Plastic parts we machine cover prototypes, insulators, gears, bushings, wear components, medical-grade PEEK parts and optical acrylic lenses: ABS and POM (Delrin) for general work, nylon 6/6 for wear, PEEK for temperature and sterilization, PTFE for chemical and low-friction use.
Plastics machine differently from metals — thermal expansion is roughly ten times higher and heat builds fast, so we run sharp polished tools, conservative speeds and climb milling to keep edges from melting or chipping. Tolerances reflect the material, not wishful thinking.
Material Grades & Properties
Engineering Plastics Grades We Machine
| Grade | Standard | Characteristics |
|---|---|---|
| POM (Delrin/Acetal) | — | Low friction, high stiffness, dimensional stability; gears, bushings, precision parts. |
| Nylon (PA6/PA66) | — | Tough and wear-resistant; absorbs moisture (dimension planning needed). |
| PEEK | — | High-performance: chemical/heat resistance; medical implants, aerospace; expensive. |
| ABS | — | Impact resistant, low cost; prototyping and housings. |
| PTFE (Teflon) | — | Near-zero friction, chemical inertness; seals and insulators; hard to hold tolerance. |
Key Properties of Machined Engineering Plastics
- ✓Light weight
- ✓Corrosion-free
- ✓Low friction options
- ✓Electrical insulation
Typical tolerances:±0.1 mm typical; thermal expansion and moisture limit precision
Applications for Engineering Plastics Parts
- Gears and bushings
- Insulators
- Seals and wear strips
- Medical device components (PEEK)
- Enclosures and jigs
Machining Notes for Engineering Plastics
Sharp positive-rake tools, moderate speeds, air blast or coolant; watch heat buildup (melting) and clamping pressure (deformation).
Finishes for Engineering Plastics Parts
- As-machined (typical)
- Vapor polishing (select plastics)
- Dyeing
Capabilities
- ABS/POM/nylon/PEEK/PTFE machining to drawing
- Sharp-tool strategies against melting and chipping
- Acrylic flame and buff polishing
- Annealing coordination for stress relief
Typical materials
ABS, POM-C (Delrin), Nylon 6/6, PEEK, PTFE, HDPE/UHMW, polycarbonate, acrylic (PMMA).
| Material / grade | Typical condition | Machinability | Where it fits |
|---|---|---|---|
| Aluminium 6061 | T6 (solution treated and aged) | Easy: free-cutting, good chip control | Brackets, housings, fixtures, prototypes into production |
| Aluminium 7075 | T6 / T651 | Harder: more tool wear, needs rigid setups | High-strength, weight-critical parts; not for welding |
| Stainless 304 / 304L | Annealed | Work-hardens: slower speeds, positive feed | General corrosion resistance, food and process equipment |
| Stainless 316 / 316L | Annealed | Tougher than 304: more tool wear | Chloride, marine, medical and pharmaceutical exposure |
| Carbon steel 1018 / 1045 | As-rolled / normalised | Easy to moderate; needs protection against rust | Shafts, plates, weldments, tooling bodies |
| Brass C360 | H02 half hard | Excellent: high speeds, clean finish | Fittings, bushings, connectors, decorative parts |
| Copper C110 | Annealed / H02 | Gummy: sharp tools and high rake angles | Conductivity, busbars, thermal management |
| Titanium Grade 5 (Ti-6Al-4V) | Mill annealed | Difficult: low speeds, heat control, tool wear | Aerospace, medical and lightweight high-strength parts |
| Engineering plastics (POM, PEEK, PA) | Extruded / annealed | Easy to gummy: soft jaws, sharp tooling | Insulation, low friction, chemical and wear parts |
Finishes
As-machined, deburred, flame/buff polished acrylic, annealed on request.
| Finish | What it does | Specify it when |
|---|---|---|
| As machined | Tool marks left visible; Ra typically 1.6-3.2 µm | The part only has to function |
| Bead blast | Uniform matte surface, hides tool marks | Cosmetic parts before anodising |
| Anodising Type II | Builds an oxide layer; colour options | Aluminium appearance plus mild corrosion and wear resistance |
| Hard anodising Type III | Thicker, harder oxide layer | Sliding or wearing aluminium surfaces |
| Chromate conversion | Thin protective film that stays conductive | Electrical bonding or grounding on aluminium |
| Electroless nickel | Uniform, hard, corrosion-resistant layer | Wear plus corrosion, including inside bores |
| Zinc plating | Economical sacrificial corrosion protection | Steel parts in indoor or sheltered service |
| Powder coat | Thick, durable, decorative layer | Appearance is the requirement |
| Passivation | Removes free iron and restores the oxide film | Stainless parts after machining |
| Stress relief / heat treatment | Relieves residual stress before or after cutting | Thin walls and tight tolerances that must survive machining |
Tolerances
ISO 2768-m general; ±0.05 mm typical, ±0.02 mm on critical features.
| Callout | What it needs | Effect on cost and lead time |
|---|---|---|
| General: ±0.25 mm / ±0.010 in | Standard tooling, dimensional check | Baseline: no adder |
| Standard: ±0.13 mm / ±0.005 in | Machine in good condition, first-article check | Small adder; the usual quoting default |
| Tight: ±0.025 mm / ±0.001 in | Ground or diamond tooling, temperature control, CMM | Step change: slower cuts plus full inspection |
| Precision: ±0.013 mm / ±0.0005 in | Finish passes, gauging, controlled environment | Machining dominates the price; often a separate operation |
| Position / angularity (GD&T) | Datum control, one setup where features are related | Depends on how many setups the datum spans |
| Surface finish Ra 0.8 µm or finer | Finer stepovers, polishing or a finishing pass | Adds a process step, not just machining time |
Related Processes
5-axis CNC machining
used for
CNC Milling
used for
Recycling
used for
Common Applications
- Turning
- cost-sensitive prototypes
- consumer goods
Process Options
- CNC machining is a subtractive manufacturing process.
