All About Conductive PLA 3D Printing Filament： Materials, Properties, Definition

Conductive PLA (Polylactic Acid) 3D printing filament refers to PLA filament that is able to transmit electrical current. Conductive PLA is one of the most popular conductive filaments due to its ease of use and relatively low cost. According to a recent study, conductive PLA shows promise in the development of sensors for use in wearable electronics. 

Conductive PLA 3D printing filament is made by mixing  conductive additives into the PLA base polymer. These additives make standard PLA slightly conductive. Some of the common additives are listed below:

1. Carbon Black: Carbon black is powdered carbon that is often used as a pigment. However, when a specific grade of carbon black is mixed in with PLA, the conductivity of the composite filament material is increased. Carbon black is the cheapest form of conductive PLA 3D printing filament. 
2. Graphene: Graphene is a planar sheet of carbon atoms arranged in a hexagonal pattern. The arrangement of the carbon atoms means that each atom has one free electron, which aids in the transmission of current. 
3. Metal-filled: Metal powder like copper or bronze can be mixed into the PLA to increase conductivity. Metal-filled PLA has some of the best conductivity ratings.

Polylactic Acid (PLA) is one of the most popular 3D printing filaments due to its low cost and ease of use. PLA is a semicrystalline thermoplastic. Its partially ordered molecular structure gives it a distinct melting point, unlike amorphous polymers, which have no such distinct phase transition. Listed below are some common properties of conductive PLA 3D printing filament:

1. The percentage of conductive PLA particles added to the base polymer is typically up to 80% by volume.
2. The resistivity of the material on a part’s XY plane, i.e. parallel with the bed plate is typically up to 30 Ω-cm.
3. The resistivity of the material along a parts’ Z axis, i.e. parallel with the bed plate is typically up to 115 Ω-cm.
4. The maximum safe current that can be transferred through the conductive PLA is typically up to 100 mA. The maximum safe voltage that can be applied across the PLA is typically up to 60 V.
5. The resistance of a 10 cm length of 1.75 mm diameter filament is typically between 2000 and 3000 Ω.

The properties of some common conductive PLA 3D printing filaments are listed in Table 1 below: 

Conductive PLA 3D printing filament is a popular choice for experimenting with electrical applications. However, there are some shortcomings that need to be understood prior to using the material. The key challenges to using conductive PLA filament are listed below:

1. Conductive PLA is still not very conductive, despite its name. These materials offer a small amount of conductivity for special applications but are not meant to efficiently transfer electrical current. Nothing is better than a metal conductor like a copper wire.
2. The addition of additives like carbon black, graphene, or metal powder will increase the brittleness of PLA. PLA is already classified as a brittle material, and conductive PLA will be even more susceptible to cracking when subjected to impact loading.
3. Only low-voltage components can be powered through conductive PLA. This characteristic considerably limits the potential applications of the material. 
4. A part printed with electrically conductive PLA 3D printer filament will have lower conductivity along the z-axis due to the fact that the individual part layers are not as seamlessly bonded to each other as the material within a particular layer. 

One big advantage of conductive PLA 3D printing filament is that it has ESD (Electrostatic Dissipative) properties. This property means that it does not allow a static charge to build up on its surface.

Why is Conductive PLA Used in 3D Printing?

Conductive PLA filament is mainly used for a range of low-voltage electrical applications, some of which are listed below:

1. Conductive PLA 3D printing filament can be used to create parts that can transmit current through their structure without the need for electrical cabling. However, this application is limited to low-power applications like powering an LED light.
2. Conductive PLA 3D printing filament can be used for electromagnetic and radio wave shielding to eliminate the interference of other signals on sensitive electronic equipment. This type of interference can produce erroneous readings which can skew scientific results.  
3. One of the best uses for conductive PLA is for capacitive sensors, i.e., sensors that respond to touch. These are low-power applications that do not require high levels of conductivity. 

How to Use Conductive PLA in 3D Printing

Printing with conductive PLA (Polylactic Acid) 3D printing filament is generally as simple as printing with standard PLA, with a few special requirements. These requirements are listed below:

1. Carbon-filled conductive PLA is very abrasive. Therefore, a hardened steel nozzle is recommended. 
2. Conductive PLA is very brittle. Therefore, it is important to ensure that the filament is guided to the nozzle as gently as possible. Any sharp bends will snap the filament. 

The specific settings to use when printing with conductive PLA 3D printing filament depends  on the filament brand. However, some general guidelines for printing with conductive PLA filament are listed in Table 2 below:

The optimal wall thickness for a conductive PLA part depends on how the product will be used.   If it is used for an ESD (electrostatic discharge) enclosure, a thicker wall thickness may be required to improve structural integrity. This requirement is because conductive PLA is structurally weaker than standard PLA. However, in general, a wall thickness of 1 mm will be good enough for most applications. 

What is a Good Wall Density for 3D Printing Conductive PLA?

The infill density for conductive PLA is best kept at 100%, meaning the part is completely solid. A solid structure will more effectively transmit current. It may be therefore beneficial to print the conductive parts of a design separately to save on material as conductive PLA is more expensive than standard PLA. 

What is the Difference Between Conductive PLA and ABS in 3D Printing?

Conductive PLA and conductive ABS (acrylonitrile butadiene styrene) will both transmit electric current in a similar matter. However, conductive ABS will have better toughness than conductive PLA.

This article presented conductive PLA 3D printing filament, explained what it is, and discussed all of the different factors to consider when using it. To learn more about conductive PLA 3D printing filament, contact a Xometry representative.

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