Background to Additive Manufacturing

Additive Manufacturing offers many advantages in the production of parts, presenting unrivalled design freedom with the ability to manufacture single or multiple components from a wide range of materials.

The method is considered as an additive process rather than a subtractive process that removes layers of material, such as milling. Other terms often used to describe the general process include 3D Printing, Additive Fabrication, Freeform Fabrication, Fabbing and Additive Layer Manufacture.

The early AM processes were established in the mid 1980s as a solution for faster product development. At this time the practices were called Rapid Prototyping, because the idea was really to produce three dimensional models or mock-ups in order to check form, fit and function.

In 1987 3D Systems began the commercialisation of the plastic processing technique known as Stereolithography (SL), offering completely new possibilities to designers and engineers and supporting the fast growing market of “short life” products. The process essentially solidifies thin layers of UV light sensitive liquid polymer using a laser and was the first commercially available AM system in the world.

In the early 1990s other polymer based AM technologies began commercialisation, including fused deposition (FDM) from Stratasys, Solid Ground Curing (SGC) from Cubital and Laminated Object Manufacturing (LOM) from Helisys. Selective Laser Sintering (SLS) from DTM was also introduced at this time, a process that fuses powder materials using a laser.

Background to Additive Manufacturing

The EOSINT M400 from EOS uses a 1 kW laser (Courtesy EOS)

Metal based AM processes were developed in the 1990s and introduced to the market soon after. At this time several companies launched systems for laser sintering approaches which were able to produce metal parts directly, providing an alternative to direct multi stage processes.

In 1994 EOS demonstrated their prototype EOSINT M160 machine based on direct metal laser sintering technology. In 1995 the company’s EOSINT M250 was launched, enabling the rapid production of metal tools. These systems were able to manufacture metal parts by sintering the powder, but in many cases the mechanical characteristics of the materials were more comparable to composites than to metal alloys, due to the combination of a low melting material (e.g. a bronze-based matrix) with a high resistant material (e.g. stainless or tool steel).

In 1998 Optomec commercialised its Laser-Engineered Net Shaping (LENS) metal powder system based on technology developed at Sandia National Labs, USA. In 1999 Röders, a German company, began marketing its Controlled Metal Buildup (CMB) machine based on technology developed at the Fraunhofer Institute for Production Technology in Germany. Also in 1999, ExtrudeHone introduced its ProMetal Rapid Tooling System RTS-300, the commercial realisation of MIT’s process for manufacturing metal parts and tooling. Similar to the use of polymers and waxes in the preparation of feedstock for the Metal Injection Moulding (MIM) process, this system was able to print a binder on a powder bed, binding the metal particles and producing “green parts” which subsequently have to be debound, sintered and infiltrated to get completely dense material.

In 2002 Precision Optical Manufacturing began sales of its Direct Metal Deposition (DMD) laser-cladding systems, a process that produces and repairs parts using metal powder.

The continuing development of AM systems has enabled the fabrication of usable parts made in the desired material in a single-step process. It is now possible to manufacture almost 100% dense functional designs. Over time these systems have become more reliable and more efficient, with the range of suitable materials growing significantly.

 

> Next page: Metal Additive Manufacturing processes

Download the latest issue of Metal AM magazine

Our latest issue is now available to view online or download in PDF format.

As well as an extensive AM industry news section, this 188-page issue includes articles and reports on:

  • From rapid prototyping to rocket engines: The evolution of 3T Additive Manufacturing
  • Natural resources and national strategies: How metal Additive Manufacturing is taking off in Australia
  • Scalmalloy® is too expensive and design optimisation only makes sense in aerospace. True or false?
  • Safety management in metal Additive Manufacturing: Observations from industry
  • Senvol: How machine learning is helping the U.S. Navy optimise AM process parameters and material performance
  • Understanding build failures in Laser Powder Bed Fusion: An overview
  • MAMC2018: Vienna hosts ASMET’s third Metal Additive Manufacturing Conference
  • Euro PM2018: The processing and properties of additively manufactured aluminium alloys
  • > More information

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