Essentium PCTG-Z ESD

Essentium is an American manufacturer of industrial 3D printers and technical filament, with branches in Asia and Europe. Essentium’s innovative 3D printing solutions are ushering many manufacturers into Industry 4.0 by helping them to prototype and manufacture in-house, increase production with excellent quality but in a quick and economical way. The Essentium materials portfolio contains numerous high-end technical filaments, mostly polymers and blends designed for exceptional strength, flexibility and high mechanical performance in the most arduous industrial conditions. The Essentium filaments have many applications across numerous disciplines, such as aerospace and defense, automotive, biomedical, contract manufacturing, consumer goods, and electronic manufacturing.

High-end technical filament

The PCTG Z filament belongs to Essentium’s family of ESD-safe materials. It is composed of >99 % copolyester and additives. On top of its ESD-safe properties, the Essentium PCTG Z is low-cost, and easy to 3D print (even in open air conditions), machine and post-process. Moreover, it has an excellent surface finish, it doesn’t mar and it is relatively unaffected by humidity.

PCTG is a high-performance entry-level engineering polymer, created by subjecting PET to glycosylation. In this process, the CHDM glycol is added to the PET backbone, replacing its ethylene glycol units with CHDM units by > 50 %. The extra dose of CHDM gives PCTG its improved mechanical properties and chemical resistance. PCTG is a slow-crystallizing semi-crystalline copolyester. The slow crystallization rate means that parts 3D printed with a PCTG filament will mostly be in the amorphous state at first. That will result in excellent optical clarity and toughness but at the cost of lower heat deflection temperature, lower tensile strength, lower elastic modulus and decreased chemical resistance.

All those properties can be improved when the amorphous PCTG is annealed to cold-crystallize it. Annealing is a commonly used process in materials science, and it involves a heat treatment aimed at making a material more workable. In the case of PCTG, it would mean putting the 3D prints in an oven at above the glass transition temperature for a few hours to improve PCTG’s thermomechanical properties by increasing its crystallinity. The ability to change from an amorphous to a semi-crystalline state in various thermal conditions is unique to PCTG. That means the user can choose the most appropriate processing method to obtain an amorphous or semi-crystalline state of PCTG, depending on the desired properties and application of the final piece. This makes PCTG an extremely versatile material. PCTG is mostly used in the biomedical industry to print medical devices such as prosthetics, as well as in manufacturing, to make jigs and fixtures.

Image 1: A circuit board rack printed with Essentium PCTG Z. Source: Essentium.

ESD safe material

Electrostatic discharge (ESD) is a phenomenon often observed in everyday life in hair static or when a “kick” or “spark” of electricity is produced upon touching a grounded object, such as a doorknob or another person. ESD events such as these are harmless in everyday life but highly risky and damaging in manufacturing operations involving electronic components. The Essentium PCTG Z filament, designed to help eliminate that problem in medium-duty electronics production, acts as a dissipator of the electrostatic discharge and safely "evacuates" it along the surface of a piece 3D printed with the PCTG Z filament. ESD safe materials are also extremely useful in industries with potentially explosive atmospheres (petrochemical plants, coal mines, flour mills, areas with powder-based 3D printers).

Usually, to make a filament ESD safe, antistatic coatings or conductive fillers (such as carbon black and graphite) are added to the filament. Fillers and coatings can, however, negatively influence the performance of the filament or the 3D printed piece, making it crumbly and marring (leaving a black mark), or even contribute to latent failure in electronics. The Z line of filament is Essentium’s way to eliminate those risks produced by standard ESD filaments containing fillers. Instead of fillers, the Essentium Z line filaments have conductive nanomaterials on the surface, so the mechanical performance of pieces printed with PCTG Z is not jeopardized. Moreover, the PCTG Z’s overall cost is significantly reduced compared to other ESD filaments since the percentage of carbon in this filament is very low (around 0.01 %). Other ESD filaments normally need to contain 20-30 % of carbon fiber to achieve the same level of surface resistivity.

Video 1: The Essentium PCTG Z compared with other ESD-safe filament. Source: Essentium.

All those qualities make the Essentium PCTG Z a very versatile, affordable and easy-to-use material, qualified for many applications. The manufacturer recommends it for the biomedical industry and the 3D printing of jigs and fixtures. Some example uses for the Essentium PCTG Z would be handheld tools, ESD part trays, general assembly fixtures for electronics, robotics and automation components, as well as parts for explosion-proof environments.