Mechanical Technology August 2016

⎪ Innovative engineering ⎪

Hannover, highlighted when he discussed the use of selective laser melting (SLM) of the first magnesium powder, Elektron MAP 43, in lightweight designs. Gieseke outlined the results of a study calculating the particle sizes, processing parameters and structures required to produce specimen components with a den- sity of over 99%. Challenges and solution approaches of AM with metals in series production was dealt with by Oliver Kaczmarzik of Concept Laser. He examined a range of issues: how to increase productivity; a modular approach that combines several AM units; automated processes; the physical separation of the construction, pre- treatment and post-processing phases; and the integration of AM manufacturing machines to Industry 4.0 standards. Both the medical technology and aviation sectors use electron beam melting (EBM) in the production of series parts. One of the firms meeting the resulting increase in demand for process and quality control solutions is the Swedish company Arcam; and Patrick Ohldin presented some of his company’s innovative developments. These include a high-resolution camera and an X-ray sensor that are integrated into the company’s quality systems. The camera takes images of the entire powder bed after melting so that quality controls can be per- formed for each layer of the process. The X-ray sensor is able to determine beam parameters such as position, focus and beam profile with exceptional accuracy. Clemens Lieberwirth from the Department of Fluid Technology and Microfluidics at the University of Rostock presented a further exciting development: an extrusion-based ad- ditive process for producing high-density metal components known as Composite Extrusion Modelling (CEM). It consists of two phases: additive manufacturing of green parts from injection-moulded metal grains; followed by industrial sintering. CEM has demonstrated distinct advantages over powder-based pro- cesses in terms of material handling and cost-effectiveness. The new trade forum was organised by Siemens’ Yves Küsters, who has been working on SLM for almost ten years and was awarded his PhD for his thesis on ‘Methodological Parameters for a Robust Blasting Process’ . His work at Siemens includes developing SLM processes and materials, with a particular focus on high-temperature alloys. Other trade forums included for the first time at the 13 th Rapid.Tech were: Additive Contract Manufacturing; Electronic Engineering; and the Automotive Industry forum. The new conference forums and the well-established trade forums – Medical Technology; Dental Technology; Design;

The selective laser melting (SLM) process With selective laser melting (SLM) thin layers of atomised fine metal powder (50 to 150  µ m) are evenly distributed using a coating mechanism onto a substrate plate, usually metal, that is attached to an indexing table that moves in the vertical (Z) axis. This takes place inside a chamber containing an inert gas, either argon or ni- trogen with oxygen levels below 500 ppm. Once each layer has been distributed, each 2D slice of the part geometry is fused by selectively melting the powder. This is accomplished with a high-power laser beam, usually an ytterbium fibre laser. The laser beam is directed in the X and Y plane using two high frequency scanning mirrors. The laser energy fully melts (fuses) the metal powder particles to form solid metal. The process is repeated layer after layer until the part is complete. SLM machines rely on STL (stereo- lithography) files, a CAD file format cre- ated for 3D-printing systems that slices a CAD model into layers, allowing the part be built slice by slice from the bottom by fusing each 2D ‘top slice’ to the previously fused layers below. q

Aviation; Tools; and Science – and the User’s Conference provided oppor-

tunities for industry professionals to discuss specific AM issues in depth. q

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Mechanical Technology — August 2016

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