Machining PTFE GF15

PTFE GF15 is a PTFE (polytetrafluoroethylene) filled with 15 % glass fibre. The lower glass-fibre content (compared with GF25) noticeably improves compressive strength, wear and creep behaviour of virgin PTFE, while retaining more of its elongation and toughness. The core PTFE advantages remain: almost universal chemical resistance, a very low coefficient of friction, -200 to +260 °C and non-flammability. GF15 is the somewhat tougher, less abrasive alternative to GF25 for sliding and sealing elements.

PTFE GF15 machines well – turning, milling, drilling and sawing give clean results; because of the glass-fibre content we use sharp, wear-resistant tools and ensure dust extraction. We consistently avoid overheating. This is how we reliably produce load-bearing sealing, sliding and bearing parts – from single pieces to series production.

PTFE GF15 is worthwhile when PTFE properties must be combined with moderate mechanical loading and a little more toughness – for example:

• Seals, sealing rings and guide bands
• Plain bearings, wear strips and guiding elements
• Piston rings and sealing elements in compressors and pumps
• Valve seats and components in chemical process technology
• Applications where the mating surface should be protected

PTFE materials are among the higher-priced engineering plastics; PTFE GF15 is in the range of virgin PTFE. The part price is mainly determined by semi-finished shape and dimension, material utilisation (offcut), machining effort and lot size. We are happy to quote binding prices on request based on your drawing.

Equally important are the limits of the material:

• Highest compressive/wear loading (then GF25 or carbon-filled)
• Contact with hydrofluoric acid, fluorine or molten alkali metals
• Strong hot alkalis (glass fibre is attacked)
• Unambiguous food contact without verification (then virgin/FDA PTFE)
• Joining by welding – not possible for PTFE (machining only)

An honest assessment – and how the disadvantages can be mitigated in practice: Advantages:

Disadvantages:

Practical tip: PTFE GF15 is the right choice when a moderate wear and creep improvement is sufficient and a little more toughness or protection of the mating surface is required. For highest compressive and wear loading GF25 is preferable; for unambiguous food contact or maximum resistance to hydrofluoric acid/alkalis, virgin PTFE.

• Better compressive and wear resistance than virgin PTFE
• Tougher and more ductile than GF25 (lower filler content)
• Almost universal chemical resistance retained
• Very low friction, -200 … +260 °C, non-flammable
• Less abrasive to mating surfaces than GF25
• Lower compressive/wear resistance than GF25
• Not resistant to hydrofluoric acid, fluorine, hot strong alkalis
• Filled grade – food contact only with verification
• Not melt-processable/weldable (machining only)
• Higher price than standard plastics