Hollow Bar in PTFE GF15 GR10 2000 mm natural

Tubes in a PTFE compound with glass fiber and graphite are used when you want to turn out bushings, bearing sleeves or valve seats without eating away a lot of material as chips. You get the same property profile as the corresponding round rod, but with a ready made hole in the middle that saves both time and material.

The material is PTFE with 15 percent glass fiber and 10 percent graphite. The PTFE base gives the well known chemical resistance where in principle everything except liquid alkali metals and certain fluorine gases leaves the material alone. The long-term temperature is 260 degrees and the flammability rating V0. The density sits around 2.17 g per cubic centimeter, high compared with engineering polymers but typical for fluoropolymers.

The additives change the mechanics without ruining the good PTFE properties. The glass fiber reduces creep, which is the biggest weakness of PTFE in mechanical applications, and raises the compressive strength appreciably. The graphite makes the sliding surface somewhat gentler and at the same time carries the friction heat away better than if only glass had been used. Together that gives a material that takes higher PV values and longer running times than pure PTFE.

The tubular format suits bushings, bearing sleeves, spring washer blanks, valve seats and stuffing box sleeves. It is common in compressors, high pressure pumps, hydraulic units and process valves. In petrochemicals and the chemical industry it is used for plain bearings that have to handle both aggressive media and periods of dry running, since the graphite lays down a transfer film on the mating surface so that a short lack of lubricant is not outright catastrophic.

Machining is uncomplicated as long as you use sharp tools. Carbide is standard, PCD wins on series work since the glass fiber wears the cutting edge. Cutting speeds of several hundred meters per minute are entirely possible at light cuts. The material expands ten times as much as steel with temperature, which comes into play on fits between the blank and a steel shaft. Count on that already in the tolerance calculation and you avoid seized bushings in the heat.

Supplied pressed in heavy tubes with practical outer and inner diameter combinations. If you need dimensions other than standard we cut to length, or if you have a drawing we do it for you. When choosing the mating surface, hardened steel with an Ra of 0.2 to 0.8 micrometers is a good starting point.

Get in touch if you are unsure whether tube or round rod suits your application best. We will go through dimensions and waste.

At 2000 mm in natural you get several dry lubricated and dimensionally stable rings out of one and the same piece.