Fused Deposition Modelling (FDM) is one of the most widely used additive manufacturing techniques in use today.
This boom is largely due to the large number of machine manufacturers and the diversity of materials available. In addition, the industrial sector is becoming increasingly familiar with new technological applications, which is opening the way for technologies such as this.
Through FDM technology we can create practically any geometry. In addition, it is a relatively inexpensive, easy to handle and fast technique, which is why FDM parts are being used in sectors such as automotive, aeronautics, decoration, industrial production tools and prototyping.
In this article, we will learn more about the origin of this technique, what it consists of, its parameters and areas of application.
Fused Deposition Modelling was developed by inventor S. Scott Crump in the late 1980s. He began commercialisation in 1990, at the same time as the founding of Stratasys, a manufacturer of FDM technology printers that is still in business today.
2005 was a pivotal year for Fused Deposition Modelling due to the rise of RepRap printers. The RepRap initiative, created by the engineer and mathematician Adrian Bowyer in England, emerged with the aim of providing a free prototyping machine that could replicate itself. This machine can manufacture physical objects from computer-generated models. Just as a computer printer can print two-dimensional images on paper, RepRap prints 3D plastic objects. This leads to the manufacture of parts.
The main applications of Fused Deposition Modelling are the production of final parts and industrial prototyping.
FDM technology is based on 3 elements:
- Printing plate or bed: used to deposit the material and print the part.
- Filament spool: material used for the prints.
- Extruder: its function is to heat and deposit the material.
Before printing, a CAD file is generated with the printing parameters and the data necessary to shape the part. The extruder is responsible for heating the material (filament) to deposit it on the plate.
This technology produces objects in a succession of layers from the bottom to the top. Thus, once a layer is deposited, the programmed distance is increased to deposit the material on top again. The process is repeated successively until the 3D model is achieved. For its execution, the filament is sucked and melted by the printer’s extruder, which deposits the material layer by layer on the printing plate.
Among other things, FDM additive manufacturing is characterised by the possibility of manufacturing with different fillers. This makes the inside of the part lighter and maximises the strength to weight ratio. The strength of the part is determined by the position, shape and percentage in relation to the total volume of the fillers.
The standard layer height used in FDM systems ranges from 50 to 400 microns. A smaller layer height produces smoother parts and captures geometries more accurately. Conversely, a larger layer height produces parts faster at a lower cost. The most common application is a layer height of 200 microns.
Polymer is by far the most frequently used raw material in Fused Deposition Modelling. However, there are also other possibilities such as the addition of fibres to the material matrix.
There is a wide variety of materials for the manufacture of parts. The choice will depend on the needs we have, as each one has different properties and characteristics.
These are the main materials and their characteristics:
PLA (Polylactic Acid)
It is the most easily printable material. It is a naturally occurring, biodegradable plastic that is both versatile and environmentally friendly. It has low resistance to heat and humidity and produces rigid and relatively strong parts that degrade over time.
ABS (Acrylonitrile Butadiene Styrene)
It is an opaque thermoplastic and an amorphous polymer that responds to heat in different ways. It has better mechanical properties, especially in terms of durability and temperature resistance.
It is more difficult to print than PLA, although it is the most used material after PLA.
Nylon (Polyamide)
It has good mechanical properties, especially in terms of impact and corrosion resistance. It is a durable material and is noted for its low temperature resistance. However, it is an expensive material that does not tolerate moisture well and requires high temperatures for printing.
TPU (Thermoplastic Polyurethane)
It is difficult to print. It has a high resistance to temperature, corrosion and impact. It is an elastomer and is used to make elastic partsor to simulate rubbers.
PC (Polycarbonate)
It has a triple resistance – mechanical, temperature and corrosion – superior to other materials. Like Nylon, it does not tolerate humidity well and needs high temperatures for printing.
In addition, there are other materials that have special characteristics; we are talking about filaments that can produce phosphorescent parts or magnetic filaments that are obtained by mixing PLA or ABS filaments with iron powder to create ferromagnetic material.
FDM printing parameters
The printing parameters vary depending on the applications and the most common are as follows:
- Type of support. This parameter is used to define the support to be used. The most frequently used are in staggered or grid lines. The first ones create parallel lines with a thickness corresponding to the nozzle of the equipment. Grid brackets create supports in the form of a grid of squares with a thickness corresponding to that of the nozzle of the equipment. The supports can be of the same material as the model or of a different material, as well as manually removable or liquid soluble.
- Print quality. This depends largely on the thickness of the print layer, which must be adjusted to the desired quality. The thinner the layer, the higher the vertical resolution of the print.
- Density of the filler. The filler to be used as internal structure if we are manufacturing totally solid objects. This parameter is important in terms of saving material and reducing the weight of the part. The percentage of filler affects the final strength of the part, its weight and the printing time.
- Wall thickness. The thickness of the walls of the printed object, i.e., the thickness of the outer sides of the printed piece.
- Support angle. Wall angle from which the software generates supports. The angle is measured from the table to the wall.
- Space between support lines in X and Y. This is a small space left between the support and the part in both axes so that it can be easily removed.
- Space between support and workpiece in Z. Small cavity between the support and the workpiece in the vertical Z axis so that the workpiece can be easily removed.
- Support density. This parameter controls the amount of support to be built in the area that will require support.
- Model base. Parameter that establishes the type of base that will be built for the part. Through the base we add contact area between the printing table and the part itself, so that it does not come off easily and thus avoid incidents during printing.
- Base density. Sets the density of material included in the base..
- Layers at the top or bottom of the model. Thickness of the horizontal faces of the model at the top.
Most FDM systems allow these parameters to be adjusted, so they should not be of concern to the designer. In this respect, the most important aspects are the size of the construction and the height of the layers.
Once the part has been created, it is essential to analyse it through tests to guarantee its optimum performance before it enters the supply chain..
At Mizar we are specialists in this technology, contact us for any queries you may have.
