How Does an FDM Printer Work?

 

By Juliet Jolly

               A Typical FDM Print

 

FDM is short for “Fused Deposition Modeling”.  This is how we describe the process used in one type of 3D printer.  3D printing is the use of a spool of special plastic filament with a melting point close to 250 degrees Celsius in order to print a physical 3D model using a virtual model that has been sliced into layers.  Here I will lay out the process which the printer must follow in order to make this possible.  I will describe the parts of a typical FDM 3D printer.  Finally, I will discuss the uses of such a device.

How Does an FDM Printer Work?

PLA Filament

All FDM printing requires plastic filament.  There are many types of filament such as PLA, ABS or TPU to name just a few of the more popular types.  For my purposes we will consider Polylactic acid or polylactide (PLA) which typically comes from corn and is considered biodegradable.  FDM printers draw the filament from the spool into a heated block and nozzle called an extruder and melts it to a liquid.  The virtual model is ran through a program called a slicer and sliced up into individual layers.  These layers are extruded one on top of each other using the nozzle just as a cake artist uses a tube of icing to decorate a cake.  This extruding is continued until the model is complete.  So what parts make up this printer?

Parts of an FDM Printer

Parts of an FDM Printer

Generally, all FDM 3D printers have a default set of parts.  All will have a heated or none heated bed.  Heated beds are preferred and will usually be set at between 50 degrees Celsius and 90 degrees Celsius depending on the material being extruded.  It is easier for a print to stick to a heated bed and this type of bed may also prevent warping of the model.  FDM printers also have stepper motors which precisely control the movements of the bed, extruder and filament in the x, y, and z axis.  The extruder moves left and right and up and down, while the bed is forward and back.   One last stepper controls the filament being pushed into the nozzle.  All of these movements and temperature is controlled by a small computer which is able to read the sliced up model or STL file, which is short for stereolithography. Which as saved as g-code.  The g-code instruction file is created by a program called a slicer.  G-code instructions are similar to text instructions which give explicate detail of how to build each slice of the model.  So, what are some possible uses of these printers?

    Typical Uses of FDM Printing

Typical FDM Printers Found in Industry

Possible uses for FDM technology include prototyping, functional parts, and developing new products.  FDM printing can be seen extensively in the auto industry which uses it in all of these areas.  NASA is even considering ways in which FDM 3D printers may be helpful in a manned mission to Mars.  They believe it could be a way to produce needed parts for equipment or even just to build the parts needed for the habitats which will be necessary to survive on the Martian planet.  Earth engineers could even use them to deliver new updated designs for parts and equipment.  All of these things are happening now and we are even seeing FDM printers being used by medical science to build artificial replacement parts for the human body.  Someday soon we might even see the first 3D printed heart being placed in a human being.

Conclusion

In conclusion, FDM is short for “Fused Deposition Modeling”, which is how we describe the process used in one type of 3D printers using a spool of special plastic filament in order to print a physical 3D model based on a virtual model that has been sliced into layers.  As seen I have laid out the process which these printers follow in order to make this possible.  I also described the parts of a typical FDM 3D printer.  Finally, I discussed the many varied uses of such devices.