Lexan 940 is a general purpose grade of polycarbonate resin used in high-stress parts requiring impact strength, clarity, and tight dimensional control. Procurement teams contend with resin price swings and long lead times that stall builds and drive up unit costs — in particular high-mix batches under 1,000 units.
Good lead report flow-line defects, gate blush, and weld-line fragility that cause rejects and rework, damaging PPAP readiness and delaying EVT-to-DVT gates. Engineering teams have a hard time juggling UL 94 V-2 ratings, optical clarity and mold-flow limits that increase tooling changes and cycle time.
To put real numbers on DFM, cycle time and cost per part, the article will map critical risks and demonstrate techniques that stabilize supply, reduce scrap and accelerate launch — with no compromises.
The Core Properties of Lexan 940
High-performance injection molding polycarbonate, a prime material, balances mechanical strength, thermal stability, and optical clarity, making it ideal for rugged, transparent components in automotive, electronics, and medical applications where success depends on quality and turnaround time.
1. Mechanical Strength
Lexan 940 resin is a PC designed for high impact and tensile strength — beating acrylics that shatter on shock and ABS that surrenders to creep. It retains its rigidity and durability even after repeated stress cycles, ensuring that hinges, snaps, and interlocks remain secure without the creep that causes rework.
In drop- or vibration-prone housings—robot sensor pods, EV charger doors, consumer device shells—it resists brittle failure and preserves threads and bosses. For aggressive dust, shock, and cold start sites, long service life and fewer field returns enable procurement teams to normalize lifetime cost rather than unit price.
2. Thermal Resistance
Lexan 940 maintains the properties at elevated temperature expected of engineering thermoplastics, with a high glass transition and dependable heat distortion resistance that safeguards fit and function during thermal spikes. This makes it a smart choice for automotive heater outlets, LED lighting frames and electronic housings that encounter duty cycles and hot spots.
It runs on regular injection presses and hot runners at normal pc melt and mold temperatures, so crews don’t need custom tooling or unusual screw designs to reach yield and takt.
3. Electrical Insulation
Dielectric strength and low dissipation factor makes it a favored insulator for connectors, relay covers, lamp housings, and low-voltage enclosures. It aids in stopping tracking and electrical breakdown in high-voltage regions, maintaining creepage and clearance margins stable over lifetime.
Apply it where components need to bear load and insulate circuits—battery management housings, robot controller doors, medical device shells.
4. Optical Clarity
Clarity comparable to glass and acrylic, but maintaining PC durability. Lenses, sight windows and clear covers take advantage of the stable light transmission and low haze that accommodates clean surface grades.
It’s great for face shields, headlamp lenses and consumer screens that require optical quality AND impact resistance.
5. Chemical Resilience
Wide compatibility with numerous cleaners and fluids powers medical packaging, filtration frames and industrial guards that confront regular washdowns. It’s tough against the ravages of time and common agents, refusing to discolor.
Note the limit: it is not resistant to hydrocarbons, so avoid fuel-contact or heavy oil immersion. It plays well outside too with UV, and water spray, and even immersion, taking it to exterior markings and safety signage.
6. Flame Retardancy
A UL94 V-0 rating fulfills rigorous safety requirements in electronics, transportation, construction, and medical devices. The FR package is tuned to retain mechanicals, trading off less on impact or flow.
Use it for cable management, infotainment bezels, lighting enclosures and public safety gear that has to pass audit quick. See the Lexan 940 datasheet for detailed properties and comparison to make sure it aligns with your specs.
Why Choose Polycarbonate for Molded Parts?
Polycarbonate (PC) — including Lexan 940 — provides an outstanding combination of impact strength, optical clarity, and thermal stability that aligns well with high-mix, low-volume, and scaled production. It fits climate tech, robotics, EV, and consumer tech where thin walls, tight tolerances, and high-reliability drive business results in injection molding environments.
- Assert polycarbonate’s superiority over other plastics for impact resistance, clarity, and processability.
PC is about 250 times stronger than glass and absorbs impact without brittle failure. It keeps form and function from -40°C to 120°C, so parts survive cold-chain logistics, outdoor loads, or under-hood heat. Its light transmission supports lenses, light pipes, and indicator windows where PMMA would crack and PETG would haze under heat.
