Polycarbonate Machining

DEK's polycarbonate machining service holds ±0.01 mm on critical features of guards, lenses and housings, with prototypes in 3–5 days and no MOQ. Every blank is annealed before finish passes.

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±0.01mm
Critical Features
3–5 days
Prototype Lead Time
No MOQ
From One Part

Transparent polycarbonate machined housing with internal features

ISO 9001:2015 Certified AS9100D and ISO 13485 certified

Why Choose CNC Polycarbonate for Tough Parts?

Polycarbonate is the transparent plastic you choose when the part will be hit, dropped or clamped: it has 10–20 times the impact strength of acrylic. It also stress-cracks with the wrong coolant and turns cloudy under a dull cutter.

We machine PC on the same 3-, 4- and 5-axis mills as your metal parts, as one of 15+ polymers in our plastic CNC machining services. Fundamentals are in our guide to CNC machining polycarbonate.

ISO 9001:2015, ISO 13485 and AS9100D
Engineer-reviewed quotes within 6 hours
IQC, IPQC, FAI and OQC inspection
Metal frames machined in the same order

Small transparent plastic medical device parts isolated

Polycarbonate Grades We Machine

From optical clear sheet to FR and medical grades, each PC type is selected for clarity, stiffness, compliance or flame rating.

Optical clear PC
88% light transmission
Lexan 9034 / Makrolon type sheet and rod: the general-purpose choice for transparent guards, windows and housings.
UV-stabilized
Outdoor guards and windows
UV-stabilized and hard-coated sheet for outdoor guards and windows; the hard coat stays intact when edges are machined dry, so we cut it without coolant.
Glass-filled PC
10–30% GF, opaque
For structural housings and fixtures that need higher stiffness and lower creep than unfilled PC and do not need transparency.
FDA / USP Class VI
Autoclavable, limited cycles
For medical and food-contact components that need a compliant grade and survive a limited number of autoclave cycles.
Flame-retardant PC
UL 94 V-0
For electrical enclosures and battery housings where the part must meet a UL 94 V-0 flame rating while staying tough.
Colored and tinted
Smoke, bronze and opal
Colored and tinted sheet for display and lighting parts that need a smoke, bronze or opal look instead of fully clear polycarbonate.

CNC milling machine cutting clear polycarbonate block

±0.01 mm
Rigid features under 50 mm
±0.05 mm
Large sheet parts, thin walls
Ra 0.8–1.6
As-machined finish (µm)
85%+
Transmission, vapor polished

Polycarbonate CNC Machining at DEK

PC cuts well with sharp carbide tools, PC-safe cooling and annealing before finish passes, inspected at 23 °C after annealing.

1

CNC Milling

CNC milling on 3-, 4- and 5-axis machines for guards, windows, fluid manifolds, enclosures and lens blanks.
2

CNC Turning

CNC turning for sight glasses, lens rings, bobbins and threaded caps, with sharp tools to keep surfaces clear.
3

Drilling and Tapping

Tapping and drilling with slow-helix drills, peck cycles and 0.1 mm oversize on clearance holes so fasteners never load the hole wall.
4

Engraving & Text Milling

Text milling and engraving for scales and legends behind clear windows; bonding of multi-piece assemblies on request.

Design & Machining Tips for Polycarbonate

How our engineers prevent stress cracking, haze and fit problems on machined polycarbonate parts.

1

Anneal Before Finishing

We anneal PC blanks at 120–125 °C for one hour per 3 mm of thickness with a slow cool. See what is annealing.
2

Solvents and Coolants

Ketones, aromatic hydrocarbons, many coolants and some threadlockers craze PC. We cut dry with air blast or a verified PC-safe coolant.
3

Thermal Expansion

65 µm/m·K is about three times aluminum: a 200 mm window in an aluminum frame needs 0.3 mm of clearance for a 30 °C swing.
4

Corners and Edges

Internal corners initiate cracks under impact: specify 1 mm radii and a 0.5 mm chamfer on all edges, and never a sharp notch at a slot end.
5

Thin Walls

1.5 mm minimum for machined walls, 2 mm on parts that will be vapor polished. Below 1 mm PC deflects and melts against the cutter.
6

Holes and Fasteners

Oversize holes by 0.1 mm, countersink and use washers: a screw tightened against a sharp hole edge cracks machined polycarbonate parts.

When to Choose Polycarbonate vs Acrylic, Ultem or ABS

How polycarbonate compares with the clear, high-heat and opaque plastics engineers most often weigh it against.

Criteria	This MaterialPolycarbonate	Acrylic	Ultem (PEI)	ABS
Best for	Guards, housings	Lenses	Autoclaving	Opaque parts
Max temp	120 °C	80 °C	170 °C	–
Impact	Highest	Lower	–	Lower
Clarity	Clear	Clearer	No	Opaque
Cost	Moderate	–	5× PC	Cheaper

Where Machined Polycarbonate Parts Are Used

Wherever a clear part must survive impact, polycarbonate replaces glass and acrylic across these industries.

CNC Machining + Finishes for Polycarbonate

Machined PC parts can receive clarity, texture or coating finishes; anodizing and plating do not apply to polycarbonate.

PC Finishes

Vapor polishing
Buff polishing
Bead blasting
Painting and masking
Laser marking

Need hard-coat or anti-fog? Ask our engineers for a quote.

Polycarbonate Machining FAQ

Common questions from engineers specifying machined polycarbonate parts.

Is polycarbonate hard to machine?

It is easy to cut but easy to ruin. PC cuts well with sharp carbide tools and moderate feeds, but incompatible coolants craze it, dull tools melt it and skipped annealing leaves stress that cracks later. A shop with a plastics process controls all three.

Why does machined polycarbonate crack after delivery?

Almost always residual stress plus a solvent: cleaning agents, threadlocker, adhesive or the wrong coolant during PC machining. Annealing after roughing and before final passes removes the stress; specifying compatible chemicals in assembly removes the trigger.

Can CNC polycarbonate parts be optically clear?

Yes. Machined faces come off the tool translucent; vapor polishing returns them to 85%+ light transmission, and flat windows can be buff polished. Acrylic still polishes clearer if optical quality is the priority.

What tolerance can you hold on polycarbonate CNC machining?

±0.01 mm on rigid features under 50 mm and ±0.05 mm on large sheet parts, measured at 23 °C after annealing. PC is the most stable of the transparent plastics, with expansion about three times that of aluminum.