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Exploring Additive Manufacture in Power Generation Devices M. Kaner, C.P. Purssell and S.J. Leigh School of Engineering, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL [email protected] Introduction Additive Manufacturing (AM), often also referred to as 3D printing, is a term used to describe the production of objects directly from computer-aided designs through the selective addition of materials layer-upon-layer, rather than through subtractive processes such as machining from solid, moulding or casting. This approach means that there are no significant pre-tooling requirements and designs can be incrementally varied without re-tooling. Thus, objects can be produced in a ‘mission-specific’ fashion, without the need for new tooling for each design. One area receiving increased recent attention is in the incorporation of electrical circuitry inside components during 3D-Printing processes. Incorporating circuits inside an object during manufacture can ensure optimum placement to achieve the desired functionality. [1] One useful electrical component that can be incorporated into a component is an electrical coil. Coils are found in various electromechanical devices from motors, generators basic inductors or MRI machines. As such, the production of a coil using 3D-Printing technology was identified as a key gateway technology to the manufacture from actuators, such as motors and solenoids to bespoke power generation components. This picture shows an example in which coils are used within electric motors . The produced coil can be tested by passing a current through the coil and measuring the magnetic field generated without it. If the generated magnetic field is greater WITH the core than without, then it can be confirmed than an electromagnet has been created successfully. Aims and Objectives • A1 – To be able to produce an electrical generation device using 3D-Printing • O1 – To be able to print an electrical coil • O2 – To demonstrate a working electrical coil by producing a simple electromagnet. Results & Discussion Summary and further work 3D-Printing processes are stimulating innovation in component design, enabling the manufacture of parts that cannot be made by traditional methods and are stimulating alternative business models and supply chain approaches such as localised manufacture and on-demand production. Recently, there has been increased interest in the utilisation of 3D-Printing in the manufacture of complex functional parts, beyond simple concept prototypes. Already at Warwick we have demonstrated the use of 3D-Printing with advanced materials for the manufacture of products with embedded sensing capability. Iron Core Pellets of ABS are mixed into Acetone and DCM into a slurry before adding Iron powder. This mixture is dried out and extruded through an extruder many times. This process of extruding and re- extruding is known as a ‘pass through’. Coil Previous methods such as coextruding copper conducting wire through the 3D Printer’s nozzle were unsuccessful as there were clear geometrical limitations with the number of turns the coil could have [1] . so a new method which is novel to this particular application was used. A coil with a larger number of turns gives a stronger magnetic field. In order for a coil to be operational, adjacent turns of the copper conducting wire must not touch otherwise the coil Electromagnet References [1] – Bayless. J et al (2010). Wire Embedding 3D Printer. Eng. Phy. University of British Columbia [2] - http://www.movingmagnet.com/, Date last accessed 05/10/2015 at 12:52 Fig. 4 - Photo of Printed Core short circuits and is rendered non- operational. By using Additive Manufacture a rotational print bed was used and the wire were coextruded with a plastic such as PLA or ABS such that they are insulated from each other and at regularly spaced intervals. G-Code was written to ensure optimal spacing without compromising the coil’s structural integrity. Previous methods attempted to feed the copper conducting wire through the 3D printing nozzle such that the wire is coextruded with the plastic out the nozzle. [1] This method was unsuccessful due to limitations of how small the hole in the side of the nozzle could be and therefore how small the diameter of the wire had to be. The cross section of the wire turned out to be too small to overcome back pressures of the plastic being extruded from the nozzle and so was unsuccessful. This new method, ensures the copper wire is extruded with the plastic by feeding the wire in after extrusion, but while the plastic is still molten. A coil with 12 turns and ten layers was then produced. The nozzle was also redesigned in order to ensure the wire is in the middle of the printed insulation Fig. 3 - Photo of Printed Coil Fig. 5 – Diagram of Assembled Electromagne t Fig. 6 – Graph Showing Magnetic Field Strength Against Arrangements of Core & Coil Current was passed through the electromagnet and the electric field surrounding it was measured by programming a microcontroller and placing the coil on top of the magnetometer. It can be seen that the strength of field WITH the core is greater than that without the core which are the results expected. Diagram of Apparatus/Methods • A bespoke 3D-Printing system was used in order to produce the electrical coils. • The system consisted of a copper wire on a spindle being fed through a needle resting on the nozzle contained by the extrusion head. This system was attached to the printer such that it moved with the extrusion head. As the molten plastic is extruded, the copper conducting wire ‘catches’ onto it and is wound around a cylindrical print bed as it rotates. Fig. 2 – Diagram of Apparatus/Methods, showing the setup. Fig. 1 – An example of how coils are used in electric motors. [2] Extrusio n Head Needle Spindle Copper Wire Nozzle
