Thermal expansion
Review grade, tool sharpness, heat removal and coolant compatibility. Agree the temperature and material condition for final measurement rather than transferring a metal cutting recipe.
Engineering Plastic CNC Machining
Assess a polymer part under its intended operating and measurement conditions. Confirm the manufacturer grade, fillers, stock condition, critical features and environment before machining and inspection are agreed.
Where engineering plastics fit
Jaquent reviews drawing-defined plastic parts for turning and milling, including wear, sealing, insulating and structural features. Commonly reviewed families include POM, PTFE, PPS, PEEK and nylon; ABS is documented in the case below. Other grades require project review.
Specify the manufacturer grade, filler content, color and supplied condition where required. Operating temperature, load, medium and moisture exposure matter together. A polymer family name does not establish a universal service temperature, chemical compatibility or regulatory suitability.
Thermal expansion, clamping, residual stress and conditioning affect dimensions. About ±0.05 mm is an existing planning reference that needs feature-specific DFM review, not an acceptance limit for every polymer or geometry. State the supported or free measurement condition and final-use requirements. Use the CNC material selection guide if the grade remains undecided.
Engineering plastics we machine
POM / acetal
Review POM grade, wear duty and critical geometry for fittings, bushings or guides. Confirm dimensional limits and measurement state for the part.
PTFE / Teflon
Specify the PTFE grade, medium, temperature, load and sealing requirement. Soft stock and movement under clamping need a suitable machining and inspection plan.
PEEK
Specify the PEEK grade, fillers and operating conditions. Temperature, load, wear and any annealing or documentation requirements are confirmed for the project.
Plastic selection guide for CNC machining
| Specified family | Functional inputs | Machining considerations | Acceptance inputs | Condition to confirm |
|---|---|---|---|---|
| POM / acetal | Load, wear, temperature and environment | Support, edge burrs and local stiffness | Critical fits and final supported/free state | Exact grade, stock and material records |
| PTFE | Medium, sealing pressure, load and temperature | Soft-stock deformation and recovery after clamping | Final geometry, restraint and measurement force | Grade and any fillers |
| PPS | Temperature, medium, load and electrical requirements | Filler-related tool wear and thin-feature stiffness | Critical dimensions and final measurement state | Manufacturer grade and filler content |
| PEEK | Temperature, load, wear and insulation requirements | Residual stress, clamping and grade-specific behavior | Required size and geometric relationships after agreed operations | Grade, fillers and any conditioning |
| Nylon PA6 / PA66 | Humidity, water, temperature and wear duty | Moisture-related movement and support | Measurement and service conditioning | Exact grade, stock and moisture state |
Plastic machining risks and DFM controls
The ABS case below contains owner-reported manufacturing facts and acceptance. No drawing, readings or inspection report was supplied for independent review. Thickness was checked individually; flatness and radial runout were sampled, and hole location was not separately inspected.
Clamp crush and spring
Soft stock dents under hard jaws and springs back when released. Control: soft jaws, distributed pads, light clamp force, and supported fixtures on thin walls.
Micro-burrs and edge quality
Some grades tear rather than shear. Control: sharp geometry, planned climb strategies where suitable, and dedicated deburr so assembly edges stay safe.
Nylon moisture and filled-grade abrasion
Nylon dimensions respond to moisture uptake and release. Filler type and content also affect machining behavior and tool choice. Identify the supplied grade and the condition required for assembly so stock preparation and inspection can be reviewed together.
CNC-Machined ABS Discs: Process Control and Inspection for a 100-Part Batch
The requirement
A customer ordered 100 ABS discs machined directly from ABS bar stock. The parts featured an outer diameter, a circular step and peripheral holes. Thickness, hole location, flatness and the alignment of the stepped diameter with the outer diameter were key production requirements.
The machining approach
The stepped diameter and outer diameter were machined in the same setup to reduce positioning error from reclamping. The peripheral holes were drilled on a machining center.
To help prevent post-machining warpage, the team controlled clamping force, separated roughing and finishing, and adjusted cutting parameters. Hole edges were deburred using in-machine chamfering followed by manual deburring.
Inspection for batch consistency
Each disc's thickness was checked with a micrometer.
Flatness was checked by batch sampling with a dial indicator on a surface plate. Radial runout of the stepped diameter relative to the outer diameter was also checked by batch sampling with an indicator, against the customer drawing limit of 0.1 mm maximum.
Hole location was not separately inspected. The radial runout check is reported as runout, without claiming a separate concentricity measurement.
Delivery outcome
The 100 discs were delivered, and the customer accepted the batch. This case illustrates how machining choices and a combination of individual thickness checks and sampled geometric checks supported the delivery of a batch of ABS components.
Discuss a similar part
Request a Quote for your ABS components. Share your drawing, quantity and critical dimensional requirements so the machining and inspection approach can be reviewed for your parts.
ABS disc photographs
Batch photograph
Stacks of machined ABS discs in a cardboard box.
Single-part detail
Handheld view of one ABS disc with peripheral holes and a circular stepped feature.
ABS disc machining footage
Lathe machining footage of the disc components from this case, with the part linkage confirmed by the owner. The video shows a machining stage; it is not inspection evidence or a record of the complete manufacturing route.
Machined engineering-plastic evidence
The pocket-milling image provides process context for polymer support, heat and chip removal. It does not identify the grade or establish dimensional acceptance. Confirm material condition, clamping and the final measurement state for your drawing.
Plastic tolerances and inspection
About ±0.05 mm is an existing plastic planning reference, subject to grade, geometry and DFM review. Agree the actual requirements for each feature, including temperature, humidity, conditioning and supported or free state during measurement. Tighter limits need review rather than a transferred metal capability.
For moisture-sensitive stock, distinguish the condition at machining and dispatch from the condition expected in service. State the agreed conditioning, temperature and humidity for acceptance, together with any assembly restraint. A dimension measured on dry, freely supported stock can change after moisture uptake or installation.
Pre-shipment inspection at the authorized manufacturing facility follows the drawing and agreed plan. Every-part checks apply to named features when specified; other checks can follow agreed sampling. Request material records, traceability, dimensional reports, customer FAI forms or a CoC in the quotation, with coverage and format confirmed. See functional tolerances and GD&T and inspection scope and required records.
Finishes and secondary operations for plastics
Controlled deburring, polishing where appropriate, cleaning, and stress-relief or annealing only when agreed are available or coordinated per project. Do not copy metal finishing language onto polymers. Coatings are grade-specific — confirm compatibility during DFM. Details: CNC surface finishes.
What to include in your plastic RFQ
Send a package that lets engineering quote without guessing:
- Exact polymer and manufacturer grade if required, plus virgin or filled and filler percentage
- Color, operating temperature, and humidity or chemical exposure
- Quantity and target delivery window
- Critical fits, threads, and cosmetic faces
- Requested traceability / FAI / MTR documents
Upload CAD via Request a Quote. The Material field can be prefilled and remains editable.
STEP and a marked PDF are recommended when available. Technical details and attachments are optional form fields; identify missing requirements for review. See quote preparation and upload formats. With a complete RFQ, we typically respond within one business day; complex multi-process projects may take 1–2 business days.
Ready to start your CNC project?
Share the available drawing, specified material and open requirements for a review of machining, finishing and inspection scope.