Hollow Bar in PTFE BR40 1000 mm natural

PTFE BR40 in tubular form is bronze filled PTFE pressed or extruded into a thin or thick walled tube. The material is built on the same recipe as the corresponding rod, around 40 percent bronze powder in a PTFE matrix, but the format opens for other parts: bushings, sleeves, slide tubes and hollow wear components where you need a ready made inner diameter and avoid turning out the center.

The bronze gives the PTFE tube dimensional stability and cold flow resistance that pure PTFE lacks. The density lands around 3.9 g/cm3, the compressive strength rises and the viscoelastic movements under load decrease. The service temperature sits in the same wide PTFE range, from about minus 200 degrees up to plus 260 degrees C continuously, with a V0 flammability rating. That means the tube handles both cryogenic applications and a hot process environment without losing character. For parts working close to the upper temperature limit of PTFE, BR40 is often a better choice than pure PTFE, because the cold flow is otherwise amplified in the heat.

The friction is low and the bronze leads friction heat away, which improves the dry running properties and raises the allowed PV level. That is worth a lot in sealing and bushing contexts where every degree counts. Chemically the material stands up to practically all industrial liquids and solvents; the matrix is a fluoropolymer and is not affected by acids, bases or polar solvents in normal use. The bronze can be attacked by strong oxidizing acid or concentrated salt solutions, though, so check the liquid in critical service and choose pure PTFE or PTFE GF if the medium is aggressive.

Typical uses are slide bushings in hydraulics and pneumatics, guide tubes in valves and pumps, hollow piston rings, wear rings in compressors, guide sleeves against moving shafts and sealing components against rotating parts. The tube can also be used for media carrying sections in chemical engineering where the combination of chemical resistance and dimensional stability matters, even though larger pressure bearing systems are normally built in PFA or PVDF. For turned parts where the material is only used as a blank, the tubular format saves both time and waste compared with starting from a solid rod.

Machining is usually done by turning to final dimension. Sharp carbide inserts with a positive rake angle give a clean surface, and clamping should be done with even pressure around the whole circumference, since PTFE based materials deform locally very easily. For fits against steel shafts you should dimension for the thermal expansion of the material; PTFE compounds expand markedly more than metal, and a fit that sits perfectly at 20 degrees can be too tight at 90 degrees if you have not done the arithmetic.

The tubes cannot be welded or bonded in a conventional way. Mechanical fastening, a press fit or a flanged connection are the usual solutions. For press fits in a metal housing an initial diameter interference usually gives a stable seat even after heat cycling, but dimension generously to avoid cracking around heavy corners. In rotating applications where the tube works as a slide bushing it is also worth thinking about the running in phase; a short period at light load and moderate speed lets the material settle against the mating surface and forms an even sliding film of PTFE and bronze.

Compared with pure PTFE tube stock, BR40 is often worth the extra cost as soon as the application involves a moving load, a pressure above a few bar or a working temperature over 100 degrees. Pure PTFE goes soft at elevated temperature and cold flows quickly under load, which leads to leaking fits and drift in the diameter. For pure sealing rings without a moving load, pure PTFE or PTFE GF often wins on chemical purity, but for the combination of seal plus plain bearing, BR40 is normally the better choice.

The 1000 mm hollow bar in natural is pre-bored and is easier to turn into pressure bearing bushings than a solid rod, with the bronze taking up the load.

Stocked dimensions in tube vary with outer diameter and wall thickness. For special dimensions or blanks cut from a drawing it is easiest to send the dimension sketch directly, and we will come back with a suggestion for the nearest standard tube and the machining cost. Need help choosing between tube, rod and sheet blank for your part? Get in touch and we will go through geometry and load case together and you get straight advice on which format gives the least waste and the best function.