PC Injection Molding
We mold Polycarbonate (PC) (and compatible grades) for functional, structural and aesthetic parts — from low-volume bridge production to high-volume runs.
Polycarbonate: Optical Clarity + Impact Strength in One Resin
PC is FirstMold's second most-molded material after ABS, prized for transparency, impact resistance and thermal stability (https://firstmold.com/pc-injection-molding/). MOLDITQUICK molds standard and modified PC on 18 Sodick injection machines plus 3 high-precision units, with in-house tooling and DFM.
Best-in-class transparency among transparent thermoplastics — optical and lighting parts need no painting.
Exceptional impact strength — the classic 'unbreakable' resin for housings, shields and lenses.
Thermal stability — parts keep working through wide temperature swings, including under-hood and lighting environments.
Modified compounds extend the range — PC/ABS for flow and cost, glass-fiber PC for stiffness, PC/PBT for chemical resistance.
Flame-retardant and UV-stabilized grades available for electronics and outdoor use.
Design freedom for large thin-walled parts — headlight lenses and covers are molded with balanced filling in multi-cavity tools.
Weld-line and gate optimization — for clear PC, gate placement is decided in DFM so flow marks stay off the optical path.
Insert and overmolding compatibility — PC overmolds onto metal inserts and TPE grips for sealed, durable assemblies.
PC Processing Parameters We Control
Drying, barrel and shrinkage windows per published PC molding data (https://firstmold.com/pc-injection-molding/), verified in-house under ISO9001 / IATF16949 control.
| Parameter | Recommended Range | Why It Matters |
|---|---|---|
| Drying | 120 °C, 3–4 h | PC is strongly hygroscopic — undried resin turns into brittle, silver-streaked parts. |
| Barrel temperature | 260–310 °C | High melt temperature is needed for full plasticization; stay below ~330 °C to avoid degradation. |
| Mold temperature | 80–120 °C | Hot molds improve flow, surface and stress performance; cold molds create high molded-in stress. |
| Mold shrinkage | 0.5–0.7 % | Predictable and low — cavity compensation is straightforward. |
| Injection speed | Medium; slower for optical parts | High speed causes jetting; balanced fill prevents flow marks on clear parts. |
| Injection pressure | 80–140 MPa typical | High enough to pack thin walls without overpacking the gate area. |
PC Grades & Compounds We Mold
Standard, filled and blended PC per FirstMold's material experience (https://firstmold.com/pc-injection-molding/).
Standard & Optical PC
Clear grades for lenses, light guides and displays — molded with hot molds and slow fill for optical quality.
- High light transmission
- High-gloss surfaces
- UV-stabilized variants
Glass-Fiber Reinforced PC
10–40 % glass for stiffness and dimensional stability in structural parts.
- Higher modulus
- Better creep resistance
- Reduced shrinkage
Flame-Retardant PC
UL94 V-0 rated grades for electronics enclosures and power applications.
- UL94 V-0 rating
- Halogen-free options
- Good colorability
PC/ABS & PC/PBT Blends
PC/ABS balances flow and cost; PC/PBT adds chemical resistance for automotive.
- Improved flow
- Chemical resistance
- Paint-ready surface
Anti-glare & light-diffusing PC
Diffusing and anti-glare grades for displays and automotive interior lighting panels.
- Uniform light spread
- Low haze options
- Automotive-approved
Common PC Defects — and How We Prevent Them
Defect set per FirstMold's PC problem-solving experience (https://firstmold.com/pc-injection-molding/).
Thick sections pack less than thin walls and sink on the cosmetic surface.
Hold-pressure profiles and uniform wall design keep surfaces flat.
Uneven cooling and high molded-in stress distort thin-walled PC.
Cooling circuit balance and hot molds (80–120 °C) control stress.
Insufficient packing leaves bubbles inside thick walls.
Segmented pressure curves and generous gates ensure full packing.
Fast first-stage fill pushes a worm-like flow across the cavity.
Medium, controlled injection speed prevents jetting on clear parts.
Residual moisture degrades the melt and clouds optical parts.
Drying to spec before molding eliminates moisture-born defects.
Molded-in stress plus solvent contact creates surface crazes and cracks.
Hot molds, stress-relief annealing and chemical-exposure review in DFM.
Where PC Injection Molding Pays
Optical & lighting
Lenses, light guides, headlight assemblies, interior lighting panels, display screens and sight glasses.
Automotive & EV
Headlight assemblies, door handles, sunroofs, rearview mirror housings and engine covers.
Electronics & industrial
Control panel covers, gear covers, lighting enclosures, cooling fan blades and inspection windows.
Consumer & personal care
VR equipment, gaming handhelds, hair dryer bodies, electric toothbrush handles, cosmetic compacts and razor handles.
Telecom & energy
Modem and router housings, junction box covers and lighting enclosure lenses in flame-retardant grades.
PC Design Rules We Enforce
- ✓Dry PC to 120 °C before molding — moisture is the number-one cause of brittle, hazy parts.
- ✓Keep walls uniform; PC flows less easily than ABS, so generous radii and smooth transitions reduce stress.
- ✓Avoid sharp notches and stress concentrators — PC is notch-sensitive under load.
- ✓Use hot molds (80–120 °C) for optical parts and to minimize molded-in stress.
- ✓For clear parts, place the gate so flow marks and weld lines stay off the optical surface.
- ✓Consider PC/ABS where flow or cost beats PC, and glass-fiber PC where stiffness does.
- ✓Avoid PC/ABS for long-term high heat — neat PC wins above roughly 100 °C continuous service.
PC Injection Molding FAQ
- ✓Q: Can PC parts be optically clear? A: Yes — with hot molds, slow balanced fill and proper drying, PC parts come out glass-clear; we mold lenses, light pipes and display windows.
- ✓Q: Does PC really need drying? A: Absolutely — 120 °C drying; undried PC produces silver streaks, voids and brittle parts.
- ✓Q: What tolerances can PC hold? A: PC's low, predictable shrinkage (0.5–0.7 %) lets us hold tight molded tolerances, verified with first-article inspection.
- ✓Q: Which industries use molded PC most? A: Automotive lighting, consumer electronics, medical device housings and industrial sight and control components.
- ✓Q: What lead time should I plan for PC parts? A: Low-volume PC parts in 7–12 days, production programs in 25–30 days, with DFM and tooling in-house.
- ✓Q: Can PC be molded with a UL94 V-0 flame rating? A: Yes — halogen-free FR-PC grades hold V-0 at thin walls for electronics enclosures.
- ✓Q: Does PC warp in thin-wall parts? A: With hot molds and balanced cooling it stays flat; we verify flatness with first-article measurement.
Related Capabilities
Explore the full range of MOLDITQUICK manufacturing services.