Plastic Materials for CNC Machining: Selection Guide
Each material has its characteristics and processing technology. The following common material introduction can help you understand how to choose the material that suits your CNC machining project. Please contact our engineering team, who will provide you with more detailed information.
Best value for money / rapid prototype validation
Start with ABS. Low cost, easy to machine, and sufficient for functional prototypes.
Upgrade to PC or Nylon if higher strength is required.
Extreme high-temperature performance (above 150°C)
Choose PEEK (continuous service up to 260°C).
If the budget is constrained and operating temperatures fall between 150–200°C, consider glass-filled Nylon (GF Nylon) as a cost-effective alternative.
High-precision fits and tight tolerances (±0.05 mm or better)
Choose POM (Delrin). It offers the best dimensional stability of any common engineering plastic — low friction, low moisture absorption, and excellent fatigue resistance.
The go-to material for gears, bearings, and precision mechanical components.
Optical transparency (lenses, display windows, light covers)
- Highest optical clarity → PMMA (Acrylic) (92% light transmission, superior optical quality)
- Transparent + high impact resistance → PC (Polycarbonate) (slightly lower clarity than PMMA, but over 10× the impact strength)
Chemical and corrosive environments (strong acids, alkalis, solvents)
- Ultimate chemical inertness → PTFE (Teflon) (resistant to virtually all chemicals, FDA-compliant)
- High chemical resistance at lower cost → HDPE or PP
- High chemical resistance + high mechanical strength → PEEK
Biocompatibility / medical device applications
- Implant-grade and sterilization-grade → PEEK (ISO 10993 biocompatibility certified, autoclave-stable)
- Non-implant medical contact parts → PC, Nylon (specific FDA-certified grades), POM
Food contact / FDA compliance
Choose from HDPE, PET, POM (Delrin 100 NC010 grade), or PP — all available in FDA 21 CFR food-contact certified grades.
Always confirm the specific grade meets requirements before ordering.
Outdoor / UV-exposed environments
- Best choice: PMMA (Acrylic) (naturally UV-stable, resists yellowing for 10+ years outdoors)
- Alternative: UV-stabilized grade PC (standard PC without UV coating will yellow)
- Avoid: Standard ABS and Nylon (rapid UV degradation without stabilizers)
High wear resistance / low friction (sliding and drive components)
- Near-zero friction → PTFE (coefficient of friction 0.04 — the lowest of any engineering plastic)
- Self-lubricating + high mechanical strength → POM (Delrin)
- High-impact wear resistance (conveyor guides, chain rails) → UHMW-PE
Lightweight + cost-sensitive design
Choose PP or HDPE (density 0.90–0.97 g/cm³ — among the lightest engineering plastics available, with very low raw material cost).
| Material | Tensile Strength | Max Service Temp | Chemical Resistance | Machinability | Impact Strength | Transparency | Cost | Best For |
|---|---|---|---|---|---|---|---|---|
| ABS | 41 MPa | 80°C | Moderate | ★★★★★ | High | Opaque | $ | Prototypes, enclosures |
| POM (Delrin) | 62 MPa | 105°C | Good | ★★★★★ | High | Opaque | $$ | Gears, precision parts |
| PC | 65 MPa | 125°C | Moderate | ★★★★ | Very High | Clear available | $$ | Guards, optical parts |
| PEEK | 100 MPa | 260°C | Excellent | ★★★ | Very High | Opaque | $$$$ | Aerospace, medical |
| Nylon PA66 | 82 MPa | 150°C | Good | ★★★★ | High | Opaque | $$ | Bearings, gears |
| Nylon GF30 | 180 MPa | 180°C | Good | ★★★ | High | Opaque | $$$ | High-strength structural |
| PTFE (Teflon) | 35 MPa | 260°C | Excellent | ★★★ | Low | Semi-clear | $$$ | Seals, chemical linings |
| PMMA (Acrylic) | 72 MPa | 95°C | Moderate | ★★★★ | Medium | Optically clear | $ | Display windows, signage |
| HDPE | 30 MPa | 80°C | Excellent | ★★★★★ | Medium | Opaque | $ | Tanks, pipes, food parts |
| PVC | 54 MPa | 70°C | Good | ★★★★ | Medium | Semi-clear avail. | $ | Pipes, electrical insulation |
| PP | 35 MPa | 110°C | Excellent | ★★★★ | Medium | Semi-clear | $ | Packaging, medical devices |
| UHMW-PE | 40 MPa | 80°C | Excellent | ★★★ | Extremely High | Opaque | $$ | Wear liners, conveyor rails |
