Sheet in PTFE CP15 1200x1200 mm natural

PTFE CP15 is a carbon-filled PTFE grade where about 15 percent carbon has been added to the base polymer. The addition does not change the basic nature of PTFE, the chemical resistance and the temperature range stay where they are, but the tendency to creep drops noticeably and the sheet handles considerably higher PV values in dry or semi-dry operation. That makes the material interesting where pure PTFE deforms too fast under load.

In terms of temperature the sheet works continuously up to around 260 degrees and takes cooling down toward cryogenic levels. Fire rating V0 according to UL 94 is typical for PTFE-based materials, which makes the grade usable in environments with fire requirements. The density is somewhat above pure PTFE because the carbon is heavier than the base matrix, count on just over 2 g/cm³.

Chemically, PTFE CP15 is one of the most resistant thermoplastics there is. It stands up to practically all acids, bases and solvents; molten alkali metal and elemental fluorine are the only real exceptions. Water absorption is negligible and the sheet does not give off any outgassing in vacuum or in cleanroom environments. The carbon filling also gives a certain electrical dissipation, which breaks the otherwise insulating behavior of PTFE.

What makes carbon-filled PTFE interesting for the designer is the wear profile. The coefficient of friction is still very low, but the compressive strength and the compressive stiffness are clearly better than in pure PTFE. A sealing lip or a plain bearing in PTFE CP15 therefore holds its shape longer under constant load, and the wear against steel goes slower.

The sheet format is often used as a blank for:

slide plates and wear strips in machines with large movements and little lubrication;

cups, gaskets and diaphragms in chemical and pharmaceutical processes;

insulating and sealing parts in high-temperature furnaces and dryers;

mechanical bushings and contact surfaces in valves.

PTFE in sheet is soft to machine. Cutting tools in carbide work well, but the sheet is tough and does not take being clamped hard; thin parts like to cold flow in the fixture. Remember that the carbon filling wears on the cutting edges faster than unfilled PTFE, sharp tools and low feeds pay off. Gluing calls for an etched surface or plasma treatment because PTFE is non-bonding by nature.

Stocked sheets come in several thicknesses, from thin sheets for gaskets up to block sizes for turning blanks and milled parts. When choosing thickness you often count on an extra allowance for final cutting and flattening because PTFE moves slightly when it is unloaded.

Do you need help choosing the right PTFE grade for a sliding, sealing or chemically exposed part? Get in touch and we will go through load and operating environment together.