- FDM fused deposition modelling
- FFF fused filament fabrication
Fused deposition modelling or fused filament fabrication is essentially the same process. It is a method of rapid prototyping that works by laying down consecutive layers of material at high temperature. This material is extruded through a heated nozzle into a fine filament and is laid down onto a heated bed to form the shape of one slice or section of the model being printed. Once complete, the bed moves away from the nozzle and the process is continued for the next layer and so-on until the model is complete.
This method of additive manufacturing is extremely cost-effective and quality models with good mechanical properties can be produced rapidly. One major drawback is that because the individual layers rely on the heat of the extruded filament to ‘fuse’ to the layer underneath, this creates a weakness between layers so great care has to be taken in selecting the most suitable orientation for printing, maximising the strength of the part in it most critical direction.
In spite of this limitation, FDM or FFF remains one of the most popular methods of rapid prototyping due to the relative low costs involved.
SLS selective laser sintering
SLS is a technology used for creating some of the most accurate and mechanically useful rapid prototypes available. It is probably the most versatile of all the technologies due to the fact that the finished parts are so durable. Many projects base their key milestone decisions on SLS manufactured parts.
The process starts with a bulk material which is held in powder form within the machine. A high energy pulse laser fuses the material together to form the
shape of the part and once complete, it is a simple process of removing the part from the powder. There is almost no post-processing required as supports are not needed for this method of production.
SLA is a form of additive manufacturing that uses UV lasers to harden a liquid plastic resin called a photopolymer. The models are built layer by layer in very high resolution and the finished parts can have the finest detail of any 3D printing technology.
The quality is so good that this form of manufacture is commonly used to create master parts that are then used to make silicon mould tools. These tools can be used to cast parts from materials that are almost indistinguishable from fully injection moulded items and is a very cost effective method for low volume production.
Fully machined parts from production type materials are gaining in popularity due to the fact that the resulting models are as close as it is possible to get to having the final mechanical and chemical properties.
Using high-speed 3, 4 or even 5 axis CNC machines, specialists in this area can produce parts surprisingly economically. These parts can then be used directly for compliance and mechanical testing of products, greatly reducing the overall time to market.