| PET | 80 MPa | 120°C | Good | ★★★★ | High | Clear available | $ | Bottles, food-grade parts |
| Material | Tensile Strength | Max Service Temp | Chemical Resistance | Machinability | Cost | Best For |
|---|---|---|---|---|---|---|
| UHMW-PE | 40 MPa | 80°C | Excellent | ★★★ | $$ | Wear liners, conveyor rails |
| PEI / Ultem | 105 MPa | 170°C | Good | ★★★ | $$$ | Aerospace, electronics, medical |
| PPS | 80 MPa | 220°C | Excellent | ★★★ | $$$ | Chemical pumps, automotive |
| PVDF | 55 MPa | 150°C | Excellent | ★★★★ | $$$ | Semiconductor, chemical process |
| PSU / PPSU | 75 MPa | 185°C | Good | ★★★★ | $$$ | Medical sterilisable parts |
| PPA | 100 MPa | 200°C | Good | ★★★ | $$$ | Automotive under-hood, connectors |
| PBT | 58 MPa | 150°C | Good | ★★★★ | $$ | Electrical connectors, housings |
| PAI / Torlon | 190 MPa | 250°C | Excellent | ★★ | $$$$ | Extreme-load bearings, aerospace |
| PI / Vespel | 86 MPa | 300°C+ | Excellent | ★★ | $$$$ | Semiconductor, high-temp aerospace |
ABS, Flame Retardant ABS
– Cost-Effective General Purpose Plastic
- Properties: High impact strength, toughness, electrical resistance
- Advantages: Low cost, excellent for prototyping, good dimensional stability.
- Applications: Functional prototypes, Automotive parts, consumer electronics (e.g., casings for computers and TVs), and household items like toys (e.g., LEGO bricks).
- Tensile Strength : 6,000 psi
- Impact Strength : 2.7 ~ 7.7 ft-lbs / in
- Heat Deflection : 203 ~ 214 ° F
Machining Notes
Recommended Tooling: HSS or carbide end mills, 2–3 flutes
Spindle Speed: 3,000–8,000 RPM
Feed Rate: 500–1,500 mm/min
Depth of Cut: 0.5–2 mm per pass
Cooling: Compressed air only (coolant can cause stress cracking)
Key Notes: ① Poor thermal conductivity — chips must be cleared frequently to prevent heat buildup;
② Thin-walled parts are prone to vibration — use proper fixturing;
③ Surface accepts paint, chrome plating, and vapor smoothing well
Acetal (POM)
– Precision Engineering Plastic
- Properties: High stiffness, low friction, excellent wear resistance, and good dimensional stability.
- Advantages: Durable, easy to machine, and resistant to moisture, chemicals, and fatigue.
- Applications: Gears, bearings, fasteners, automotive components, and electrical insulators, bushings, precision components
- Tensile Strength: ~62 MPa (depends on grade).
- Impact Strength: Moderate, with excellent resistance to repeated stress.
- Heat Deflection: ~105°C under load.
Machining Notes
Recommended Tooling: Carbide end mills, 2–4 flutes, 15–20° rake angle
Spindle Speed: 2,000–6,000 RPM
Feed Rate: 300–800 mm/min
Depth of Cut: 0.3–1.5 mm per pass
Cooling: Dry machining or compressed air — avoid water-based coolants
Key Notes: ① POM is ideal for tight tolerances — standard achievable tolerance is ±0.05 mm;
② Material carries slight internal stress; allow 24 hours at room temperature before final dimensional inspection;
③ Produces a formaldehyde-like odor during machining — ensure adequate workshop ventilation
PC
– Transparent High-Impact Plastic
- Properties: Exceptional impact resistance, optical transparency, high strength, and good dimensional stability.
- Advantages: Very tough, can be transparent, good heat resistance, UV-resistant
- Applications: Safety goggles, automotive headlights, medical equipment, and optical lenses, display windows, protective shields
- Tensile Strength : 8,000-9,500 psi
- Impact Strength : 2.0-16.0 ft-lbs/in
- Heat Deflection : 270-280° F
Machining Notes
Recommended Tooling: Sharp carbide end mills, 2 flutes — dull tools cause material smearing
Spindle Speed: 2,000–5,000 RPM
Feed Rate: 400–1,000 mm/min
Depth of Cut: 0.5–2 mm per pass
Cooling: Dry machining or compressed air — **never use chlorinated solvent-based coolants**
Key Notes: ① For optically clear parts, tools must be extremely sharp — worn tools cause surface hazing;
② PC is stress-sensitive — avoid over-clamping during fixturing;
③ For optical-grade surface finish, follow with polishing or stress-relief annealing
PEEK (Polyetheretherketone)
– High-Performance Engineering Thermoplastic
- Properties: Outstanding mechanical properties, exceptional chemical resistance, high-temperature tolerance (up to 260°C) , and low wear and friction.
