How to choose the right PTFE filler for your application

How to choose the right PTFE filler for your application

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Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that is widely popular due to its many benefits that can be adapted for use in a variety of industries and applications. The unique properties of PTFE make it useful for both domestic and commercial applications. These properties include:

  • 327 °C. a very high melting point of
  • hydrophobicity
  • chemically inert
  • low coefficient of friction
  • high tensile strength

Why Filled PTFE Compound?

Despite the many advantages of PTFE, it has one major disadvantage. Because it is highly flexible, it can easily deform under pressure or heavy load applications. However, adding filler to the compound can help solve the problem while giving the compound advantages of both filler and PTFE.

Fluon+ filled PTFE compounds are composed of pigments and fillers such as glass, carbon, graphics and metal powders (bronze and molybdenum disulfide). These molding powders offer superior wear resistance, creep resistance, thermal conductivity and electrical conductivity over virgin PTFE resins. Filled PTFE compounds preserve many properties including low coefficient of friction, excellent chemical resistance and a wide service temperature range.

Choosing the Right PTFE Filler

So how do you decide which PTFE filler is right for your application? Read below as we break down the most popular PTFE fillers and the performance benefits they can bring to your premises.

fiber glass

Glass-filled PTFE compounds are the most universally used. Adding glass makes the compound stronger and more durable, while reducing ductility and creep. It can be used at service temperatures from -268 °C to +260 °C in chemical applications ranging from liquid oxygen to fuming nitric acid. It can also be used for severe wear pads for railway cars and self-lubricating compressor rings for non-aluminum cylinders. Similar to virgin PTFE, glass-filled PTFE is also chemically inert.

Ideal Application for Glass Filled PTFE

  • self-lubricating bearings
  • Gaskets (static-dissolving, other)
  • Seal (all types)
  • compressor rings

Molybdenum disulfide (MoS2)

A harder and more slippery material is obtained by adding a molybdenum disulfide (MoS2) filler to your PTFE compound. MoS2 is often used with glass or bronze resulting in better compression and improved wear resistance. In addition, it has a low coefficient of friction and helps reduce torque at start-up.

Ideal application for PTFE filled with molybdenum disulfide

  • self-lubricating bearings
  • piston rings and seals
  • Big-Billet / Skewed Sheet

graphite powder

Graphite-filled PTFE offers the same benefits as carbon-filled PTFE but does not improve wear resistance like carbon-filled PTFE. Graphite offers excellent self-lubricating properties and reduces the coefficient of friction. When mixed with carbon, glass, or both compounds, all 3 additives are beneficial.

Ideal Application for Graphite Filled PTFE

  • self-lubricating bearings
  • Gaskets (static-dissolving, other)
  • Seal (all types)
  • Rings (V, O, Back-up)

bronze powder

Ideal for applications that demand good thermal and electrical conductivity, bronze-filled PTFE is a great choice for bearings, seals and valve seats/liners used in applications such as vehicle engines. Adding bronze to PTFE also improves wear resistance, it also reduces the non-stick properties and chemical inertness of PTFE.

Ideal Application for Bronze Filled PTFE

  • self-lubricating bearings
  • Seal (all types)
  • Valve Seats / Liner

Minerals

Mineral-filled PTFE is often used for applications in the medical, pharmaceutical and food processing industries. The addition of minerals to PTFE provides excellent load and wear resistance as well as good chemical resistance. It is FDA compliant and can withstand strict hygiene requirements. Mineral-filled PTFE can be combined with brass, bronze, steel, stainless steel and aluminum to obtain additional properties.

Ideal Application for mineral filled PTFE

  • self-lubricating bearings
  • Gaskets (static-dissolving, other)
  • Seal (all types)
  • compressor rings
  • bushings
  • wear pads
  • trust washers

polyester

Polyester-filled PTFE compounds exhibit superior heat and wear resistance as well as dimensional stability and corrosion resistance for molded or extruded parts. The selection of a highly crystalline polyester filler for the PTFE compound will also provide good creep resistance and excellent load-bearing capacity. This makes them ideal filler compounds to help extend the service life of bearings, seals, rotors and other parts in demanding applications.

Ideal Application for Polyester Filled PTFE

  • self-lubricating bearings
  • compressor rings
  • Big-Billet / Skive Sheet
  • seals
  • rotors

Polyphenylene Sulfide (PPS)

Polyphenylene sulfide (PPS) improves the wear and friction properties of PTFE. It also has high thermal resistance and excellent mechanical and extrusion resistance making it good for use in precision tolerance machined components such as backup rings. It has excellent chemical resistance and no known solvents below 200 °C (392 °F).

Ideal application for PPS filled PTFE

  • self-lubricating bearings
  • Gaskets (static-dissolving, other)
  • compressor rings

polyimide

Polyimide refers to a class of synthetic polymers. When added to PTFE, the polyimide forms a compound that is low in abrasive and non-abrasive. Because of these characteristics, polyimide-filled PTFE is ideal for applications involving soft mating surfaces such as steel, aluminum or other plastics.

Ideal Application for Polyimide Filled PTFE

  • self-lubricating bearings
  • compressor rings
  • piston rings/seal
  • Big-Billet / Skive Sheet

Stainless Steel

Stainless steel filled PTFE is ideal for applications using steam and hot liquids because it works well at high temperatures. In addition, it enhances the strength and load bearing capacity of the PTFE compound to which it is added. This type of PTFE is suitable for mechanical uses as well as for use in the food and beverage industry, which requires FDA compliance. It is extremely hard to wear to the extent that it can cause wear on adjacent surfaces.

Ideal Application for Stainless Steel Filled PTFE

  • Gaskets (static-dissolving, other)
  • Seal (all types)
  • Valve Seats / Liner

PTFE in its natural state is an incredibly versatile material with many performance benefits. Adding fillers can help to overcome its disadvantages while adding performance properties to the compound. Having an understanding of the performance properties required for your application will enable you to select the right filler for your premises.

AGC’s Fluon+ PTFE compounds are produced in an environmentally friendly manner. They are easily processed in automatic molding equipment and are mainly used in automotive parts. Non-pelletized compounds are used in applications that demand the highest mechanical strength. Contact an AGC product specialist to learn more about creating the right PTFE compound for your application.

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