Hardware Design and Implementation of an Electromagnetic Levitation System in an Additive Manufacturing Environment

Abstract

Magnetic Levitation and Additive Manufacturing are two promising fields with ever growing interest in several industrial settings. There is, however, negligible overlap between the two fields. This research aims to combine the ability of electromagnetism to successfully levitate an aluminum disc using Electrodynamic Suspension (EDS), with Laser Powder Bed Fusion (LPBF) based additive manufacturing to enhance the complexity of fabricated objects. This provides a higher degree of freedom for manufacturing, and gives the user the ability to deposit material on the flip side of substrate, all through just one print activity.

Electromagnetic system designed for this research comprises of two sets of oppositely wound concentric coils, seated in a pure-iron core. An aluminum disc is selected for levitation purposes due to its high compatibility with the additive manufacturing environment. ANSYS Maxwell, a FEMM based software is selected for design of the system. The coils are optimized for high levitation forces in the axial (Z-axis) direction, as well as restoration forces in the lateral (R-axis) direction using a 5ARMS input supply, in the range of 50 - 1000Hz. A thermal analysis is conducted to ensure system suitability for 20 minutes of activity in an additive manufacturing machine.

Intrinsic coil parameters such as inductance and its reactance effects are investigated through resonant frequency and time constant step response analyses. Low and high voltage experiments are conducted to correlate system output current and magnetic field density with simulations. An enclosure is constructed according to CSA (Canadian Standards Association) guidelines to perform experiments at 300VRMS , 1.5kW.

Experimental debugging is performed to tune system performance to optimal capability. The relative permeability of the core is studied at low magnetic field density outputs and corrected accordingly. The strength of coils is established, and magnetomotive force of the overall system is increased using a custom variable resistor setup in parallel with one set of coils. The levitative ability of the system is improved and matched to simulations. Finally, levitation is accomplished, with and without a payload suspension, to show viability for additive manufacturing applications.

Future work is discussed to expand further on current progress and highlight drawbacks of the established system. Recommendations are made to modify system components based on their material and geometric characteristics. A possible control model is discussed to ensure stability of levitation. The viability of magnetic levitation for additive manufacturing is hence established, and novel results are presented.