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deliver a high flexible and tailored solution. Like the
Trumpf DMD system, the Trumpf bespoke solutions also
produce near net shaped parts. (See Figure 11)
Canadian based Accufusion (www.accufusion.com), a spin
out company from the Canadian National Research
Council also market and sell a modular powder feed laser
process called Laser Consolidation. Unlike other power
feed systems, Laser Consolidation works by pulsing both
the laser beam and powder into an accurately controlled
melt pool. The results is a net shaped part that requires
little (if any) post process finishing. (See Figure 12) Figures 12 – Motorsport exhaust port
manufactured using ACCUFUSION Laser
Consolidation process (diameter 40mm)
Overview of powder feed technologies
Like all technologies, powder feed technologies have their advantages and disadvantages. When
compared to powder bed systems, powder feed systems are relatively fast in depositing material.
They also have larger build enveloped and most significantly they allow the deposition of material onto
a substrate, which could be an existing part. Powder deposition systems are therefore often used to
add detailed features onto much larger fabricated structures.
The drawback of powder feed technology is that it is often expensive to operate, as they have a large
machine foot-print, require a significant volume of inert shielding gas and often produce only net
Copyright - Econolyst 2008 www.econolyst.co.uk
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Direct Rapid Manufacturing of Metallic Parts – A UK Industry overview 2008
shaped parts which require post-process CNC machining. However for certain applications in the tool
making, defence and aerospace sectors, powder feed technologies will have a significant future
impact.
Powder Bed RM
Powder bed ALM systems are enclosed machine tools very much on the scale of a small 3-axis CNC
machine. They incorporate a build chamber into which powder material is deposited onto a build
platform. The build platform is allowed to move down in the Z-axis in incremental steps equal to the
desired layer thickness. An energy source such as a laser or electron beam is then directed into the
build chamber. In the case of a laser beam, this is directed onto the surface of the build platform using
scanning mirrors. In the case of an electron beam the beam is directed onto the build platform using
magnetic fields.
The process starts by depositing a single layer of powder, typically 0.02mm – 0.2mm onto the build
platform. Following pre-heating, the laser or electron beam is then scanned across the surface
creating a moving melt pool’. This consolidates the powder material to the both the particles around it,
but also the material below. By scanning both the profile and internal cross section of a slice, a layer
can be consolidated that represents a slice taken from the original CAD file. After the layer is
consolidated, the build platform moves down by a single layer thickness and another layer of loose
powder is deposited. The melting process is then repeated using the scan data for the next layer,
before the platform is indexed again and new powder is added. The process is repeated over and over
again until the last layer is consolidated. With laser based direct metal systems the whole process
takes place in an inert gas atmosphere. However, for the electron beam system the process takes
place in a vacuum.
To-date a wide range of production engineering metals have been processed using powder bed ALM
systems, these include, stainless Steel (17-4, 316L, Ph1), tools steel (20ES – 91RW) and Maraging
steel (18 Mar 300), Cobalt Chromium, Inconel 625, Titanium (Ti pure, TIAl6V4, Ti Al6 Nb7) and
Aluminium (Al Si 12 Mg, ALSi12). Research and development is also being conducted to
commercialise Inconel 600 and 718, beryllium, copper and hastelloy. (See Figures 13, 14, 15 & 16)
Figure 13 – Polished cobalt chrome part
made using EOS Direct Metal Laser Sintering
Figure 14 – Injection Mould tooling inserts made
in Tool Steel using the Concept Laser Cusing
System. Note – the parts have been sectioned to
show the internal cooling flow channels
Powder bed direct metal systems are available from a number of companies, all of which are currently
based within Europe. Direct Laser Technologies are available from MCP Tooling Technologies Ltd
located is Stone Staffordshire (www.mcp-group.com), Electro Optical Systems (EOS) GmbH, based in
Munich Germany (www.eos.info), Concept Laser, part of the Hoffman Tooling Group based in
Copyright - Econolyst 2008 www.econolyst.co.uk
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Direct Rapid Manufacturing of Metallic Parts – A UK Industry overview 2008
Lichtenfels Germany, and Phenix Systems of Clermont Ferrand in France (www.phenix-systems.com).
　
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