Compared with ABS, PC maintains higher notched impact and better dimensional stability across temperature swings. It is water-resistant and UV-stabilizable, extending outdoor life for e-mobility housings. For electronics, PC’s electrical insulation and availability in UL94 V-0 flame-retardant grades reduce compliance risk in chargers, battery modules, and medical enclosures.
- Explain how polycarbonate injection molding enables complex part geometries and thin wall designs.
PC flows well at these shear rates and reproduces very fine features, enabling ribs, living hinges (short-term), snap-fits, and lattice zones. Thin walls as low as 0.5–1.0 mm are possible with appropriate gate design and venting, which culls weight yet maintains stiffness because of PC’s high strength-weight ratio.
For EV sensor brackets and drone housings, this supports weight goals without sacrificing energy absorption. Stable rheology and low warpage maintains lens concentricity, gear tooth fidelity and seal land flatness.
- Emphasize cost reduction in volume production due to excellent tool surface reproduction and low maintenance molding.
PC picks up polished tool finishes well, minimizing secondary polishing for optical parts. Stable shrink and superior melt strength reduce scrap from short shots and sinks. Hot runner-friendly grades eliminate runner waste and durable cycles minimize mold cleaning when dryers and resin handling are optimized.
Net result: shorter cycle times, fewer regrind loops, and lower per-part cost at scale.
- Highlight polycarbonate’s adaptability for overmolding, multi-material assemblies, and high gloss finishes.
PC bonds superbly in two-shot with TPEs for seals and grips, and welds beautifully to PC/ABS for a perfect balance of aesthetics and heat performance. It enables vapor polishing and hard coats for high gloss and scratch resistant lenses/UI covers.
For robotics HMI windows, medical device covers, and outdoor sensor domes, this blend of adhesion, clarity, UV stability, and coatability accelerates design freeze and lowers part count while ensuring that the materials used meet high standards.
Need Your Parts Molded with High-Performance, Flame-Retardant Polycarbonate?
Our platform connects you with experts in Lexan 940, providing an instant quote for parts that meet strict tolerances, UL 94 V-0 compliance, and high-quality cosmetic standards.
Get Your Lexan 940 Parts Molded to Perfection!
A Designer’s Guide to Lexan 940
Lexan 940 is a UL94 V-0 PC for injection molding offering solid impact, good optical clarity and stable outdoor performance to UV and water exposure. Design with it for housings, light guides, bezels and medical and consumer electronics parts where flame rating and aesthetics count.
Keep away from hydrocarbons, though; the resin is not resistant to fuels or a lot of oils. Check details with the datasheet when benchmarking against other PC grades or blends.
Wall Thickness
Aim for nominal walls of 1.5–3.0 mm to balance flow, strength and sink control. Thin optics may be able to go lower with diligent gating and venting, but prepare for increased shear and more narrow process windows.
Maintain consistent thickness throughout the piece to minimize stress and warpage. If variations are needed, taper smoothly (≤10% over 25 mm). Design ribs at 40–60% of nominal wall to stiffen without sinks.
|
Application type |
Typical wall (mm) |
|---|---|
|
Light pipes, lenses |
0.8–1.5 |
|
Handheld housings |
1.5–2.5 |
|
Structural covers/brackets |
2.0–3.0 |
|
EMI/RFI shielded shells (coated) |
2.0–2.5 |
For snap-fits, begin at 1.5–2.0 mm beams with generous radii confirmed with FEA + strain targets < 0.6% at use temperature.
Draft Angles
Utilize draft in injection molding environments to facilitate ejection and safeguard optical faces, starting at 1.0–2.0° on polished surfaces and increasing with texture depth.
- High-gloss (SPI A): 1.0–1.5°
- Matte (SPI B/C): 1.5–2.0°
- Textured (VDI 12–24): 2.0–3.0° plus 0.4° per 0.01 mm texture depth
- Ribs/bosses: ≥0.5° per side
- Window features: add lifters/strippers vs. zero draft. Don’t push it.
