Polyimide PI CNC machining
PI parts for high-temperature and insulating applications
We CNC mill and turn polyimide (PI) parts to customer drawings. Before cutting starts, we review the specific grade, stock form, working conditions, geometry, and tolerance requirements to assess feasibility.
PI is not one interchangeable material. Grades can differ in filler content, stiffness, wear behavior, and dimensional stability. We do not assume every grade suits the same temperature, load, or insulation requirements.
Material grade and stock form are part of the machining review—not just the polymer name.
3 / 4 / 5-axis
Milling options for prismatic parts and multi-face features
Turning to Swiss-type
Processes for bushings, sleeves, pins, and slender parts
±0.01 mm*
Listed capability for many machines, subject to part and material conditions
ISO 9001 · ISO 13485 · AS9100D · ISO 14001 · IATF 16949
Quality management systems certified within each certificate’s defined scope
*Listed machine figures describe capability under suitable conditions. PI grade, wall thickness, feature size, clamping, and stress relief affect achievable tolerance.
Start with the material
Why we review PI grade by grade
An unfilled PI sheet, a graphite-filled grade, and a PTFE-modified grade may behave very differently during cutting and in service. Thermal expansion, moisture pickup, and dimensional change after material removal can also vary. We check the datasheet and the intended application before quoting.
Temperature
We check continuous and peak service temperatures for the specific grade, not the polymer family.
Mechanical load
We consider compression, bending, and clamping or fastening forces in the assembly.
Electrical insulation
We confirm the required insulation properties and whether any filler could affect them.
Dimensional stability
We review expected dimensional behavior across the operating temperature range.
When these inputs are missing, we ask for them before proceeding. Quoting without them can result in parts that pass an initial inspection but move out of tolerance in service.
Material supply and part geometry
Stock forms shape the machining plan
PI is commonly supplied as sheet, plate, rod, or block. Stock form affects material removal, residual stress, and the practical approach to flatness and roundness. We can work with customer-supplied material or discuss sourcing for the project.
Sheet and plate
Suitable for flat parts, spacers, washers, and insulating plates. Thin sheet can distort when clamped; parts below a few millimeters thick may need a planned support strategy and multi-step cutting.
Rod
Used for turned bushings, sleeves, pins, and insulating shafts. Rod diameter and straightness matter; long, slender parts may need support or a Swiss-type approach.
Block
Useful for complex milled housings and brackets. Heavy removal may release residual stress, so we may rough the part, allow it to settle, and then finish.
Supply and traceability
Tell us the stock form and size, whether you need us to recommend stock, and whether your supplier can provide certified material traceability. We confirm the required stock size before quoting.
Process selection
We choose the process around the part
Geometry and tolerance requirements—not equipment availability alone—guide our process selection. Reducing setups can help preserve relationships between features.
CNC milling
Our 3-axis machining centers handle many flat-faced and prismatic parts, including plates, brackets, and insulating mounts. 4-axis and 5-axis machining can suit parts with multiple faces or angled features that would otherwise require multiple setups.
CNC turning
Our CNC lathes produce bushings, sleeves, spacers, and round insulating parts. We establish outside-diameter and bore concentricity during setup and check it with a concentricity measuring instrument when specified.
Turn-mill machining
For turned diameters combined with milled flats, slots, or cross-holes, turn-mill equipment can reduce handling between operations and help keep feature relationships consistent.
Swiss-type machining
For small, slender components, Swiss-type lathes support the material close to the cutting zone. This can help with small-diameter pins and fine turned features where deflection is a concern. Our Swiss-type equipment includes 5-axis and 6-axis lathes.
Auxiliary operations
We use conventional milling and small surface grinders for preparation, datum faces, and finishing steps where the drawing requires them.
Equipment capacity
A broad machining setup for varied PI part families
The listed machine figures describe capability under suitable conditions. PI tolerance depends on grade, wall thickness, feature size, and how the part is clamped and relieved. We confirm expected capability during the review and flag tolerances we do not expect the material to hold reliably.
