Polycarbonate Injection Moulding: Properties and Applications
Polycarbonate injection moulding: transparent, impact-resistant engineering plastic. Tensile strength 70MPa, light transmittance 89%. Optical and electronic grade PC for lenses, safety, and medical applications.
Polycarbonate Injection Moulding: Properties and Applications
Polycarbonate (PC) is a transparent engineering thermoplastic known for its exceptional impact resistance, heat resistance, and optical performance. With a notched Izod impact strength of 850 J/m and light transmittance of 89%, PC is the material of choice for parts that must combine clarity with toughness.
At FIRMFG, we mould all PC grades including transparent, colored, flame-retardant (V-0), glass-filled, medical-grade, and optical-grade. PC is widely used in optical lenses, LED lighting, safety equipment, medical devices, and automotive lenses.
This guide covers PC material properties, grades, design guidelines, processing requirements, and post-processing options. Or, skip ahead and request a quote for an immediate price and lead time.
Polycarbonate Quick Specifications
Key material specifications for polycarbonate injection moulding.
| Specification | Value |
|---|---|
| Tensile Strength | 70 MPa |
| Light Transmittance | 89% |
| Heat Deflection Temperature | 135°C |
| Density | 1.20 g/cm³ |
| Shrinkage | 0.5 – 0.7% |
| Processing Temperature | 280 – 320°C |
Polycarbonate Material Properties
Complete mechanical, optical, thermal, electrical, and chemical properties for PC thermoplastic.
| Category | Property | Value |
|---|---|---|
| Mechanical | Tensile Strength | 70 MPa |
| Mechanical | Flexural Strength | 100 MPa |
| Mechanical | Impact Strength (Izod Notched) | 850 J/m |
| Mechanical | Hardness (Rockwell M) | 70 |
| Optical | Light Transmittance | 89% (3 mm thickness) |
| Optical | Haze | < 1% |
| Optical | Refractive Index | 1.586 |
| Thermal | Heat Deflection Temperature | 135°C (at 1.82 MPa) |
| Thermal | Continuous Use Temperature | 120°C |
| Thermal | CLTE (Coefficient of Linear Thermal Expansion) | 65 µm/m·°C |
| Electrical | Dielectric Strength | 30 kV/mm |
| Electrical | Volume Resistivity | 10¹⁷ Ω·cm |
| Chemical | Acid Resistance | Good |
| Chemical | Alkali Resistance | Good |
| Chemical | Solvent Resistance | Poor (stress cracks in hydrocarbons) |
Polycarbonate Grades
Select the right PC grade for your application. All grades are available in custom colors.
Transparent PC
Optically clear general-purpose polycarbonate with 89% light transmittance. The standard choice for transparent parts requiring high impact resistance.
Best for: Windows, transparent covers, display panels
Colored PC
Pigmented polycarbonate available in any custom color via masterbatch. Retains transparency properties in translucent tints or becomes fully opaque.
Best for: Tinted lenses, colored housings, decorative parts
Flame-Retardant PC (V-0)
UL94 V-0 rated self-extinguishing grade for electrical and electronic safety. Halogen-free options available for environmental compliance.
Best for: Electrical enclosures, battery housings, connectors
Glass-Filled PC (GF20/GF30)
20–30% glass fiber reinforced for enhanced stiffness, dimensional stability, and creep resistance. Reduced shrinkage and improved heat performance.
Best for: Structural housings, load-bearing parts, internal brackets
Medical-Grade PC
USP Class VI and ISO 10993 biocompatible grades for medical device applications. Gamma and EtO sterilisable, drug-contact safe.
Best for: Medical devices, IV connectors, surgical instruments
Optical-Grade PC
Ultra-low haze, high-clarity grades optimized for precision optical components. Superior refractive index consistency and surface quality.
Best for: Optical lenses, LED optics, light guides, precision optics
Polycarbonate Design Guidelines
DFM rules for moulding high-quality PC parts. PC requires careful stress management and moisture control to avoid cracking and defects.
| Design Feature | Guideline |
|---|---|
| Minimum Wall Thickness | 1.0 mm |
| Draft Angle | 1° minimum (1.5° for textured surfaces) |
| Rib Design | Rib thickness ≤ 60% of nominal wall; avoid thick junctions |
| Gate Design | Edge or fan gates; avoid pin gates near stress points |
| Stress Control | Minimise sharp corners; radius ≥ 0.5 mm to prevent stress cracking |
| Tolerance | ± 0.05 mm (precision achievable with PC) |
| Drying Requirement | 120°C for 3 – 4 hours before processing (moisture < 0.02%) |
PC Processing Requirements
Polycarbonate demands precise temperature, drying, and shear control to achieve defect-free transparent parts.
| Parameter | Value |
|---|---|
| Melt Temperature | 280 – 320°C |
| Mold Temperature | 80 – 120°C |
| Drying | 120°C for 3 – 4 hours (moisture < 0.02%) |
| Injection Pressure | 80 – 150 MPa |
| Screw Speed | Low shear — 40 – 70 rpm to avoid degradation |
| Screw Design | General-purpose or low-compression screw; L/D ratio 20:1 or higher |
Proper drying is critical — undried PC hydrolyses during moulding, causing silver streaks, bubbles, and drastically reduced impact strength. We use desiccant dryers with moisture analysers on every PC production run.