Gating Strategy
Balanced flow minimizes stress whitening and weld-line appearance in transparent components. For wide, cosmetic surfaces, utilize edge or fan gates, pin gates for small, concealed features, hot runners to minimize shear and maintain low residence time.
Checklist:
- Gate into thicker sections; flow from thick to thin
- Keep shear rate moderate to protect clarity
- Place weld lines away from cosmetic zones and snaps
- Vent at 0.02–0.04 mm; add vacuum assist for optics
- Use sequential valve gating for large bezels
- Validate with Moldflow and short-shot studies
Surface Finish
High gloss, matte and fine textures are possible with tool steel polished to SPI A or etched according to VDI. Tool quality drives clarity – spray-on release agents can haze surfaces, so prefer tuned draft and mold temp to sprays.
Flame polish can enhance edge clarity on gates or witness lines; never overheat yellows PC. Common defects include splay from moisture (dry to 0.02% or lower), flow lines from low melt or cold gates, blush from high shear, and weld shadows in clear zones.
Control, dry, melt 270–310°C, mold 80–110°C, balanced runner. Work with PC molders who can close loops quickly and reach cosmetic and UL targets.
Processing and Manufacturing Insights
Lexan 940, a PC (CAS 25766-59-0), fits high-impact, tight-tolerance parts in electronics, medical and industrial housings where UL94 V-0 flame performance, dimensional stability and clean surface finish count.
Accurate temperature control and aggressive drying halt moisture-induced defects which present as splay, bubbles or brittle parts. Aim for resin moisture under 0.02% by desiccant drying at 110–120 C for 3–4 hours and check with a moisture analyzer on critical runs. Maintain melt at 280–310°C and mold at 80–110°C to equilibrate flow and stress. Employ closed-loop barrel zones and insulated manifolds to reduce thermal drift. For optical characteristics, reduce the frame and confirm with DSC and rheology data attached to lot numbers for trackable runs.
Standard thermoplastics tooling is sufficient and effective for Lexan 940 when adjusted for PC’s increased viscosity. General-purpose screws with 2.2–2.5 L/D compression, hot-runner systems with valve gates, and polished, vented molds work well.
No hydrocarbon-based mold releases, PC is not hydrocarbon resistant, which limits use in under-the-hood applications. Stainless or hard-coated tool steels reduce plate-out and wear from higher melt temps. For outdoor use—UV, water, or immersion—spec UV-stabilized grades and validate with accelerated weathering data.
Fine-tune shot size, injection speed, and cooling to stabilize quality and cycle time. Maintain shot size at 30–70% of barrel capacity to prevent residence-time degradation. Begin with fast-to-moderate fill to 95–98% then switch early to hold to cap the gate and control sink. Tune gate freeze by weighing components along hold-pressure ramps. Proximity cooling circuits to core/cavity surfaces, ±2°C uniformity, with conformal cooling on thick sections. Anticipate normal cycles of 25–55 s depending on wall (1.8–3.5 mm) and surface finish. Use annealing at 120–125°C for 1–2 hours on stress-critical parts.
Collaborate with PC-savvy suppliers to de-risk scale-up and compliance. Your right partner provides UL file stewardship, lot-specific viscosity and moisture certificates, and DOE-backed molding windows. That counts in regulated devices where flame ratings (UL94 V-0) and optical clarity meet throughput. It helps separate material choices: for example, when a design lists cast metal rods (zirconium, yttrium, ytterbium, 99–99.2% purity, diameters from 1.5 mm × 500 mm to 6.35 mm × 50 mm) produced by casting, a seasoned PC supplier can flag galvanic or chemical interface risks and propose inserts or coatings that keep assemblies stable.
The Unseen Factor: Material Consistency
Reliable material strength drives dependable yields, reliable turnaround times, and smooth audits, particularly in injection molding environments. For Lexan 940 polycarbonate, tight control of molecular structure and additives ensures parts are dimensionally stable, optically clear, and UL94 V-0 compliant in 1.5 mm walls. This consistency is crucial for consumer electronics, EV subsystems, and medical housings shipped globally.
Batch-to-Batch
Even slight variation in molecular weight distribution shifts melt flow index (MFR), altering fill pressure and shear history. That results in uneven shrink, warpage, knit-line weakness, and gloss swings.
