Title: Polycarbonate vs ABS Injection Molding: A Detailed Comparison

Meta description: Explore the differences between polycarbonate and ABS injection molding. Learn about their properties, applications, molding considerations, and how to choose between them.

Introduction

Polycarbonate and ABS are two of the most widely used engineering thermoplastics for injection molded components across industries like automotive, consumer products, electronics, and medical devices. But what exactly are polycarbonate and ABS, how do their properties differ, and how should you choose between them for your application? This in-depth guide provides a detailed comparison of polycarbonate vs ABS injection molding.

Overview of Polycarbonate Injection Molding

Polycarbonate (PC) is an amorphous thermoplastic known for its exceptional impact strength, transparency, heat resistance, and dimensional stability. Some key properties include:

High tensile and flexural strength
Low creep under load
Wide operating temp range (-40°C to 145°C)
Good electrical insulation
Inherently flame retardant

UV/weathering resistant grades available

Polycarbonate is commonly molded into parts like safety glazing, lenses, transparent covers, and housings that demand durability and resilience. Medical devices also utilize polycarbonate for sterilizable and biocompatible components.

Overview of ABS Injection Molding

ABS (acrylonitrile butadiene styrene) is an amorphous copolymer thermoplastic with well-balanced mechanical properties, chemical resistance, and low cost. Typical properties are:

Good dimensional stability
High impact strength even at low temps
Moderate tensile and flexural strength
Heat deflection temp around 100°C
Good electrical insulation

Easy to color and finish

ABS finds wide use in mass-produced consumer products, automotive interiors, protective equipment, pipes/fittings, and business machines. It offers a versatile balance of strength, appearance, and affordability.

How Polycarbonate and ABS Compare for Injection Molding

Polycarbonate and ABS plastics demonstrate distinct differences when injection molded:

Mechanical Properties

PC has very high impact strength. ABS impact strength is modest in comparison.
PC maintains tensile and flexural strength advantages at elevated temperatures vs. ABS
PC has better long-term creep resistance under heavy loads

Thermal Properties

PC retains high impact resistance at low temperatures while ABS becomes brittle when cold
PC withstands higher application temperatures (above 100°C) vs. ABS

Optical Properties

Polycarbonate has extremely high light transmission and clarity unmatched by ABS
PC is naturally transparent. ABS is translucent off-white unless colored.

Molding Considerations

PC flows faster during mold filling vs. ABS, allowing for easier fill of thin sections
PC generally requires higher mold temperatures than ABS due to its higher melting point
PC is more sensitive to moisture than ABS. Drying is critical.

Cost Differences

Polycarbonate resin prices are up to 50% higher than ABS resin prices per pound

So in summary, polycarbonate demonstrates superior optical clarity, impact strength, heat resistance, and creep resistance compared to ABS but at a higher cost.

Applications and Use Cases for Polycarbonate vs ABS

With their different property profiles, polycarbonate and ABS each suit certain applications better:

Polycarbonate is ideal for:

Transparent glazing, lenses
Protective equipment like helmets, face shields
Medical devices and labware needing sterilization ability
Electrical/electronic enclosures and insulators
Automotive headlamps, instrument panels

ABS excels at:

Consumer appliances and electronics
Automotive trim components
Protective gear like helmets
Fluid handling parts - pipes, fittings
Business equipment housings

Toys

Essentially, polycarbonate fits applications demanding optics, impact strength, heat or load resistance, and sterilization compatibility. ABS provides a less costly option for more moderate mechanical and thermal needs.

Design and Manufacturing Guidelines for Polycarbonate and ABS

Proper design and manufacturing practices are important for injection molding quality parts from both polycarbonate and ABS:

Observe recommended nominal wall thicknesses: 1.5-3mm for PC, 1-3mm for ABS
Include generous radiused corners and fillets to alleviate stress concentrations
Use a >3° draft angle and avoid sharp corners to ease demolding
Gate into thick sections and away from cosmetic surfaces
Utilize venting, overflow, and generous tolerance ranges to minimize sinks and warpage

For PC, use a hot runner manifold and ensure thorough drying before molding
For ABS, use high mold temperatures up to 80°C to achieve complete fill

In summary, applying fundamental injection molding design principles to both PC and ABS will yield the best results. Tailor specific parameters to the material's unique requirements.

Choosing Between Polycarbonate vs ABS for Your Project

When selecting polycarbonate or ABS for your application, consider factors like:

Mechanical requirements - PC provides greater impact strength, strength/stiffness at higher temperatures, and creep resistance under long-term loads.
Thermal requirements - PC suits higher heat applications up to 145°C. ABS is limited to around 80-100°C.
Optical needs - Polycarbonate has superior light transmission and clarity if optics are critical.
Chemical exposure risks - ABS offers better chemical resistance than PC for some exposures.
Sterilization needs - Polycarbonate can withstand sterilization by autoclaving or gamma radiation.

Part size and geometry complexity - PC flows better for intricate thin-wall or long-flow length parts.
Cost targets - ABS will generally be the more economical material option.

By weighing these factors against your product requirements, you can determine whether polycarbonate or ABS makes the best fit for your particular injection molding application.

Conclusion

This guide covered a detailed polycarbonate vs ABS injection molding comparison. While both versatile thermoplastics, polycarbonate demonstrates superior optical clarity, impact and heat resistance, and long-term load capabilities compared to ABS. ABS provides a less costly option where extreme performance is not needed. By understanding their differing property profiles and molding behaviors, you can make an informed material selection tailored to your product's demands.

Polycarbonate vs Abs Injection Molding: A Detailed Comparison