01
Bores that wander after annealing
Parts that leave the machine on size can creep out of tolerance once they see 150 °C. Glass-filled PEI makes it worse. We rough, stress-relieve, then finish so the final cut is the last one the part sees.
PEI / Ultem CNC Machining
Precision CNC Machined PEI Plastic Components
PEI holds tight tolerances at high temperature. We machine it on 5-axis centers to ±0.005 mm, from one prototype to 10,000+ parts. Free DFM analysis within 12 hours.
±0.005 mm tolerance16 five-axis centersNo MOQ12-hour quote100% inspection
±0.005 mmMachining tolerance
16Simultaneous 5-axis centers
99.99%Qualification rate
3–5 daysParts ship in
Where PEI jobs go wrong
Four failures that cost you a build
PEI punishes the wrong setup. Check whether any of these sound familiar.
02
Chips that weld instead of clear
PEI has low thermal conductivity, so heat stays at the edge. Run the wrong feed and you get smeared flutes, burned corners, and a scrapped cavity. Sharp tooling, air blast, and conservative depth of cut keep the cut clean.
03
Thin walls that deflect mid-cut
A 0.8 mm PEI rib will push away from the cutter before it shears. Light radial passes and support on both sides hold the wall. Otherwise you chase a dimension that keeps moving and burn a day on one part.
04
Quotes that hide the second operation
A shop quotes milling only, then adds fixtures, annealing, and CMM time after you place the order. Your program slips a week and nobody flagged it. We price the whole route up front.
How we run PEI
Machining PEI is a thermal problem before it is a geometry problem
Tooling, fixturing, and stress relief decided before the first cut.
Tooling and heat
Keep the heat in the chip, not in the part
PEI cuts like a hard, brittle plastic. Unfilled grades machine cleanly with sharp carbide at high surface speed. The 30% glass-filled grades dull an edge fast, so we change tools on a count rather than on a schedule.
We use air blast instead of flood coolant. PEI absorbs moisture and does not need the cooling, and dry chips are easier to clear from pockets. Compressed air keeps the cavity clean and the part dry.
- 1Sharp carbide, high rakeCuts PEI instead of rubbing it
- 2Air blast, no floodKeeps PEI dry and chips clear
- 3Conservative depth of cutLimits heat at the cutting edge
Fixturing and stability
Hold the part without crushing it
PEI is stiff for a plastic but it is not aluminum. Clamp it like metal and you mark the surface; clamp it light and it moves. Soft jaws machined to the part profile spread the load and hold size.
For thin ribs and long bores, we rough oversize, let the part relax, then take a light finishing pass. On a 4,000 mm envelope, we can hold a long PEI beam flat without a custom weldment fixture.
- 1Soft jaws to profileClamping pressure spread over the face
- 2Rough, relax, finishFinal cut lands on a stable part
- 3Ø400 mm rotary tableBores and slots in one setup
Grade selection
Which PEI grade fits your part
Pick the grade before you pick the tolerance. The two interact.
| Grade | Best for | Watch out for |
|---|---|---|
| PEI unfilled | Transparent parts, tight bores | Lower stiffness at 170 °C |
| PEI 30% glass filled | Structural brackets, high load | Tool wear, abrasive chips |
| PEI 30% carbon filled | Stiffness and EMI shielding | Conductive, not for insulators |
| PEI extruded rod | Prototypes, low volume | Residual stress in thick sections |
| PEI injection molded | High volume, simple shapes | Tooling cost above 10,000 parts |
What we do
Services that cover the whole PEI part
One shop from first article to production run.
01
5-Axis CNC Machining
16 simultaneous 5-axis centers cut complex PEI geometry in fewer setups. Fewer setups means fewer chances to lose a datum.
02
4-Axis and 3-Axis Milling
39 mills handle flat plates, housings, and manifolds. Good fit when the part has one dominant face and simple side features.
03
CNC Turning and Mill-Turn
16 mill-turn centers turn and mill PEI bushings, insulators, and threaded bodies without a second operation.
04
Rapid Prototyping
One-off PEI parts ship in 3–5 days. Useful for fit checks before you commit to a molded design.
05
Surface Finishing
Bead blasting, tumbling, and polishing. PEI takes a matte or gloss finish without a coating.
06
Inspection and Reporting
100% inspection before shipment with reports on request. Raw material, in-process, and final checks.