Additive drift —heat stabilizers, UV package or mold release—can dull clarity, reduce impact at low temp, or change adhesion for secondary ops.
Test each resin lot on receipt: MFR at 300 °C/1.2 kg, moisture content (<0.02%), density, color/clarity (YI, haze), and DSC for thermal signature. Or run a short plaque or spiral flow to snatch up real-world fill variances prior to gathering production.
Record resin batch numbers on travelers, ERP receipts, and mold shot logs. Connect to cavity data, press settings and QA results so you can perform root cause analysis or a recall response in hours, not days.
Checklist:
- Certificate of Analysis cross-check: MFR, IZOD, UL file
- Moisture reading pre-dry and post-dry
- First-article dimensions and weight
- Optical check: haze/clarity, surface gloss
- Mechanical spot check: IZOD or flexural modulus proxy
- Gate vestige and knit-line visual
- Color ΔE vs. master standard
- Retain samples and pellets, 12 months
Performance Reliability
Lexan 940 exhibits run-to-run stability when dried and processed within window (dry 120 °C, 3–4 h, melt 280–310 °C). That stability is what delivers impact strength, transparency and V-0 flame rating across tools and sites.
Audit completed parts quarterly. Pull sections from early/mid/late shift and various cavities. Inspect mechanicals, opticals and environmental resistance (UV, water, chemicals) as consistency rules long-term durability and field returns.
Key metrics to trend:
- MFR (g/10 min)
- Notched Izod (kJ/m²)
- Tensile modulus (MPa)
- Haze (%), yellowness index
- UL94 status at target thickness
- Warp (mm) and shrink (%)
- Heat deflection temp (°C)
Global Supply
Lexan 940 is sold through worldwide distributors with technical support. For scale, bi-sourced approved PC grades and alternates with matching MFR and UL files.
Consider lead times and regional stock, MOQ and on-site molding support. Maintain 4–8 weeks safety stock at the resin and finished-goods levels.
OTIF, batch variability, and responsiveness are all supplier scorecard factors. Connect buy contracts to projected ramps to minimize risk to price surges and shortages.
Struggling to Design for Lexan 940 Without Causing Sink Marks or Splay?
Our manufacturing experts can provide a detailed DFM review of your design, helping you optimize wall thickness, gating, and draft angles specifically for Lexan 940 to ensure a flawless, cost-effective molding process.
Get a Free DFM Review for Your Polycarbonate Design!
Exploring Material Alternatives
Material choice hinges on end-use demands—temperature, chemicals, stress profile, regulatory class, sustainability targets, and total landed cost. For teams vetting Lexan 940 (flame-retardant polycarbonate), the goal is fit-for-purpose performance without overengineering.
What follows compares practical substitutions by property, process, and risk, with notes on where they shine and where they fall short.
- Acrylic (PMMA) fits covers, guards, and light pipes when clarity and scratch resistance matter more than impact. It machines and polishes well, but its impact strength and heat deflection fall below Lexan 940, and it lacks inherent flame retardance.
- ABS is a solid pick for housings and interiors that need good toughness, easy molding, and paintability. It cannot match PC’s optical clarity or high heat resistance and needs FR grades to meet UL 94 V-0.
- Nylon (PA6/PA66) suits gears, clips, and wear parts. Glass-filled grades boost stiffness and creep resistance. Moisture uptake can shift dimensions and properties, and flame performance varies.
- Versus a lot of engineering thermoplastics, Lexan 940 provides a powerful combination of impact strength, optical clarity and UL 94 V-0 at thin walls, with robust processing and wide regulatory acceptance.
- It beats acrylic on toughness and ABS on clarity and FR consistency, and equals or beats general-purpose nylons on impact. Trade-offs comprise increased resin cost and susceptibility to select solvents.
- For high-heat or demanding sterilization, PPSU adds hydrolytic stability, toughness and repeated steam cycles, serving fluid-contact and aerospace interiors.
- Medical, Eastman Tritan Copolyester MX731 delivers high flow for thin walls and clarity, BPA-free, biocompatible and sterilizable. For sustainability goals, look to bio or biodegradable plastics for low-heat, low-stress components, and recycled-content PC or PC/ABS to reduce footprint while maintaining in-spec performance.
