PTFE (Polytetrafluoroethylene)

Complete property data sheet for unfilled PTFE — mechanical, thermal, electrical and physical values, each with its ASTM test method — plus what PTFE does and does not resist chemically, and how it behaves on a lathe or mill.

Data verified 2026-09-29 · based on ASTM D4894-19

Mechanical Properties

Thermal Properties

Electrical & Physical Properties

Weight & Volume Calculator

Machining PTFE

PTFE machines on standard metalworking equipment but needs a different instinct. It is soft (Shore D55) and has almost no elastic recovery, so a heavily clamped workpiece deforms and springs back after the cut — the finished dimension depends on how hard the vise was tightened. Use soft jaws, clamp only as firmly as the cut requires, and support thin sections.

Tooling should be sharp, high-rake and polished, with generous clearance angles, because PTFE's low friction means the chip slides rather than curls and a dull edge simply rubs and generates heat. The thermal expansion figure above tells the rest of the story: at 135 µm/m·°C, a 200 mm PTFE part grows 0.27 mm for every 10 °C of temperature change. Cutting tolerances only make sense when the measurement temperature and the service temperature are both stated.

Coolant is optional — PTFE's heat resistance means dry machining is usually fine and avoids contaminating a material often chosen for its chemical purity. Do not use compressed air to clear chips if the part will go into food, pharmaceutical or semiconductor service; captured particles are the usual contamination source.

Where PTFE Is the Right Choice

PTFE is specified for a specific combination of properties that no other unfilled plastic offers together: near-universal chemical resistance, the lowest coefficient of friction of any solid polymer, a continuous service temperature of 260 °C, and a dielectric constant that stays flat across frequency.

Its weakness is mechanical. Tensile strength is only 25 MPa and the material cold-flows — under sustained compressive load it deforms permanently, even at room temperature, which is why PTFE gaskets take a set and PTFE bearings are limited to low PV values. Filled grades (glass, carbon, bronze) address this at the cost of chemical resistance and machinability.

Compared with the alternatives: PEEK is far stronger and stiffer with a similar temperature ceiling, at roughly 8–12× the cost; PVDF is stiffer and stronger but has a much narrower chemical window; UHMW-PE has comparable friction and better abrasion resistance but a ceiling of only 80 °C. PTFE remains the answer when chemistry and friction dominate and load does not.

How to Read This Data Sheet

Values are typical published figures for unfilled, natural-grade PTFE, measured on standard test specimens. Every row names the test method it came from, because a polymer property without its test method is not a comparable number — tensile strength measured to ASTM D638 and to ISO 527 differ systematically, and impact values depend heavily on specimen geometry.

Two caveats apply to every figure here. First, temperature: polymer properties are far more temperature-sensitive than metal properties, and a tensile strength quoted at 23 °C tells you little about the same material at 100 °C. Second, conditioning: hygroscopic plastics such as nylon absorb moisture from the air, and absorbed water acts as a plasticiser — the same grade can be stiff and strong when dry and significantly tougher but weaker when conditioned. Where a property is strongly affected by moisture, the row notes it.

Filled, reinforced, lubricated and impact-modified grades of the same base polymer differ substantially from these figures. Use this page to compare materials and to shortlist; use the specific grade's data sheet for design calculations.

Frequently Asked Questions

What is the density of PTFE?

2.16 g/cm³, which is heavier than water and heavy for a plastic — about 1.8× the density of nylon. Density matters for two practical reasons: it sets the weight of a finished part through the material's cost per kilogram, and it is the number this page's weight calculator uses to convert a volume into a mass.

Can PTFE be machined?

Yes, but it behaves unlike any metal. PTFE is soft and waxy, cuts with a stringy continuous chip, and expands roughly ten times more than steel for the same temperature rise — so a dimension cut cold is not the dimension in service. Use sharp, high-rake tooling, light feeds and generous clearance; clamping pressure alone is enough to deform the part and make the finished size wrong.

How do I choose between PTFE and another engineering plastic?

Choose PTFE when you need chemical inertness, the lowest available friction, or a wide continuous service temperature — and when the part carries little mechanical load. Choose something else when the part must hold a dimension under sustained load or resist abrasion.

What chemicals attack PTFE?

Very few, and the exceptions are specific. PTFE is attacked by molten alkali metals (sodium, potassium), by fluorine and some fluorine compounds at elevated temperature, and by certain halogenated solvents under pressure. Everything else — all common acids, bases, solvents, oxidisers and fuels — leaves it unchanged up to its service temperature. Note that the limit is often the filler or the seal carrier rather than the PTFE itself.

Why does PTFE creep, and how do I design around it?

PTFE's molecules slide past one another under sustained load, so a part under constant compression deforms permanently — 12% in 24 hours at only 6.9 MPa. Design around it by keeping sustained compressive stress low (typically below 3.5 MPa), by using a filled grade, or by capturing the PTFE in a metal housing that limits the deformation. Never rely on PTFE alone to maintain a preload or an interference fit.

Is PTFE safe for food and medical contact?

Virgin PTFE is chemically inert and is widely used for food-contact and implantable applications, but the qualification is grade-specific rather than a property of the polymer family. Processing aids and fillers affect the result, and some grades carry FDA or USP Class VI listings while others do not. Confirm the specific grade's regulatory documentation.

Related

• PEEK Properties
• Nylon 6/6 Properties
• Delrin (POM-H) Properties
• Plastic Service Temperature Chart
• Plastic Chemical Compatibility
• Plastic Machining Tolerance Chart

Value Sources

Each data column on this page is tied to the source it came from. The numbers in square brackets correspond to the table headers above.

Data Sources

Cross-checked against:

• Published PTFE stock-shape data sheets from two independent suppliers (values agree within typical range)
• Chemical resistance checked against published compatibility tables for the specific media listed
• Electrical values consistent with PTFE's known position as a low-loss dielectric

Values are typical published figures for unfilled, natural-grade resin at 23 °C, dry as molded unless the row states otherwise. They are not specification minima. Design to the specific grade's data sheet, and derate for the service temperature and moisture condition the part will actually see.

Cite This Page

Every value on this page is traceable to the sources listed above. If you use the data in a document, paper or report, cite it as:

Each row in the tables above also has a permanent link — hover a row and use the # link to cite a single value rather than the whole page.