Custom Plastic CNC Machining
- 3-, 4- and 5-axis CNC milling & turning
- Prototypes & low-volume production
- Tolerances to ±0.10 mm
- Ships to 50+ countries
Companies Served
Parts Manufactured
Years in Business
Countries Served
RpProto provides CNC plastic machining services with tight tolerance, quick turnaround times, and reasonable price. We have hundreds of state-of-the-art 3-axis, 4-axis, and 5-axis CNC milling machines to manufacture precision parts with complex geometries.
We have rich knowledge of thermoset and thermoplastic-engineered materials. We can fulfil complex orders for prototypes and low-volume production runs in various plastics and surface finish options.
CNC plastic machining can reduce setup time and cost since it enables us to make complex parts in a single setup. RpProto has been delivering CNC plastic machining and fabricating plastic components for global customers at competitive pricing for more than 20 years.
18+ Plastics for CNC Machining
From commodity thermoplastics to high-performance engineering polymers. Each material page includes full mechanical data, machining notes, and application examples.
General-purpose thermoplastic. Excellent machinability, dimensional stability, impact resistance.
High-performance polymer. Withstands 260 °C, chemical attack, and radiation. Medical & aerospace grade.
Low friction, high stiffness, excellent dimensional stability. Ideal for gears, bushings, and sliding parts.
Excellent impact strength, abrasion resistance, and fatigue endurance. Widely used in mechanical parts.
High impact strength, optical clarity, and heat resistance. Suitable for transparent housings and lenses.
Crystal clarity and excellent weatherability. Common substitute for glass in displays, lenses, and covers.
Lowest coefficient of friction of any solid. Chemically inert, wide temperature range, FDA compliant.
Chemical resistance, low density, and good fatigue resistance. Ideal for lab equipment and containers.
High strength-to-weight ratio, flame retardant, UL94 V-0 rated. Aerospace interior and medical applications.
Low-cost, chemically resistant, lightweight. Tanks, pipes, food-contact, and industrial components.
Rigid, durable, flame-retardant. Electrical insulation, plumbing fittings, and structural panels.
Autoclavable, hydrolysis-resistant. Leading choice for sterilizable medical and dental components.
Also available: PET, LDPE, PSU, PS, Acetal — view all plastic materials →
Tight Tolerances
Hundreds of machines at our Xiamen facility. The right axis configuration is selected based on part geometry, tolerance requirements, and production volume.
3-Axis CNC Machining
Best for prismatic parts that don’t require access from multiple sides. Fastest setup and most cost-effective for simple geometries.
- Drilling, pocketing, slotting
- Flat and stepped surfaces
- Standard brackets and plates
- Most cost-effective option
4-Axis CNC Machining
Adds rotational access to one additional face, enabling side-milling of slots, holes, and other features without re-fixturing.
- Helical and spiral features
- Holes & slots on part sides
- Cylindrical and tubular parts
- Reduced setup vs. re-fixturing
5-Axis CNC Machining
Full simultaneous motion across all five axes. Produces the most intricate geometries and undercuts in a single setup — highest precision.
- Complex contoured surfaces
- Undercuts and deep pockets
- Aerospace & medical parts
- Best surface finish quality
Standard Tolerances
Our standard tolerances apply to all plastic CNC machined parts unless a drawing specifying tighter requirements is supplied. With a formal GD&T drawing, tolerance quality equivalent to IT11 or better can be achieved on stable materials such as POM and PEEK.
Note: hygroscopic materials such as Nylon (PA66) can absorb atmospheric moisture and show slight dimensional variation. Our engineers account for this in production planning.
| Dimension | Tolerances |
|---|---|
| 0.5 – 6.00 mm | ± 0.10 mm |
| 6.00 – 30.00 mm | ± 0.20 mm |
| 30.00 – 120.00 mm | ± 0.30 mm |
| 120.00 – 400.00 mm | ± 0.50 mm |
| 400.00 – 1000.00 mm | ± 0.80 mm |
| Angular: ±0.5° | |
| Surface Roughness 3.2μm Ra | |
With drawing: Tolerance quality equivalent to IT11 can be achieved.
Without drawing: ISO 2768 medium
Key Advantages
Fast Turnaround — No Tooling Required
Unlike injection molding (which requires 4–8 weeks and $3,000–$30,000 in mold tooling), CNC machining begins the moment your CAD file is approved. Prototype lead times as short as 3–5 business days.
Cost-Effective for 1–500 Parts
No minimum order quantities. CNC is the most economical technology for quantities from a single prototype up to several hundred production parts. Injection molding only becomes competitive above ~1,000 units.
Tight Tolerances to ±0.10 mm
CNC machining consistently achieves tighter tolerances than FDM 3D printing (±0.5 mm typical) or vacuum casting (±0.2 mm). Critical for parts that must mate, seal, or fit within assemblies.
Isotropic Mechanical Properties
Machined parts inherit the full mechanical properties of the base material in all directions — unlike 3D-printed parts, which are weaker along the Z (layer) axis. What you spec is what you get.
Surface Finishes for Plastic Parts
Multiple finishes can be combined on a single part. Our engineers recommend the optimal process for your material and application.
Painting / Coating
Wet spray, rubber coat, or PU paint. Materials such as Nylon and PP require flame or corona pre-treatment to ensure paint adhesion before coating.
Pad Printing & Laser Marking
Add logos, part numbers, or instructions directly onto the plastic surface. Laser marking offers permanent, high-resolution results without ink.
Polishing
Progressive sanding (400→2000 grit) followed by buffing. Achieves semi-gloss or gloss surface. Essential for PMMA/Acrylic optical clarity.
Inspection & Quality Assurance
Incoming Material Inspection
All raw plastic stock is verified against material certificates before entering production. No unqualified material reaches the machine.
In-Process Quality Control
Critical dimensions are checked during machining to catch deviations early, before full production runs.
3D Coordinate Measuring Machine
Final parts are inspected using a CMM for complex geometries and multi-feature dimensional verification. Inspection reports available on request.
Upload your CAD files and provide further project details.
We'll analyse your design and send you a quotation.
We'll begin the manufacturing process after you accept our quote. We also offer finishing options.
The manufacturing process will be finished very soon, and Your custom parts will be shipped to you.
CNC Plastic Machining FAQs
Plastic CNC machining is a subtractive manufacturing process in which a computer-controlled cutting tool removes material from a solid plastic block to produce a precision part. Using 3-axis, 4-axis, or 5-axis CNC mills and lathes, complex geometries can be achieved with tolerances as tight as ±0.10 mm — tighter than most 3D-printed parts and without the tooling investment required by injection molding.
RpProto’s standard tolerances range from ±0.10 mm for small features (0.5–6 mm) up to ±0.80 mm for large spans (400–1000 mm). Angular tolerance is ±0.5° and default surface roughness is Ra 3.2 μm. With a technical drawing specifying tighter requirements, we can achieve tolerance quality equivalent to IT11 or better on stable materials such as POM and PEEK. Note that hygroscopic plastics like Nylon can exhibit slight dimensional variation due to moisture absorption — our engineers plan for this in production.