Impact Resistance
Izod notched strength 640–850 J/m (ASTM D256). Survives repeated drop impact at room temperature — essential for device housings, safety equipment.
Polycarbonate Injection Molding for Optical & Structural PC Parts
PC molding planned around your drawing and material.
FECISION coordinates polycarbonate tooling and molding through manufacturing partners. Cavity tolerances, optical finish, tool life and machine suitability are reviewed for the exact resin grade, part geometry and production volume.
Production-Site Quality ReviewMaterial & Process MatchingProject-Specific DocumentationQuantities Confirmed with QuoteDimensional Inspection
DFMGeometry and
tooling review
tooling review
GradeOptical and
structural needs
structural needs
ScopeProduction-site
qualification
qualification
QuoteQuantity and
timing review
timing review
Material Overview
Why Engineers Specify Polycarbonate for Demanding Injection Molded Parts
Polycarbonate's Izod notched impact strength of 640–850 J/m — roughly 40× higher than standard acrylic — is why it shows up in riot shields, aircraft cabin windows, and surgical instrument housings where component failure isn't an acceptable outcome.
During a PC project review, the manufacturing partner evaluates wall transitions, gates and expected part loading: most PC part failures we see at DFM stage trace back to wall thickness irregularities and gate position, not material quality. A 0.8 mm thin section adjacent to a 3.5 mm rib will always show stress whitening under load — not because the PC is weak, but because the mold design created a molecular orientation that the material can't carry.
PC also requires careful moisture management. Pellets dried below 0.02% moisture before entering the barrel — our process uses desiccant-hopper dryers running continuously at 110–120 °C. Skip that step and you'll see silver streaks in the first shot. The material tells you immediately when something in the process is off, which is either frustrating or useful depending on how you think about it.
More material available on our Material Services →640 J/m
Heat Deflection
HDT 120–130 °C at 1.82 MPa (ASTM D648). Survives autoclave sterilization cycles and continuous service in environments up to 115 °C.
Optical Clarity
Light transmittance 88–90% (ASTM D1003). Refractive index 1.586. Suitable for lenses, instrument windows, and display covers requiring near-glass clarity.
Dimensional Stability
Shrinkage 0.5–0.7% (uniform, amorphous). Low warpage versus semi-crystalline alternatives. Consistent across cavities in multi-cavity tooling.
Biocompatibility
Medical applications require documentation for the exact resin grade, intended contact and processing conditions. Material test data and the selected production-site scope are reviewed together.
Flame Rating
UL94 V-0 flame-retardant grades available (Makrolon FR) for electronic enclosures, connectors, and electrical components requiring regulatory compliance.
Material Grades
PC Grade Selection
Not all polycarbonate performs equally under injection conditions. Viscosity, flame rating, fiber reinforcement, and biocompatibility requirements determine grade selection before the mold design begins.
Makrolon 2458 / Lexan 940
PrimaryStandard optical-grade PC — Covestro / SABIC
This is what we reach for on the majority of PC jobs — lens covers, display bezels, and enclosures where transparency and structural integrity both matter. Lexan 940 specifically has been the industry workhorse for 30 years for good reason: consistent melt flow (10 g/10 min at 300 °C), predictable shrinkage, and clean mold release.
- Light transmittance
- 88–90%
- Tensile strength
- 55–65 MPa
- HDT (1.82 MPa)
- 120–130 °C
- Shrinkage
- 0.5–0.7%
- Mold temp.
- 70–100 °C
Makrolon FR / Lexan 500R
Flame RetardantUL94 V-0 rated — electronic enclosures
When the end-use product needs UL94 V-0 — power supply housings, EV battery components, electrical connectors — we switch to FR-grade PC. The flame-retardant additives don't meaningfully change the mold setup, but they do affect gate sizing (the material runs slightly stiffer) and surface appearance (slight haze vs unfilled PC).
- Flame rating
- UL94 V-0
- HDT (1.82 MPa)
- 115–125 °C
- Impact (notched Izod)
- 600–750 J/m
- Melt flow index
- 8–12 g/10min
PC GF10 / GF20
Glass-Filled10–20% glass fiber — structural brackets & housings
Glass-filled PC trades optical clarity for stiffness. We run GF grades for structural brackets, camera mounts, and medical device chassis where creep under load is a concern. The tradeoff: glass fibers surface at the mold wall and create a textured finish — polished A-surface is not achievable without secondary operations. Also note: GF PC is abrasive; we use S136 hardened cavities rated for GF grades.
