Materials for 3D printers using FDM technology

Fused Deposition Modelling (FDM) – or Fused Filament Fabrication (FFF) as it is also known in the open source community – is perhaps the most common process used in lower cost 3D printers such as desktop machines and less expensive professional printers. FDM/FFF technology is employed in the RepRapPro, Ultimaker, MakerBot and 3D Systems Cube and CubePro printer ranges. A great advantage of FDM printers is their relative low cost, in addition to highly affordable material costs, makes them the preferred choice for rapid prototyping applications. Click here to see the leading FDM 3D printers available from RS Components.

 

Filament Options

Filament for FDM printers is usually rolled on a spool and is mainly thermoplastic or thermoplastic/organic-material blends.  However some manufacturers only accept proprietary reels or cartridges in their machines.  The main purpose for restricting filaments to the manufacturer’s own is to ensure the filament is of high quality. Poor quality filament can lead to printing issues such as inconsistent extrusion due to irregular diameter filament, which can cause sub-standard results. This type of poor quality filament is a leading cause of extruder failure due to the material either being too thin with the result that no filament makes it to the hot extrusion nozzle, or being too thick and the extruder motor cannot push it through the nozzle. So, the diameter tolerance is an important metric and should be less than 0.05mm for 1.75mm diameter filament.

Filament spools are available in two basic filament thickness standards – 1.75mm or 3mm diameter – the filament thickness that you choose will depend on the specific make and model of your 3D printer with filament also coming in an increasingly wide range of colours and materials.

While there are many different types of filament available, the two most common materials used in FDM printers are PLA (Polylactic Acid) and ABS (Acrylonitrile Butadiene Styrene). PLA is the better known perhaps and the most popular in the home environment, partly due to its biodegradable properties, but also because it does not emit unpleasant chemical fumes during the printing process.

 

PLA (Polylactic Acid) is a thermoplastic-polyester made from eco-friendly plant matter, making it food safe and biodegradable. It is strong, but will melt at a lower temperature compared to ABS, which clearly limits the range of applications. But because it does not necessitate a heated build platform, it is the material of choice for many 3D printers. Industrially it is used to make many containers.

 

ABS (Acrylonitrile Butadiene Styrene) is a petroleum derived thermoplastic. As it is amorphous it has no true melting point. ABS therefore becomes increasingly soft with the increase in temperature. Generally, it is resistant to many acids and alcohol, but soluble in acetone.

ABS is usually more difficult to print than PLA and often does not deliver fine surface details, but it is harder and more impact resistant, and therefore it is more often used for mechanical parts or parts that are more likely to be exposed to the elements. Industrially, it is used to make products such as helmets or sports canoes, for example.

 

Table 1: Differences between ABS and PLA (supplied by Verbatim)

Characteristic

ABS

PLA

Made from

Petroleum based.

Plant based (generally corn, soy beans, etc.)

Key features

Harder and more impact resistant, hence often used for mechanical parts or parts to be exposed to the elements.

In general, easier to print.

Availability

Very common, has been around for a long time.

Less common, but the most popular among bio-based plastic.

Smell

Some report a bad plastic smell with ABS, but even with traditional 3D printers it is less noxious than a permanent marker.

PLA is reputed as having more of a corn-like/sweet smell.

Hardness

Hard, impact resistant and tough, and has a decent flex or ‘bend’ to it.

Hard, but more brittle than ABS when bent. More likely to snap when bent/flexed.

Heat settings

210-2500C

175-2200C

Usage

Heated build platform recommended.

Heated build platform not required.

Post processing

Can be cut, filed, or glued. Acetone can be used to render its surface smooth and shiny.

Can be cut, filed, or glued. Doesn't work with Acetone.

Vulnerabilities

Less vulnerable to degradation due to moisture and sunlight, as well as over-heating in processing. Generally more stable and more resistant to chemicals.

Vulnerable to degradation due to moisture and sunlight, as well as over-heating in processing. It can droop if it gets too hot.

Appearance

Generally glossy, but very varied.

Options for various translucencies.

Environment & Recycling

Classed under recycling Number 7, which means that although it can be recycled, many local recycling programs do not accept ABS. Some programs do now take ABS, with Number 7 materials generally being recycled into plastic lumber and other.

PLA is a bio-plastic, which means it degrades, but outside of an industrial composting facility, it does so very slowly. Options for recycling and commercial composting exist, but require a little extra effort on the part of the consumer.

 

 

Other Materials

In addition to the most popular choices of ABS and PLA, a breadth of materials are available that can exhibit fire-retardant or electrically conductive properties, among many others. For example, while ‘hard’ PLA is the most common material, a soft PLA variant is becoming increasingly available and allows the printing of more flexible objects, although the material is more complex to handle when printing.

Another material is PVA (Polyvinyl Alcohol), which is a synthetic polymer that dissolves in water. FDM printers that have two nozzles can simultaneously print PVA and usually ABS. Following printing, objects can be submerged in water allowing the PVA to dissolve and leaving the ABS material, enabling the building of complex objects with overhangs or floating or movable parts, for example. HIPS (High-Impact Polystyrene) is a petrochemical synthetic polymer and like PVA is dissolvable, but in limonene. This again enables the creation of structures that are impossible to build without support.

More exotic materials have also been developed such as wood and stone. FDM filament has been developed combining wood fibre with thermoplastics, thereby enabling the printing of wooden-like objects. Stone-like filaments are thermoplastics embedded with finely milled chalk. TPE (Thermoplastic Elastomer) is a combination of polymers that has both thermoplastic and rubber characteristics, and offers the building of objects with soft and flexible structures.

Conductive ABS filament can be used for the conduction of electric current, or static dissipation or EMI shielding. Conductive and anti-static ABS offers features such as excellent mechanical strength, impact resistance and excellent heat and low temperature resistance.

Nylon is a synthetic thermoplastic polymer that is also becoming a more common material used in 3D printing. While it is hard, strong and flexible, it is difficult to use, as it often requires higher temperatures. And finally, PET (Polyethylene Terephthalate or polyester) is a widely used polymer and typically comes as transparent or clear material, but it can be found in coloured versions. The lightweight material offers high mechanical strength and is also temperature and impact resistant, as well as being recyclable.

 

Storage and Availability

Once you’ve purchased your filament, correct storage is important. Over time, most plastic will absorb moisture, thus creating small water bubbles in the filament. These bubbles when heated at the extruder nozzle will quickly reach boiling point, thus exploding and gushing material everywhere rather than it being carefully positioned in its correct place. Therefore the use of desiccant dehumidifiers to absorb moisture is important.

Available here via RS Components is a range of 3D printer PLA- and ABS-filament spools in many different colours including beige, black, blue, clear, green, grey, magenta, orange and red from companies such as Verbatim and 3D Systems, as well as RS branded filament.