Wearbands & Guide Rings
Prevents metal-to-metal contact between pistons/rods & bores/glands, and absorbs transverse loads. Filled PTFE material gives good load capacity with low friction and stick-slip-free operation. Protects critical sealing lips from contamination and dieseling effects. Cost-effective, and allows designers freedom in hardware material selection. Higher static loads are permissible.
PTFE is a plastic that offers high chemical resistance, low and high temperature capability, resistance to weathering, low friction, electrical & thermal insulation, and “slipperiness”.
PTFE Mechanical properties are often enhanced by adding fillers (see paragraph below). It has excellent thermal and electrical insulation properties and a low coefficient of friction. PTFE is very dense and cannot be melt-processed — it must be compressed and sintered to form useful shapes.
PTFE’s mechanical properties can be enhanced by adding fillers such as glass fibers, carbon, graphite, molybdenum disulphide, and bronze. Generally, filled PTFE’s maintain their excellent chemical and high temperature characteristics, while fillers improve mechanical strength, stability, and wear resistance.
Typical Filler Properties
|Filler||Physical Form||Amount (% Weight)||Effect of Filler|
|Glass Fibers||Milled Fibers||Up to 40% (also in combination with - graphite, MoS2, and carbon)|
|Carbon||Powder||Up to 35% (also in combination with graphite, bronze, and glass)|
|Carbon Fibers||Milled Fibers||Up to 30%|
|Graphite||Powder||Up to 25% (also in combination with glass, bronze, and carbon)|
|Bronze||Powder||Up to 60% (also in combination with carbon, graphite, and MoS2)|
|Molybdenum Disulfide (MoS2)||Powder||Up to 5% (also in combination with glass and bronze)|
|Stainless Steel||Powder||Up to 60%|
|Polymers||Powder||Up to 20% (also in combination with inorganic fillers)|
|Pigments||Powder||Up to 2%|