Transparent Engineering Thermoplastic
Polycarbonate (PC) Material Guide
Polycarbonate material is a transparent engineering thermoplastic known for combining glass-like clarity with exceptional impact strength—roughly 250 times stronger than glass and 30 times stronger than acrylic.
Engineers choose polycarbonate when a part must stay clear, survive impact, and hold tolerances through machining or molding. This guide covers core properties, common grades, applications, achievable tolerances, and how PC compares to acrylic and other transparent plastics.
1.20 g/cm³
Density
60–70 MPa
Tensile strength
850 J/m
Notched Izod impact
−40 to +120°C
Service temperature
Material Fundamentals
What Is Polycarbonate Material?
Polycarbonate is an amorphous thermoplastic polymer containing carbonate groups in its backbone. Most commercial grades are produced from bisphenol A (BPA) and phosgene, yielding a material that is stiff, tough, and optically clear in its natural state.
Unlike semi-crystalline plastics such as nylon or acetal, polycarbonate’s amorphous structure gives it predictable, isotropic behavior—critical for optical parts and precision-machined components where dimensional consistency matters.
Mechanical Properties
Impact strength 250× glass, tensile strength 60–70 MPa
Thermal Properties
Service temperature −40°C to +120°C, Tg ~147°C
Optical Properties
88–90% light transmission, refractive index 1.585
Electrical Properties
Dielectric strength 16–17 kV/mm, volume resistivity >10¹⁵ Ω·cm
Amorphous Engineering Plastic
Predictable isotropic behavior ideal for optical and precision-machined parts.
Material Grades
Common Polycarbonate Grades & Forms
Polycarbonate material comes in dozens of commercial formulations. The most common for machined parts include general-purpose, UV-stabilized, and reinforced grades.
Standard grade
General-Purpose PC
The default choice for most machined parts. Good balance of clarity, toughness, and machinability. Available as extruded or cast sheet, rod, and plate.
- Best for: general-purpose parts, prototypes, and housings.
- Forms: sheet, rod, plate, and tube.
- Capacity: sheet 0.5 mm to 100+ mm thick.
Outdoor grade
UV-Stabilized PC
Includes UV absorbers that slow yellowing and embrittlement under sunlight. Standard for outdoor enclosures, skylights, and automotive glazing.
- Best for: exterior applications and long-term outdoor exposure.
- Advantages: extends service life, reduces yellowing.
- Applications: skylights, machine guards, vehicle windows.
Reinforced grade
Glass-Filled PC
Fiberglass reinforcement boosts stiffness and reduces creep and thermal expansion. Ideal for structural parts requiring higher rigidity.
- Best for: structural components and high-stiffness applications.
- Trade-offs: opaque appearance, reduced impact strength.
- Benefits: flexural modulus up to 7+ GPa.
Engineering benefits
Why Choose Polycarbonate?
Polycarbonate’s property profile is what earns it the “engineering thermoplastic” label. Here’s how it performs across the categories engineers care about most.
Outstanding Impact Strength
Notched Izod impact strength around 850 J/m—roughly 30× acrylic and 250× standard glass. PC is the default when parts must survive impact.
Optical Clarity
Clear polycarbonate transmits 88–90% of visible light at 2 mm thickness with a refractive index of 1.585, approaching glass at a fraction of the weight.
Wide Service Temperature
Continuous service from −40°C to +120°C. Short-term peaks near 135°C are tolerable, making PC suitable for both cryogenic and elevated-temperature environments.
Good Dimensional Stability
Amorphous structure delivers predictable, isotropic behavior—critical for optical parts and precision-machined components where consistency matters.
Inherent Flame Resistance
Many grades achieve UL 94 V-2 to V-0 without halogenated additives, making PC a default for UL-listed electrical enclosures and connectors.
Easy to Process
Injection molds, extrudes, thermoforms, and machines well. Bonds and welds with standard solvent and ultrasonic methods for easy assembly.
Forms & comparisons
Polycarbonate Forms & Material Comparisons
We machine polycarbonate in sheet, rod, and tube forms, and help you choose the right transparent plastic for your application.