Polycarbonate vs PMMA vs ABS
Compare polycarbonate against PMMA (acrylic) and ABS to choose the right transparent or engineering material.
| Feature | Polycarbonate (PC) | PMMA (Acrylic) | ABS |
|---|---|---|---|
| Impact Resistance | Excellent (850 J/m) | Poor (20 J/m) | Good (200 J/m) |
| Transparency | 89% (3 mm) | 92% (3 mm) | Opaque |
| Heat Resistance | 135°C | 95°C | 95°C |
| UV Stability | Fair (yellows without coating) | Excellent | Good |
| Cost | Medium | Medium | Low |
| Scratch Resistance | Fair (needs hard coat) | Good | Fair |
| Typical Applications | Optical, safety, medical | Lighting, display, signage | Consumer housings, automotive |
Polycarbonate offers the best combination of impact resistance, transparency, and heat resistance. Choose PMMA for maximum clarity and UV stability, and ABS for cost-effective opaque applications.
Polycarbonate Post-Processing Options
PC accepts protective and decorative coatings that enhance durability and appearance.
Hard Coating
Silicone or acrylic hardcoat that dramatically improves scratch and abrasion resistance for transparent surfaces.
Anti-UV Coating
UV-blocking coating that prevents yellowing and degradation of PC parts exposed to sunlight and outdoor conditions.
Printing
Pad printing and silk screening for logos, labels, and functional markings on both transparent and opaque PC parts.
Metallization
Vacuum metallization for reflective or conductive surfaces. Used for reflectors, EMI shielding, and decorative finishes.
Explore our full range of surface finishing services for plastic parts.
Polycarbonate Injection Moulding FAQ
Answers to the most common questions about polycarbonate injection moulding at FIRMFG.
QHow transparent is polycarbonate?
Polycarbonate has a light transmittance of 89% at 3 mm thickness, which is excellent for an impact-resistant thermoplastic. Optical-grade PC grades achieve even higher clarity with haze below 1%. While PMMA (acrylic) offers marginally higher transparency at 92%, PC provides far superior impact resistance — making it the preferred choice for transparent parts that must withstand impact.
QWhat is the impact resistance of polycarbonate?
Polycarbonate has outstanding impact resistance, with a notched Izod impact strength of approximately 850 J/m — one of the highest of any thermoplastic. This is roughly 4x that of ABS and over 40x that of PMMA. PC does not shatter on impact, making it ideal for safety visors, bullet-resistant glazing, and protective equipment.
QWhat is the heat resistance of polycarbonate?
Polycarbonate has a heat deflection temperature of 135°C at 1.82 MPa and a continuous use temperature of approximately 120°C. This is significantly higher than ABS (95°C) and PMMA (95°C). Glass-filled PC grades push HDT to 145°C. PC is suitable for applications exposed to sustained heat such as LED lighting housings, automotive under-hood components, and electrical enclosures.
QIs polycarbonate medical grade?
Yes. Medical-grade polycarbonate is available in USP Class VI and ISO 10993 biocompatible formulations. These grades are gamma radiation and EtO sterilisable, making them suitable for single-use and reusable medical devices including IV connectors, blood reservoirs, surgical instrument housings, and drug delivery components. Specify medical-grade PC at quoting and request biocompatibility documentation.
QDoes polycarbonate need drying before moulding?
Yes. Polycarbonate is hygroscopic and must be dried at 120°C for 3–4 hours before processing, reducing moisture content below 0.02%. Undried PC will hydrolyse during moulding, causing silver streaks, bubbles, and a significant reduction in mechanical properties — particularly impact strength. We use desiccant dryers and moisture analysers to ensure proper drying before every production run.
QHow much does polycarbonate moulding cost?
Polycarbonate is a mid-priced engineering thermoplastic. Material cost is higher than ABS but lower than high-performance polymers like PEEK. Mold cost is moderate ($3,000–$15,000 for aluminum, $10,000–$50,000+ for steel). Per-part cost ranges from $3–$20 depending on part size, complexity, and volume. Optical and medical grades carry a premium. For a precise quote, upload your CAD files and we will provide a detailed cost breakdown.
Applications of Polycarbonate Injection Moulding
PC serves industries where transparency, impact resistance, and heat resistance are critical.
Optical Lenses
Camera lenses, eyewear, precision optics
LED Light Covers
Lamp diffusers, LED housings, light guides
Electronic Displays
Display panels, touch screens, bezels
Safety Visors
Protective goggles, face shields, visors
Medical Devices
IV connectors, surgical housings, reservoirs
Automotive Lenses
Headlight lenses, taillight covers, mirrors
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Learn MoreStart Your Polycarbonate Project
Upload your CAD files and get a free polycarbonate injection moulding quote within 24 hours. All PC grades available. Hard coating, UV coating, and optical finishes. ISO 9001 quality, production-grade materials.