Basics of 3D Printing Technology

Published at: May 10th 2024

Photo of 3D printed heart using human cells on the table

3D printing is an additive manufacturing method that creates a physical object from a digital model file. The technology works by adding layer upon layer of material to build up a complete object.

The advantage of 3D printing over traditional manufacturing techniques is that it allows for more complex shapes to be produced while using less material.

Picture 1. 3D printed heart using human cells (source: nocamels.com)

What are the main 3D printing technologies?

1. Fused Deposition Modeling (FDM):

How it works: FDM 3D printers extrude melted plastic filament through a nozzle to build up layers.
Applications: Prototypes, prosthetics, architectural models etc.

Picture 2. FDM 3D printer (source: HLH Rapid)

2. Stereolithography (SLA):

How it works: SLA is a process where a light source cures liquid resin into hardened plastic.
Applications: High-detail models, dental crowns, and jewelry.

Picture 3. SLA 3D printer (source: 3dprintingdublin.com)

3. Selective Laser Sintering (SLS):

How it works: SLS 3D printers use a high-power laser to sinter small particles of polymer powder into a solid structure based on a 3D model.
Applications: Functional prototypes, aerospace components and medical implants.

Picture 4. SLS 3D printer (source: zongheng3d.com)

What are the most common materials used in 3D printing?

1. PLA (Polylactic Acid):

Characteristics: Low-temperature printing, flexible, less prone to warping, sub-par durability and heat stability.
Projects: Prototypes, decorative items.

2. ABS (Acrylonitrile Butadiene Styrene):

Characteristics: High-temperature printing, heat-stable, chemically stable, durable, rigid, soluble in acetone
Projects: Functional parts, outdoor items, automotive components.

3. PETG (Polyethylene Terephthalate Glycol-Modified):

Characteristics: High strength, high impact resistance, heat-stable, chemically stable, clear, prone to damage by UV
Projects: Protective components, mechanical parts, objects that will come into contact with food

How does 3D printing work?

1. CAD Model Creation (Computer-Aided Design):

The first step is creating a 3D digital model of the object you want to print. This can be done using CAD modeling software (such as Catia, Fusion360, SolidWorks or Creo), a 3D scanner or even photogrammetry software.

Picture 5. 3D model of a gear in SolidWorks

A great place for absolute beginners to start is Tinkercad - 3D Design. You can start building anything you desire without any prerequisites.

The digital model serves as the blueprint for the physical object. Once complete, it needs to be converted into a 3D printer-compatible format, typically an STL file. This file contains instructions for the printer on where to place each layer of material to construct the final object.

2. Slicing:

In the second step, we prepare the model for printing. This involves using slicing software (often called a “slicer”).
The slicer takes the 3D model and divides it into multiple layers (slices). These slices represent the layers that the printer will deposit one above the other during the actual printing process.
Parameters like layer thickness, wall thickness, printing speed, extruder temperature, and bed temperature are configured in the slicer. It generates a .gcode file containing instructions for the printer.

Picture 6. 3D model of a gear exportedfrom SolidWorks and sliced in Prusa slicer

3. Setting Up the Machine:

Before printing, the 3D printer must be set up. This involves ensuring the printer knows its build boundaries, nozzle diameter, and material diameter.
Proper configuration is crucial to avoid failed prints.

4. 3D Printing:

Using the STL file and .gcodeinstructions, the 3D printer gets to work.
The printer deposits material layer by layer, following the instructions from the .gcode. It can use various materials, including plastics, metals, ceramics, and even bioinks.
The process continues until the entire object is built up.

Picture 7. 3D printed gear

5. Post Processing:

Once the printing is complete, some post-processing steps may be necessary. These can include removing support structures, sanding, painting, or curing (for resin-based prints).