Polycarbonate has properties nobody argues with and a temperament nobody enjoys. It warps violently, needs a 300 °C hotend, hydrolyses if it is damp and cracks if it is stressed near a solvent. ABS is easy to process, cheap and tough, and gives up at around 95 °C.
Blend the two and you get a material with most of the polycarbonate's stiffness and heat resistance and most of the ABS's manners. This is not a hobbyist compromise — PC/ABS is one of the highest-volume engineering blends in industry, and it is what a great many laptop shells, instrument panels, power-tool housings and automotive interior mouldings are actually made of.
Where the properties land
Heat deflection between 95 and 120 °C: below polycarbonate's 110 to 140, comfortably above ABS's 88 to 100. Tensile of 45 to 60 MPa, again between the two. Nothing surprising, and that predictability is part of the appeal.
The interesting number is shrinkage, at 0.4% to 0.7% against polycarbonate's 0.5% to 0.8%. The ranges overlap, so on paper the improvement looks slight — and in practice it is decisive, because polycarbonate combines its contraction with extreme stiffness, and a stiff material cannot relieve stress by yielding. The ABS phase gives the blend somewhere for that stress to go.
On a 180 mm console panel the arithmetic works out like this: at PC-ABS's mid-range 0.55% the part arrives at 179.01 mm and needs a 1.00 mm correction; in unblended polycarbonate at the top of its range it arrives at 178.56 mm and needs 1.45 mm. Half a millimetre of difference on the compensation is the small part of the story. The large part is that the polycarbonate version is far more likely to have lifted a corner before you could measure it at all. Feed your own panel dimension to the shrinkage compensation calculator and it will scale that correction linearly. What no calculator can tell you is which of the two materials still had all four corners on the plate when the print finished.
The processing window is the real gift
Nozzle 250 to 280 °C. That is the number that changes who can print this material: a great many all-metal hotends stop at 280 or 300 °C, and polycarbonate's 270 to 310 °C sits awkwardly against them while PC-ABS fits comfortably. Bed 100 to 115 °C, enclosure required.
Drying at 80 °C for 6 to 8 hours. The carbonate links in the polycarbonate phase hydrolyse in the melt exactly as they do in the unblended polymer, so this is a chemical requirement and not a surface-quality one. Wet PC-ABS produces parts that look acceptable and break early.
Bed adhesion behaves like ABS with more pull at the corners — a hot bed with a glue-stick film, and a brim on anything with a large footprint.
The ratio matters, and almost nobody prints it on the spool
"PC-ABS" describes a family rather than one recipe. Industrial blends run anywhere from roughly equal parts to heavily polycarbonate-dominant, and the properties track that ratio directly: more polycarbonate means more heat resistance, more stiffness and more warping; more ABS means an easier print and a lower ceiling.
Filament brands very rarely state which end of the range they have supplied, which means two spools both labelled PC-ABS can want different temperatures and behave differently on a large part. The usable proxies are the manufacturer's stated heat deflection — a figure near 120 °C indicates a polycarbonate-rich blend, one near 95 °C an ABS-rich one — and the printing temperature they recommend. If neither is published, treat the first spool as an unknown and run a temperature tower.
There is a related repair use worth knowing: because so many automotive interior and electronics parts are moulded in this blend, printing a replacement in PC-ABS gives you a part with the same thermal expansion, the same solvent sensitivities and the same feel as the original. Matching the material is often more useful than exceeding it.
Where the blend falls short
- Outdoor use. The ABS phase brings its butadiene rubber and therefore its ultraviolet vulnerability, and the polycarbonate phase yellows in sunlight on its own account. This is an indoor material twice over.
- Cost. $40 to $75 per kilogram, close to polycarbonate itself, so the blend is not a way to save money — it is a way to get a part finished.
- Open-frame printers, unconditionally.
- Chemical exposure. It inherits polycarbonate's stress-cracking sensitivity, so isopropyl alcohol, many oils and some adhesives can craze a stressed part. Clean it with soapy water.
- Maximum heat. If the requirement is genuinely above about 120 °C, the blend is not enough and you are back to polycarbonate or a fibre-filled polyamide.
- Transparency. The blend is opaque, which removes one of polycarbonate's distinctive capabilities entirely.
Where it is the sensible choice
Electronics housings that sit near a power supply. Automotive interior brackets, vents and trim, which is where the industrial volume goes. Instrument enclosures and control panels. Structural covers that must not soften on a warm day but do not need to survive an engine bay. Prototype parts that will eventually be moulded in the same blend, so that the prototype behaves like the production part.
The decision rule is short. If a part needs to hold shape above where ABS gives up, and you want it to print without a fight, this is the material. If it needs polycarbonate's clarity, its impact performance or its top-end temperature, the blend will not get you there and the PC against ABS comparison covers what each end of the trade actually buys.