3D Printing: Rapid Prototyping

translated from German with Deepl

Rapid Prototyping
A big word. A buzzword with increasing importance in today’s industry. Ever shorter product cycles and constant pressure to innovate are leading to ever shorter development times, further increasing the importance of rapid prototyping.
But what is rapid prototyping? By definition, it is a manufacturing process that converts 3D data directly and quickly into workpieces without manual detours or molds. And what was a prototype again? Everyone knows the word, but not everyone is aware of what can be behind it.
There are different types of prototypes on which different product features can be tested. The classic prototype is a single piece, which is supposed to correspond 1:1 to the serial product, without using serial production processes. Often, the prototype directly precedes series production as a pilot series and is used for tests and approvals.

Functional samples, on the other hand, are used for trials and tests of the functional features. The appearance is usually secondary here. Design models or mock-up’s are used to evaluate a design for aesthetics, ergonomics and acceptability. They can be 3D printed, paper models, or even a model made of plasticine (clay), as in the automotive industry.

Back to rapid prototyping.
The best known and most widely used process at the moment is 3D printing.

Systems are getting cheaper all the time and do-it-yourself enthusiasts are already rubbing their hands. Even though good printers are still very expensive, they are now also being used for everyday products, such as hearing aids and glasses, or even in medical technology.

All 3D printers work additively. This means that a workpiece is built up layer by layer from one or more liquid or solid materials. Depending on the process, this is possible with or without a support structure. A wide variety of metals, plastics or ceramics can be processed.

Here is a brief overview of some of the currently most popular processes:

Selective Laser Sintering (SLS).
A laser melts layers of a powder together to form the finished workpiece with good mechanical properties and no support structures. This is particularly suitable for design and ergonomic models or simple functional samples.
Electron Beam Melting (EBM/EBAM)
Works in a similar way to SLS. However, instead of plastic, metallic powder is fused under vacuum.
Fused Deposition Modeling (FDM)
Probably the best-known and most affordable process. Plastic is melted in a nozzle and applied layer by layer, line by line. Usually PLA or ABS is used. In the meantime, flexible, transparent or wood-infused materials can also be used.

Translated with www.DeepL.com/Translator (free version)

Demonstration object of an “Archimedean screw” in which the screw elements, channel elements, gears and the blade wheel were created in the 3D printer using the FDM process.

  • Multi Jet Modeling (MJM)
    Similar to FDM, a liquid, light-sensitive material is applied layer by layer via a nozzle.
    Unlike FDM, curing takes place by means of light.

  • Stereolithography (STL/ SLA)
    The mother of all 3D printing processes but still up-to-date. The component is built up from a light-curing liquid using a laser.

  • Continuous Liquid Interface Production (CLIP)
    Recently ready for the market, this technology is 25-100 times faster than previous processes. Parts can be produced with virtually no visible layers. The range of materials that can be used is also very interesting. Any type of polymer can be used. The operating principle is based on layer-by-layer curing at the bottom of the pool using UV light, with oxygen used to prevent curing where no material should be.

Nice video on the above CLIP process:
The Eiffel Tower from the 3D Printer
Source: 3DPrint.com (Carbon3D’s Super Fast 3D Printer Printing an Eiffel Tower )

Other branches of industry are also following suit. Manufacturers of injection molded parts now offer special injection molds at much lower prices (rapid tooling). Aluminum is often used here instead of steel, which limits the number of parts that can be produced from such a mold. Another process is “Space Puzzle Molding”. Here, modular elements are used which are assembled into a mold by means of a mold frame. After molding, it must be disassembled.
These are extremely interesting solutions for prototypes or initial small series, as it is possible to work with materials that are close to series production or identical.
Some specialized companies now also use models from the 3D printer to produce molds for plastic parts. This makes it possible to produce parts in small quantities from materials that are close to series production.
Conventional manufacturing processes such as CNC milling and turning should not be forgotten. Here, too, technology is constantly evolving, and so are the possibilities for molding.

But above all, the world is excited about the possibilities of 3D printing and one already reads about printed buildings, pizzas, batteries, prostheses or even organs. That everyone will soon be able to print everything themselves at home, as predicted, is probably still somewhat illusory. The fact is, however, that 3D printing is already an integral part of today’s industry and is competing with classic manufacturing processes in the corresponding quantity ranges. No expensive tools are required and thanks to the almost total freedom of form, the way of thinking in product development is also changing.

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