Powder Bed Fusion

High speed sintering is a physical binder-jetting process that allows the tool-less production of functional prototypes as well as final consumer parts. The HSS process combines the advantages of two existing additive processes: selective laser sintering and binder jetting. While laser sintering already allows many powder materials to be sintered into functional prototypes today, binder jetting impresses with its high printing rates in terms of size and speed of the construction site. High Speed Sintering thus allows the economical processing of larger plots as well as a wider selection of materials.

In the HSS process, a thin layer of plastic granulate, such as PA 12 powder, is applied on to a heated building platform. An inkjet print head then moves over the entire surface of the platform and moistens the areas of the construction site with infrared light-absorbing ink, on which the prototype is to be produced. The building platform is then irradiated with infrared light. The wetted areas absorb the heat, which sinters the powder layer underneath. However, the unprinted powder remains loose. After sintering, the building platform is lowered by the thickness of one layer. The process is repeated until the assembly of a component is completed. The sintered parts are then cooled down in a controlled manner in the installation space before they can be removed and unpacked. In contrast to laser-based processes, the entire building platform can be printed in just one uninterrupted process. This enables a constant layering time, irrespective of the size and complexity of the parts. Inert gas atmosphere is also not necessary for the HSS printing process.

HSS printers from voxeljet offer unprecedented open sourcing possibilities. With the new ProPrint control software, users can program and insert customer-specific macros in just a few steps to adapt the printer to the desired material parameters and process operations. In addition, the software can also be used for individual process data mining, enabling the recording and evaluation of a wide variety of process data as required. Moreover, the user can process different powder materials, as the powder material does not necessarily have to be purchased from voxeljet.

Evonik and HP have co-developed a 3D-printable thermoplastic elastomer that enables breakthrough applications for HP’s Multi Jet Fusion™ technology.

Evonik and HP’s new TPA powder is a flexible, lightweight-construction material distinguished by its very low density of 1.01 g/cm³ and a Shore A hardness of 91. The high-performance powder is excellently suited for production of functional high-tech 3D plastic parts—prototypes as well as series products—that call for high extensibility and energy return, such as sports equipment or automobile components.

The new ready-to-use powder material meets all the processability criteria required for optimized, production-grade parts developed for HP’s Multi Jet Fusion™ technology. The powder enables fast, high-quality parts to be produced using HP’s Jet Fusion 4200 series of 3D printers, resulting in an efficient, reliable experience.

The advantages are twofold: The process works about ten times as fast as other additive processes, and the indirect fusion protects the polymer chains so that the defined properties of the material are retained. Evonik participates in HP’s Open Platform Program and provide additional powder materials for Multi Jet Fusion™ technology.

Evonik launched the first polymer powder material for the additive manufacturing market - SLS technology - in 1996. Today, we continue to set key standards applicable to the 3D printing of plastic materials.

Selective laser sintering (SLS) is based on the principle of the layer-wise build-up of a structure by combining powders to form a part. In general, the process can be characterized as follows:

• specification of a three-dimensional model in the form of CAD data
• no use of molding tools
• generative build-up; molding occurs not by removal of material, but by applying it to any type of desired geometry
• offers freedom of design

Evonik has many years of experience in developing and processing products that lead towards new 3D printing processes. Based on CAD data sets, 3D printing generates complex components through the layerwise application of polymer powders, filaments, fluids, binders or other suitable materials.

The principle is always the same: A material is laid down layer by layer. In practice, however, a wide variety of processes lead to the same result. One of the most important processes is selective laser sintering (SLS). Here, a powder is melted by means of a laser, layer by layer. This produces very precisely detailed and robust components made of either plastic or metal.