- Flexural modulus
- 5,000–7,500 MPa
- Tensile strength
- 80–120 MPa
- Shrinkage (flow dir.)
- 0.1–0.3%
- Surface finish
- SPI B2–C1 max
PC/ABS Blends
Blend — Cost BalancedCycoloy C1200 / Bayblend T45 and equivalents
PC/ABS sits in an interesting middle ground — it loses some impact and heat resistance compared to straight PC, but processes more easily (lower barrel temperature 230–260 °C vs PC's 280–310 °C) and costs 15–25% less per kilogram. For consumer device enclosures where ABS-level aesthetics are acceptable but PC-level structural rigidity is needed, it's the right choice.
- Barrel temp.
- 230–260 °C
- HDT (1.82 MPa)
- 95–110 °C
- Impact strength
- 400–600 J/m
- Shrinkage
- 0.4–0.7%
How It Works
Our Polycarbonate Injection Molding Process
Six controlled stages, each with a documented checkpoint. PC requires tighter process discipline than commodity resins — barrel temperature, moisture content, injection speed, and mold temperature all interact in ways that show up immediately in part quality.
DFM Review
Wall uniformity, gate location, draft angles, and rib geometry reviewed before CAM programming. PC-specific red flags: wall transitions above 25% change, gate positions that create jetting on optical surfaces.
Precision Tooling
S136 cavity steel machined to ±0.01 mm via slow-wire EDM on critical dimensions. Optical surfaces diamond-polished to SPI A1 (Ra ≤0.012 µm). Mirror polish completed before any gate fitting.
Material Pre-Drying
PC pellets dried at 110–120 °C for 4–6 hours in desiccant-hopper dryers. Dewpoint monitored continuously (<−30 °C). Moisture must be below 0.02% — we verify with Karl Fischer titration on medical-grade runs.
Injection & Process Control
Barrel 280–310 °C, mold 80–110 °C. Injection speed profiled to reduce shear stress on PC chains and prevent optical distortion (birefringence). Scientific molding DOE used on first article to lock process window.
In-Process Inspection
First-article measured on CMM (±0.002 mm system accuracy). Optical-grade parts inspected under diffused 500-lux light box for surface defects. Birefringence checked via polarized light where specified.
Post-Process & Delivery
Optional annealing at 100–120 °C to relieve molded-in stress before shipment. Parts individually bagged in anti-scratch film. Full batch record and dimensional report shipped with every order.
Design for Manufacturability
PC Injection Molding DFM: Where Part Failures Are Prevented
Our DFM for PC parts runs through eight specific checkpoints before the mold design is locked. PC failure modes are predictable when you know what to look for.
Explore our injection mold tooling capabilities →- Wall uniformity check — transitions below 25% thickness change per step
- Gate location analysis — fan or edge gate for optical surfaces; sub gate for auto-degating
- Rib-to-wall ratio — maximum 0.6:1 to prevent sink marks on A-surface
- Boss wall thickness — PC bosses above 60% nominal wall accumulate heat, void internally
- Draft angle — minimum 1° on polished optical surfaces, 0.5° on textured faces
- Moldflow fill simulation — balancing multi-cavity tools and confirming weld line positions
Common PC DFM Issues We Flag
Stress Cracking at Undercuts
PC doesn't flex during ejection the way PE or PP does. Any undercut above 0.8 mm per side requires a slider or lifter — forced ejection creates stress whitening or delayed cracking under load.
Max undercut: 0.8 mm/side without mechanismBirefringence in Optical Parts
Fast injection speed + low mold temperature + thin walls = molecular orientation that shows as rainbow banding under polarized light. Optical lenses require injection speed profiling and mold temperature ≥80 °C to allow molecular relaxation before freeze-off.
Mold temp ≥80 °C for optical-grade PCChemical Compatibility of Mold Release
PC has poor resistance to hydrocarbon-based mold release agents — they cause stress cracking within days of part production. Silicone-based internal lubricants or dry mold release only. This catches people by surprise on first PC runs.