Available Forms
Sheet: 0.5 mm to 100+ mm thick, clear or tinted. The standard starting form for CNC machined parts.
Rod: 6 mm to 200+ mm diameter. Ideal for turned and milled cylindrical components.
Tube: For sight glasses, fluid handling, and hollow structural parts.
Film: 0.125 mm to 0.75 mm for membrane switches, overlays, and thin-gauge applications.
Other Grades: FDA-compliant/food-grade (21 CFR 177.1580), hard-coated/abrasion-resistant, and optical low-haze grades.
Limitations & When to Choose an Alternative
Scratches easily: Specify hard-coated grades or apply a coating post-machining.
Stress cracking: PC is attacked by alkalis, aromatic solvents, and chlorinated solvents. Always screen chemicals against compatibility charts.
UV yellowing: Unstabilized PC yellows under prolonged UV. Use UV-stabilized grades for outdoor exposure.
Creep: Higher creep under sustained load than PEEK or acetal. Glass-filled grades close this gap.
Cost: More expensive than acrylic or polystyrene, less than PEEK. Consider acrylic for static indoor display applications.
Comparison
Acrylic (PMMA)
Lower cost, better scratch resistance and UV stability, but 30× lower impact strength than PC.
Comparison
Tritan
BPA-free with high chemical resistance. Common in consumer products and medical devices.
Comparison
PETG
Low cost, easy to fabricate and thermoform. Lower max service temperature at 65°C.
Comparison
PEEK
For sustained high loads and aggressive chemicals where PC’s creep or chemical resistance is insufficient.
Engineering data
Polycarbonate at a Glance
These values represent general-purpose polycarbonate. Specific grades shift individual properties. Always verify against the supplier’s data sheet before finalizing tolerances.
| Property | Typical Value | Test Standard |
|---|---|---|
| Density | 1.20 g/cm³ | ASTM D792 |
| Tensile Strength | 60–70 MPa | ASTM D638 |
| Flexural Modulus | 2.3–2.4 GPa | ASTM D790 |
| Notched Izod Impact | 850 J/m | ASTM D256 |
| Heat Deflection Temp (1.8 MPa) | 132°C | ASTM D648 |
| Service Temperature | −40°C to +120°C | n/a |
| Light Transmission (2 mm) | 88–90% | ASTM D1003 |
| Refractive Index | 1.585 | n/a |
| Water Absorption (24 hr) | 0.15% | ASTM D570 |
| Flammability (UL 94) | V-2 to V-0 (grade dependent) | UL 94 |
| Machinability | Good (with proper tooling) | n/a |
Machining data
Machining Polycarbonate: Tolerances & DFM
Polycarbonate machines well, but it punishes sloppy process control. Here’s what separates a clean PC part from a cracked one.
Achievable Tolerances & Surface Finishes
| Feature Type | Standard Tolerance | Precision Tolerance |
|---|---|---|
| Linear dimensions (≤100 mm) | ±0.005″ (±0.13 mm) | ±0.001″ (±0.025 mm) |
| Linear dimensions (>100 mm) | ±0.010″ (±0.25 mm) | ±0.002″ (±0.05 mm) |
| Hole diameters | ±0.005″ (±0.13 mm) | ±0.001″ (±0.025 mm) |
| Surface roughness (Ra) | 3.2 µm (as machined) | 0.4 µm (optical finish) |
| Optical clarity | As machined (slight haze) | Vapor polished (full clarity) |
Tighter than ±0.001 in. is possible on small parts but requires climate-controlled machining and stress-relieved stock. View our precision CNC machining capabilities.
Common DFM Pitfalls
- Sharp internal corners: Specify minimum 0.5 mm radius; 1 mm is safer. PC is notch-sensitive and sharp corners concentrate stress.
- Thin walls below 1 mm: Possible, but expect chatter and warpage during machining.
- Over-tolerancing: Calling ±0.0005 in. where ±0.003 in. would function fine drives cost up 2–3×.
