Metal Additive Manufacturing Technologies Used Today
Figure 1: Technology Map of metal Additive Manufacturing technologies (Source: AMPOWER)
Many people associate metal Additive Manufacturing with the process of Laser Beam Powder Bed Fusion, which has by far the highest installed machine base today. However, there are 17 other metal AM principles and each one has a different set of characteristics regarding design rules, material and part properties as well as process chain, cost structure and AM Maturity Index. To select the best solutions to an engineering problem, it is required to understand all options. In the end, the application must choose the right technology, not vice versa.
Powder Bed Fusion technologies dominate the metal Additive Manufacturing market
In 2019, Powder Bed Fusion generated 85 % of the revenue of the system suppliers. This is a relative increase of 5 % compared to the previous year. DED technologies took a market share of global system sales revenue of 8.3 %, while Metal FDM, BJT and Other technologies sum up to about 7 %. The suppliers project that in 5 years the revenue market share of Powder Bed Fusion will drop to 63 %. The suppliers of DED systems see an increase of market share to 11.1 %. Combined, the sinter-based technologies Metal FDM and Binder Jetting are projected to grow from 5 % to 13 % market share in 2024. AMPOWER expects the development phase of finding solutions and establish a production around the debinding and sintering process will be critical to the success of these technologies. The group of other technologies has a strong believe in the success of their respective method and thus predicts an annual growth of CAGR 85.7 % until 2024.
Figure 2: System sales revenue by technology in 2019 (Source: AMPOWER Report 2020)
LB-PBF is the leading metal Additive Manufacturing technology
The most known metal Additive Manufacturing technology is LB-PBF or Laser Beam Powder Bed Fusion, also known as Selective Laser Melting (SLM). With an installed base of several thousand systems, the technology is now widespread and used in many applications in production.
The main benefits of LB-PBF technology are good mechanical properties of the resulting parts, their high density and fine resolution. The technology is well-established with a large variety of available metal alloys. It is a single-stage production that enables a high freedom of design. Scrap material is reduced through near net shape production and recycling of the unmelted powder.
However, internal residual stresses that are induced during cooling constitute a restriction since they can lead to part deformations or cracks. Support structures to counteract such stresses must be removed after the building process. The relatively rough surface, moreover, typically requires several post-processing steps. The investment costs for machine systems as well as the feedstock material are considerably high and may pose a limiting factor on potential business cases.
The main limitation of a wider use for LB-PBF is the high cost caused by low process speed and high material and system cost. Many of today’s upcoming metal AM technologies claim to solve this problem mainly by introducing much higher process speed and use of low-cost feed stock material.
Figure 3: Technology principle of Laser Beam Powder Bed Fusion (Source: AMPOWER Report 2020)
Powder Laser Deposition and WAAM enable high deposition rates for blanks
Powder Feed Laser Energy Deposition, also known as Laser Metal Deposition (LMD) is a welding technology used for many years. Recently the technology is adopted as an Additive Manufacturing technology by system integrators and off-the-shelf system providers.
Powder Laser Deposition is a welding technology in which a laser forms a melt pool on a metallic parts’ surface. At the same time a powder feedstock is blown through a nozzle into the process zone, where it is preheated by the laser and then absorbed by the melt pool. After solidifying, raised welding beads remain. By repeating the process, the welding beads are built on top of each other and a three-dimensional structure is formed. Powder Laser Deposition is a sub-group of the Direct Energy Deposition technologies. Typical for DED technologies is the high deposition rate of material, which is locally applied to form near net-shape blanks.
Figure 4: Technology principle of Powder Laser Deposition (Source: AMPOWER Report 2020)
Wire Arc Deposition, also known as Wire Arc Additive Manufacturing, is based on conventional wire-based welding processes such as MIG, MAG and TIG welding. Due to its simplicity and low-cost input material, the technology promises very high build rates at low cost. However, to achieve the full flexibility that Additive Manufacturing claims, further development efforts in data preparation are still necessary.
Wire Electric Arc and Wire Plasma Arc Deposition are Direct Energy Deposition processes based on conventional wire-based welding such as MIG, MAG, TIG and plasma welding. For Wire Arc Deposition, existing, off-the-shelf welding equipment can be used. The welding power is provided by an electric or plasma arc that melts the feedstock to create the weld bead. The wire is fed with a conventional wire-feeding system to the working area. The motion of the welding torch can be provided either by a robotic or a gantries system. An Additive Manufacturing process is achieved by welding beads next and on top of each other until a three-dimensional part is built in a desired geometry. Wire arc deposition technologies have a comparatively high deposition rates of material within the group of DED technologies. Wire Arc Deposition is almost always used to form near net-shape blanks.
Figure 5: Technology principle of Wire Arc Deposition (Source: AMPOWER Report 2020)
Metal Additive Manufacturing technology on the brink of industrialization
Looking at the system supplier announcements and presentation, one gets the impression that every metal Additive Manufacturing technology is ready for use in high volume serial application. However, out of 18 different metal Additive Manufacturing technologies, only 5 are deemed to be ready for industrial use, with 2 more technologies that will achieve this status within a timeframe of 2 years. The evaluation is performed through the AM Maturity Index. AMPOWER introduces this index to assess the industrialization level, which includes rating of the current status quo in terms of technology and industrial use.
Figure 6: Maturity Index of metal Additive Manufacturing technologies in 2020 (Source: AMPOWER Report 2020)