Additive Manufacturing Process Classification, Applications, Trends, Opportunities, and Challenges
Additive Manufacturing (AM), also known as 3D printing, is a revolutionary layer-by-layer fabrication technology poised to become one of the most valued forms of manufacturing in history. Industrialized countries are investing in AM to lead in innovation amid the next industrial revolution, Industry 4.0. The technology has sparked global interest, with a 50-fold increase in Google searches for “3D Printing” from 2012 to 2016.
In November 2015, the United Nations urged countries to invest in AM, forecasting substantial business expansions and explosive economic growth, estimating a global economic impact of $550 billion per year by 2030. Various sectors, including aerospace, medical, automotive, and defense, are integrating AM technologies, shifting from traditional to advanced manufacturing methods.
The history of AM dates back to the 1980s, with Charles Hull’s Stereolithography Apparatus marking the beginning of modern AM. As machine costs decreased in the 2000s, AM became more accessible, and new technologies like material jetting emerged. The COVID-19 pandemic showcased AM’s potential for localized manufacturing and on-demand production.
To address skill gaps in AM adoption, educational institutions are incorporating AM courses into curricula. Knowledge of AM concepts, technology, and software is essential for this paradigm shift, and efforts are underway to integrate them into educational platforms.
AM Standard Definition and Classification
ASTM and ISO have formed two committees to create standards for Additive Manufacturing (AM). These committees define AM based on ASTM ISO/ASTM52900, developed by Subcommittee F42.91.
“Additive manufacturing (AM) is process of joining materials to make parts from 3D model data,usually layer upon layer, as opposed to subtractive manufacturing and formative manufacturing methodologies.”
Additionally, the standard categorizes Additive Manufacturing (AM) into seven processes:
- Binder Jetting
- Directed Energy Deposition
- Material Extrusion
- Material Jetting
- Powder Bed Fusion
- Sheet Lamination
- VAT Photopolymerization
Each AM process is briefly defined:
- Binder jetting: Selective deposition of a liquid bonding agent to join powder materials.
- Directed energy deposition: Fusion of materials using focused thermal energy during deposition.
- Material extrusion: Selective dispensing of material through a nozzle.
- Material jetting: Selective deposition of droplets of build material.
- Powder bed fusion: Selective fusion of regions in a powder bed using thermal energy.
- Sheet lamination: Bonding sheets of material to form a part.
- VAT photopolymerization: Selective curing of liquid photopolymer in a vat through light-activated polymerization.
Why Metal Additive Manufacturing?
Metal Additive Manufacturing (AM) has gained widespread enthusiasm in both industry and academia due to several key factors. Notable among these are:
1.On-Demand Low-Cost Rapid Prototyping:
- AM facilitates the cost-effective and rapid production of functional prototypes.
- The quick turnaround accelerates the design cycle, allowing products like molds to be operational in 2–3 months, compared to the 4–6 months in conventional processes.
2.Simpler Supply Chain for Effective Low-Volume Production:
- AM addresses the challenges of low-volume niche production, offering a more feasible solution.
- It supersedes time-consuming and expensive manufacturing techniques, providing efficiency for low-volume manufacturing.
3.Lowering AM Material Costs:
- Initial costs for AM are generally lower than conventional methods due to minimal tool and jig/fixtures requirements.
- AM’s simplified supply chain is expected to lead to increased low-volume manufacturing when the supply chain is more established.
4.Geometric Complexity at No Extra Cost:
- AM allows the fabrication of complex shapes economically, offering a platform for “design for use” rather than “design for manufacture.”
- However, attention is needed as not all complex parts are manufacturable, and process constraints in metal AM may limit design freedom.
5.Lightweighting:
- AM is linked with topology optimization, enabling the design and manufacture of high-strength yet lightweight structures.
- Reduction in material consumption is crucial for cost-effective and environmentally friendly product development.
6.Parts Consolidation:
- AM enables the consolidation of parts, simplifying design, reducing costs, minimizing material loss, and enhancing overall performance.
- Some applications eliminate the need for assembly, fostering product performance through lightweighting and consolidation.
7.Functionally Graded Materials (FGMs) and Structures (FGSs):
- AM allows the integration of multiple advanced materials into one component, creating FGMs and FGSs with gradual variations in compositions.
- Directed Energy Deposition (DED) is a promising technology for developing such structures.
8.Conformal Cooling Channels:
- AM provides designers with freedom to incorporate conformal cooling channels into designs, enhancing uniform cooling and increasing productivity.
- Designers can optimize sub-conformal channels for improved performance.
9.Parts Repair and Refurbishment:
- AM, especially DED processes, serves as a safe technology for repairing tooling, extending tool life, and avoiding the need for replacement.
- The technology is valuable for addressing machining errors and last-minute engineering changes.
10.Health and Humanitarian Benefits:
- AM provides various advantages in the health sector, ranging from custom prosthetics to organ manufacturing.
- Precise AM replicas can significantly reduce surgery time, especially in the production of personalized medical items.
Market Size: Current and Future Estimation
Applications of Metal AM
Three main classes of AM processes, namely Powder Bed Fusion (PBF), Directed Energy Deposition (DED), and Binder Jetting (BJ), are widely integrated into mainstream metal manufacturing.
Metal AM has a track record of providing innovative solutions in medical, dental, aerospace, defense, energy, resources, and automotive industries.
Medical and Dental
- Metal AM, specifically Powder Bed Fusion (PBF) processes, has been employed for producing medical devices, surgery guides, implants, prosthetics, orthotics, dental items, crowns, and bridges.
