As explained in our previous article on the FDM technique, Fused Deposition Modelling involves melting materials and depositing them in layers to create parts.
This technology has many advantages for manufacturers: reduced costs, increased production rates and greater accuracy than other manufacturing techniques. Because the process is so versatile, it can be used in a wide range of industries, including healthcare, consumer goods and architecture.
The FDM technology step-by-step
FDM technology builds three-dimensional parts by fusing and depositing plastic filaments through a computer-controlled extrusion head.
The process consists of the following steps:
1. Design – creating the 3D model and part cutting
As with other FA technologies, the process always starts with the design of a three-dimensional model using CAD software. The model will be exported to a laminating program in .STL (Standard Triangle Language) format and this will generate a CMB file according to the selected printing parameters.
2. Loading the spool with thermoplastic filament
Before printing, the spool must be loaded with thermoplastic filament. This filament is the material used for FDM printing and melts when it passes through the nozzles at working temperature.
3. Start of deposition
Once the previous steps have been completed, the head movement begins and the deposition starts. Layer after layer of material is deposited to replicate the 3D model that has been fed into the printer. After deposition, each layer adopts the temperature of the working chamber, which is tempered.
4. Repeating the layer deposition process
After the completion of one layer, the printing platform moves down to make room for the deposition of the next layer. This layer overlaps the previous one and the process is repeated until the part is complete.
When it is time to remove the support material, the material used must be taken into account. The Soluble Support Material method uses an automated support removal system whereby the material is removed through an agitated water-based detergent solution. There is another method called Break Away Support Material, which consists of removing the supports manually (usually with a pair of needle nose pliers).
Some aspects to consider
Elastic instability is caused by the solidification of the thermoplastic material after layer-by-layer deposition. Regardless of the geometry of the material, it will have different cooling rates on different parts of its surface. Thus, in the deformation, the material chosen will play an important role as some plastic materials are more sensitive to deformation.
Adhesion of the layers
As a general rule, the greater the adhesion of the layers, the greater the strength of the part. FDM technology is based on layer deposition, so the high temperature of the material would contribute to good layer bonding.
Print size and layer heights
The height of the layers is decisive in this technology. The lower the layer height, the higher the resolution to reproduce geometries. Also, to produce a smaller layer height, more manufacturing time is spent than to produce a thicker layer (i.e. the thicker the layer, the fewer times the path is made).
Thus, we can say that if a small layer height is maintained, smooth parts with curved geometries can be produced. On the contrary, a higher layer height will allow a higher speed to be produced.
Therefore, whenever it is necessary to produce curved geometries or precise edges, it will be necessary to opt for a small height; when this precision in height is not required, it will be possible to produce faster by maintaining a larger layer height.
FDM technology is ideal for printing prototypes and functional parts faster. In addition, it allows a wide range of sizes to be printed because it has fewer restrictions on its print area. It also accepts a wide variety of materials which, although they can undergo some modification, produce optimal results. Lead times are short and it is a more cost-effective technology for producing customised thermoplastic parts.
At Mizar we are specialists in this technology, contact us and find out more!