Polycarbonate CNC Machining Services
Polycarbonate is a transparent, impact-resistant amorphous thermoplastic used for machine guards, lenses, light pipes and protective covers where acrylic is too brittle.
Clear, UV-stabilised and glass-filled grades
Tolerances to +/-0.10 mm on plastic parts
Polishing, coating and bonding available
What Is Polycarbonate?
Why polycarbonate stays clear under impact when acrylic cracks, and where chemical resistance rules it out.
Polycarbonate is an amorphous thermoplastic that combines a glass-like transparency with the impact strength of an engineering plastic. At roughly 70 MPa tensile strength and an elongation at break of 130 percent, it bends and absorbs energy before failing. That is why polycarbonate is specified for protective guards, riot shields, machine windows, ophthalmic lenses and LED light pipes.
Polycarbonate vs acrylic
Acrylic is harder and clearer, but it cracks under impact. Polycarbonate is more ductile and survives blows and vibrations that would shatter acrylic. For covers and guards that take knocks, polycarbonate is the standard. For decorative lenses and display cases, acrylic usually wins because of its optical clarity and scratch resistance.
Design limits
Polycarbonate is attacked by concentrated alkalis, ketones and many solvents, so cleaning agent choice matters. It is also more expensive than ABS and lets through more UV unless a UV-stabilised grade is specified.
Related capabilities: CNC Machining, CNC Milling, CNC Turning, 5-Axis Machining. Dimensional limits, thread rules and surface roughness grades are listed on the tolerances and specifications page, and volume-based routing is covered under production solutions.
Polycarbonate Mechanical Properties
Typical values at room temperature for the condition most often machined. Use them for material screening, then confirm against the mill certificate for the exact heat and product form.
| Property | Typical value |
|---|---|
| Density | 1.20 g/cm3 |
| Ultimate tensile strength | about 70 MPa |
| Tensile yield strength | about 60 MPa |
| Elongation at break | about 130 percent |
| Elastic modulus | 2.4 GPa |
| Continuous service temperature | 115 to 130 C |
| Glass transition temperature | about 150 C |
| Water absorption | about 0.3 percent at 24 hours |
| Haze (clear grade) | less than 1.5 percent at 3 mm thickness |
| Impact strength | about 600 to 900 J/m Izod, no break common |
Typical room-temperature values compiled from public ASM, MatWeb and mill datasheets. Actual values vary with temper, section thickness and product form; request the EN 10204 3.1 certificate for critical applications.
Machining Characteristics of Polycarbonate
How the material behaves in the cut, and what that means for tooling, fixtures, cycle time and achievable tolerance.
Sharp polished tools
Rough tooling melts and smears the surface. Polished carbide with positive rake is the baseline.
Heat and coolant
Moderate cutting speeds to keep heat away from the glass transition. Air blast or water-based coolant over petroleum oils.
Burr and crack avoidance
Dull tools or high feed rates crack the part at the cut edge; deburring is best done with a light bead blast or by hand.
Tight tolerance
+/-0.10 mm typical for plastic features. Tighter tolerances need stress-relieved stock and a final pass on a thermally stable part.
Bonding
Solvent bonding is limited to compatible solvents and gives lower strength joints. Adhesive bonding is preferred for structural assemblies.
Polishing
Mechanical polishing restores transparent surfaces to near-optical quality; vapour polishing is also possible with selected solvents.
Design and Machining Checklist
Practical rules that reduce cost and scrap on Polycarbonate parts. Share them with your design team before the drawing is frozen.
- Use UV-stabilised grade for any part that sees direct sunlight to prevent yellowing.
- Specify at least 1.5 mm wall thickness for covers; thin sections fracture easily under impact.
- Allow generous internal radii of 1 mm or more to prevent crack initiation in stress-bearing parts.
- Avoid strong alkalis and aggressive cleaners; use mild soap and water or compatible plastic cleaners.
- Re-quote as acrylic if the part is decorative and not subject to impact; polycarbonate costs significantly more.
- Consider glass-filled polycarbonate for structural parts that need extra stiffness and lower thermal expansion.
Surface Finishing Options
Finishes are selected for corrosion resistance, wear, appearance, electrical behaviour or cleanliness. Specify only what the function needs.
As-Machined
Ra 0.4 to 1.6 um, optically clear on polished edges.
Bead Blasting
Fine bead blast produces a uniform translucent finish that hides light tool marks.
Polishing
Mechanical polish to near-optical clarity for covers, lenses and light pipes.
Hard Coat
Scratch-resistant UV-cured hard coat applied to clear covers for high-touch surfaces.
Anti-Fog and Anti-Static Coatings
Functional coatings applied for medical, food and electronic housings where condensation or static is unacceptable.
Adhesive Bonding
Polycarbonate bonds with structural adhesives and is ultrasonic-weldable for assembly of multi-piece guards.
Typical Applications
Where Polycarbonate is most often specified, and why it wins against the alternatives.
Safety guards and machine covers
Transparent machine guards, inspection windows and operator enclosures in industrial equipment.
Electrical and electronics
Clear covers for status panels, displays and instrument windows where impact resistance is required.
Automotive and transport
Headlamp lenses, interior light covers and instrument panels in road and rail vehicles.
LED light pipes and lenses
Optical components for industrial and architectural lighting that need to withstand vibration and impact.
Medical device housings
Clear enclosures for diagnostic equipment and laboratory devices where visibility is needed.
Architectural glazing
Glazed panels, partitions and roofing elements that benefit from transparency and impact strength.
Need Polycarbonate parts quoted?
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