Part of our Complete Guide to Wire Arc Additive Manufacturing →
Additive manufacturing (AM), commonly also known as industrial 3D printing, is a process that allows for the creation of three-dimensional objects by adding material layer by layer based on digital 3D models. It is a group of production processes that build physical parts layer by layer from 3D model data, as opposed to subtractive methods that remove material from a solid block.
Additive manufacturing includes seven process categories defined by ISO/ASTM 52900 we will explore further in this piece of content. Among the seven Additive Manufacturing categories, at MX3D, we use the ArcDED, and we deliver large-scale metal AM parts for industries including: energy, maritime, automotive, defense, Art & Design, and architecture since 2014, by using robotic WAAM technology applied with our Metal AM M1 and MX Systems.
Definition of Additive Manufacturing
Additive manufacturing (AM) is a group of production processes that build physical parts layer by layer from 3D model data, as opposed to subtractive methods that carve material shapes out of a solid block. It is standardized under ISO/ASTM 52900, which defines seven process categories, that will be explained and expanded later.
The term “additive” is used to highlight that it adds material, unlike “subtractive” methods that cut it away. People often use the terms 3D printing, rapid prototyping, and digital manufacturing to mean the same thing.
Additive Manufacturing vs 3D Printing: What’s the Difference?
While often used to mean the same thing, there is a historical distinction. Industry convention dictated that “3D printing” referred to desktop prototyping, while “additive manufacturing” described heavy-duty, production-grade industrial processes
Today, ISO/ASTM uses them synonymously. The practical distinction remains in the workplace: engineers typically use AM, the umbrella term, when specifying structural or production parts, while 3D printing remains the everyday, accessible term. This clears up the common question regarding the difference between 3D printing and additive manufacturing.
Find out about more differences in our WAAM vs casting and forging.
How Additive Manufacturing Works
Regardless of the specific material or machine, the AM process generally follows a standard five-step workflow:
Design: Creating a CAD model or scan (STEP, STL, 3MF).
Slicing / path planning: Using software like MetalXL WAAM software to convert geometry into machine instructions (G-code or equivalent).
Build: The machine deposits, sinters, or cures material layer by layer, after which a fully printed part results.
Post-processing: Tasks such as support removal, heat treatment, CNC finishing, and NDT inspection.
Qualification: Testing the part against its specification, which can include dimensional, mechanical, and chemical checks. It’s important to understand that our materials are qualified before, and that the parts are qualified separately, to ensure the best quality.
Note: For large metal parts, steps 3-5 look very different from desktop 3D printing. Industrial AM systems, like WAAM, are integrated production cells with welding power sources, robotic motion, and inline monitoring.
The 7 Categories of Additive Manufacturing
The ISO/ASTM 52900 standard classifies additive manufacturing into seven distinct process categories. Understanding these helps clarify which technology is suited for specific materials and applications.
| Category | Process Family | Typical Materials | Common Applications |
| Binder Jetting (BJT) | Liquid binder on powder bed | Metal, sand, ceramic | Sand casting molds, metal prototypes |
| Directed Energy Deposition (DED) | Focused energy melts material as deposited | Metal wire or powder | Large parts, repair, cladding (includes WAAM) |
| Material Extrusion (MEX) | Thermoplastic extruded through the nozzle | Polymers, composites | Prototyping, end-use polymer parts |
| Material Jetting (MJT) | Droplets of photopolymer cured by UV | Photopolymers, waxes | High-detail prototypes, medical models |
| Powder Bed Fusion (PBF) | Laser or electron beam fuses powder | Metal, polymer | Aerospace brackets, medical implants |
| Sheet Lamination (SHL) | Sheets are bonded and cut | Paper, metal, composite | Niche tooling, hybrid parts |
| Vat Photopolymerization (VPP) | UV-cured resin in a vat | Photopolymers | Jewelry, dental, miniatures |
Binder Jetting (BJT): Works by depositing a liquid binding agent onto a powder bed. It is known for its speed and is often used for sand casting molds and metal prototypes.
Directed energy deposition (DED): Uses focused energy to melt material, such as metal wire or powder, as it is deposited. This category includes WAAM (Wire Arc Additive Manufacturing), which is the wire-based DED subset. It is ideal for large parts, repair, and cladding. Learn more in our guide on What is WAAM?.
Material Extrusion (MEX): Involves extruding a thermoplastic through a heated nozzle. This is widely used for prototyping and creating end-use polymer parts from polymers and composites.
Material Jetting (MJT): Droplets of photopolymer are deposited and instantly cured by UV light. This is used for high-detail prototypes and medical models using photopolymers and waxes.
Powder Bed Fusion (PBF): Utilizes a laser or electron beam to fuse metal or polymer powder. Common applications include aerospace brackets and medical implants.
Sheet Lamination (SHL): Sheets of material (paper, metal, or composite) are bonded together and then cut. This is generally used for niche tooling and hybrid parts.
Vat Photopolymerization (VPP): A liquid photopolymer resin in a vat is selectively cured by UV light. It is highly favored for jewelry, dental applications, and miniatures.
