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Glossary · Filament

3D printing

PCTG

A printing material from the PETG family, but considerably more impact-resistant. It is about as easy to print.

Explained in more detail

PCTG is a glycol-modified copolyester and is chemically closely related to PETG. Manufacturers mainly emphasise the higher impact strength: Fiberlogy gives 92 kJ/m² for its PCTG in the notched Izod test according to ISO 180, against 5 to 8 kJ/m² for PETG. Heat deflection temperature, by contrast, is in the range of PETG: Fiberlogy gives 64 °C at 1.8 MPa and 76 °C at 0.45 MPa according to ISO 75. It recommends 250 to 270 °C at the nozzle and 90 °C at the bed; an enclosure is not necessary. According to Spectrum, transparent grades look clearer than PETG.

Where does the term come from?

PCT stands for polycyclohexylene dimethylene terephthalate, and the G, as in PETG, stands for glycol modification. PCTG and PETG contain the same basic building blocks in different proportions, which gives rise to their different properties.

In practice

  • Drying: Fiberlogy gives 60 °C for 4 hours.
  • Use part cooling sparingly, and Fiberlogy recommends 0 to 25%.
  • On smooth PEI, as with PETG, use an adhesive as a separating layer, and according to Fiberlogy textured PEI works without.
  • The impact strength values come from manufacturer tests. Compare only values measured to the same standard.

Not to be confused

PCTG is not PC (polycarbonate): the name sounds similar, but PCTG is a polyester like PETG and much less heat-resistant than PC.

Frequently asked questions

Is PCTG better than PETG?

For impact strength, significantly so according to manufacturers, and for heat deflection temperature, about the same. It prints similarly but often needs slightly higher temperatures.

Does PCTG need an enclosure?

Not according to Fiberlogy. Like PETG, it shrinks little and hardly warps as long as the first layer adheres well.