PTFE sheets are the most versatile form of PTFE available — used as gasket stock, tank and vessel linings, slide pads, conveyor surfaces, laboratory bench covers, and machining blanks for flat components. But not all PTFE sheets are the same: the two main types — skived sheets and molded (compression moulded) sheets — have distinct manufacturing processes, property profiles, and ideal applications.
Understanding the difference ensures you specify the right product for your requirement — and avoid the common mistake of ordering skived sheet where molded is needed, or vice versa.
Manufacturing: Skived vs Molded
Skived PTFE Sheet
- A large sintered PTFE billet is mounted on a precision lathe
- A sharp blade peels a continuous thin layer from the rotating billet — like unrolling a coil
- Results in thin, flexible sheet with excellent surface finish on both sides
- Maximum thickness: ~6 mm (practical limit for skiving)
- Best properties: flatness, surface smoothness, thinness, large sheet area
- Slight anisotropy from the skiving direction
Molded PTFE Sheet
- PTFE powder is filled into a flat rectangular mould
- Compressed at high pressure, ejected, and sintered in an oven
- Can produce thick sheets up to 100mm+
- Isotropic properties — same in all directions
- Best properties: thickness range, compressive strength, uniformity in thick sections
- Surface finish slightly rougher than skived; may need machining for precision surfaces
Size and Thickness Ranges
| Type | Thickness Range | Sheet Dimensions | Typical Tolerance |
|---|---|---|---|
| Skived Sheet | 0.5 mm – 6 mm | Up to 1500 × 1500 mm | ±0.1 mm on thickness |
| Molded Sheet | 3 mm – 100 mm | Up to 600 × 600 mm (varies by thickness) | ±0.3–0.5 mm on thickness |
When to Use Each Type
| Application | Recommended Type | Reason |
|---|---|---|
| Gasket cutting (thin gaskets 1–3 mm) | Skived sheet | Consistent thin tolerance; smooth surface conforms well to flange face |
| Gasket cutting (thick gaskets 4–10 mm) | Molded sheet | Better compressive strength; less cold flow under bolt load |
| Tank and vessel linings | Skived sheet | Thin, flexible sheet bonds and conforms to curved vessel walls |
| Slide pads and bearing pads | Molded sheet | Higher compressive strength; dimensional stability under load |
| Lab bench and chemical-resistant surfaces | Skived sheet (3–6 mm) | Flat, smooth surface; wide sheet dimensions; easy to cut to size |
| Machining flat components from blank | Molded sheet | Isotropic properties; thick enough for facing and profiling |
| Electrical insulation panels | Either, depending on thickness required | Both provide excellent dielectric properties |
| PTFE-lined pipe inner surfaces | Skived sheet | Thin, flexible; can be rolled and inserted into pipe bore |
Available Grades in Sheet Form
Both skived and molded sheets are available in the full range of PTFE grades:
- Virgin PTFE — Food-safe, pharmaceutical grade, maximum chemical resistance. White/off-white colour.
- Glass Filled PTFE (15–25%) — Improved stiffness and creep resistance. For structural gaskets and high-load slide surfaces.
- Carbon/Graphite Filled — Wear-resistant slide surfaces, anti-static applications. Black colour.
- Bronze Filled — Maximum load slide pads for structural bearing applications. Bronze/gold colour.
Cutting and Fabricating PTFE Sheet
PTFE sheet can be cut, punched, drilled, and machined with standard workshop tooling:
- Knife cutting: Thin skived sheets (up to 3 mm) can be cut with a sharp utility knife against a straight edge or template.
- Die punching: Gasket shapes can be efficiently punched from sheet using steel rule dies on a hand or hydraulic press.
- Water jet cutting: The preferred method for complex gasket shapes from thick sheet — clean, burr-free, and dimensionally accurate.
- CNC milling: For precision flat components requiring tight dimensional tolerances on sheet stock.
- Laser cutting: Not recommended — the high temperature of laser cutting degrades PTFE locally and may produce toxic fumes.
PTFE Sheet Standards
PTFE sheet materials are specified under:
- ASTM D1457 — Standard specification for PTFE molding and extrusion materials (covers base polymer requirements)
- ASTM D3308 — Specification for PTFE resin-coated glass fabrics
- DIN 16936 — German/European standard for PTFE semi-finished products including sheet
- BS 4073 — British standard for PTFE sheet, rod, and tube
Frequently Asked Questions
What thickness of PTFE sheet is used for gaskets?
The standard thickness for most industrial pipe flange gaskets is 1.5 mm (1/16") to 3.2 mm (1/8"). For high-temperature or high-pressure service where cold flow is a concern, use 4.5–6 mm thick glass-filled or chemically modified PTFE sheet rather than virgin PTFE. For spiral wound gaskets with PTFE filler, the PTFE thickness is much thinner (0.25–0.5 mm) but is wound inside a metal spiral cage that prevents cold flow.
Can PTFE sheet be bonded to other materials?
Standard virgin PTFE has extremely low surface energy and cannot be bonded with conventional adhesives. However, chemically treated PTFE (sodium-etched surface) can be bonded to rubber, metal, or other substrates with structural adhesives. Alternatively, PTFE sheet can be mechanically retained by edge clamping, routing into grooves, or using compression fittings. For applications requiring bonded PTFE surfaces, specify chemically treated PTFE parts.
Is there a difference in chemical resistance between skived and molded PTFE sheet?
No — the chemical resistance is determined entirely by the PTFE grade (virgin, glass-filled, etc.), not by whether the sheet is skived or molded. Both skived and molded virgin PTFE sheet resist the same chemicals equally well.
PTFE Sheets — Standard & Custom Sizes
Skived sheets, molded sheets, all grades. Supply in full sheets, cut pieces, or finished gaskets to your specifications.
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