May 3, 2016 | By Kira

Imagine being able to apply full color and richly textured surfaces to a 3D model within seconds, without compromising vibrancy, detail, or a high quality finish. Full color 3D printing is one option—if you eliminate the ‘within seconds’ part, of course. But in manufacturing, time is money, and the ability to create structurally complex and full colored objects quickly and cheaply would be a major industry boon.

Enter: Computational Thermoforming. Though the name itself isn’t too exciting, this new manufacturing technique, developed by ETH Zurich and Disney Research Zurich, could have a significant impact on fabrication communities, from hobbyists to industrial packaging manufacturers.

Described by ETH as a “clever combination” of traditional thermoforming and advanced software, Computation Thermoforming allows for custom and unique objects with complex colored surfaces to be produced much faster and with a superior finish than with existing color 3D printing technology. In addition, the equipment and materials are available off-the-shelf, making it affordable and accessible.

Thermoforming 2.0

Thermoforming is an established industrial method for mass-producing everything from food packaging (think yogurt containers and disposable cups) to automotive parts (including door and dash panels, plastic pallets and utility vehicle beds.)

The traditional thermoforming process consists of heating a plastic sheet until it is pliable. It is then draped over a mold, secured until cooled, and then trimmed from the mold to create a usable product.

While thermoforming is ideal for mass-producing standard industrial goods, on a smaller scale, it has its drawbacks. “The industrial method is not suitable for inexpensive manufacture of small batches or even individual pieces of complex shape or color-printed models,” explained Christian Schüller, ETH doctoral student and developer of the Computational Thermoforming process.

Pre-Distorted Color Simulations

The key to the Computational method, as the name implies, is therefore the computed simulation component. Schüller and Olga Sorkine-Hornung, supervising professor at the Interactive Geometry Lab, developed software that simulates the image of the 3D model’s surface, prints the image in full color, and then transfers it onto a 2D plastic sheet.

That colored plastic sheet is then heated and, with extremely precise positioning, placed overtop of a gypsum mold (made from a 3D printed PLA negative). A vacuum quickly sucks the air out from between the plastic and the mold, causing the former to take the latter’s shape, with the colors and textures perfectly aligned, creating a faithful, full color replica of the original 3D design. It’s almost like a three-dimensional, high-tech version of a stamp or temporary tattoo, but with a glossy, permanent, and extremely vibrant finish.

One of the most impressive aspects of the software is how it is able to precisely account for the distortion between the 2D image and how it will be stretched onto the 3D model. "The deformation of the plastic also changes the printed image. But our software accurately calculates and compensates for this deformation," said Schüller.

Faster and Cheapter than Color 3D Printing

Schüller and his team tested the process on a variety of objects to prove its versatility. These include a detailed Chinese mask, an RC car model, and food and nature replicats.

In each case—and with the Chinese mask in particular—the colors and details were perfectly transferred from digital 3D, to physical 2D, to a final 3D object. “The detail is reproduced exactly in the copy,” said Schüller. In fact, ETH Zurich’s models provided more vivid colors than hydrographics techniques, and a superior surface finish than a model made on an professional color 3D printer.

"The replica has a high quality appearance, and for many applications it's cheaper and faster than today's 3D color printing process," says Schüller.

One limitation so far is that the process can only create objects with a high-gloss finish, meaning objects made from metal, wood, or stone might not look as authentic. However for generic plastic goods, Computational Thermoforming provides a great aesthetic.

Although quite different from full color 3D printing as we know it, traditional additive manufacturing still plays an important role in the process. Indeed, the very first step is to 3D print a negative mold of the object using PLA material. This negative mold then filled with heat-resistant gypsum. Once the gypsum is set, the PLA is melted and peeled away, and the gypsum mold is used for thermoforming. All of the necessary equipment is readily available, and the gypsum cast can be re-used multiple times for cost and time savings.

ETH Zurich believes that Computational Thermoforming has extensive industrial applications. Because of its low cost, a key example for manufacturers would be rapid prototyping before large-scale production. Architectural firms, model-makers or nearly any type of 3D designer could also benefit from making full color mock-ups quickly and cheaply. Though certainly no replacement for other manufacturing techniques, especially in high-volume situations, Computational Thermoforming could present an attractive alternative to color 3D printing.

The method was recently described by ETH Zurich in a scientific publication, and will be presented at the SIGGRAPH 2016 conference this summer. For a step-by-step visual guide to the Computational Thermoforming process, watch Schüller's informative video below:

 

 

Posted in 3D Printing Technology

 

 

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MarcC IoM wrote at 5/4/2016 10:31:46 PM:

Nothing new hear T-Sim being doing this for years....

Ioan Festeu wrote at 5/4/2016 5:59:25 PM:

Brilliant! Hats off!

Edward Simpson wrote at 5/4/2016 1:47:15 AM:

So someone combined a bubble jet with a 3D printer and a vacuum former. Interesting results.



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