Classes on Mass personalization of medical devices held during the UBORA Design School 2018.
Part 1 - Fundamentals
Additive Manufacturing technologies
Additive manufacturing (AM) is a process of making a 3D solid object of virtually any shape from a digital model. It is achieved using an additive process, where successive layers of material are laid down in different shapes.
AM technologies can be classified according to ASTM/ISO 52900 in:
- Binder jetting: AM process in which a liquid bonding agent is selectively deposited to join powder materials;
- Directed energy deposition: AM process in which focused thermal energy is used to fuse materials by melting as they are being deposited (note: “Focused thermal energy” means that an energy source (e.g. laser, electron beam, or plasma arc) is focused to melt the materials being deposited);
- Material extrusion: AM process in which material is selectively dispensed through a nozzle or orifice
- Material jetting: AM process in which droplets of build material are selectively deposited (note: example materials include photopolymer and wax)
- Powder bed fusion: AM process in which thermal energy selectively fuses regions of a powder bed;
- Sheet lamination: AM process in which sheets of material are bonded to form a part;
- Vat photopolymerisation: AM process in which liquid photopolymer in a vat is selectively cured by light-activated polymerization.
Additive manufacturing process workflow
The general workflow consists of 7 steps:
- Solid 3D Modelling. The starting point of all AM processes is a digital model representing the object to be fabricated. It can be designed from scratch, using a Computer Aided Design (CAD) software, or obtained by the elaboration of data from specific intrumentation (e.g. segmentation of tomographic data from CT/MR scan).
- Export (Tessellation / Voxelization). Export of the 3D solid model into a fileformat which can be interpreted bu the Computer Aided Manufacturing (CAM) software. The file can describe just the (closed) surface of the 3D model (know as polygon based rapresentation) or its the voxels, the "bricks" which compose the entire volume (both surface and inner parts). .
- Support Generation. Support will be generated to increase the stability of the object during its fabrication (e.g for overhangs). Supports can be influenced by the orientation of the part and by the specific additive manufacturing technology.
- “Slicing” of the Model
- Model Physical Buildup
- Cleanup and Post Curing
- Surface Finishing