ABS and polycarbonate are the two plastics that show up in nearly every enclosure decision, and they are not interchangeable. In one line: choose ABS when you want an economical, easy-to-mold, easy-to-finish opaque housing, and choose polycarbonate when the part must survive impact, heat, or has to be transparent. Both are amorphous thermoplastics, both injection mold well, and both appear in half the electronics on your desk — but they differ enough in toughness, temperature limit, chemical resistance, and price that picking the wrong one shows up either as field failures or as an unnecessary premium on every unit you ship.

The Comparison, Side by Side

  • Impact strength. Polycarbonate is the standout among transparent plastics — face shields, machine guarding, and instrument covers are made from it. ABS is respectably tough for everyday use but will crack under an impact polycarbonate absorbs.
  • Heat resistance. ABS begins softening in the range of roughly 185–210 °F; polycarbonate holds up meaningfully higher, into the 240–265 °F neighborhood. If your product contains a power supply, a motor, or lives in a hot environment, that gap is often the deciding factor.
  • Transparency. Polycarbonate is nearly glass-clear. ABS is always opaque. Display windows, lenses, and light pipes are polycarbonate territory.
  • Cost. ABS is significantly cheaper per pound, and it molds faster and more forgivingly, so the total delta is larger than the resin price alone suggests.
  • Molding and finishing. ABS tolerates process variation, paints beautifully, glues easily, and accepts plating and textures. Polycarbonate demands rigorous drying, higher barrel and tool temperatures, and precise gate design — process errors turn into molded-in stress and later cracking.
  • Chemical resistance. This is polycarbonate's weak point. Certain oils, solvents, and cleaning agents cause environmental stress cracking. ABS handles routine household exposure better, though it has its own solvent sensitivities.
  • Outdoor and UV. Both yellow and lose toughness in sunlight without UV stabilization. Outdoor products need stabilized grades of either material — this is not a reason to prefer one over the other.

When ABS Is the Right Call

ABS is the economical default for enclosures: household consumer goods, office equipment, toys, internal panels, and instruments that neither get hot nor take hard knocks. It is available everywhere, easy to color-match, easy to bond, and forgiving of small design imperfections. If your product sits on a desk and is not expected to survive a drop from height, ABS is very likely sufficient, and the savings compound across a production run.

All the standard molding rules apply in full: uniform wall thickness, generous radii, properly proportioned ribs, and adequate draft. Get those wrong and material choice will not save you — see our guides to design for manufacturing and the injection molding defects that bad geometry produces.

When Polycarbonate Earns Its Premium

Polycarbonate becomes the right answer when any one of these is true:

  • A hard impact requirement — handheld products that get dropped, field equipment, protective covers, guarding.
  • Elevated operating temperature — enclosures around power electronics, lighting, or heat-generating assemblies.
  • Transparency — windows, lenses, diffusers, light guides.
  • Flammability performance — flame-retardant polycarbonate grades are common in electrical products, and a required flammability rating often drives the material decision outright.
  • Sterilization — specific polycarbonate grades tolerate repeated autoclave or chemical sterilization cycles, which is why the material is common in medical and laboratory equipment housings.

The Third Option: PC/ABS Blend

Between the two sits one of the most widely used engineering materials in consumer hardware: the PC/ABS blend. It takes better impact and heat performance than plain ABS, combined with easier processing and lower cost than pure polycarbonate. You will find it in premium electronics housings, automotive interiors, and portable equipment. If your requirements land in the middle of the scale — tougher than ABS but not demanding polycarbonate's full capability — the blend is usually the correct answer, and it is often the answer engineers forget to consider.

There Is No Single "ABS"

Both materials are sold in dozens of commercial grades: glass-fiber filled for stiffness, flame-retardant, UV-stabilized, optical clarity grades, high-flow grades for thin walls, and plating grades. The spread between two grades of the same polymer can exceed the difference between the polymers themselves. Adding glass fiber, for example, can dramatically increase stiffness and reduce shrinkage while making the part more brittle and accelerating tool wear.

So the real decision is never "ABS or polycarbonate." It is a specific grade, identified by name, with a datasheet, chosen against numbered product requirements. Write the grade into the drawing and the bill of materials — see our BOM guide — so that no one substitutes a cheaper resin at the factory without telling you.

How to Actually Decide

  • Write down the extremes. Maximum internal and ambient temperature, drop height and orientation, chemicals the surface will contact, indoor or outdoor, expected service life.
  • Check regulatory drivers. Flammability rating, food contact, and sealing requirements narrow the grade list before any preference does — sealing in particular ties back to IP ratings.
  • Price both options at your real volume. A small per-pound difference multiplied across a production run can pay for a lot of engineering.
  • Prototype in the real resin, not a lookalike. A 3D-printed part in a similar-sounding filament will mislead you about stiffness and impact behavior — the gap is explained in our comparison of ABS vs PLA and, for low volumes in production-like material, in our article on urethane casting.

Material choice intersects with tool design, finishing, and compliance all at once, so treat it as a system decision rather than a shopping decision. Our broader guide on how to choose plastic for your product puts both materials in context with the rest of the family.

Get the Material Decision Right Before the Tool Is Cut

Projects House specifies materials, grades, and tolerances as part of mechanical design — with the molder's process window and your compliance requirements both in view. Deciding between ABS, polycarbonate, and a blend for a product in development? Send us the operating conditions through our contact form and we will recommend a grade you can put on a drawing. More in our mechanical engineering knowledge center.