Despite the abundance of specialized additive technologies, ISO/ASTM 52900:2021 offers a fundamental categorization for the seven prevalent forms of 3D printing.
Over the course of its extensive history, 3D printing technology has undergone significant evolution through various avenues employing diverse materials and methodologies. This diverse landscape can often pose challenges in distinguishing between different 3D printing technologies, particularly given the abundance of acronyms involved. For instance, discerning whether a new machine operates on SLA or SLS principles might prove perplexing. Thankfully, the ISO/ASTM 52900:2021 standard serves as a valuable reference point for engineers seeking to enhance their understanding of additive manufacturing (AM). This standard delineates seven distinct AM process categories, encapsulating the predominant array of 3D printing technologies utilized in contemporary applications.
1) Binder jetting
Binder jetting is a manufacturing process that selectively deposits a binding agent onto successive layers of powdered materials such as polymers, ceramics, and metals. This technique, known for its speed and scalability, offers versatility in material choices. However, achieving consistent mechanical properties in parts produced through binder jetting often requires specific post-processing methods.
2) Directed energy deposition (DED)
Directed Energy Deposition (DED), also referred to as laser-engineered net shaping (LENS) or direct metal deposition (DMD), is a manufacturing technique that concentrates thermal energy to liquefy and add material onto a substrate, incrementally building up layers. This method is particularly beneficial for fabricating sizable components with intricate designs. Although commonly utilized for metals, DED can also be employed for ceramics and composites.
3) Material extrusion
Often referred to as fused filament fabrication (FFF) or fused deposition modeling (FDM), material extrusion is the process of selectively dispensing material through a nozzle or orifice. This method is popular for prototyping and rapid tooling because of its affordability and user-friendly nature.
4) Powder bed fusion (PBF) Powder bed fusion involves the selective fusion of regions within a powder bed using either a laser or an electron beam. This manufacturing process necessitates a precisely controlled environment, often employing inert gases like argon or nitrogen to prevent the oxidation of metal powders. Within the realm of powder bed fusion, various specialized techniques exist, including selective laser sintering (SLS) and selective laser melting (SLM). These techniques enable the creation of intricate structures with high precision and reliability.
5) Material jetting
Similar to the concept of inkjet printing, this method involves the precise deposition of droplets of a chosen feedstock material, like photopolymer resins or wax. In the instance of photopolymer resins, these materials are solidified using ultraviolet light after each layer is deposited. Material jetting offers the advantage of simultaneous deposition of various materials, facilitating the fabrication of parts with multiple colors or materials.
6) Sheet lamination
Sheet lamination is a fabrication method that entails the fusion of thin layers of material to produce components. Unlike traditional methods employing filament, powder, or liquid feedstock, sheet lamination utilizes pre-cut sheets of various materials such as paper, plastic, or metal, ranging from 100 to 500 microns in thickness. The bonding processes involved in sheet lamination encompass chemical adhesion, thermal bonding, and ultrasonic welding. This technique offers notable advantages, including affordability and simplicity, yet its components often exhibit drawbacks such as limited resolution and mechanical robustness.
7) Vat photopolymerization
Vat photopolymerization is the second-most popular method of 3D printing, involving the selective curing of a liquid photopolymer using targeted light. This technique primarily encompasses stereolithography (SLA) and digital light processing (DLP). SLA printers produce smoother surfaces compared to DLP printers, and they can accommodate larger build volumes without compromising resolution. Conversely, DLP printers are typically more cost-effective than SLA machines and boast faster printing speeds. This is because DLP polymerizes an entire layer at once, whereas SLA requires the repetitive tracing of a single, narrow laser across the part.
Other 3D Printing Processes
The 3D printing techniques outlined in ISO/ASTM 52900:2021 are comprehensive and widely utilized in contemporary applications. Nonetheless, several specialized forms of 3D printing exist beyond the scope of this standard. These include bioprinting, which frequently utilizes extrusion or inkjet methodologies, concrete printing, and the selective thermoplastic electrophotographic process (STEP). Additionally, hybrid manufacturing, integrating DED or wire arc additive manufacturing (WAAM) with traditional manufacturing techniques, represents another innovative approach.
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