allowing 3D printers to achieve better results with less waste.

The process, created by Kensuke Takagishi and Shinjiro Umezu of Tokyo’s Waseda University, addresses the issue of surface “ribbing,” or the rough appearance due to grooves between layers of resin material that’s often seen when printing on the lower-cost fused deposition modeling (FDM) printers used by home 3D-printing enthusiasts.

There are currently two approaches for overcoming the issue of ribbing on home 3D printing. One involves polishing or grinding down the grooves to reduce the roughness of the printed items. But this not only adds additional work to the process and cost for materials, it also creates a whole lot of dust that needs to be dealt with.

The other employs vaporized solvents that melt and smooth the surface, which has the advantage of capturing some of the dissolved material in the bottom of the grooves and thus improving the structural integrity and smoothness, while wasting less resin. But the complexity of the machine used for this process, along with the indiscriminate dissolution of the entire surface and the need to handle large quantities of flammable solvents, makes this approach far from ideal.

Visual result of changing solvent application pen: d-1 shows how better-fitting pen tip preserves intended surface detail for more accurate result than larger one (d-2). (Image courtesy of Waseda University.)
Visual result of changing solvent application pen: d-1 shows how better-fitting pen tip preserves intended surface detail for more accurate result than larger one (d-2). (Image courtesy of Waseda University.)

Called 3D chemical melting finishing (CMF), the method invented by Takagishi and Umezu employs a felt-tip–like pen that can be used to apply solvent selectively to certain areas of a finished, printed piece that need smoothing. The pen tool includes interchangeable tips that allow increased precision in shaping.

The authors describe the process of working with the pen in their recently published research article in Scientific Reports: “In this method, a pen-style device is filled with a chemical able to dissolve the materials used for building the 3D-printed structures. By controlling the behavior of this pen-style device, the convex parts of the layer grooves on the surface of the 3D-printed structure are dissolved, which, in turn, fills the concave parts. The layer grooves are thus smoothed.”

According to the researchers, 3D CMF offers significant advantages over the previous methods by removing less material, creating less waste, achieving more precise shaping and using less solvent—all of which adds up to lower costs and better safety for small-scale 3D printing applications.

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