Thursday, January 24, 2013

Electron beam melting

Electron beam melting

Apparently, Electron Beam Melting is a process by which 3D printing of Titanium objects of any shape can be created. Here is what Wikipedia has on the subject so far:

Electron beam melting

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Electron beam melting (EBM) is a type of additive manufacturing for metal parts. It is often classified as a rapid manufacturing method. The technology manufactures parts by melting metal powder layer by layer with an electron beam in a high vacuum. Unlike some metal sintering techniques, the parts are fully dense, void-free, and extremely strong.

Contents

Technology

This solid freeform fabrication method produces fully dense metal parts directly from metal powder with characteristics of the target material. The EBM machine reads data from a 3D CAD model and lays down successive layers of powdered material. These layers are melted together utilizing a computer controlled electron beam. In this way it builds up the parts. The process takes place under vacuum, which makes it suited to manufacture parts in reactive materials with a high affinity for oxygen, e.g. titanium.
The melted material is from a pure alloy in powder form of the final material to be fabricated (no filler). For that reason the electron beam technology doesn't require additional thermal treatment to obtain the full mechanical properties of the parts. That aspect allows classification of EBM with selective laser melting (SLM) where competing technologies like SLS and DMLS require thermal treatment after fabrication. Comparatively to SLM and DMLS, EBM has a generally superior build rate because of its higher energy density and scanning method.
The EBM process operates at an elevated temperature, typically between 700 and 1 000 °C, producing parts that are virtually free from residual stress, and eliminating the need for heat treatment after the build.
Melt rate: up to 80 cm3/h. Minimum layer thickness: 0.05 millimetres (0.0020 in). Tolerance capability: +/- 0.2 mm.
This technology was developed by Arcam AB in Sweden.[1]

Market

Titanium alloys are widely used with this technology which makes it a suitable choice for the medical implant market.
CE-certified acetabular cups are in series production with EBM since 2007 by two European orthopedic implant manufacturers, Adler Ortho and Lima Corporate. The acetabular cups are manufactured with integrated, engineered trabecular structures for enhanced osseointegration, and more than 20.000 cups have been implanted to date.
The U.S. implant manufacturer Exactech has also received FDA clearance for an acetabular cup manufactured with the EBM technology.
Aerospace and other highly demanding mechanical applications are also targeted.
The EBM process was recently developed for manufacturing parts in gamma titanium aluminide, and is currently used by Avio S.p.A. for the production of turbine blades in γ-TiAl for aero engines.

See also

References

  1. ^ “A Year Filled With Promising R&D”. Wohlers Associates, Inc. November/December 2002

Further reading

  • Manufacturing Engineering and Technology Fifth Edition. Serope Kalpakjian.

External links

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Electron beam melting

I found more on this under the heading :"Electron Beam Technology"

Electron beam technology

From Wikipedia, the free encyclopedia
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Free electrons in vacuum can be influenced by electric and magnetic fields as to form a fine beam. At the spot of collision of the beam with the particles of the solid-state matter, most portion of the kinetic energy of electrons is transferred into heat. The main advantage of this method is the possibility of very fast local heating, which can be precisely electronically (computer) controlled. The high concentration of power in a small volume of matter, which can be reached in this way results in very fast increase of temperature in the spot of impact causing the melting or even evaporation of any material, depending on working conditions. This makes the electron beam an excellent tool in many applications.

Contents

Electron beam melting

Any material can be melted by an electron beam in vacuum. This source of heat is absolutely clean, as well as the vacuum environment, so the purest materials can be produced in electron beam vacuum furnaces. For the production or refinement of rare and refractory metals the vacuum furnaces are of smaller volume, but for steels large furnaces with capacity in metric tons and electron beam power of megawatts are operated in industrialized countries.

Electron beam welding

The above mentioned specific advantages of electron beam heating find the widest use in welding applications. Since the beginning of electron beam welding in industrial scale (end of 1950s) a countless number of electron beam welders with working vacuum chambers volume ranging from a few liters up to hundreds cubic meters, provided with electron guns with the power up to 100 kW have been designed and are used world wide.

Electron beam surface treatment

The modern electron beam welders are usually provided with computer controlled deflection system, which can position the beam very fast and accurate over the selected area of the work-piece surface. Thanks to the high speed of heating, only a thin surface layer of the material is influenced, e.g. for "hardened", annealing, tempering, texturing, polishing(with argon gas present) etc. If the electron beam is used to cut a shallow trough in the surface, then repeatedly moving horizontally along the trough at high speeds it creates a small pile of ejected melted metal at the end of the trough, Upon repetition spike structures can be created up to a millimeter high. These can aid bonding between different materials and modify surface roughness of the metal.

Electron beam additive manufacturing

Additive manufacturing is the process of joining materials to make objects from 3D model data, usually by melting powder material layer upon layer. Melting in vacuum by a computer controlled scanning electron beam is very advantageous. Electron beam direct manufacturing (DM) is the first commercially available, large-scale, fully programmable means of achieving near net shape parts.

Electron beam machining

Electron-beam machining is a process where high-velocity electrons concentrated into a narrow beam with very high planar power density in the focus cross-section are directed toward the work piece, creating heat and vaporizing the material. Electron beam machining can be used for very accurate cutting or boring of a wide variety of metals. Surface finish is better and kerf width is narrower than those for other thermal cutting processes, but because the equipment acquisition costs are very high, the use of this technology is therefore limited economically.

Electron beam lithography

Electron lithograph is a device in which a very fine electron beam is used to create micro-structures in the resist that can subsequently be transferred to the substrate material, often by etching. It was developed for manufacturing integrated circuits, and is also used for creating nanotechnology architectures. Electron beams with diameter ranging from 2 up to hundreds nano meters, are used in electron lithographs.
The form of maskless lithography has found wide usage in photomask-making used in photolithography, low-volume production of semiconductor components, and research & development. The electron lithograph is also used to produce computer-generated holograms (CGH).

Electron beam metal powder production

The source billet metal is electron beam melted while being spun vigorously powder is produced as the metal cools while flying off the metal bar.

Electron beam Physical Vapour deposition

Method of deposition in a vacuum thereby producing thin film solar cells by depositing thin layers of metals on to a backing structure.

Electron microscope

An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image.

References

  • Schultz, H.: Electron beam welding, Abington Publishing
  • Von Dobeneck, D.: Electron Beam Welding – Examples of 30 Years of Job-Shop Experience
  • www.ebt.isibrno: Electron beam welding (in Czech and/or English)
  • Visser, A.: Werkstofabtrag Durch Elektronen-und Photonenstrahlen; Verlag,Blaue Reihe, Heft 104
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Electron beam technology
 
 

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