Additive vs Subtractive Manufacturing
Additive and subtractive manufacturing are generally complementary rather than competitive. In fact, most industrial AM (partially) parts go through subtractive CNC finishing to achieve precise final tolerances. When choosing between traditional manufacturing and additive manufacturing, a good general rule of thumb is: if a casted or forged part also requires CNC-ing afterwards, Additive manufacturing will be the better alternative. This is especially because of the lead-time reduction.
| Factor | Additive | Subtractive |
| Starting point | 3D model | Billet or block |
| Material waste | ~5-10% | 70-90% |
| Tooling cost | €0 | Fixtures, tooling |
| Geometric freedom | High | Medium |
| Surface finish | Post-processing often needed | Excellent as-machined |
| Lead time for new parts | Days | Weeks (if tooling needed) |
| Best fit | Complex geometries, low-medium volume | Precision features, high volume |
Benefits of Additive Manufacturing
While additive manufacturing offers significant advantages, it is important to understand where it excels and where traditional methods are more appropriate.
Key Benefits:
Design freedom: AM enables topology optimization, internal channels, and consolidated assemblies.
Reduced material waste: Waste is typically 5-10% for AM versus 70-90% for CNC.
Shorter lead times: Production takes days to weeks, compared to months required for casting or forging tooling.
On-demand / localized production: Eliminates tooling lock-in.
Part consolidation: A single printed part can replace assemblies of 250 components.
Lightweighting: Possible through the use of lattice structures and topology optimization.
Spare parts for legacy equipment: Can be produced without the need for molds.
Digital warehouses: No more storage room is necessary for keeping spare parts. Start a new print whenever a new part is needed.
Limitations and When AM Is Not the Answer
Limitations vary dramatically by process family. Common limitations include:
Post-processing is almost always required for industrial parts.
The surface finish rarely matches the precision of the CNC directly as-printed. However, this is may also be the case with traditional manufacturing.
Certification and qualification can be slow in regulated industries or industries that are still adopting the technology
Process selection matters greatly: for example, WAAM is suited for large metal parts, PBF is best for fine detail, and MEX is typically used for polymer prototyping.
Industrial Applications by Sector
Different AM categories serve different industries based on their unique material and scale requirements:
Energy (oil, gas, wind, nuclear): AM is used for large pressure components, impellers, and spare parts for legacy infrastructure.
Maritime: Applications include propellers, rudder parts, and on-demand spares for vessels. Read more about WAAM in the maritime sector.
Defense: Useful for localized production, brackets, and high-performance alloys.
Architecture and construction: Employs AM for structural nodes, facade elements, and bespoke metalwork.
Automotive: Primarily utilizes AM for prototyping, tooling, and small-series performance parts.
Where Does WAAM Fit in the AM Landscape?
Wire Arc Additive Manufacturing (WAAM) is the wire-based subset of Directed Energy Deposition (DED).
When comparing DED processes like WAAM against Powder Bed Fusion (PBF), scale and economics are the primary differentiators. WAAM excels at large-scale production, capable of printing parts ranging from 100mm to over 5x5x5 meters. It boasts deposition rates of 2 to 15 kg/h, compared to the much slower 0.1 to 0.5 kg/h typical of PBF systems.
Furthermore, WAAM utilizes standard welding wire (costing around €5-€15/kg), which offers a massive material cost advantage over atomized metal powders (€50-€200/kg).
If a required part exceeds a standard PBF build chamber, if tight lead times are critical, or if raw material costs dominate the budget, WAAM is usually the most economically favorable AM process. MX3D has specialized in delivering these large-scale metal AM parts across the energy, maritime, defense, and architecture sectors since 2014.
Find out more about the WAAM technology we use at MX3D and how we apply it to our products and services, such as 24/7 print on demand with our Metal AM M1 and MX Systems.
FAQ
What is additive manufacturing in simple words?
Additive manufacturing is a production method that builds a physical part layer by layer from a 3D digital model, using processes like powder bed fusion, material extrusion, or wire arc deposition. It is the industrial name for what is commonly called metal 3D printing.
What is the difference between 3D printing and additive manufacturing?
While they are often used as synonyms, 3D printing historically refers to desktop or prototyping applications, whereas additive manufacturing typically refers to production-grade industrial processes.
What are the 7 categories of additive manufacturing?
The 7 categories defined by ISO/ASTM 52900 are Binder Jetting (BJT), Directed Energy Deposition (DED), Material Extrusion (MEX), Material Jetting (MJT), Powder Bed Fusion (PBF), Sheet Lamination (SHL), and Vat Photopolymerization (VPP).
What are the main benefits of additive manufacturing?
The main benefits include high design freedom, reduced material waste (5-10%), shorter lead times, part consolidation, lightweighting, and the ability to produce on-demand spare parts for legacy equipment.
Where is additive manufacturing used in industry?
It is widely used across various sectors, including energy, maritime, defense and aerospace, architecture and construction, automotive, and medical fields.
