Polycarbonate vs ABS Injection Molding: A Comparative Guide on Properties, Processing and Applications
Polycarbonate vs ABS Injection Molding
Polycarbonate vs ABS Injection Molding: A Comparative Guide on Properties, Processing and Applications
Meta description: Detailed guide comparing polycarbonate and ABS injection molding – their properties, mold design considerations, processing parameters, pros/cons, and ideal application areas.
Introduction
Polycarbonate and ABS are two of the most widely used engineering thermoplastics for injection molding applications across industries.
Polycarbonate (PC) offers an unbeatable combination of toughness, heat resistance, and optical clarity. ABS or acrylonitrile butadiene styrene provides strength, rigidity and high-impact resistance at low cost. Exploring Polycarbonate Injection Molding
Both polycarbonate injection molding and ABS injection molding have unique advantages and limitations. This comprehensive guide will compare them across various aspects to help you choose the right material for your application needs:
We will cover:
- Material properties of polycarbonate vs ABS
- Key differences in mold design
- Variances in processing parameters
- Relative pros and cons
- Typical application areas
- Cost comparison
- FAQs
Let’s get started!
Material Properties: Polycarbonate vs ABS
The intrinsic properties of a plastic resin greatly influence its molding behavior and suitability for different applications. Understanding ABS Injection Molding
| Polycarbonate | ABS | |
|---|---|---|
| Strength | Very high | Medium to high |
| Stiffness and rigidity | High | Medium to high |
| Impact resistance | Extremely high | High |
| Heat tolerance | 130-140°C | 80-100°C |
| UV/weather resistance | Superior | Moderate |
| Chemical resistance | Good | Fair |
| Flammability | Highly flammable | Moderately flammable |
| Optical clarity | Excellent | Opaque (unless specially formulated) |
Polycarbonate demonstrates very high strength and impact resistance combined with optical transparency. ABS offers a good balance of strength, rigidity and economy.
Mold Design Differences
Mold design must be optimized keeping in mind the unique molding characteristics of each plastic:
- Polycarbonate injection molding needs venting to release trapped air and gases. Generous draft angles (>2°) are required to facilitate part ejection.
- ABS molding can tolerate lesser draft angles (~1°). Mold cooling is critical to avoid shrinkage and warpage.
- Surface defects like sink marks, weld lines etc. are more prominent in ABS than polycarbonate parts.
- ABS molds must withstand abrasion from glass fibers added for reinforcement.
- Polycarbonate molds require higher precision to capture optical clarity and cosmetic quality.
Variances in Processing Parameters
Injection molding process settings need to be tailored to each material’s molding behavior:
| Polycarbonate | ABS | |
|---|---|---|
| Melt temperature | 280-320°C | 220-270°C |
| Mold temperature | 80-110°C | 40-70°C |
| Injection speed | Medium to high | Medium |
| Packing pressure | Medium to high | Medium |
| Back pressure | Low | Medium |
| Cooling time | Longer | Shorter |
Polycarbonate has a higher melt viscosity hence needs higher temperature, pressure and speed. ABS solidifies faster allowing shorter cooling and cycle times.
Pros and Cons Comparison
| Polycarbonate Injection Molding | ABS Injection Molding | ||
|---|---|---|---|
| Pros | – Extremely impact resistant <br>- Excellent optical clarity <br>- Heat resistance up to 140°C | – Economical <br>- Good strength and rigidity <br>- Ease of coloring/customization | |
| Cons | – High mold and material cost <br>- Thermally unstable <br>- Prone to stress cracking | – Limited heat resistance <br>- Higher shrinkage <br>- Easier to scratch/mar |
Polycarbonate suits demanding applications despite higher cost. ABS provides the optimal balance of performance, ease of molding and cost for mass market uses.
Typical Application Areas
Polycarbonate is ideal for:
- Transparent protective gear – faceshields, lenses
- Automotive headlamps, reflectors, instrument clusters
- Electrical components, circuit housings
- Medical devices like dialyzers, oxygenators
- Houseware items – blender jars, microwave trays
- Transparent packaging
ABS works well for:
- Automotive trim parts – vent grilles, dashboards
- Consumer appliances – vacuum cleaners, microwaves
- Electronic housings, computer keyboards
- Office supplies – rulers, staplers, folders
- Toys like building blocks, puzzles
- Piping and fittings
Both offer high versatility across industries. Material choice depends on technical needs and cost targets.
Cost Comparison
Polycarbonate is around 40-60% more expensive than ABS on average.
Polycarbonate: $2.5-3.5/lb
ABS: $1.5-2.5/lb
But polycarbonate provides transparency and heat resistance which ABS lacks. It is cost-effective for certain applications despite higher price.
FAQs
Q. Which has higher impact strength – polycarbonate or ABS?
A. Polycarbonate has extremely high impact resistance, 2-3 times that of ABS. PC is virtually unbreakable under normal conditions.
Q. Can polycarbonate and ABS be welded together?
A. Yes, two-shot molding or co-injection processes allow molding PC and ABS into a single part, combining their best properties.
Q. Does polycarbonate yellow over time?
A. All plastics degrade on prolonged UV exposure. But PC retains optical clarity much longer than ABS due to inherent stability.
Q. What finish is easier to achieve in ABS parts?
A. ABS allows high-gloss finishes more easily than polycarbonate. Texturing ABS is also simpler.
Q. Which material can withstand higher temperatures?
A. Polycarbonate has heat deflection temperature of 130-135°C, compared to 80-100°C for ABS. PC retains strength and rigidity at elevated temperatures.
Conclusion
Polycarbonate and ABS both offer immense utility for injection molding myriad products. Polycarbonate provides unbeatable clarity, toughness and heat performance but at higher cost. ABS gives the optimal balance of strength, ease of molding and economy for high volume applications.
By understanding their relative properties, molding behavior and capabilities, you can make the right material selection for your specific application needs.
