Who does not know the Replicator from Star Trek Next Generation: Once briefly “Earl Gray, hot” breathes in and already emerges out of now a steaming cup of tea. Science Fiction? Not necessarily. Even if it does not yet work with the Indian highland tea, at least the replicated cup is now reality.
Behind the keyword 3D printing or rapid prototyping are hidden a whole series of processes, with which three-dimensional structures can be produced from plastic, ceramic or metal. The corresponding devices have long since outgrown children's shoes and belong to the standard repertoire of various design and development departments.
Where formerly highly specialized model builders have created functional models or molds in painstaking manual work, today a mouse click is sufficient to create a physical image of a 3D CAD drawing.
In terms of functional principle, most 3D printing processes are quite similar. First, a thin layer of the material is applied to a carrier plate. Where a solid structure is to be formed, the material - e.g. By laser melting -
Thereafter, the carrier plate travels downwards by a few millimeter fractions, the next material layer is applied and, in turn, solidified where a structure is to be produced, and at the same time connected to the underlying structure. This process is repeated layer by layer until the entire body has been created.
Non-solidified material - typically in the form of a fine powder - can be removed and reused at the end of the process. The remaining model remains. Complex structures can be created even in inaccessible cavities. For example, the American company EOS showed an extremely complex injection nozzle, in the interior life of which various bores and guide vanes provide a strong turbulence.
The whole is manufactured in a super-wash of high-strength Kobald steel. As long as the non-molten material can be removed from the interior through appropriate openings, such complex, internal structures have virtually no limits. At the Euromold trade fair in 2009, the Objet manufacturer printed the fully mobile model of a bicycle chain in just one operation.
The bolts, tabs and rollers of the chain are separated by a thin layer of unmelted powder which can be removed by compressed air after printing.
From the above-described method, there are various modifications. More or less common is, however, all the layer-like structure of the workpiece, in which the construction platform travels downwards as a Z-axis with progressive completion. Instead of powder, the work piece can also be formed in a liquid epoxy resin bath.
In this stereolithography process (SLI and SLA, respectively, developed in 1986), the epoxy resin cures where a focused laser beam hits the surface. Here, too, the model is created layer by layer. The bodies produced by SLI shine through particularly smooth surfaces. Depending on the starting material, soft, rubber-like models can also be created.
The FDM method (Fused Deposition Modeling) is completely without laser and light. Here, the model is produced layer by layer - as pressed from a toothpaste tube - from liquid, thermoplastic plastic.
The print head is reminiscent of the principle of a hot-melt glue gun only that the material is not fed in rods, but in the form of a plastic wire. In the 3DP process, the material powder is sprayed with a solvent or adhesive through an inkjet-like print head Br>
A special feature is the 3D color printing developed by the company Z Corporation. The devices, marketed by Kisters AG in the United States, use up to five print heads (cyan, magenta, yellow, black and clear) Print
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