Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) rank among the most widely specified thermoplastics for injection molding across industries. This beginner’s guide will examine key characteristics, processing considerations and common applications for these exceptionally versatile engineering resins. Discover why polycarbonate injection molding and ABS injection molding feature prominently in everything from electronics and automotive components to medical devices and consumer products.
Overview of Polycarbonate Properties
Boasting an unmatched combination of optical clarity, high temperature resistance, impact strength and dimensional stability, polycarbonate grades have emerged as a plastic engineer’s Swiss Army Knife over 60+ years of development.
Strength & Stiffness
PC exhibits very high tensile and flexural strength exceeding 10,000 psi, combined with rigidity near ABS. These enable structural applications across a wide temperature range from -20°F to 280°F.
Impact Resistance
With resilience surpassing acrylic and ABS, PC withstands sudden force or drops without fracture – making it ideal for protective equipment like helmets/face shields.
Optical Clarity
Exceptional light transmission through crystal clear polycarbonate proves useful in lighting, sight glasses, machine guards, lenses for cameras/glasses and decorative objects.
Heat/Chemical Resistance
Polcarbonate offers extensive chemical compatibility plus thermal performance retention even after repeated steam sterilization – driving usage in medical devices.
Overview of ABS Properties
The three component copolymer composition of ABS combines strength, rigidity, and heat resistance of Acrylonitrile and Styrene resins – modified by the impact toughness contribution from polybutadiene rubber dispersed within. This diverse property set makes ABS suitable for:
Dimensional Stability
Low moisture absorption compared to other commodity resins enables durable precise parts – important in assemblies, fittings, mechanical housings and the like.
Chemical Resistance
Acrylonitrile imparts resistance to acids/alkalis for usage in plumbing fittings and laboratory equipment exposed to corrosive substances.
Thermal Properties
Heat Deflection Temperatures approaching 200°F facilitate ABS usage in boiling water and select auto underhood applications.
Aesthetics
Easily colored opaque finishes with metallic, pearlescent and realistic woodgrain textures make ABS a frequent choice for appliance housings, furniture and consumer electronics cases.
Molding Process Considerations
Adjusting parameters like melt temp, fill rate, mold temp, hold pressure/time counters the higher processing viscosity and shrinkage of engineering resins:
Polycarbonate
- Slow Fill Rates (~25% of ABS)
- High Mold Temps (80-120°C)
- Generous Gates/ Runners
- Delayed Hold Pressure
ABS
- Moderate Fill Velocities
- Standard Mold Temps (45-60°C)
- Conventional Gates/Runners
- Medium Hold Times
These differences mean separating PC and ABS workflows using dedicated tooling. Prevent cross-contamination as even small amounts of ABS degrade PC properties and cosmetics.
Common Applications
The practical benefits of PC and ABS combine across diverse markets, for example:
Polycarbonate
- Protective Goggles, Face Shields
- Medical Equipment Housing
- Transparent Machine Guards
- Headlight and Taillight Lenses
- Bullet-Resistant Security Glazing
ABS
- Automotive Interior Trims
- Consumer Appliance Casings
- Plumbing Pipes & Fittings
- Electronic Device Enclosures
- Protective Gear Components
The distinctive durability, working range and aesthetics empower polycarbonate and ABS resins for usage across safety critical, household and industrial categories. Correct material selection and processing assures high performance molded products benefitting countless aspects of modern life.