Reinforced blends (PC/ABS, PC/PBT, glass- or mineral-filled PC) assist in adjusting modulus, creep and dimensional stability. Check UL ratings and chemical charts early.
Equilibrate performance, cost and sustainability. Verify operating temperatures, chemicals and mechanical loads, verify recyclability or recycled content, and consider processability and supply risk. Treat FR and chemical resistance standards as hard gates in EV, robotics, and industrial controls.
At Wefab.ai, AI-driven DFM screens resin choices against wall thickness, draft, gate layout, and UL targets, then simulates cost and lead-time impact across suppliers.
Teams witness tangible trade-offs, frequently chopping lead time 34% and PO cycle time 85% while maintaining quality with computer-vision inspections.
Conclusion
In industries such as climate tech, robotics, electric vehicles (EVs), and consumer hardware, manufacturers face significant challenges, including unpredictable timelines, fluctuating costs, and stringent regulatory requirements. Delays in production can derail launch schedules, while material inconsistencies, such as resin variations, lead to increased scrap, compromised part fit, and inconsistent test outcomes. Utilizing high-performance resins like Lexan 940 mitigates these risks by offering consistent impact strength, thermal stability, and flame-retardant properties across batches. This resin supports thin-wall designs, snap fits, and clear gating with stable flow, reducing tool wear, enabling color coordination, and streamlining UL compliance with minimal rework. By integrating such materials with a strategic approach, engineering teams can maintain Design for Manufacturing (DfM) objectives, while procurement benefits from predictable lead times and cost stability.
Wefab.ai enhances this process by providing a seamless, AI-driven platform that optimizes material selection, DfM, and supply chain coordination, ensuring high-quality, scalable production with reduced waste and accelerated timelines. Ready to transform your manufacturing outcomes? Explore Wefab.ai’s advanced manufacturing capabilities and AI-driven DfM and material selection solutions, and request an instant quote to drive precision and efficiency in your projects.
Frequently Asked Questions
What is Lexan 940, and where is it used?
Lexan 940 is a UL general purpose rated PC resin, often used in injection molding environments. It provides high impact strength, good stiffness, and dimension stability, making it ideal for applications like electrical housings and automotive interiors.
What key properties set Lexan 940 apart?
It integrates high impact resistance with good heat and flame resistance (UL 94, grade dependent), making it ideal for injection molding environments. This material remains tough over a broad temperature range and exhibits good dimensional stability for precision molded parts.
How does Lexan 940 support consistent molding quality?
It has known flow and shrinkage characteristics, which ensures consistent dimensions in injection molding environments. Dry the resin to low moisture content and keep melt temperatures within supplier specs to maintain surface finish, strength, and cycle consistency.
What processing guidelines matter most for Lexan 940?
To achieve optimal results in injection molding environments, dry materials to under 0.02% moisture and try melt temperatures within the supplier’s recommended window while using moderate injection speeds to avoid shear.
Why choose polycarbonate for molded parts over other plastics?
Polycarbonate, a prime material in injection molding environments, offers exceptional impact strength, clarity for transparent grades, and thermal stability. It resists load-induced cracking, making it more durable than ABS or acrylic for safety-critical components.
How does material consistency affect part performance?
Stable resin quality in injection molding environments and controlled processing minimizes warpage, stress whitening, and dimensional drift. This consistency enhances fit, long-term reliability, and safety compliance, particularly in multi-cavity or high-volume production.
What design tips help when specifying Lexan 940?
To optimize injection molding environments, employ consistent wall thickness, incorporate generous radii, and maintain correct rib-to-wall ratios (roughly 40–60% of wall). Additionally, adding draft angles will facilitate ejection and help avoid sharp corners, which can increase stress concentration and impact performance.
Are there alternatives to Lexan 940 for specific needs?
Yes. Consider PC/ABS blends for improved processability, higher flow PC grades for thin walls, or specialized flame-retardant PC for stricter safety codes in injection molding environments. For manufacturing support and DFM reviews, Wefab.ai can evaluate resin options and mold strategy.
