Additive Manufacturing – Principles and Applications MEC454 PDF

Additive Manufacturing – Principles and Applications MEC454 Metal Additive Manufacturing October 7th 2024 Week 2 Prof Kamran Mumtaz Additive Manufacturing – Principles and Applications MEC454 Part 1 – Introduction to Metal AM and Industry Growth Part 2 – Laser Powder Bed Fusion (LPBF) & Applicat...

Additive Manufacturing – Principles and Applications MEC454 Metal Additive Manufacturing October 7th 2024 Week 2 Prof Kamran Mumtaz Additive Manufacturing – Principles and Applications MEC454 Part 1 – Introduction to Metal AM and Industry Growth Part 2 – Laser Powder Bed Fusion (LPBF) & Applications Part 3 – Part Properties (PBF) and Post-Processing Part 4 – Materials & Process Comparisons Part 5 – Other Metal Processes Additive Manufacturing – Principles and Applications MEC454 Metal Additive Manufacturing October 7th 2024 Week 2 Part 1 of 5 - Introduction to Metal AM and Industry Growth Prof Kamran Mumtaz  But first…. Think about the evolution of the bicycle  What has changed? - Design innovation - Materials innovation - Manufacturing innovation  Innovation in Manufacturing - Can change the way we think about design - Lead to improved products/materials with enhanced capability - Make things cheaper/better quality/more accessible  Growth in Applications for Metals High performance cycling Dental Aerospace fuel injector Automotive Jewellery  Growth Source: smartech analysis  Growth US, UK, Germany, France, China in top 5 Metals Market  IP Landscape Source 3dprint.com Techtonic Shifts Techtonic Shifts Conventional Metal Processing What is a metal? -Closely packed atomic structure, lose their outer shell electrons -Solid (exception Hg) -Higher density than most non metals -Typically hard -Generally malleable, ductile & fusible -Shiny, good conductors of electricity/heat  Conventional Metal Processing Casting Subtractive/cutting (material removal) Milling Investment casting Turning Die casting Grinding etc. Spin casting Sand casting etc. Forming (no material removal) Joining Extrusion Drawing Bending Welding Forging Brazing Powder Metallurgy Soldering Rolling etc. Riveting Additive Manufacturing? Or its own category all together  Metal Additive Manufacturing What’s good about it? Geometric freedom Customisation Quicker to Market Cost Savings Improved Design/Performance  Metal AM Techniques Powder Bed Fusion Powder/Wire Feed Binder Jetting Sheet Lamination Other Additive Manufacturing – Principles and Applications MEC454 Metal Additive Manufacturing Week 2 Part 2 of 5 – Laser Powder Bed Fusion & Applications Prof Kamran Mumtaz Advanced Additive Manufacturing Group Laser Powder Bed Fusion (LPBF)  LPBF Most widely and extensively used AM process for the production of metal parts Uses thermal energy, typically laser or electron beam Can produce high density fully functional parts in one step Excellent mechanical properties Good material variety and part properties Laser Powder Bed Fusion (LPBF) -Thin layers of metallic powder deposited onto substrate/base plate and melted with thermal energy from laser or electron beam -Unused powder recycled Laser or Electron beam Metal AM Applications  Metal Applications - Bugatti wanted to make brake callipers more lightweight - Used geometric freedom available within additive manufacturing to re-design print lightweight brake calliper from titanium Metal Applications  Metal AM Applications Aerospace GE Fuel Injector manufactured using AM as one part (conventional manufacturing requires 20 metal parts to be welded together) Manufactured for LEAP engine  Metal AM Applications Confidence in processes and materials - Exhaustive testing for high performance components - Contributed to building the world largest 3D printed flying engine component Rolls Royce Trent Engine Stator vanes for ring of vanes using electron beam melting  Metal AM Applications Aerospace GE titanium fan blades to be manufactured using AM for full scale production. Saves 50% material compared to conventional manufacturing (forged and machined) Titanium alloys– high tensile strength/toughness and low weight makes it desirable for aerospace Nickel alloys – high mechanical strength and resistance to creep at high temperatures, good corrosive resistance makes alloy suitable for engine components  Metal AM Applications Automotive  Metal AM Applications Automotive High volume production of BMW roof brackets  Metal AM Applications Automotive Bloodhound Project, chassis bolt housing produced at the UoS Land vehicle will attempt 1000mph  Metal AM Applications Medical implants Custom fit, Walter Reed National Military Center have implanted 1000s cranial implants Ti64 and TiCp used in implants due to biocompatibility (non toxic and not rejected by body). Lower modulus of elasticity to more closely match that of a human bone.  