- Advantages: Extreme environment performance, biocompatible, wear resistant
- Applications: Aerospace components, medical devices, automotive under-hood parts, oil & gas equipment
- Tensile Strength : 14,000 psi
Impact Strength : 1.55 ft-lbs/in
Heat Deflection : 285-482° F
Machining Notes
Recommended Tooling: Carbide or PCD (polycrystalline diamond) end mills, 2–4 flutes
Spindle Speed: 1,500–4,000 RPM
Feed Rate: 200–600 mm/min
Depth of Cut: 0.2–1 mm per pass
Cooling: Compressed air preferred; water-based coolant acceptable with rust inhibitor
Key Notes: ① PEEK has poor thermal conductivity — use premium carbide tooling as tool wear is accelerated;
② Rough machine to 0.3–0.5 mm stock, then finish machine in a separate operation;
③ Post-machining annealing at 120°C for 2 hours recommended to relieve residual stress;
④ High material cost — validate geometry with ABS prototypes before committing to PEEK
Nylon (PA6, PA66, PA12), Nylon + Glass-Filled
– Strong & Flexible Engineering Plastic
- Properties: High strength, good impact resistance, durable, wear-resistant, and resistant to chemicals and heat.
- Advantages: Chemical resistance, maintains properties over wide temperature range, good electrical insulation
- Applications: Bushings, washers, gears, automotive components, industrial parts
- Tensile Strength : 10,000 psi
- Impact Strength : 0.6 ft-lbs/in
- Heat Deflection : 200-370° F
Machining Notes
Recommended Tooling: HSS or carbide, 2–4 flutes, sharp cutting edges
Spindle Speed: 2,000–5,000 RPM
Feed Rate: 400–1,000 mm/min
Depth of Cut: 0.5–2 mm per pass
Cooling: Dry machining only — **water-based coolants cause moisture absorption and dimensional change**
Key Notes: ① **Moisture absorption is the biggest risk** — dry material at 80°C for 4–8 hours before machining; store finished parts in sealed bags;
② Glass-filled grades are significantly more abrasive to tooling — use carbide;
③ High thermal expansion coefficient — for precision parts, account for ambient temperature during inspection
PP
- Properties: Lightweight, flexible, chemical-resistant, and moisture-resistant.
- Advantages: Low cost, good fatigue resistance, and versatile for various applications.
- Applications: Packaging, containers, automotive components, medical devices, and living hinges.
- Tensile Strength : 4,200 psi
- Impact Strength : 1.2 ft-lbs /in
- Heat Deflection : 96 ~ 195 °F
Machining Notes
Recommended Tooling: HSS or carbide, 2–3 flutes, large rake angle
Spindle Speed: 2,000–6,000 RPM
Feed Rate: 500–1,500 mm/min
Depth of Cut: 0.5–2 mm per pass
Cooling: Dry machining or compressed air
Key Notes: ① PP has high elasticity and tends to spring back during cutting — use sharp tools with a light, low-force cutting strategy;
② Semi-crystalline structure results in lower dimensional stability than POM after machining — not recommended for high-precision mating applications
PET (Polyethylene Terephthalate)
- Properties: High strength, transparency, and excellent moisture and chemical resistance.
- Advantages: Recyclable and ideal for food-grade applications.
- Applications: Bottles, food containers, and fibers for textiles.
- Tensile Strength : 11,500 psi
- Impact Strength : 0.6 ft-lbs/in
- Heat Deflection : 175-240° F
PMMA (Acrylic)
– Optical Clarity Plastic
- Properties: Superior optical clarity (92% light transmission), UV stability, weather resistant
- Advantages: Excellent optical clarity, scratch-resistant, cost-effective, and weather-resistant.
- Applications: Display windows, signage, optical components, automotive light covers, Lenses
- Tensile Strength : 10,800 psi
- Impact Strength : 6.8 ft-lb / in²
- Heat Deflection : 185 ~ 210 °F
Machining Notes
Recommended Tooling: Carbide O-flute end mill (single flute) — purpose-designed for acrylic
Spindle Speed: 8,000–18,000 RPM (high RPM, low cutting force)
Feed Rate: 1,000–3,000 mm/min
Depth of Cut: 0.3–1 mm per pass
Cooling: Compressed air only — **never use water-based coolant** (causes surface whitening)
Key Notes: ① PMMA is **brittle** — slow entry and exit moves are essential to prevent chipping;
② To preserve optical clarity, tooling must be razor-sharp — any vibration causes surface scratches;
③ Final surface quality can be further enhanced with flame polishing or solvent polishing
PTFE (Teflon)
– Ultra-Low Friction Plastic
- Properties: Chemically resistant, thermally stable (-200°C to 260°C), non-stick, low friction, and excellent electrical insulation.