- No moisture control: PC absorbs water; pre-dry stock at 120°C for 3–4 hours before final-pass machining on tight-tolerance parts.
Upload your CAD file—every Baetro quote includes free DFM feedback from our engineering team.
Machining best practices
Machining Quality & Workholding
Quality is built into every stage of our polycarbonate machining process, from tooling selection to final inspection.
Tooling & Coolant Recommendations
- Tooling: Sharp, high-positive-rake carbide tools. Dull edges generate heat and leave stress in the surface.
- Speeds/feeds: Moderate surface speeds (200–400 m/min) with aggressive chip loads to keep heat out of the part.
- Coolant: Air blast or mist preferred. If liquid coolant is used, verify chemical compatibility; water-soluble coolants with neutral pH are generally safe.
- Chip evacuation: PC produces stringy chips; use high-helix end mills and good air blast to clear them.
- Thermal conductivity: Low (~0.20 W/m·K), so heat stays localized at the cutting edge.
Workholding & Stress-Cracking Prevention
Polycarbonate is notch-sensitive and stress-crack-prone. Residual stress from clamping becomes a crack initiator if the part later contacts an incompatible chemical.
- Clamp with uniform, moderate pressure; avoid point loads and over-tightening.
- Use soft jaws or distributed fixtures for thin-walled parts.
- Pre-dry stock at 120°C for 3–4 hours before tight-tolerance machining.
- Always screen chemicals against PC compatibility charts before specifying.
Applications
Industries We Serve with Polycarbonate
Polycarbonate material shows up anywhere transparency, toughness, and heat resistance intersect. These industries account for the bulk of machined PC parts.
Industry
Medical Devices
Surgical instrument housings, blood filter bowls, diagnostic equipment windows, and fluid manifolds. FDA-compliant and biocompatible grades support sterilization by EtO and gamma radiation.
Industry
Electronics & Electrical
Enclosures, connector housings, light pipes, LED lenses, and insulator blocks. PC’s dielectric properties and flame resistance make it a default for UL-listed products.
Industry
Automotive & Transportation
Headlamp lenses, instrument cluster windows, interior trim, and sensor housings. UV-stabilized grades are mandatory for exterior applications.
Industry
Safety, Security & Construction
Bullet-resistant glazing (in laminated assemblies), machine guards, face shields, security windows, and skylights. This is where PC’s impact strength earns its reputation.
Industry
Consumer Products
Reusable water bottles, appliance windows, eyeglass lenses, and protective cases. BPA-free alternatives like Tritan have displaced PC in some consumer segments.
Industry
Optical & Lighting
LED lenses, light guides, optical windows, and display covers. Low-haze and optical grades are available for demanding light-transmission applications.
Prototypes & Production
Polycarbonate Parts: Prototype to Production
CNC milling enables a seamless transition from prototype to production—same process, same quality, scaled to your volume.
Prototype PC Milling
Fast parts for design validation without tooling commitments.
- No minimum order quantity—order 1 piece
- 3–7 day standard lead times
- Same tolerances and quality as production parts
- Free DFM feedback for manufacturability issues
- Multiple material options for design comparison
Low-Volume Production
10–1,000 parts with cost-effective CNC milling and flexible scheduling.
- Economical for volumes up to 1,000+ parts depending on complexity
- Consistent quality across batches with documented processes
- Easy design changes between runs without tooling modification
- Ideal for product launches, limited editions, and bridge production
High-Volume Production
Optimized programs, in-process inspection, and dedicated machine capacity ensure throughput for larger production runs.
- Cycle time optimization for high-volume efficiency
- In-process and final inspection routines
- Dedicated machines for consistent throughput
How it works
Our CNC Machining Process for PC
Working with Baetro is straightforward. Here is the controlled process from CAD file upload to finished polycarbonate parts.
Upload Your CAD File
Send your design in STEP, IGES, SolidWorks, or Parasolid format. STEP files are preferred for polycarbonate machining projects.
Receive Quote + DFM Feedback
In under 60 seconds, review pricing, lead time, and manufacturability notes for thin walls, deep pockets, or inaccessible features.
