PTFE CNC-machined parts are functional components made from polytetrafluoroethylene using computer numerical control (CNC) precision machining techniques (such as turning, milling, drilling, and engraving). PTFE is the most classic type of fluoroplastic. It is formed by polymerizing tetrafluoroethylene monomer. All hydrogen atoms in its molecular chain are replaced by fluorine atoms, forming a "perfluorinated" inert structure. This gives the material unparalleled chemical stability, ultra-low friction coefficient, and excellent temperature resistance, earning it the nickname "the king of corrosion resistance" and "solid lubricant" in the industrial field.
PTFE CNC-machined parts are widely used in applications requiring stringent material performance. Common applications include seals, bearing bushings, insulators, corrosion-resistant pipe fittings, and brackets for high-frequency electronic equipment. CNC machining enables high-precision manufacturing (with tolerances typically within ±0.01-0.05mm) of complex geometries (such as special-shaped holes, precision threads, and tiny grooves) to meet personalized functional requirements.
Mechanical Properties
PTFE's unique structure makes its mechanical properties significantly different from other engineering plastics:
- Tensile Strength: 20-35 MPa (lower than general-purpose plastics like PA6/POM, but higher than soft rubber);
- Elongation at Break: ≥300% (Highly tough, deforms significantly rather than cracking when subjected to stress);
- Flexural Strength: Approximately 40-50 MPa (Suitable for medium bending loads, but with limited rigidity);
- Compressive Strength: Approximately 10-15 MPa (Stable at low pressures, requires filler modification for high pressures);
- Hardness (Shore D): 50-60 (Harder than rubber, but softer than metal/engineering plastics).
Typical Applications: PTFE parts are used in components requiring cushioning, vibration reduction, or flexible sealing (such as gaskets and O-rings). However, its low rigidity makes it unsuitable for withstanding high axial pressure. (Filling with glass fiber or carbon fiber is required for high-strength support).
Chemical Properties
PTFE is one of the most chemically stable solid materials known, being virtually immune to all chemical media:
Acid and Alkali Resistance: It exhibits no reaction to highly corrosive reagents such as aqua regia (concentrated nitric acid + concentrated hydrochloric acid), hydrofluoric acid (HF), concentrated sulfuric acid (98%), and concentrated sodium hydroxide (40%) at temperatures ranging from room temperature to 250°C.
Organic Solvent Resistance: It is stable to almost all organic solvents (such as acetone, ethanol, benzene, toluene, and chloroform) (it may swell slightly at high temperatures, but this swelling recovers upon cooling).
Other Media Resistance: It is resistant to water (including boiling water), steam, oxidizing agents (such as hydrogen peroxide), and reducing agents (such as sodium sulfite).
Special Advantages: PTFE is irreplaceable in highly corrosive chemical production (such as electroplating tanks and pickling lines), laboratory equipment (such as reactor linings), and pharmaceutical/food-grade corrosion-resistant equipment. CNC-machined parts can be exposed to extreme chemical environments (such as pipe joints and valve sealing surfaces).
Thermal Properties
- Melting Point: Approximately 327°C (theoretical value; in actual processing, it begins to soften and flow at 380-400°C);
- Continuous Use Temperature: -200°C to 260°C (limited to short-term high temperatures of 280-300°C);
- Low-Temperature Toughness: Remains flexible (does not crack) at -200°C (in liquid nitrogen), making it suitable for use in extremely cold regions.
Typical Applications: PTFE parts are used in high-temperature chemical reaction equipment (such as pyrolysis furnace seals) and low-temperature refrigeration systems (such as liquid nitrogen pipeline flange gaskets). Its wide temperature range stability far exceeds that of ordinary plastics (e.g., nylon has a temperature resistance of ≤120°C; PEEK, while having a high temperature resistance, is expensive).
Friction and Wear Resistance
PTFE has the lowest kinetic friction coefficient in nature (0.04-0.10 under dry friction conditions) and excellent self-lubricating properties:
- Friction coefficient: Approximately 0.04-0.10 when rubbing against steel (unlubricated), lower than graphite (0.1-0.2) and molybdenum disulfide (0.1-0.15);
- Wear rate: In sliding friction, PTFE wear is only 1/10-1/5 that of nylon (PA6) (although pure PTFE has poor wear resistance and requires filler modification);
- Self-lubricating properties: It can operate smoothly under low-speed and medium-load conditions (e.g., bearing bushings and guide rails) without the need for additional lubricant.
Special Limitations: Pure PTFE has insufficient wear resistance (prone to wear due to long-term friction). However, this deficiency can be significantly improved by filling it with fillers such as carbon fiber (CF), graphite (Gr), molybdenum disulfide (MoS₂), and bronze powder (Cu). (For example, carbon fiber-filled PTFE improves wear resistance by 5-10 times) to meet the requirements of high-load friction scenarios.
Electrical Properties
- Insulation Resistance: Volume Resistivity > 10¹⁸ Ω·cm (close to ideal insulator);
- Dielectric Strength: ≥ 60 kV/mm (much higher than air's 3 kV/mm, resistant to high-voltage breakdown);
- Dielectric Constant: 2.0-2.1 (extremely low and stable, low signal transmission loss);
- Dielectric Loss Tangent: 0.0002-0.0005 (extremely low, with virtually no energy loss at high frequencies).
Typical Applications: PTFE CNC-machined parts are the preferred material for high-frequency electronic devices (such as 5G communication filter brackets and radar antenna insulation components), high-voltage cable connectors, and insulating components for semiconductor manufacturing equipment (such as PCB support frames and electrode isolation rings).
