PTFE Piston and Guide Rings
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Benefits • PTFE - even without lubrication -excels at offering an exceptionally low coefficient of friction in combination with metals and plastics • PTFE is highly anti-adhesive, without any stick-slip effect • PTFE has high elongation properties enabling easy fitting of sealing and guide elements to one-piece pistons • PTFE - when subjected to moderate stress - offers an exceptionally wide (for plastics) thermal operating range from -200 °C to +260 °C • PTFE is chemically resistant to nearly all solid, liquid and gaseous media • PTFE is age-resistant, noncombustible and physiologically neutral in the stated temperature range Ptfe piston rings have been manufactured and used in oil-free compressors for many years. The demand for seals suitable for oil-free applications has grown considerably in recent years. This development has largely been driven by increased awareness of environmental concerns, more stringent regulations and the constant need to achieve further cost reductions. By fine-tuning filler contents and manufacturing processes we have developed a system range of PTFE special compounds enabling us to offer the optimum compound even for extreme application conditions.

Fields of Application Meanwhile, our solutions have established themselves as essential elements in numerous industrial, engineering and consumer goods sectors. Selected examples include: • Compressors operating under full and low-lube conditions • Gas rotary pumps • Expansion machinery • Liquid gas and vacuum pumps • Wobble piston compressors • Rotation compressors for loading/unloading of silos • Generation of oil-free compressed air for the food processing industry, pharmaceutical industry and dentistry • Compressed air for the crafts and do-it-yourself market • Pneumatic hammer drills •...

A piston ring always seals two surfaces. It is pressed against the cylinder wall and the groove flank by the pressure load and its inherent pre-loading force. PTFE piston rings are self-clamping. Consequently, in most cases, there is no need to back the ring by a clamping spring. For compressors with upright cylinders self-clamp­ ing piston rings up to app. 700 mm can be manufactured. Limit Values, PTFE Piston Rings (1) Median piston speed up to Max. pressure differences to be sealed bar 100 Wirkungsgrad unterschiedlicher Kolbenring-Stoßarten Grenzwerte PTFE-Kolbendichtringe(1) Efficiency...

Compounds The selection of the suitable compound is largely affected by the contact surface, medium used and a number of other factors. Please contact our application engineers to discuss your requirements. Contact Surfaces In wear tests to determine the most favorable wear resistance of PTFE compounds with sealing and guide elements for compressors gray cast iron (e.g. fine-laminar gray cast iron) has found to be a particularly favorable contact surface. However, whenever there is a risk of corrosion due to the humidity contained in the gas, high-alloyed chrome steels, hard-anodized...

Benefits • Chemical and thermal resistance to virtually all media used in hydraulics and pneumatics • Suitable for use with non-hard-ened contact surfaces • High bearing capacity, pressure resistance and low wear • No stick-slip even with low sliding speeds and high transverse loads • Minimal lubrication required • Extremely low breakaway forces even after prolonged downtimes • Large compound selection, e.g. wear-resistant PTFE compounds for oil-free applications • Easy installation due to cut grooves Guide rings and bands serve to prevent any contact of the piston and/or rod with the...

Guide Rings and Bands Guide Ring Versions Straight Joint Scarf Joint Shouldered with straight Joint Guide rings with scarf joints provide the advantage of fully running across the cylinder contact surface, thus causing no “markings” on the surface unlike the straight joint. Guide rings with straight or scarf joints can only be fitted if no more than 1/3 of the guide ring width overruns the valve nests inside the cylinder. If several valve nests are overrun, one-piece shrink-fitted guide rings are used. Depending on the respective application, piston guide rings with axial and/or radial...

Guide Band Versions Preferential Ranges, Guide Bands a) Hydraulics (PTFE-bronze) Nominal Groove Groove Base Radial Dimensions Width Gauge Clearance G w/rod guide w/piston max. E/2 Width Thickness H s A H9 guide B f8 b) Pneumatics (PTFE-carbon) Nominal Groove Groove Base Radial Dimensions Width Gauge Clearance G w/rod guide w/piston max. E/2 Width Thickness H s A H9 guide B f8 4,0 1,55 4,1 + 0,1 B + 3,1 A – 3,1 0,3 8,0 1,55 8,1 + 0,1 B + 3,1 A – 3,1 0,3 10,0 1,55 10,2 + 0,1 B + 3,1 A – 3,1 0,3 15,0 1,55 15,2 + 0,2 B + 3,1 A – 3,1 0,3 Installation Example Surface Quality See Spring-Energiz

The PTFE laminated piston is a gapless enclosure of the piston skirt made from aluminum or gray cast iron with a PTFE film. Characteristics: • Maximum use of the available guide surface • High-temperature-resistant PTFE metal composite • Minimal thickness of the PTFE guide band casing Applications and Typical Uses • In dry-running compressors as plunger piston guide for compressing 100% oil-free air • To achieve minimum friction and to serve as an optimum guide for low-lube operations • Armature plating for solenoid valves • Piston plating for gas meters Limit Values of the Permanent PTFE...

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