- Biocompatible metals like titanium, tantalum, and nickel alloys are commonly used in metal AM for medical applications due to their established process-property records.
- Design freedom in creating complex parts with internal pores, facilitating cell growth, and producing patient-specific components based on anatomy imaging, has fueled interest in AM within the medical and dental industry.
- Porosity and selective stiffness are crucial for medical devices, and BJ is valuable for its ability to produce implants with controlled porosity.
- Next-generation customized porous implants aim to integrate better with surrounding bone, enhancing fluid and cell-laden permeability.
- Functionally graded porous implants/scaffolds are designed based on interconnected triply periodic minimal surfaces (TPMS).
Aerospace and Defense
Metal AM, especially in the aerospace and defense sector, began to be adopted by major organizations and agencies such as GE Aviation, Lockheed Martin, SpaceX, the U.S. Department of Defense, and the U.S. Air Force.
- AM holds unique appeal for this sector due to its potential for minimizing material waste, achieving lightweighting, reducing assembly needs through component consolidation, and the ability to produce highly complex parts, ultimately resulting in reduced fuel consumption and certification costs.
- The aerospace industry is known for its stringent testing and certification procedures to evaluate part performance based on safety requirements.
- Before we witness a majority of components in airplanes or spacecraft being 3D printed, further improvements are needed in the repeatability, reliability, and control of metal AM systems.
- Significant components of the GE9X engine were reported to be additively manufactured by GE Additive.
- In space applications, examples include SpaceX launching a communication satellite with a 3D-printed aluminum component, specifically an antenna horn mounting strut.
- In rocket engine applications, major companies like SpaceX, NASA, and Aerojet Rocketdyn continue their efforts to adopt AM for rocket engine components.
Communication
The communication industry is experiencing growth in the development of advanced antennas using AM technology. This is driven by the increasing bandwidth demands of telecommunication devices on Earth. As higher wave frequencies become necessary to meet these demands, the complexity of controlling them also rises. AM processes offer the capability to manufacture intricate metal and plastic antennas with complex shapes and different materials, presenting significant opportunities for the communication sector.
Advanced AM-made RF antenna structures have the potential to transform the design, production, and maintenance of communication devices. The integration of AM in the antenna design process supports customization and enhances antenna performance in the field. Optisys has reported success in reducing the number of parts, antenna weight through topology optimization, as well as lead times and production costs. The challenge of surface roughness in metal parts printed by LPBF for certain frequencies is being addressed, aiming to make printed antennas usable without additional post-processing.
Energy and Resources
AM has become an increasingly common process for producing end-use functional parts in low volumes in the energy industry. In cases where AM-made parts require tooling, it can offer an option to create lightweight structures with complex internal features. Therefore, the next generation of components in the energy, oil, and gas sector significantly benefits from AM, especially for parts that need to exhibit performance and environmental standards. A notable application of AM in this industry is seen in the development of spare parts. DED-based AM processes provide solutions for rapid, on-demand printing, and quick repair of existing components. Reports indicate that AM has been used in this sector for prototyping, low-volume production, or repairs of various parts such as gas turbine nozzles, sand control screens, hydraulic components, nozzles for downhole cleanout tools, seals, liner hanger spikes, drill bits, and many more.
Automotive
AM’s involvement in the automotive sector dates back to the 1980s. Customized plastic parts for luxury and personalized car interiors are now 3D printed.
Plastic AM processes widely used for developing jigs, fixtures, and prototypes. Metal AM primarily applied to prototypes, heritage parts, spare parts, and tools. Metal AM used for producing end-use parts in luxury and race car sectors. Examples include Ford’s anti-theft wheel locks and DS Automobile’s titanium door handle frames.
Industry Trends:
Automotive industry trends shifting toward direct AM production of final metal parts. Major automotive companies investing in in-house AM capabilities and forming alliances.
IDAM Project in Germany:
- “Industrialization and Digitization of Additive Manufacturing for Automotive Series Processes (IDAM)” project initiated in 2019.
- Aims to facilitate the adoption of metal AM in automotive production.
AM to play a key role in transforming the automotive supply chain. Potential benefits include reduced lead time, lower material usage, lightweight components, on-demand production, and decentralized manufacturing.
Economic/Environmental Benefits and Societal Impact
Reduced Greenhouse Gas Emissions:
- Manufacturing contributes to 19% of global greenhouse gas emissions and 31% of the US total energy usage.
- AM technologies are greener, with up to 50% energy savings and less material waste.
Energy Savings and Weight Reduction:
- Metal-based AM minimizes machining, reducing the need for toxic cutting fluids.
- AM parts contribute to weight reductions (50–100 kg per aircraft), leading to significant fuel cost savings.
Carbon Footprint Considerations:
- Recent reports suggest metal AM has a higher carbon footprint compared to conventional methods for non-optimized geometries.
- Sustainability in AM usage correlates with geometric complexity, favoring hollow shells, lattices, and features with complex curvatures.
AM Trends, Challenges, and Opportunities
Additive Manufacturing (AM) presents a paradigm shift in design, allowing intricate designs without traditional constraints. It is expected to reduce capital needs for low-volume manufacturing, promoting local production. Companies explore strategic paths for adoption, emphasizing value addition. Life Cycle Assessment (LCA) is crucial for evaluating environmental impact. Challenges include limited qualified materials, speed issues, and the need for industry-wide standards. Opportunities lie in innovative solutions, automation, and skill development to address gaps. The cyber-physical nature of AM raises security concerns. In summary, while challenges exist, AM offers transformative potential across industries.