Approve and Place Order
Select grade, finish, quantity, and shipping method. Your project manager confirms the order and production schedule.
Production Machining
Parts are CNC milled with sharp carbide tooling, moderate speeds, and air-blast cooling to prevent heat buildup and stress cracking.
Final Inspection
Every part receives final inspection on CMM equipment, with surface finish verification and dimensional reports when required.
Ship with Documentation
Parts are packaged with inspection reports, material certifications, and required documents, then shipped worldwide by express carrier.
Cost considerations
Polycarbonate Cost Factors
Understanding what drives polycarbonate machining costs helps you make informed design and material decisions.
- Material Grade: General-purpose PC is economical; UV-stabilized, glass-filled, and optical grades increase material cost.
- Part Complexity: Thin walls, deep pockets, and tight internal radii increase machining time and fixturing requirements.
- Tolerances: Optical-grade finishes (Ra 0.4 µm) and ±0.001 in. tolerances require slower feeds and secondary polishing.
- Surface Finish: As-machined is cheapest; vapor polishing, hard coating, or custom textures add cost.
- Order Quantity: Low volumes have higher per-part cost due to setup; high volumes reduce per-part cost significantly.
- Lead Time: Standard 3–7 day lead times included; expedited delivery increases cost.
FAQ
Polycarbonate Material FAQs
Answers to common questions about polycarbonate properties, machining, grades, and applications.
What is polycarbonate material used for?
Polycarbonate material is used wherever transparency, impact resistance, and heat tolerance intersect: machine guards, medical device housings, headlamp lenses, bullet-resistant glazing, electrical enclosures, and consumer products. It’s the default engineering plastic when acrylic is too brittle and glass is too heavy or fragile.
Is polycarbonate stronger than acrylic?
Yes, significantly. Polycarbonate has roughly 30× the impact strength of acrylic and far better low-temperature toughness. Acrylic wins on scratch resistance, optical polish, UV stability, and cost. The right choice depends on whether the part faces impact or just needs to look good.
Can polycarbonate be CNC machined?
Yes. Polycarbonate machines well with sharp carbide tooling, moderate speeds, and air-blast cooling. We routinely hold ±0.001 in. tolerances and Ra 0.4 µm surface finishes on PC parts. The main risks are stress cracking from poor workholding, dull tooling, or incompatible coolants—all manageable with proper process control.
Is polycarbonate food safe?
Standard polycarbonate is FDA-compliant for food contact under 21 CFR 177.1580, but it contains BPA, which has driven many consumer brands to BPA-free alternatives like Tritan. For industrial food processing equipment, FDA-grade PC remains common and appropriate. Confirm regulatory requirements for your specific market before specifying.
Does polycarbonate yellow over time?
Unstabilized polycarbonate yellows under prolonged UV exposure, typically noticeable after 1–3 years outdoors. UV-stabilized grades dramatically extend service life, and hard coatings add further protection. For indoor use away from direct sunlight, yellowing is rarely an issue within normal product lifetimes.
What’s the difference between polycarbonate and Lexan?
Lexan is SABIC’s trade name for polycarbonate; they’re the same base material. When a drawing calls out Lexan, it’s almost always specifying polycarbonate material in general. Other common trade names include Makrolon (Covestro) and Calibre (Trinseo).
Quote-ready manufacturing
Get Precision Polycarbonate Parts from Baetro
Baetro machines polycarbonate material to ±0.001 in. with optical-grade finishes, from single prototypes to production runs of 10,000+. Every order includes free DFM review, no minimum order quantity, and 3–7 day standard lead times.
Ready to get started? Upload your CAD file for an instant quote with live pricing, lead times, and free DFM feedback. Our engineers review every design—not just price it—helping you reduce machining costs, improve manufacturability, and achieve better performance.
Parts ship in 3–7 days. No minimum order quantity. ISO 9001 & AS9100 certified.
Not ready to upload a file? Contact our engineers to discuss your project, review material options, or get guidance on tolerance selection.