Sheet in PTFE BR60 GR 1200x1200 mm natural

Sheets in PTFE BR60 GR are pressed and sintered blanks where the PTFE matrix is filled with both bronze and graphite. The bronze lifts the mechanical performance of the material and improves heat conduction; the graphite holds down the friction that otherwise rises somewhat when hard particles are pressed into the polymer. The result is a compound type that handles pressure and wear better than pure PTFE while staying low in friction against steel and other polished mating tracks. The natural color is gray black as a result of the bronze and the graphite; the surface is matte straight from sintering and can be fine machined to lower roughness if needed.

The range of use is governed by the temperature and chemical picture of the material. The long term temperature is 260 degrees, and in shorter peaks the material takes even more without breaking down. Down to around minus 200 degrees it works as well, which makes it useful in chilled processes. The fire rating is V0 to UL 94, an interesting point in environments where fire requirements govern the material choice. Chemically very little bites on the material; even hot acids and concentrated bases are handled with no visible effect, and most organic solvents do not attack the polymer even at raised temperature. Density is high, around 3.7 g/cm³, which follows from the bronze content.

The sheet format finds its place in applications where a flat surface does the job. Wear surface in press tools and in equipment for sheet metal drawing, slide plates under heavy goods that have to be pushed, calibration plates in extrusion, gasket blanks in valve bodies, slide strips on lift tables. In the chemical process industry, sheets are used as lining in vessels, troughs and centrifuges where aggressive media would otherwise attack steel. In the pharmaceutical and food industries, PTFE based materials are picked for the inert surface and the low adhesion, but formal certification always has to be confirmed per delivered batch.

Machinability is good. You mill, drill, water jet cut and turn the material with sharp carbide inserts. Since the bronze is abrasive on tools, diamond coated inserts are a reasonable choice for large runs. Feeds should be kept moderate and the cutting edge has to be sharp; a worn edge gives fuzzy surfaces and dimensions that drift. PTFE cold flows, so tolerances and flatness should be measured after a part has rested, not straight after cutting. For joining, gluing is awkward without etching since the surface is inert; mechanical fastening, bolted joints or pressing are the more common solutions. Seals against the mating track hold better if the mating surface is polished or honed to low surface roughness.

Two practical points usually come up in the planning. The first is linear expansion. PTFE moves considerably more with temperature than metal does, so on larger parts or with high temperature differences the clearance has to be worked through so that sliding surfaces do not get pressed tight. The second is load over time. Even with bronze and graphite filler the material creeps under constant high pressure, and the design pressure has to be kept within the long term limit of the material for the dimensions to hold through the whole duty cycle.

The sheets come in a wide span of thicknesses, from a millimeter or so up to several centimeters, in sizes that suit both finished parts and cut blanks. In the choice it is often thickness and flatness requirements that govern. Thinner sheets are easier to form and cut more readily into gasket blanks, thicker sheets take higher point loads without deforming and are the starting point for turned parts that need a solid blank to work from. Standard sizes are often around 500 x 500 and 1000 x 1000 millimeters, but cutting to size is a simple thing to add.

The material stands out when you need the combination of chemical inertness, high temperature and the ability to slide under load. In the very most abrasive environments there are other filled PTFE grades that fit better, but for most machine applications BR60 GR gives a good balance between cost and function.

The 1200x1200 mm format in natural gives plenty of material for sliding surfaces that have to carry pressure and run dry at the same time.

Do you need help choosing between pure PTFE, bronze filled, carbon fiber reinforced or a compound with graphite? Send over the drawing and the operating conditions, and we will go through the choice together.