Capability range
What we can hold on PEI
Numbers from our floor, not a brochure.
| Item | Range | Notes |
|---|---|---|
| Tolerance | ±0.005 mm (±0.0002 in) | On critical features |
| Surface finish | Ra 0.8–1.6 μm | As-machined standard |
| Max part size | 4,000 mm | Long beams, rails, panels |
| Rotary work | Ø400 mm table | Bores and slots, one setup |
| Volume | 1 to 10,000+ parts | No minimum order quantity |
| Lead time | Quote in 12 hours | Parts ship in 3–5 days |
Why GreatLight
Built for plastic and metal in the same shop
Fifteen years of tooling decisions, backed by numbers.
2011
15 years in business
Founded in 2011. Three wholly-owned plants and 7,600 m² of floor space in Dongguan and Singapore.
127
High-precision CNC machines
16 five-axis centers, 12 four-axis mills, 27 three-axis machines, and 16 mill-turn centers under one roof.
±0.005
Millimeter tolerance
Held on critical PEI features, with 100% inspection and reports available on request.
12 h
Quote turnaround
Quotation and free DFM analysis within 12 hours. Production can start within 24 hours of approval.
99.99%
Qualification rate
Raw material check, in-process monitoring, and final inspection before anything leaves the dock.
<2%
Late-delivery risk
Historical late-delivery probability below 2%. Parts ship in 3–5 days on standard work.
7,600 m²Manufacturing space
150Technicians
3Wholly-owned plants
10,000+Part runs supported
Where PEI parts go
Industries that specify PEI
Aerospace
Interior brackets and duct parts that must pass smoke and flammability rules.
- ±0.005 mm
- 100% inspection
Automotive and EV
Under-hood connectors and sensor housings that see 150 °C and stay on size.
- IATF 16949
- 3–5 day ship
Robotics and Automation
Insulating links and gripper jaws that need stiffness without adding weight.
- 5-axis
- No MOQ
Medical Devices
Sterilizable housings and manifolds where PEI survives repeated autoclave cycles.
- ISO 13485
- NDA on request
FAQs
Questions engineers ask before sending a PEI job
What tolerance can you hold on PEI?
We hold ±0.005 mm on critical features of PEI parts. That figure assumes the part is not so thin that it deflects under its own clamping load.
If your drawing calls out tighter than that, send it anyway. We will tell you in the DFM review whether the geometry supports it or whether the design needs a change.
Does PEI need annealing after machining?
Sometimes. Thick sections and parts that will run above 150 °C benefit from a stress-relief cycle between roughing and finishing.
Thin plates and small bushings usually do not need it. We decide per part based on wall thickness and the temperature it will see in service.
Which PEI grade should I pick?
Unfilled PEI for transparency, tight bores, and electrical insulation. It machines cleanly and takes a good finish.
Glass-filled PEI for structural parts that carry load. It is stiffer and more dimensionally stable, but it wears tooling and the chips are abrasive. Carbon-filled grades add stiffness but turn the part conductive.
Can you machine PEI and metal parts for the same assembly?
Yes. We cut aluminum, stainless, steel, titanium, and plastics in the same shop, so an assembly with a PEI insulator and a metal housing stays in one production route.
That matters for tolerance stack-up. Holding both halves to the same datum avoids a mismatch when the parts meet.
What is the minimum order quantity for PEI parts?
There is no minimum order quantity. We run everything from a single prototype to 10,000+ part runs.
One-off PEI work is common for fit checks. If the design later moves to injection molding, the CNC part becomes your reference.
How fast can I get a quote and parts?
Quotation and free DFM analysis come back within 12 hours. Production can start within 24 hours of approval.
Standard parts ship in 3–5 days. Our historical late-delivery probability is below 2%.
Will you sign an NDA for my PEI design?
Yes. Uploads are secure and confidential, and we sign an NDA on request.
That covers drawings, CAD files, and any process notes you share during the DFM review.
What surface finish can PEI take?
As-machined PEI comes off the machine around Ra 1.6–3.2 μm. Our standard finishing target is Ra 0.8–1.6 μm, and we can reach Ra 0.2–0.8 μm on sealing faces.
Bead blasting gives a uniform matte look. Polishing brings unfilled PEI close to its natural amber transparency.
Send your PEI drawing and get a quote in 12 hours
Free DFM analysis, no minimum order quantity, and 100% inspection before shipment.
12-hour quote100% inspectionNo MOQNDA on request
