innovations CASTING
Creating Rapid Molds With 3D Printing 3
D printing off ers a quick means to produce sand cores and molds, without tooling,
for small quantities of cast metal testing and prototype assemblies and components. In contrast to conven-
tional mold making, in which the production of pattern plates or core boxes alone can take several weeks, 3D printing makes it pos- sible to “print” smaller sand molds in as little as a few hours. T e molds are created in an automated process based on CAD data using the layer building method, which consists of the repeated application of 300 microme- ter-thick quartz sand layers selectively glued together with a binder. After printing, the mold is unpacked and cleaned of excess sand. 3D print technology places fewer
restrictions on the designer’s freedom of scope. Designs can be made true to their structure without having to watch for draft angles or undercuts. Even molds that have been modifi ed during the testing phase can be printed im- mediately in accordance with the new CAD data, without requir- ing tool modifi cations. Current 3D printing
systems from Voxeljet Technology GmbH, Friedburg, Germany, create high-quality sand molds and cores for metalcast- ing in accordance with customer specifi cations. T e company’s U.S. partner is 3D Systems Corp., Rock Hill, S.C. “Never before have we
printed such a broad spec- trum of molds and assisted so many customers from diff erent industries,” said Dr. Ingo Ederer, CEO of Voxeljet. Due to the lack of tool costs up to a certain batch
production of smaller parts. T e machine operates at
Fig. 1. Voxeljet’s 3D printer VX4000 can produce large sand molds up to 282.5 cu. ft. in volume.
more than three times the build speed of the company’s standard printers, but with the same resolution and precision. T is is possible because of its wide print head, which results in time and cost savings for users. Building platforms are alternately inserted into the process station to allow for continuous building in three- shift operations. (Fig. 2). T is 3D print technology
recently was used to produce the Batoidea chair, created by Belgian designer Peter Donders
size, 3D printing can be signifi cantly less expensive than conventional methods. “T e smaller the batch size, the
greater the cost advantage off ered by our Voxeljet technology,” Ederer said. “And depending on the complexity and size of the molds, 3D printing can still be the preferred choice for batch sizes of several hundred parts.” T e VX4000 machine can produce 13.1 x 6.6 x 3.3-ft. sand molds with a volume of 282.5 cu. ft., which provides suffi cient room for the rapid produc- tion of large individual molds (Fig. 1). Or, it can be used for the effi cient
(Fig. 3). Its design conjures up the image of an elegantly gliding stingray. T e chair, made of cast aluminum, was deemed too expensive to make without the use of 3D print technology. Donders was able to turn his unconventional ideas into reality using the Rhino3D modeling program. T e CAD data set required for 3D printing was automati- cally available on the computer follow- ing completion of the work. Five sand molds were needed to
produce the large chair, with the larg- est individual mold measuring 0.04 x 28 x 15 in. T e fi nal design consisted of a thin-walled aluminum cast structure, which underwent further processing until the application of
the fi nishing varnish. Visit
www.3dsystems.com for more information.
Fig. 2. Building platforms are alternately inserted into the process station to allow for continuous building in three-shift operations.
48 | METAL CASTING DESIGN & PURCHASING | Nov/Dec 2012
Fig. 3. This cast aluminum designer chair was produced with Voxeljet 3D printing technology.
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