3D printing, more formally referred to as additive manufacturing (AM), is a manufacturing methodology in which three-dimensional objects are fabricated directly from digital design data. The process builds components layer by layer from materials such as thermoplastic polymers, photopolymers, metal powders, or composite feedstocks.

In contrast to subtractive manufacturing processes—where material is removed from a solid block—or formative processes that rely on molds and tooling, additive manufacturing constructs parts through sequential material deposition. Each layer is fused or bonded to the previous one through thermal, photochemical, or metallurgical mechanisms, ultimately forming a fully realized three-dimensional structure based on the original CAD model.

This layer-wise fabrication approach enables the production of highly complex geometries that would be difficult or impossible to achieve using conventional manufacturing techniques. It also provides advantages in material efficiency, design optimization, and part consolidation.

Additive Manufacturing (3D Printing) Workflow

Digital Modeling Phase

In the additive manufacturing workflow, the process begins with creating a 3D digital model using computer-aided design (CAD) software such as AutoCAD or SolidWorks.

This model fully defines the geometry and dimensional parameters of the planned part to print and is typically exported into industry-standard file formats such as STL or 3MF.

※ CAD is the use of computer software to create and edit digital designs, including 2D drawings and 3D models. It is widely used in engineering and product design, and in 3D printing it serves as the starting point for creating printable models.

Slicing Phase

Slicing software (such as Cura or PrusaSlicer) converts the 3D model into layers along the Z-axis based on a predefined layer height.

During this process, the model is divided into a series of 2D cross-sectional layers, and toolpaths are generated for each layer. For every slice, the software calculates the outer perimeters, internal infill paths, and any required support structures. The final result is a machine-readable instruction file (typically G-code) that directs the printer’s movement and material deposition.

Fabrication Phase

In the fabrication phase, the printer constructs the physical object by depositing material layer by layer according to the generated toolpaths.

Taking Fused Deposition Modeling (FDM) as an example: Thermoplastic materials such as PLA, ABS, and PETG are heated in the hotend until they reach a molten state, then extruded through a nozzle at a controlled flow rate and deposited precisely along predefined paths, building the part layer by layer.

Bonding of the layers occurs through thermal diffusion and molecular chain entanglement. The resulting strength between layers is influenced by:

• Interlayer temperature
• Extrusion rate
• Cooling rate

Post-Processing Phase

After printing, post-processing is often required to achieve the desired mechanical properties or surface finish:

• Support removal
• Surface finishing (e.g., sanding, bead blasting)
• Annealing (to improve crystallinity and mechanical strength)
• Post-curing (for resin-based printing processes)

In the manufacturing field, traditional methods can be broadly categorized based on how materials change during the forming process:

Formative Manufacturing

Formative manufacturing, also known as material transfer, involves changing the shape, structure, or properties of the material without altering its total volume. Common formative methods include:

• Casting: Pouring molten metal into a mold and allowing it to solidify into a part. This is ideal for producing complex shapes.
• Forging: Applying pressure to metal billets, causing plastic deformation to form parts with specific mechanical properties.

Other processes like rolling, extrusion, and drawing also fall under formative manufacturing. The primary focus here is on transforming the material rather than removing it, resulting in little to no material loss.

Subtractive Manufacturing

Subtractive manufacturing, also known as machining or material removal, is characterized by the gradual reduction of material. The process involves controlled cutting or removal of material to achieve the desired part shape and dimensions. Common subtractive methods include:

• Grinding: Using abrasive wheels to refine surfaces.
• Machining: Such as turning, milling, planing, and drilling, where tools remove excess material.

Specialized processes like electrical discharge machining (EDM), electrochemical machining (ECM), and laser cutting also fall under this category.

Subtractive manufacturing offers high precision and surface quality, but results in lower material efficiency, especially for complex parts, leading to significant waste.

Additive Manufacturing (3D Printing)

Additive manufacturing (3D printing) builds parts layer by layer, adding material to achieve the desired shape. This method has become a hallmark of modern manufacturing.

Here’s a comparison of the three methods:

1. Design Freedom

Additive manufacturing enables the fabrication of complex geometries without traditional tooling constraints. Structures can be easily optimized for topology, lattice infills, internal channels, and graded architectures can be produced directly thus expanding the opportunities for practical designs.

2. Material Efficiency

AM follows a near-net-shape production model, depositing material only where needed. Compared to conventional machining, this significantly reduces waste and improves feedstock utilization, particularly in metal applications.

3. Digital Workflow

The process is fully digitally driven, integrating CAD modeling, simulation, slicing, and toolpath generation. Reduced reliance on molds and fixtures shortens development cycles and increases manufacturing flexibility.

4. Rapid Iteration

Without the need for dedicated tooling, 3D printing supports rapid prototyping, low-volume production, and customized manufacturing, accelerating design validation and product development.

5. Multi-Material Potential

Certain AM systems allow multi-material deposition within a single build, enabling functional integration of different materials in a unified component.

6. Process Sensitivity

Accuracy, surface finish, and mechanical performance are strongly influenced by process parameters. Interlayer adhesion and anisotropic behavior remain important engineering considerations in structural applications.