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representation, whereas near net parts will require some form of post process finishing or machining
to achieve their ultimate geometric tolerance.
Sheet Consolidation RM
The concept of sheet consolidation or lamination is not new. For many years, tooling companies in the
Far East have manufactured low pressure foam moulding tools by cutting out a tool cavity profile into
hundreds of steel sheets, which are then assembled, clamped and bonded to make a laminate tool.
More recently, this concept has been adopted by US based Solidica Inc. (www.solidica.com) and
incorporated into their Ultrasonic Compaction (UC) Form-ationTM Machine tool. It should be noted that
this process is not truly additive, as it also required a significant level of in-processes machining.
UC works by taking sheet material in the form of foil, which is then placed on a build platform. A
rotating ultrasonic sonoatrode connected to a transducer is then passed over the foil causing localised
bonding of the foil to the platform. A CNC milling head then subtractively machines the profile of the
first layer into the foil. The platform is then lowered by one layer thickness and a second layer of foil is
positioned over the first. The ultrasonic consolidation processes and machining are then repeated.
This cycle is continued until the geometry is complete.
UC has some advantages compared to other metallic ALM processes, as it can be used to bond
dissimilar materials, manufacture metal matrix composites and to build parts with embedded optical
fibres’. UC is also a net shaped process, which is governed by the accuracy of the machining head
within the process cell. However, part complexity is seriously restricted, as the system is incapable of
easily processing overhanging or re-entrant features. Moreover, the process is also highly wasteful, as
expensive ultrasonic welded metallic foil is machined away as waste.
Powder Feed RM
Research into metallic feed systems started in the late
1980’s using MIG welding torches fitted to multi-axis
robots, as a way of building up material onto expensive
damaged parts, such as turbine blades or mould tools. In
the 1990’s welding wire was replaced with blown powder,
which although much slower, enabled far better melt-pool
control and subsequent part accuracy. (See Figure 10)
The principle of a powder feed system is to take a jet of
metallic powder and literarily fire this into the path of a
laser beam. At the point of convergence, the powder is
melted. By moving the laser beam and powder feed
nozzle over a substrate, using either a 3 or 5-axis CNC
machine or robot, layers of material can be deposited onto the substrate at the point of convergence.
Figure 10 – The direct powder deposition
process using a TRUMPF DMD machine cell
Powder feed technology is available either as complete machine tool systems or as modular solutions.
Copyright - Econolyst 2008 www.econolyst.co.uk
4
Direct Rapid Manufacturing of Metallic Parts – A UK Industry overview 2008
Powder feed – Systems
Powder feed systems, intended in some cases exclusively as repair technology, include the LENS
850-R and 750 systems from Optomec Inc. (www.optomec.com), the Huffman Corporation HP115 and
HC-205 systems (www.huffmancorp.com) and the Trumpf DMD 505 System (www.trumpf.de). In each
case these technologies produce, near net shaped parts that will require some post process finishing
of critical surfaces.
More recently, machine tool company Hermle Innovaris (www.innovaris.de) have launched the
Alchemy C40 high material deposition system. Unlike other powder systems, the C40 does not use a
laser to melt the powder, but relies on supersonic jetting of the powder onto the substrate causing
localised super-plastic deformation and bonding. This supersonic jetting is achieved through the
expansion of super-heated steam. The main benefit of the C40 is the very high deposition rate
achieved by the process when compared to laser systems. The system also incorporates a multi-axis
CNC milling centre, which is used to datum the top of the layer following deposition, but also, like the
Solidica process, to cut out the exact profile of each layer, resulting in a net shaped part.
Figure 11 – Internal configuration of a
TRUMPF Direct Metal Deposition Powder
Feed solution using modular robot & laser
Powder feed - Solutions
In addition to commercial powder feed systems, a number
of companies have taken the approach of selling modular
powder feed solutions. Leading German machine tool
manufacture Trump (www.trumpf.de) sells a number of
modular solutions where a laser head can be integrated
with an industrial robot and powder feed systems, to
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