In-Situ Monitoring of Magnetically Augmented Additive Manufacturing

Abstract

Through advancements in technology over the last several years, additive manufacturing has become increasingly mainstream in the manufacturing process. Additive manufacturing has several traits which would theoretically make it superior to traditional subtractive manufacturing techniques. Additive techniques allow for fabrication of increasingly complex parts while maintaining design flexibility, reducing waste, and limiting costs. While this ability to manufacture complex parts is certainly applicable to the external structure, additive manufacturing will allow for control over the internal structure of a part as well. From this, porous components can be created which match desired mechanical properties somewhat independently of the material actually used for manufacturing. However, many of these advancements require further refinement of the additive manufacturing processes intrinsic to them. One of the techniques suggested as a method of improving additive manufacturing processes is the incorporation of magnets into the manufacturing process. These magnets are used to direct the flow of the melted metal with more precision. Experiments were conducted in order to evaluate the effects of the introduction of magnets on parts printed using Laser Powder Bed Fusion. Stainless steel 316L, a relatively cheap and easy to print steel, was printed onto a Ti64 substrate using both spot welding and line scanning. It was observed that magnets had an effect on the melt pool and the keyhole depth through and analysis of the spot welding. Additionally, the various magnets also changed the flow of particles in the melted areas generated through line scanning. While quantifying the magnetic fields' effects will require additional research and time, there is strong evidence that they could be a viable solution to increasing additive manufacturing’s precision. While magnets are being explored as a way to augment current additive methods, certain parts of the basic process also benefit from further refinement. These aspects include the focal distance, dwell time, and power of the laser. In order to explore these variables, direct energy deposition was used in a modified form of spot welding. The printed SS316L showed that increased laser power or dwell time created a non-ideal ring of material around the print area. Additionally, an attempt to print hydroxyapatite ceramic on Ti64 was made to test for validity of future experimentation involving the two materials. From this it was clear that major issues arose when endeavoring to print a material with a higher melting point than the substrate. From these results the various processes intrinsic to additive manufacturing can be further refined.