FDM (Fused Deposition Manufacturing) technology is based on liquefying a filament of thermoplastic resin and selectively depositing this material layer by layer to build a specific part. Material density can be regulated within the part volume from almost solid to almost empty cavity with full walls. Professional FDM machines can build parts from the range of layer thicknesses: 0,12; 0,18; 0,25; 0,33mm in heated thermostatic chamber to assure equal material shrinkage over hole part volume.
FDM technology requires supporting structures made either from dissolved or break-away material.
Dissolved material is much easier to remove than the break-away.
Parts made of the most popular material which is ABS can be treated with variety of finishing methods like chemical smoothing, mechanical smoothing, painting and vacuum metallisation. There is always a certain porosity in FDM parts which needs to be sealed if the parts requires it.
Models made of FDM technology are rigid with high impact resistance close to injection moulded parts however there is big difference in tensile strength due to weaker material connection across the layer than along the layers. This property needs to be taken under consideration if the prototype is supposed to be mechanically tested.
Most popular materials used in FDM technology are: ABS, PC-ABS, PC, PPSF, PEI, PA12.