Round Rod in PTFE CF10 2000 mm natural

Round rods in PTFE CF10 are a carbon fiber reinforced version where the PTFE matrix is filled with about 10 percent chopped carbon fiber. The fiber content is not large in percent, but the effect on the mechanical properties is clear. The material gets stiffer, less sensitive to creep under constant load, and it holds its dimensions better when the temperature moves. The low friction and the chemical inertness of pure PTFE are still there, but in a somewhat harder and tougher form. The natural color is dark gray because of the carbon fiber; the surface is matte and relatively smooth straight from sintering.

In terms of temperature, the material works in the same window as pure PTFE. The long term temperature is around 260 degrees, and at the other end of the scale the material is usable down to cryogenic temperatures around minus 200 degrees. The fire rating is V0 according to UL 94. Chemically, PTFE CF10 is still very broad in what it takes. Most acids, bases and organic solvents are handled without the material breaking down, even at elevated temperatures. Hot oils and hot alkalis do not cause any noticeable degradation either. The density is slightly above pure PTFE, around 2.1 to 2.2 g/cm³, since carbon fiber is lighter than metallic fillers such as bronze.

It is exactly the wear and creep resistance that makes carbon fiber reinforced PTFE interesting in round rod format. Round rods are used for turned parts: sliding bushings, piston rings, valve seats, guides in pneumatics and hydraulics, shaft sleeves and small machine parts that have to rotate or slide in media with high demands on chemistry and temperature. Since CF10 creeps less than pure PTFE, the sliding clearance can be kept more even over a longer running time, which is valuable in seals and guides where leakage or play is critical. In stuffing boxes and valve seals the material gives a good balance between chemical inertness and dimensional stability.

Machining is normally done by turning and milling. The material cuts easily with sharp carbide inserts, and low feeds combined with a keen edge give a fine surface. The carbon fiber is hard and wears on the insert, so carbide or diamond coated inserts are a sensible investment for larger runs. Air cooling usually works well; liquid cooling is rarely needed but can be used for rough machining. PTFE cold flows even in the CF filled version, so tolerances should be measured after the part has rested for an hour or so, not right at cutoff.

Bonding works poorly without chemical etching of the surface, since PTFE is inert. Mechanical fasteners, screwed or press fit joints are more common. When choosing between pure PTFE, a bronze filled or a carbon fiber reinforced grade, the load picture decides. Pure PTFE is the softest and creeps the most under load, but it has the lowest friction. Bronze filled PTFE conducts heat better, is harder and suits bearings that move wet or lubricated. Carbon fiber reinforced PTFE is a good middle choice where you want higher stiffness and better creep resistance without losing too much of the low friction, and with the advantage that carbon fiber is not electrically conductive in the same way as bronze.

Round rods are supplied in a range of diameters from a few millimeters up to several hundred millimeters, often in standard lengths of around one meter. When you choose, it is wise to think about two things. The first is the diameter margin for machining, since the surface of sintered blanks can have some ovality and may need rough turning before the finishing pass. Count on chips. The second is the linear expansion, which is high for PTFE based materials and needs to be worked through if the operating temperature varies a lot, so that fits do not lock up or end up too loose.

When turned parts are mounted, pressing and screwed joints work well. For rotating bushings it is common to allow a sliding clearance in the cold state so that the movement still works when the system heats up. The mating surface does not have to be hard if the load is moderate, but a polished or honed inside of the housing shortens the run in distance and extends the service life in bearings with a high speed product. For gaskets and seal rings that are to be turned from the rod, it pays to rough turn the blank and let it rest before finishing, because the cold flow can otherwise give small dimensional deviations after the part is fitted.

Do you want help finding the right PTFE grade for a part you have already drawn? Send over the sketch, and we will go through the options together.

In the double length, 2000 mm in natural, the carbon fiber reinforced rod is enough for several stiff bushings.