Metal AM Applications Dental AM used in dental labs to produce dental copings, bridges, crowns and partial denture frameworks Cobalt Chrome (and Titanium) alloys used. Excellent strength and corrosion and wear resistance.  Metal AM Applications Jewellery/Fashion Capitalise on geometric freedom and to produce complex/intricate geometries Used to produce jewellery in precious metals Metal AM Applications Weight saving Metal AM Applications Weight saving  Metal AM Applications Weight saving Titanium, engine cover door hinge. Used to be cast, with topology optimisation and use of SLM there is a 65% weight saving with no loss in mechanical properties Additive Manufacturing – Principles and Applications MEC454 Metal Additive Manufacturing Week 2 Part 3 of 5 – Part properties & Post-Processing Prof Kamran Mumtaz Advanced Additive Manufacturing Group Laser Powder Bed Fusion Part Properties  Process Control Control of material, process parameters and environment conditions have major influence on final properties of part, e.g. microstructure, density, surface roughness etc. Thermal Energy Power Spot Size etc. Scanning Environment Speed COMPONENT Inert gas/vacuum Hatch distance Pressure etc. Exposure time/dwell etc. Powder Bed Powder Morphology Powder particle size distribution Layer thickness Substrate type Pre-heat etc.  LPBF – Part Properties High Density Complete melting in single step, parts produced to full density  Can match of exceed properties of cast and approaches that of wrought  Less than full density compromises fracture toughness and fatigue properties. Could lead to premature failure, act as crack initiation sites when subjected to cyclic stress  Compliance to specifications for toughness and Z fatigue properties critical in aerospace industry and Axis 0.5mm orthopaedic and dental implants X Steel Alloy (316L)  LPBF – Part Properties Fine Microstructure Rapid melting and cooling of thin layers of material Uniform microstructure Some material segregation may occur, but on a smaller scale compared to casting processes. Chemical composition is more uniform Z than casting resulting in better Axis 25um mechanical properties X Etched CoCr Alloy  LPBF – Part Properties Custom Microstructures Vary processing parameters/conditions to control microstructure Source: AluRheinfelden & D. Buchbinder Fraunhofer ILT  LPBF – Part Properties Comparison of mechanical properties of Ti-6Al-4V LPBF – Part Properties  Metal processing Post-processing considerations  LPBF – Post-processing Parts may require following operations for complete parts Removal of excess powder – tapping, compressed air, ultrasonic Thermal processing – relieve stress of or improve mechanical properties. Furnace cycles or HIPPING to reduce pores and heal micro-cracks Support removal – Wire EDM or band saw to cut parts off platform. Often hand finishing (with pliers) to pull off remaining supports Surface finishing operations - machining, shot-peening, tumbling and hand benching, electro-polishing, abrasive flow machining (for internal cavities). Micro-machining, chemical reaction at surface of material driven by fluid flow  LPBF - Limitations Residual Stress Surface Finish  LPBF - Limitations Some parts require support/anchors due to thermal warpage Rapid heating/cooling Large thermal variations Stresses/warpage Limits geometric freedom, Incurs post processing and cost for anchor removal Cannot easily stack parts on top of each other (as with polymer SLS) 10mm M1 LPBF - Limitations Warpage 10mm 10mm Metal Anchors/Supports 49 Slide 49 M1 Removes the requirement for anchors/supports within the Selective Laser Process (SLM) Improving