Industries worldwide are now developing prototypes from 3D metal printing. Slowing the adoption of this form of additive manufacturing beyond prototyping and into larger-scale production is the high cost of system acquisition, resulting in industries that deploy 3D metal printing producing only small quantities of very expensive and complex structures with low weight and high strength, such as those increasingly required in aerospace, medical technology or auto racing.
Despite its high costs, it is difficult to overlook the value of 3D metal printing when compared to subtractive material processing, casting processes or even other types of additive manufacturing. Production of a workpiece by 3D metal printing allows for completely new designs. In a single operation, it is possible to create structures with a high degree of geometrical freedom that would otherwise have to be assembled from several individual workpieces.
For the 3D printing process, a workpiece is generated on the computer using CAD and is then optimised for printing. Based on the generated print data, the workpiece is then created in the build space of the printer from layer-by-layer laser melting using a powdery material. The powder is applied in thin layers, which are smoothed to the set layer thickness between 10 and 100 micrometres by using a variation of a doctor’s blade. After the printing, the workpiece is cleaned, removed from the building platform and, if necessary, reworked. Mostly metals or metal alloys — ranging from stainless steel, aluminium, and titanium to precious metals such as gold — are processed as powdery pressure media. This essentially determines the properties of the product and represents a cost-intensive element of the manufacturing process.
Standard industrial CW lasers (continuous wave) are used for locally precise melting of the powder, with laser beams being controlled by powerful galvanometer scanners. The type and quality of the exposure, achieved by the laser beam and the resulting melting of the powder, have a major influence on the properties of the workpiece, such as its density and surface quality. The control parameters of the laser also affect the setup speed during 3D printing. Optimised process monitoring and control at the melting point can, therefore, have a positive influence on the quality of the process and the product.
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