Fused Deposition Modelling — A Short Introduction
10 May 2017
Fused deposition modelling remains one of the most popular techniques for 3D printing amongst hobbyists, AM bureaus and industrial manufacturing companies alike. In this tutorial, we’ll take a closer look at the mechanics of the process and share some practical tips for getting the most out of your chosen materials and 3D printers.
What is fused deposition modelling?
Fused deposition modelling prints 3D objects by using a heated filament to manually build up layers of material. A thermoplastic material is heated to a semi-liquid state, after which an extrusion head builds the layers on a heated printing bed. To avoid any drooping during and after printing, water-soluble support materials are typically used, then removed later.
The thermoplastics used in FDM are highly versatile and durable, allowing for a high level of accuracy and stability. Although printed parts created using FDM typically have quite a rough finish, a variety of post-processing techniques are available, so smoother finishes are quite achievable. A number of options for colouring are also available, including impregnating the material and painting or coating at the end of the printing process.
FDM is a popular choice for prototyping projects, as functional parts can be created from the same materials that will be used for the final production versions. It is also used for low-volume production applications.
Acrylonitrile butadiene styrene (ABS) has long been the most widely used FDM material for for both prototypes and production parts, thanks to its strength, temperature resistance and versatility. PLA is a close second, and is a good option for 3D models with lots of fine detail, although the finish parts will be quite brittle, so it is not necessarily suitable for functional parts. Polycarbonate (PC) and polyetherimide (PEI) are also popular choices. In particular, PC is the best FDM material to choose if mechanical strength is a major concern.
One notable quality of certain FDM materials is that they are suitable for food, drink and medical applications. Good examples would be PC-ISO, PPSF and ULTEM 9085, although the various nylon filaments now available for FDM printing are rapidly increasing in popularity in this area.
Getting great results from your fused deposition modelling projects
Regardless of the material you eventually choose and the specific model of printer you are utilising, there are a few practical things you can do to optimise their performance and get the best possible end result. Bear these points in mind as you prepare your 3D model for printing:
- If filament is clogging the nozzle during the printing process, check the extrusion and retraction speeds.
- If overhangs are creeping into your printed parts, try a small reduction in the extrusion temperature.
- Consider your part’s purpose when selecting the infill settings, as this will help determine the overall strength of the finished result. For functional items, higher infill settings (i.e. 75% or more) will be required, while in other cases, the infill can be lowered to reduce material costs and speed up the printing time.
- Are the right platform adhesion settings selected? If you are experiencing warping at the base of your part during printing, it could be that the wrong platform adhesion setting has been selected, so the part is not properly sticking to the printing bed.
- Will any post-processing be required, either for aesthetic or functional reasons? Parts produced using FDM have naturally porous finishes, which may be problematic if the part is being used for food, drink or medical applications. In such cases, the finish will need to be sealed after printing.
- Make sure your printing area is properly ventilated. Certain materials used for FDM — including the ever-popular ABS — give off fumes during the printing process that can potentially irritate sensitive individuals. Always print in a properly ventilated area and supply staff with gloves, safety goggles etc. if necessary.