SLM design freedom Reduces time/cost involved in removing supports Potential to increase SLM productivity Master, 19/07/2011  LPBF - Limitations Stress can cause problems even after support have been removed. This can be relieved with thermal processing (e.g. furnace cycles) Support removal – Wire EDM or band saw to cut parts off platform. Often hand finishing (with pliers) to pull off remaining supports  LPBF - Limitations Surface roughness can be reduced during build by: Using smaller powder particles Laser re-melt strategies Orientating parts differently  LPBF - Limitations Surface roughness can be reduced during build by: Using smaller powder particles Laser re-melt strategies Orientating parts differently  LPBF - Limitations Surface roughness can be reduced after a build by: -Machining, shot-peening, tumbling and hand benching, electo-polishing, abrasive flow machining (for internal cavities) micro-machining, chemical reaction a surface of material driven by fluid flow  LPBF - Limitations Matsuura SLM Process Hybrid – additive and subtractive manufacturing  LPBF - Limitations Change design to reduce support  LPBF - Limitations Change orientation to reduce number of supports How much does it cost to make these parts? Metal AM costs Metal AM costs Metal AM costs Additive Manufacturing – Principles and Applications MEC454 Metal Additive Manufacturing Week 2 Part 4 of 5 – Materials and Process Comparisons Prof Kamran Mumtaz Advanced Additive Manufacturing Group Laser Powder Bed Fusion Materials  Materials – PBF Metal Powders Powders are manufactured in different ways and come in different shapes and sizes (morphology) Spherical powders are best, flow/deposit well and increase powder packing density  Do not degrade as easily as polymers Spherical (Good) Irregular (bad) Flows well, increase packing Will not flow well, powder may density agglomerate  Materials – PBF Metal Powders Average particle sizes for SLM 40-50um, slightly larger for EBM (powder is sized within an upper and lower range) Finer powder particles, require less energy to melt and can reduce surface roughness and increase powder packing, however can be dangerous, risk of inhalation and cause dust explosion (especially with reactive metals e.g titanium, magnesium, aluminium) Larger powder particles safer to handle, but increase surface roughness (side) and require more energy to melt Increase powder packing  Materials – PBF Gas Atomisation used to create powder Extensive variety of materials available: Steel alloys (316L, 17-4 etc.) (~£80/kg) Titanium, commercially pure and alloys (TiCp, Ti-6Al-4V etc.) (~£140/kg) Aluminium alloys (AlSi12, AlSi10Mg etc.) (~£60/kg) Nickel alloys (In625, 718 etc.) (~£120/kg) Cobalt Chrome alloys (Co28Cr6Mo) (~£90/kg) Copper (~£70/kg) Gold (~£9000/kg)  Powder Bed Fusion Laser & Electron Beam Systems  PBF - Lasers Laser Based Systems Materials are melted by ABSORBING laser energy Typically fibre laser used Laser are versatile, accurate and have a high energy density  PBF - Lasers Laser Based Systems System are know as Selective Laser Melting (SLM) or Direct Metal Laser Sintering (DMLS), we will use SLM to describe process Powder layer of 20-40um deposited Laser operate 50W-1kW powers Builds at ~30-50cm3/h Process most metals Chamber is purged with inert gas (argon/nitrogen to prevent oxidation Uses galvo mirrors to direct laser energy and “draw” part geometric  LPBF – Commercial Systems Laser Based Systems Typical System (EOS M280) Key system characteristics – Build volume: up to 250x250x300mm – Up to 400W Yb fibre laser – Spot size: 100μm – Layer thickness: 20μm to 80μm – Build speed Up to 32.4 cm3/h – up to 200C powder bed pre-heat Part Surface finish – As built: Ra~4-10μm – After polishing: Ra~0.04-0.5μm Minimum wall thickness / feature size 0.04mm Accuracy – +/- 0.2mm  PBF – Electron Beam Electron Beam Based Systems Materials are melted by transfer of kinetic energy from incoming electrons Process known as Electron Beam Melting (EBM) by Arcam No moving mechanical part to deflect electron beam, therefore extremely quick scanning. High energy density beam that can be split into multiple beams 55-80cm3/h build speed Can only process conductive materials Operates in vacuum, pressure