25 three-axis machining centers, listed at ±0.01 mm
1 four-axis machining center, listed at ±0.01 mm
8 5-axis CNC machines, at ±0.01 mm
43 CNC lathes, listed at ±0.01 mm
30 automatic lathes, listed at ±0.02 mm
15 CNC turn-mill machines, listed at ±0.01 mm
4 + 2 + 4 five-axis, six-axis, and other Swiss-type lathes, listed at ±0.01 mm
7 gang-type CNC lathes, listed at ±0.01 mm
20 screw machines, listed at ±0.05 mm
4 + 2 conventional milling machines and small surface grinders for auxiliary work
Inspection and quality
Dimensional control for PI parts
We measure PI parts under controlled room conditions and check them against the drawing. Because temperature and moisture can affect dimensions, we recommend stating measurement conditions in the drawing or RFQ. Inspection scope is agreed before production, not after.
Our quality management systems are certified to ISO 9001, ISO 13485, AS9100D, ISO 14001, and IATF 16949, within the defined scope of each certificate. Ask us for current certificates and scope if required for supplier qualification.
Inspection resources
- Coordinate measuring machine for 3D dimensional and geometric inspection
- Five 2D optical measuring systems for profiles, hole positions, and small features
- Height measuring instruments and height gauges
- Concentricity measuring instrument
- Surface roughness tester for finish verification
- Digital and dial calipers, micrometers, and gauge blocks for in-process and final checks
- Thread ring and plug gauges from M1.0 to M16
- Pin gauges for hole diameter and fit
If you need a first-article report, dimensional records, or feature-specific inspection data, include the requirement in your RFQ.
Design and process risks
Where PI machining can go wrong
We review common risks early and adjust the process to the confirmed grade, geometry, and application. Open one topic for details.
Chipping and edge damage +
Thin walls, sharp corners, and small holes close to edges can chip, particularly in unfilled or brittle grades. We adjust tool geometry, feed, and support, and avoid unnecessary sharp internal corners where the design allows a small radius.
Heat and tool wear +
Some PI grades are abrasive, and filled grades can wear tools faster than unfilled stock. Poor chip evacuation can also cause local heating and surface defects. We set cutting parameters through trial cuts for each grade.
Residual stress and distortion +
Heavy material removal can release stress, and thin sections may warp after the fixture is released. For tight flatness or concentricity, we may rough, allow the part to relieve, and then finish.
Dimensional change +
PI expands differently from metals, and moisture can affect some grades. Clearances designed for metal-to-metal fits may bind or loosen. We can review clearances and fits as part of the design check.
Surface finish +
Tool marks or fibers may be visible depending on grade and finishing pass. If a sealing face, bearing surface, or visible finish matters, specify the roughness value and measurement method.
Project fit
Which PI projects fit our process?
This is a starting point, not a substitute for reviewing the actual grade, geometry, and working conditions.
When machining from stock may not be the best route
Some applications may suit a different material or production method, such as molding for higher volumes or geometry better suited to that process. If we see a concern, we will raise it during the review rather than quote a machined part that may not perform.
| Project condition | Our typical approach |
|---|---|
| Insulating parts with a clear grade and datasheet | Review and quote after material confirmation |
| Small turned bushings or pins in PI rod | Turning or Swiss-type machining, depending on length and diameter |
| Flat or prismatic insulating plates | 3-axis milling with stress-aware sequencing |
| Multi-face housings or angled features | 4-axis or 5-axis milling to reduce setups |
| Thin sheet with tight flatness | Feasibility review first; support strategy may be required |
| Unknown operating temperature or load | We hold the quote until conditions are defined |
| Prototype to validate a material choice | Possible once grade and stock form are confirmed |
RFQ checklist
What to send with your PI machining request
Complete information helps us assess feasibility sooner. If you do not have everything, send what you have and we will identify what is missing and which details affect feasibility.
- PDF or STEP drawing with dimensions, tolerances, and GD&T callouts
- PI grade and supplier datasheet, or your approved material specification
- Stock form and size, or a note that you need us to recommend it
- Continuous and peak operating temperature range
- Mechanical loads, clamping conditions, and assembly fit requirements
- Electrical insulation requirements, if applicable
- Surface finish requirements and measurement method
- Inspection needs, including first-article or dimensional report requirements
- Annual or project quantity, and whether you need prototypes, repeat orders, or production runs
PI machining feasibility review
Send us your drawing and working conditions
Share your complete material specification, PI grade or datasheet, stock form, drawing, temperature range, load conditions, and quantities. We will review material suitability, machining approach, tolerance risk, and inspection scope, then respond with a quotation or questions.
Our address is Yabian Community, Shajing Street, Baoan District, Shenzhen, China. You can also use the YJCNC contact form to submit files and project details.
Submit your PI project