- Advantages: Unmatched chemical resistance, non-stick surface, self-lubricating
- Applications: Seals, gaskets, medical implants, non-stick cookware, electrical insulators, and chemical tank linings
- Tensile Strength : 2,900 ~ 5,100 PSI
- Impact Strength : 2.0 ~ 6.0 ft-lbs / in
- Heat Deflection : 500 ° F
Machining Notes
Recommended Tooling: Sharp HSS or carbide, high rake angle (15–30°)
Spindle Speed: 3,000–8,000 RPM
Feed Rate: 500–1,500 mm/min
Depth of Cut: 0.2–1 mm per pass
Cooling: Dry machining — PTFE is self-lubricating, no coolant required
Key Notes: ① PTFE is extremely soft and exhibits **creep** (slow deformation under sustained load) — achievable tolerance is typically ±0.1 mm; not suitable for applications requiring extremely tight fits;
② Apply clamping force evenly to prevent localized distortion;
③ PTFE dust must be cleared promptly — at temperatures above 200°C, PTFE decomposition produces hazardous fumes; ensure adequate ventilation
HDPE
– Chemical-Resistant Economical Plastic
- Properties: High strength-to-weight ratio, chemical resistance, impact resistance
- Advantages: Lightweight, moisture resistant, FDA compliant options available, easy to machine, cost-effective
- Applications: Chemical storage and moisture-resistant applications, Tanks, containers, pipes, marine components, food handling equipment
- Tensile Strength: 4,000 ~ 4,500 psi
- Impact Strength: 1.0 ~ 4.0 ft-lbs / in
- Heat Deflection: 130 ~ 180 °F
Machining Notes
Recommended Tooling: HSS or carbide, 2–3 flutes, large clearance angle
Spindle Speed: 3,000–8,000 RPM
Feed Rate: 600–2,000 mm/min
Depth of Cut: 0.5–2 mm per pass
Cooling: Dry machining or compressed air
Key Notes: ① HDPE is very soft and prone to galling — keep tools sharp at all times;
② Large thermal expansion coefficient — account for temperature effects on large-format parts;
③ HDPE offers the **lowest machining cost** among common engineering plastics
PVC (Polyvinyl Chloride)
– Durable Industrial Plastic
- Properties: High tensile strength, chemical resistance, flame-resistant
- Advantages: Cost-effective, versatile, good mechanical properties
- Applications: Pipes, fittings, medical equipment, and electrical insulation, Industrial applications requiring durability and chemical resistance.
- Tensile Strength : 7,800 PSI
- Impact Strength : 0.8 ft-lbs / in
- Heat Deflection : 162 ~ 172 ° F
Machining Notes
Recommended Tooling: Carbide, 2–4 flutes
Spindle Speed: 2,000–5,000 RPM
Feed Rate: 400–1,200 mm/min
Depth of Cut: 0.5–2 mm per pass
Cooling: Dry machining or compressed air — **do not machine above 60°C**
Key Notes: ① PVC releases **hydrogen chloride (HCl) gas** when overheated — this is hazardous to operators and corrosive to machine components; mandatory ventilation is required;
② Relatively brittle — plan toolpaths carefully for deep cavities;
③ Offers excellent cost-to-performance ratio compared to other engineering plastics
UHMW-PE
– Extreme Wear Resistance Plastic
- Properties: Exceptionally high impact resistance (highest of all thermoplastics), excellent abrasion resistance, low coefficient of friction (0.10–0.22), self-lubricating, chemical resistant, noise-dampening
- Advantages: Outstanding toughness, lightweight, FDA-compliant grades available, lower cost than engineering polymers with similar wear performance
- Applications: Conveyor wear strips and guide rails, chain guide components, wear liners, cutting boards, marine dock fenders, bulk material chutes, star wheels, food processing equipment
- Tensile Strength: 5,800 psi
- Impact Strength: No Break
- Heat Deflection: 176°F
PEI
– High-Temperature Transparent Engineering Thermoplastic
- Properties: High strength and stiffness, inherent flame retardancy (no additives required), excellent electrical insulation, good dimensional stability, transparent amber colour in unfilled form
- Advantages: UL94 V-0 rated, autoclave-sterilisable, lower cost alternative to PEEK for applications up to 170°C, good resistance to hydrolysis
- Applications: Aerospace interior components (FAR 25.853 compliant), medical surgical instruments, electrical/electronic connectors, semiconductor test fixtures, food-service equipment
- Key Grades: Ultem 1010 (unfilled), Ultem 2300 (30% glass-filled for higher stiffness), Ultem 1010 CG (food/medical contact)
