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04/02/2024|Basics, opportunities and challenges of additive manufacturing

What is Additive Manufacturing?

Additive manufacturing is a process in which materials are built up, layer by layer, to create three-dimensional parts from 3D model data. The manufacturing process, also known as 3D printing, has its industrial origins in the mid-1980s. Patented by U.S. physicist Chuck Hall, the stereolithography process used a laser beam to harden liquid plastic layer by layer. This allowed the industry to produce material mechanically. Any component with complex shapes and internal structures could be produced from a 3D CAD model.

Since then, the limitless design freedom of additive manufacturing has inspired researchers around the world and continues to inspire the development of new processes and material applications. Plastic is no longer the only material used. Ceramics, organic tissues, and a variety of metals are also utilized. The possibilities of additive manufacturing are far from exhausted and there is every reason to believe that the use of additive processes will be on the rise in all areas of industrial production.

Additive processes: The glorious seven

Additive manufacturing
DMG MORI presents itself with the additive manufacturing machines LASERTEC SLM and LASERTEC DED or LASERTEC DED hybrid as a unique turnkey partner for powder bed and powder nozzle technologies with holistic process integration. (Source: DMG MORI)

In principle, metal 3D printers are similar to the processes in an inkjet printer.  This is why the term 3D printing is more commonly used. ISO/ASTM 52900 categorizes commercially available additive manufacturing systems into seven different processes. Their basic principles differ significantly, particularly regarding the materials used and how the material layers are built. For example, the base material for 3D printing can be liquid, powdery, viscous or solid. Depending on the technology, the material is solidified and built by melting, sintering, laminating, bonding, or polymerizing.

Seven additive manufacturing techniques
The basic standard, DIN EN ISO/ASTM 52900, classifies commercial additive manufacturing systems into 7 processes that differ in the way material layers are created.

Powder Bed Fusion (PBF)

Powder bed fusion (DIN: powder bed-based fusion) is the dominant process in the metals industry. Components are produced by building up material layer by layer. The individual layers correspond to horizontal "slices" of a three-dimensional CAD image of the part to be produced. These layers are then used to calculate a control program that directs a laser or electron beam across these cuts with high precision to fuse the material over their entire surface. The area adheres to the previous layer and solidifies as the material cools. Once the layer has melted, a new layer of powder is applied. DMG MORI is successfully represented in the market with the LASERTEC SLM series.

Material Extrusion (MEX)

In the material extrusion process, material is selectively dispensed through a nozzle or orifice. The moving nozzle, also known as an extruder, applies a layer of material, after which either the extruder or the build platform is raised or lowered and the process is repeated. Various materials can be printed with MEX. These are mostly thermoplastics (e.g. ABS, Nylon, PEEK, PLA). In general, material extrusion can process paste-like materials. These include concrete or ceramics, but also food products such as chocolate or dough.

Vat Photo Polymerisation (VPP)

In the VPP process (DIN: bath-based photopolymerization), liquid polymer resin is selectively cured in a tank by light-activated polymerization. The two common types of VPP use either a laser or light-emitting diodes (LEDs) in conjunction with digital light processing (DLP) as the energy source to cure the resin. Laser-based VPP systems typically cure one layer before the build volume is lowered and a new layer of liquid photopolymer is applied to the build area.

Binder Jetting (BJT)

In binder jetting (DIN: free-jet binder application), a print head applies droplets of a binder to the material and fuses the particles together in a predetermined pattern. Polymers, metals, ceramics, or sand can be processed. Once a layer is completed, the print platform moves down and a new layer of powder is applied to the build platform. Parts produced by the binder jetting process typically require post-processing to improve their mechanical properties. This may involve adding an additional adhesive or placing the part in an oven to sinter the particles.

Material Jetting (MJT)

In the MJT process (DIN: free-jet material application), droplets of a photopolymer or other wax-like material are selectively applied through nozzle heads. UV light is used to cure and solidify the material. Once a layer is cured, the nozzles of the print head apply new material layer by layer. This process can be used to print different combinations of materials to create different material properties or colors throughout the part.

Directed Energy Deposition (DED)

In the Directed Energy Deposition process (DIN: material application with directed energy input), a material is melted by the application of directed thermal energy. The starting material is either a metallic powder or wire. The process produces near-net-shape parts and typically requires machining to achieve the required tolerances. For this reason, the DED process is often combined with a milling machine (marketed by DMG MORI as the LASERTEC DED hybrid series). The DED process can also machine more than one material. A special feature is that it can also be used to repair damaged parts by applying the material directly to the damaged areas.

Sheet Lamination (SHL)

Sheet lamination (DIN: layer lamination) is the joining of components by stacking and laminating thin layers of material using an adhesive or welding process. Materials that can be laminated include metal, paper, polymers, or composites. The layer contours are usually created in a machining process before or after a layer or material is applied. Possible process variants are Ultrasonic Additive Manufacturing (UAM), Selective Deposition Lamination (SDL) or Laminated Object Manufacturing (LOM). Compared to other additive techniques, these processes are relatively inexpensive and fast, but also offer a less precise design.

Additive manufacturing: a promising technology 

The enormous versatility of additive manufacturing is evident in the variety of shapes and materials that can be processed. As a result, additive manufacturing has already established itself in many application areas, such as mechanical engineering, tool and mold making, medical technology, and aerospace. Looking at the remarkable potential of 3D printing technology, it is still at the beginning of its possibilities. Overall, it is said to have the power to profoundly and sustainably change industrial manufacturing - always driven by the vision of being able to produce individualized, customized products quickly and cost-effectively. Materials, component size, accuracy, reliability and repeatability are at the heart of the development process. Other challenges include automated post-processing, standardization of additive manufacturing and testing procedures, and training for operators and engineers responsible for designing and building additive parts, CNC machines, and machining centers.

Versatile beyond industrial use

The story of additive manufacturing is not limited to industry. In medicine, for example, potential applications range from education and diagnostics to the preparation of surgical procedures and the manufacture of individual medical implants and prostheses. Great hopes are also being placed in the vision of "bioprinting," the "printing" of the body's own cells. However, 3D printing with organic materials is still in the basic research stage.

In construction and architecture, the possibilities of additive manufacturing are more tangible and therefore easier to imagine. The production of 3D design models for construction planning is already commonplace. Even printing the shell of a house is no longer a utopian dream. The productivity, cnc automation, and environmental benefits of additive manufacturing are driving the implementation of these applications.

Additive manufacturing processes spark interest in technology and innovation 

3D printing and additive manufacturing are becoming increasingly popular in the private sector as well. This is evidenced not only by the popularity of materialized self-images, but also by the printers offered by discount stores and the numerous 3D communities where inventors share tricks and data. There is a generally positive mood surrounding additive manufacturing processes, which has the valuable side effect of increasing interest in technology and innovation in society. The countless small examples from the private sector clearly show how 3D printing can significantly reduce environmental impact through low energy and material consumption and less waste in customized production.

Do you want to learn more about DMG MORI's exceptional additive manufacturing offerings? Our blog post "The future of additive manufacturing processes" gives you an insight into the LASERTEC SLM series powder bed machines and the unique benefits of the LASERTEC DED and LASERTEC DED hybrid machines.