3D Printing: a journey into the world of three-dimensional objects

As article of #tech category, a read about 3D printing’s functioning represents an occasion for tech beginners to be introduced into the amazing world of innovation, and it is for other experts a way to discover how BionIT Labs uses 3D printing for Adam’s Hand.

The origins of 3D printing

3D printing, also known as “Additive Manufacturing” (AM), “Rapid Prototyping” (RP), or “Solid Freeform Fabrication” (SFF), is a process of joining materials to create objects from 3D model data, usually layer by layer.

The first technology of commercial rapid prototyping was defined in 1986 “stereolithography” by Charles Hull, and he also developed the STL (Surface Tessellation Language) file format.

The 3D-printing process

This technology creates objects by adding materials layer by layer on the build plate with reduced waste, achieving satisfactory geometric accuracy.

The first stage of the process is the creation of a meshed 3D computer model, which can be obtained using image data acquired through 3D scanning of existing objects or structures built with the help of Computer-Aided Design (CAD) softwares.

After that, a STL (Surface Tessellation Language) file is commonly originated, which is loaded into a printing software.

This software slices again a mesh data, creating a build file of 2D layers, then sent to the 3D printing machine.

Finally, the 3D printer produces the component on a layer by layer basis, through a series of cross-sectional slices.

If needed, the possible supports may be removed and, in the case of stereolithography, the printed product (green part) needs a post-curing phase with an UV cure station that will make 3D print strong and stable.

The materials used for 3D printing

The materials that can be used in 3D printing processes are thermoplastic polymer materials, such as acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), polyamide (PA) and polycarbonate (PC) as well as thermosetting polymer materials like epoxy resins.

ABS, PLA, PA and PC are usually used for the FDM (Fusion Deposition Modeling) process, that starts from solid materials in the form of wire bibs.

Epoxy resins, instead, are reactive materials that require thermal or UV-assisted curing to complete the polymerization process. They initially exhibit a low viscosity, which rises as the curing process proceeds.

Therefore, epoxy resins are suitable for heat or UV assistedprinting process, like stereolithography (SLA), digital light processing (DLP) or UV LCD technology.

3D printing case-uses

However, it is only in the past few years that 3D printing has been fully applied in several industries, to obtain results ranging from initial prototypes to fully-working and ready-to-market products. In particular, 3D printing of polymers has found application in many different fields:

  • in aerospace industries, for creating complex and lightweight structures;
  • in architectural industries, for creating structural models;
  • in artistic field, for artifact replication or education purposes;
  • in the medical field, for printing tissues and organs.

However, the wide industrial application of 3D printed polymers is limited from several drawbacks, such as lack of strength and functionality in the case of fully functional and load-bearing parts.

New applications are emerging as more and more novel materials are developed and AM technologies are continuously being developed, mainly due to the undeniable advantages of this technology compared to the traditional Subtractive Manufacturing (SM) technique.

The advantages of 3D printing

The use of 3D-printing facilitates production processes in different fields. We may say that, among others, there are three main advantages of 3D-printing compared to subtractive manufacturing:

  • production of highly complex geometries, which would be impossible to realize through standard SM;
  • customization capabilities, which allows for the production of personalized and unique objects at low cost;
  • chance to combine an assembly of parts into one single components, reducing the overall weight and optimizing the mechanical properties of the assembly.
from 3D Natives website

The possibility to 3D print small quantities of customized products with relatively low costs is particularly useful in the biomedical field, whereby unique patient-customized products are typically required. In our case, innovative 3D printing technologies allowed us to reach never-seen customization capabilities for some of Adam’s Hand components.

3D printing and Adam’s Hand: the added-value for a high-quality product

In BionIT Labs we use 3D printing to product some of Adam’s Hand components, mainly during the prototyping and the design validation stages; 3D printing, however, has a big role also in the production phase of Adam’s Hand fingers and of its cover.

In particular, for phalanges’ production we use FDM technology, using 3D Roboze One printer and special high-resistance techno-polymers built for high-end mechanical applications, such as the CarbonPA.

This printer uses a rapid prototyping technique, where a plastic filament, mainly composed by a thermoplastic polymer, passes inside a heated extrusion nozzle that leads it to fusion; after that, the molten material is deposited layer by layer on the build plate.

On the other hand, for the hand cover’s production, we use stereolithography technology, with a photosensitive resins which is polymerized through a laser beam.

In our laboratory we use Formlabs Form3 3D printer, which is based on LFS (Low Force Stereolithography) technology: it allows us to obtain very high levels of detail, thanks to a smart calibration of the laser’s force, depending on the geometric model to be printed.

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