Silicone release only — no hydrocarbon spraysHot Runner Nozzle Temperature
PC degrades at ≥340 °C. Nozzle tip temperature must stay 280–315 °C — too hot and yellowing appears in the first 50 shots; too cold and the gate freezes mid-fill. We calibrate per-nozzle on tool qualification.
Nozzle: 280–315 °C strict windowQuality System
Precision Control & Quality Assurance for PC Parts
The following parameters are discussed during tooling and inspection planning. PC's low shrinkage makes it possible to hold tight tolerances — but only if the measurement system resolution is high enough to verify them reliably.
DrawingCritical dimensions and inspection method agreed per feature
FinishOptical and cosmetic acceptance criteria specified for the part
RecordsMaterial and inspection documentation agreed for the order
DryingDrying method and moisture limit based on the selected resin grade
Production-Site Quality ReviewMaterial & Process MatchingProject-Specific DocumentationQuantities Confirmed with QuoteDimensional Inspection
- PC (Polycarbonate) is widely used in medical device housings, surgical instrument handles, and IV connectors due to its exceptional clarity, impact resistance, and ability to withstand sterilization cycles.
- FECISION coordinates PC component molding with the selected manufacturing partner. Medical projects require a review of the resin documentation, production-site qualification, component use and agreed inspection records. Our medical injection molding services cover the project review and manufacturing documentation needed for the specified component.
Application Areas
Industries That Rely on Polycarbonate Injection Molding
PC grades are used across optical, structural and other component applications. Each program requires a separate review of material data, intended use, production-site suitability and acceptance criteria.
Medical & Diagnostics
Microfluidic cartridges, IVD reagent housings, surgical instrument bodies, and transparent diagnostic chamber covers. Exact resin grade, production-site scope and any controlled-environment requirement are reviewed for each project.
Microfluidic chipsIVD housingsSurgical instrument handlesDiagnostic chamber covers
Consumer Electronics
Camera lens covers, LED diffuser plates, display bezels, and device enclosures where SPI A2 or better cosmetic finish is required. PC's scratch resistance (Rockwell M70) keeps surfaces presentable through production handling.
Camera lens coversLED diffusersDisplay bezelsDevice enclosures
Aerospace & Defense
Instrument panel lenses, HUD covers, avionics enclosures. The selected resin grade, environmental requirements and customer qualification conditions must be reviewed before the manufacturing scope is accepted.
HUD coversAvionics enclosuresInstrument lenses
Industrial Electronics
Connector housings, sensor covers, terminal blocks, and switching enclosures requiring UL94 V-0 flame rating. PC/ABS blends handle the majority of these applications at lower cost while meeting most thermal and impact specifications.
Connector housingsSensor coversTerminal blocksSwitching enclosures
Polycarbonate Injection Molding — Buyer Questions Answered
Use these questions to prepare your drawing, material requirements and quotation request.
How are wall thickness and tolerances reviewed for PC parts?⊙
We review the exact PC grade, part dimensions, wall transitions, gate location and expected loads. Drawing tolerances are confirmed per feature with the selected manufacturing partner; a material name alone does not establish an achievable tolerance.
How does PC compare with PMMA for a molded component?⊙
PC is commonly considered where impact resistance is important, while PMMA is often selected for optical clarity and weathering performance. Compare the actual resin data, coating requirements and service environment before choosing either material.
How is mold steel selected for a PC project?⊙
Tool steel is selected for the expected volume, resin reinforcement, corrosion exposure and required surface finish. Optical cavities and abrasive grades may require different steels or maintenance plans, which are reviewed during tooling design.
Can you support PC/ABS blends?⊙
PC/ABS blends can be reviewed for suitable housing and structural applications. Provide the preferred grade or performance requirements so we can compare material data, molding conditions and the appropriate production site.
What is the minimum order quantity?⊙
Trial quantities and the practical production batch are confirmed in the quotation. Tooling investment, resin purchasing, cavity count and any validation requirements all affect the suitable order size.
Which secondary operations can be considered?⊙
Annealing, coating, printing, insert installation and assembly can be reviewed for the selected grade and part design. Specify the required cosmetic, optical and functional results so the quotation can define the operations and acceptance tests.
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