Material selection
PC vs PC/ABS
PC/ABS is often sold as "PC with easier molding," and that is true as far as it goes. What it understates is what the blend gives up to get there: heat resistance, tensile strength, and every trace of optical clarity all step down once ABS enters the mix. The numbers below are the same published datasheet values used on each material's own page, set side by side.
| Polycarbonate | PC/ABS | |
|---|---|---|
| Density | 1.20 g/cm³ | 1.13 g/cm³ |
| Tensile strength | 60–70 MPa | 55 MPa |
| Flexural modulus | 2.3 GPa | 2.3 GPa |
| Heat deflection (1.8 MPa) | 130 °C | 100–115 °C |
| Mold shrinkage | 0.5–0.7 % | 0.5–0.7 % |
| Optical clarity | 88 % light transmission, clear | Opaque, no transparent grade |
| Relative cost | Medium | Medium |
Published values for unfilled grades at 23 °C unless stated, taken from each material's own datasheet page. Confirm against the supplier datasheet for the grade you specify.
What Polycarbonate is
Polycarbonate is the material you specify when a part has to survive an impact without shattering: notched Izod impact is roughly ten times that of acrylic, and it fails by yielding rather than cracking. It is optically clear, 88 percent light transmission in the natural grade, and rated for continuous use around 115–125 °C, with a heat deflection temperature of 130 °C well above PC/ABS's range. The trade-off is processing difficulty and chemical sensitivity: it needs thorough drying, 4 hours at 120 °C to below 0.02 percent moisture, before every run, and many solvents, alkalis, and some cleaning agents cause stress cracking.
What PC/ABS is
PC/ABS is a blend, not a copolymer, and the ratio between the two resins is adjustable, so the property set moves with the grade. Polycarbonate supplies heat resistance and impact strength; ABS supplies flow, low-temperature impact, and a surface that finishes well without the stress-cracking risk straight PC carries on tensile features. It processes at a lower melt temperature, 250–280 °C against PC's 280–320 °C, dries faster, 3 to 4 hours at 90–100 °C against PC's 4 hours at 120 °C, and holds texture better, which is why it is the standard material for automotive interior trim and equipment housings that need to pass a drop test but still look molded rather than industrial. What it gives up against straight PC is 15 to 30 °C of heat deflection temperature, some tensile strength, and all optical clarity: PC/ABS does not come in a transparent grade.
PC against PC/ABS
| Polycarbonate | PC/ABS | |
|---|---|---|
| Heat deflection | 130 °C, the higher of the two | 100–115 °C, adequate for most enclosures, not for sustained near-boiling or engine-bay heat |
| Impact strength | Best of the two, fails by yielding rather than cracking | Strong but a step below straight PC, with better low-temperature impact than PC alone |
| Tensile strength | 60–70 MPa | 55 MPa |
| Optical clarity | 88 % transmission, genuinely transparent | Opaque, no transparent grade exists |
| Processing | Demanding: dry 4 h at 120 °C, melt 280–320 °C, higher injection pressure and larger gates | Forgiving: dry 3–4 h at 90–100 °C, melt 250–280 °C, better flow, thinner walls achievable |
| Cosmetic finish | Good, but stress-cracking risk on parts held in tension | Better: holds texture well, the default for visible trim surfaces |
| Chemical resistance | Sensitive: many solvents and alkalis cause stress cracking | Similar sensitivity, closer to PC than to ABS, but the ABS phase adds some tolerance |
| Relative cost | Medium | Medium, faster cycles from easier processing can lower per-part cost |
Which one, for which part
- Clear or optically demanding parts, lenses, light pipes, sight glasses, machine guards you need to see through, is PC's case: PC/ABS has no transparent grade at all.
- Parts rated above about 115 °C, or exposed to sustained high heat, favour PC: its 130 °C heat deflection temperature clears PC/ABS's 100–115 °C ceiling.
- Cosmetic housings and trim that need a clean molded finish without secondary painting is PC/ABS's case: it holds texture better and is more forgiving to mold.
- High-volume parts where cycle time and tool wear matter lean PC/ABS: its lower melt temperature and better flow generally mean faster cycles and less stress on the tool.
- Parts under sustained tensile stress near chemical exposure: neither is ideal, but PC/ABS's ABS phase gives slightly more tolerance than straight PC, which is more notch- and stress-crack-sensitive.
Our status
Trumould molds both Polycarbonate and PC/ABS in-house, and PC/ABS also runs through our 3D printing capability for housing and enclosure prototypes. Send the part, the temperature and optical requirements it has to meet, and target volume, and the quote states which resin is recommended and why, not just a price for whichever one you asked about first.
Specifying this part?
Send your CAD and target volumes. We come back with a price, a lead time, and any material or design notes that would reduce either.