- Finishing Options: Black Oxide, Electropolishing, ENP, Media Blasting, Nickel Plating, Passivation, Powder Coating, Tumble Polishing, Zinc Plating, Vibratory Tumbling
- EPX 82 is processed using Carbon DLS
- MUD is a type of mold that uses a standard injection molding frame.
- Different taper turning methods suit different jobs. Compound slides often handle short tapers, while CNC interpolation and taper attachments improve repeatability on longer parts
- G92 is used by programming one or more G92's right after the G76 threading cycle
- Estimates are provided through an auto-quoted method.
- EDM relies on a voltage and a thin wire
- Advanced machining processes like micro-machining and EDM are used to create small, precise mold cavities and cores
Surface Finish Reference
- The finish of MoldTech MT11010 is a fine matte texture.
- The finish of MoldTech MT11020 is a medium matte texture.
- The finish of MoldTech MT11030 is a coarse matte texture.
- SPI A-1 has a surface roughness of 0.012–0.025 µm.
- SPI B-2 has a finish of Medium semi-gloss.
- SPI B-2 has a surface roughness of 0.10–0.15 µm.
- SPI C-3 has a surface roughness of 0.63–0.70 µm.
- Super high gloss, polished with a Grade #3 (6000-grit) diamond buff to Ra 0.012–0.025 µm.
- Medium semi-gloss, finished with 400-grit paper to Ra 0.10–0.15 µm.
- Normal matte, polished with 320-grit stone to Ra 0.63–0.70 µm.
Tolerance Reference
- The tolerance with drawing for CNC Milling is as low as +/- 0.005 mm.
- FDM 3D printing offers a low-cost component with average accuracy and uses thermoplastics for 3D printing.
- Wire Cut EDM is highly accurate.
- The U6 H.E.A.T machine achieves tight tolerances.
- Die sinker EDM is capable of maintaining tight tolerances
- The shop needs to have CNC machines that can achieve a specific tolerance.
Industries We Serve
- antennas
- automotive
- CNC machined parts
- custom parts
- electronics
- medical diagnostic
- optical displays
- optical_systems
Material Reference
- ABS
- Austenitic Stainless Steel
- Carbon steel
- ceramic
- composites
- Copper - T2
- copper or graphite
- Hardened Materials
- High Impact Polystyrene
- Low-density polyethylene
- MDF
- metal
- Polybutylene Terephthalate
- SUS304
- thermoplastics
- thick metal sheets
- tungsten carbide
Frequently asked questions
PEEK or Delrin for my application?
Delrin (POM-C) suits precision mechanical parts at moderate cost; PEEK suits high temperature, sterilization and chemical exposure at a premium. We recommend based on the operating environment.
Why are plastic tolerances wider than metal?
Plastics expand and relax with temperature and stress roughly ten times more than metals. ±0.05 mm is typical; we hold ±0.02 mm on critical features with stable material and controlled process.
Can you machine clear acrylic parts?
Yes. We machine acrylic with sharp tools and polish to transparency where the geometry allows — send the drawing and indicate which faces must stay optically clear.
What is the minimum order quantity (MOQ)?
Prototypes from 1 pc. Low-volume production typical 50-500 pcs. No forced MOQ on custom parts; unit price drops with volume.
What is the typical lead time?
Industry benchmark: instant-quote platforms deliver prototypes in 1-3 business days. Our own production: prototypes 5-10 working days, including in-house QC and shipping. Production: 2-4 weeks depending on quantity/finishing. Express options exist; finishing adds days.
How do I get a quote and what information do you need?
3D files (STEP/IGS) + 2D drawing with tolerances. Material, quantity, finish, destination country. Quote turnaround: 24-48h typical.
How is quality controlled?
First-article inspection in our own shop before the first production order. In-process checks. Final inspection report (dimensions) with shipment. Material certs (mill test reports) on request.
Is my design protected?
NDA before file exchange. Files used only for your production. No resale of custom designs.
Which material should I choose?
Function first: strength, weight, corrosion, cost. Common pairings: 6061 general, 304/316 corrosive env., PEEK medical. See materials guide pages.
Which surface finish do I need?
Anodizing for aluminum corrosion/wear/color. Passivation for stainless. Plating for conductivity/steel protection. Cosmetic vs functional distinction.
How do you ship and what terms?
DHL/FedEx/UPS express for samples and small batches. Air/sea freight for production volumes. Incoterms: EXW/FOB/DAP/DDP options.
Sources · 4
- hubs.comIndustry peer technical page
- xometry.comIndustry peer technical page
- uneedpm.comUnclassified source
- us.arrk.comUnclassified source
Technical references cited for verifiability — not supplier recommendations. Browse the research library.
Capability commitments on this page are owner-confirmed (2026-09-21).