- Tensile Strength: 15,200 psi
- Impact Strength: 1.0 ft-lbs/in
- Heat Deflection: 392°F
- Max Service Temp: 340°F
PPS
– High-Temperature Chemical-Resistant Engineering Thermoplastic
Properties: Outstanding chemical inertness (resists nearly all solvents below 200°C), very low moisture absorption (<0.02%), excellent dimensional stability, inherent flame retardancy (UL94 V-0), good electrical properties
Advantages: Stable at high operating temperatures with minimal creep, resistant to steam sterilisation, low warpage after machining
Applications: Chemical pump and valve components, automotive under-hood sensor housings, electrical connectors in high-humidity environments, semiconductor process equipment parts, industrial filter housings
- Key Grades: PPS unfilled (best machinability), PPS GF40 (glass-filled, higher stiffness, most common), PPS CF30 (carbon-filled, highest strength)
- Tensile Strength: 11,600 psi
- Impact Strength: 0.5 ft-lbs/in
- Heat Deflection: 428–500°F
PI
– Ultimate High-Temperature Engineering Thermoplastic
Properties: Highest continuous service temperature of any thermoplastic (300°C+), extremely low coefficient of thermal expansion, near-zero moisture absorption, excellent electrical insulation over the full temperature range, radiation-resistant
Advantages: Performs continuously at temperatures that cause PEEK and PAI to soften; near-zero outgassing for vacuum and space applications; self-lubricating grades available; operates across the widest temperature range of any engineering polymer
Applications: Semiconductor wafer handling and test fixtures (high-vacuum environments), spacecraft structural components, cryogenic pump seals and bearings, nuclear industry components, high-altitude aircraft bushings, ion implantation equipment
Common Grades: SP-1 (unfilled, highest temperature), SP-21 (15% graphite, self-lubricating), SP-22 (15% MoS₂, lowest friction), SCP-5000 (carbon-filled, highest strength)
Tensile Strength: 12,500 psi
Impact Strength: 0.9 ft-lbs/in
Cont. Service Temp: 572°F
Cryogenic Limit: -452°F
PPA
– High-Temperature Semi-Aromatic Polyamide
- Properties: Superior heat resistance compared to standard polyamides (PA6/PA66), very low moisture absorption relative to other nylons, excellent dimensional stability, high chemical resistance to motor oils, fuels, and coolants, inherently stiffer than PA66 at elevated temperatures
- Advantages: Retains mechanical properties at temperatures where PA66 softens significantly; dimensional stability virtually unaffected by humidity; enables direct metal replacement in thermal environments up to 200°C
- Applications: Automotive cooling system components (coolant reservoirs, thermostat housings), air intake manifolds and charge-air ducts, EV battery cell separators and housings, electrical connector bodies, oil pan inserts, transmission components
- Common Grades: PPA GF33 (33% glass-filled, most common), PPA GF50 (highest stiffness), PPA mineral-filled (improved surface and reduced warpage)
- Key Difference vs PA66: PPA offers 50–80°C higher continuous service temperature, 5–20× lower moisture absorption, and significantly better property retention in wet/hot environments
- Tensile Strength: 14,500 psi
- Impact Strength: 1.5–2.5 ft-lbs/in
- Heat Deflection: 390–500°F
- Moisture Absorption: 0.12–0.30%
FAQs
ABS, polycarbonate, POM (Delrin), and HDPE are among the easiest plastics to machine due to their good machinability and dimensional stability.
Delrin (POM) is the best choice for tight tolerance work due to its high stiffness, rigidity, and excellent dimensional stability.
No. Rigid plastics with Shore D hardness of 50+ are ideal. Soft, flexible materials like silicone or rubber tend to deform during machining.
CNC machining offers tighter tolerances, superior surface finishes, and access to engineering-grade materials. It's ideal for functional parts and low-volume production. 3D printing is better for complex geometries and very low volumes.
HDPE, PET, POM (Delrin), and certain grades of Nylon are FDA compliant for food handling applications.
Use proper cooling, select materials with low thermal expansion, avoid asymmetric material removal, and consider stress-relief annealing for critical parts.