Build-chamber preheating system for SLM

Additive manufacturing (AM) of metal components attracts substantial attention. By employing AM, highly complex parts can be generated with additional functionalities such as contour near cooling, sensor systems, or permeable structures. With regard to selective laser melting filigree parts can be generated in a near net shape fashion. However, alloys processible via SLM are limited. Improved SLM manufacturing conditions can be achieved either by material adjustments consistent powder heating up to 800 °C. Thus, an optimized heat distribution in the SLM build chamber is achieved by heating the process wall in addition to the standardly heated baseplate.

Previous investigations by the applicants show that SLM processing of Stellite 6 using a standard build platform heating of 200°C lead to significant cracks in the test specimens, already after a few millimeters. Even an adjustment of the exposure parameters, which addressed the lowest possible energy input, did not lead to a successful result. A representative light microscope image of a Stellite 6 specimen produced by SLM.

The preliminary work is intended to illustrate in general that the crack-free SLM processing of Stellite 6 using an in-house developed build chamber heater was successfully carried out by the applicants. However, it must be mentioned that the used prototype of the build chamber heater could not be used robustly and that the build chamber is comparatively small with a diameter of 100mm and a height of 110 mm. Against this background, a new, reproducibly processable build chamber heater was developed. This version has a build chamber with a diameter of 160 mm and a height of 170 mm. The achievable preheating temperatures can be set up to 900°C. In addition to additive manufacturing, the material properties are the essential component of this application