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March 4, 2001

3 Min Read
Electron beams meet CAD files to build tooling

This mold insert, which measures about 4 by 4 by 3 inches, took less than 10 hours to make from a CAD drawing using Arcam's electron beam technology. Arcam AB, a development company from Göteborg, Sweden, is using electron beam melting (EBM) technology to produce geometrically complex metal parts directly from a CAD file with no intermediate stages. Mold inserts for plastics injection molding and metal casting are the company’s highest-priority markets. Five systems, one outside the company, are in beta testing, and the firm expects to market a commercial product near the middle of 2001.   Talking with IMM in his display at the EuroMold show in Frankfurt, Germany, Arcam Managing Director Lars- Erik Andersson said that even though there are other technologies for free-form fabrication (FFF)—producing a final product direct from a CAD model—Arcam’s technology is different. The most obvious comparison is to laser sintering, which also fabricates directly into metal. Such systems, however, do not offer the same freedom of choice in materials, says Andersson, and they rely on binding agents in the metal powder, which Arcam does not.The Basics
Arcam’s system is currently housed in a machine called the EBM S12 that is 1 by 2 by 2m (3 by 6 by 6 ft). To begin producing a metal piece, the first step is to slice the CAD model into segments .1 mm thick. Arcam’s preparation program then calculates the optimum path to build the detail of the part with a homogenous structure.   During production, the machine controls and directs a 4-kW electron beam traveling at about half the speed of light onto metal powder. The kinetic energy of the electron beam melts a powder layer precisely as given in the CAD model. As soon as one layer has melted, a new layer of metal is added until the final shape is achieved. Excess metal powder is then removed and the piece is ready for production or for further processing, such as spark machining.   In its initial stage, Arcam’s EBM technology is optimized to process material equivalent to normal tool steel; parts have been made from steel with a hardness equivalent to H-13. The company notes that since the method can be adapted to all castable metallic materials, it is working on modifications to use other materials.Capabilities
The EBM technology allows production of details so geometrically complex as to be considered unmakeable in conventional production, says Andersson. For example, a piece can have both external and internal double curvature surfaces. The EBM system is an adding process; therefore, no physical tools have to access any of the details to work them. Arcam says this is an obvious advantage in general, and in particular for optimizing cooling channels inside a tool.   The work chamber in the current Arcam machine is 250 by 250 by 200 mm (9.75 by 9.75 by 7.8 inches), and Arcam says the build time for a piece of that size is about 20 hours, depending on geometric complexity. Energy efficiency is in the realm of 90 percent and the process is comparatively environmentally friendly. The forming takes place in a vacuum. No buffer gases or additives of any kind are required, no waste or debris is produced, and the machine is reportedly clean and quiet. The programming is designed to run unattended and can be connected to and monitored from a mobile phone or the Internet.   The expected base selling price for the system will be around $300,000, nearing $400,000 with options. Andersson says payback can be relatively quick thanks to the speed at which the system produces mold inserts.Contact information
Arcam AB
Göteborg, Sweden
Lars-Erik Andersson
Phone: +46 (31) 708 38 30
Fax: +46 (31) 708 38 38
Web: www.arcam.com
E-mail: [email protected]
 

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