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PET
PET (Polyethylene Terephthalate) is a semi-crystalline thermoplastic polyester widely recognized for its excellent mechanical strength, dimensional stability, and FDA-compliant food-contact safety. As the dominant material for beverage bottles and food packaging, PET combines good barrier properties against moisture and gases with crystal-clear transparency in amorphous grades. Beyond packaging, engineering-grade PET (e.g., PET-P, Rynite®) offers superior stiffness, low friction, and excellent electrical properties, making it a strong candidate for precision mechanical and electrical components.
Mechanical Properties
- Density: 1.38 g/cm³
- Tensile Strength: 55 MPa
- Yield Strength: 55 MPa
- Elongation at Break: 250%
- Flexural Modulus: 2,400 MPa
- Hardness: Rockwell M 106
- Heat Deflection Temperature: 70°C @ 1.8 MPa
- Melting Point: 250–265°C
- Thermal Conductivity: 0.24 W/m·K
- Coefficient of Thermal Expansion: 7.0 × 10⁻⁵ /°C
- Water Absorption: 0.1–0.2%
- Flammability Rating: HB (UL94)
Advantages
🟢 FDA-compliant food-contact safety — the global standard material for beverage bottles and food packaging; fully recyclable (resin code #1)
🟢 Excellent dimensional stability and low creep — maintains tight tolerances under sustained mechanical loads, ideal for precision components
🟢 Good electrical insulation and dielectric properties — low dissipation factor and high dielectric strength suitable for electrical and electronic applications
🟢 Clear transparency in amorphous grades — enables visual inspection of contents in packaging and medical device applications
Machining & Manufacturing
| Parameter | Specification | Notes |
| Cutting Speed | Turning: 200–400 m/minMilling: 600–1500 RPM (Ø6–Ø12 mm end mills) | Do not use excessive speed to avoid heat accumulation |
| Tooling | Unfilled PET: Sharp carbide tools with 5°–15° positive rakeGlass-filled PET: Carbide or PCD inserts with edge treatment | Polished flutes prevent material adhesion |
| Coolant | Water-based flood coolant for general use; air blast for light finishing | Check coolant compatibility for food-grade components |
| Chip Control | Unfilled PET: Semi-continuous chips, turning feed 0.1–0.25 mm/revGlass-filled PET: Abrasive powdery chips | Ensure thorough chip removal |
| Surface Finish | Unfilled PET turning: Ra 0.8–1.6 μm; Ra 0.4–0.8 μm with diamond toolsGlass-filled PET: Ra 1.6–3.2 μm | Fiber exposure affects surface quality of filled grades |
| Dimensional Considerations | PET-P has better dimensional stability than standard PET | Let parts stand 2–4 hours at workshop temperature before final inspection |
Common Applications
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