Materials:
General description
PTFE (polytetrafluoroethylene) is a polymer with a linear macromolecular structure, made by means of the polymerization of tetrafluoroethylene. PTFE passes into a gel-like state above the melting point of +327 °C. Its high viscosity and shearing sensitivity prevent thermoplastic processing using traditional techniques such as injection moulding and screw extrusion. PTFE is compression moulded at room temperature and then sintered. Due to its unique combination of excellent properties, PTFE can be considered to be a special-grade technical plastic.
The fact that PTFE is made from finely ground powder in a compression and sintering process gives rise to ideal prerequisites for the manufacture of compounds. For this reason, PTFE compounds are usually filled with anorganic fillers such as powdered metal to achieve really specific properties.
The standard blends of PTFE compounds thus have considerable advantages with regard to their mechanothermal behaviour:
• Increased wear resistance
• Lower deformation under load
• Lower linear thermal elongation
• Increased thermal conductivity
Mechanical engineering
Thanks to its anti-friction and sliding properties, PTFE – usually filled – is primarily used for bushings, plain bearings, slideway strips, piston rings for non-lubricated compressors, poppet valves, and sealing elements.
Application example:
Valve seats
Valves seats made from PTFE 207 are characterized by their impermeability, excellent
dimensional stability, and low wear rate in steam and hot air applications.
General description
PEEK is a semi-crystalline thermoplastic which has practically all of the properties expected of a high-performance plastic. It is ideal for applications requiring high performance in extreme conditions with regard to temperature, chemicals, weather resistance, mechanical properties, abrasion resistance, resistance to high- energy radiation, and flame-retardant behaviour, etc. Along with its modified types, PEEK forms a unique group of materials for challenging applications.
Characteristics and properties
• Very high maximum service temperature limit in air (long-term exposure to +250 °C, short-term exposure to +310 °C)
• High mechanical strength, rigidity, and hardness, even at high temperatures
• Exceptional resistance to chemicals and hydrolysis
• Exceptional wear resistance and good sliding properties (particularly in the case of types containing CF and CF + PTFE + graphite)
• Very high dimensional stability
• Inherent flame-retardant behaviour and very low smoke development in the case of a fire
• Good electrical insulation properties and favourable dielectric behaviour (this does not apply to the types with added graphite and carbon fibres)
Range of applications and application examples
Pump wearing rings
Wearing rings made from PEEK + 30% CF in centrifugal pumps allow more narrow running tolerances, which increases efficiency. In addition, corrosion, pitting, and wear problems are eliminated.
Bearing bushings, bearings, seals, and retaining rings
In application scenarios ranging from the aeronautics industry to drilling machines in oil fields, components made from PEEK are used due to improved performance and reliability.
General description
Polyamides are used for a wide range of technical applications which require high toughness, mechanical strength, and good sliding and abrasion behavior. Of particular noteworthy here are construction elements for drives technology such as gear wheels, plain bearings, and idler pulleys.
Characteristics and properties
• High mechanical strength, rigidity, hardness, and toughness
• Good fatigue resistance
• High mechanical damping ability
• Good sliding and emergency running properties
• Very high wear resistance
• Good electrical insulation properties
• Good resistance to high-energy radiation (gamma and X-rays)
• Good machinability
Bearings
PA 6 G SL offers a service life up to 10 times longer than that of an unmodified polyamide 6, e.g. for the pivot bearing bushing of a mining dumper truck.
Rollers, wheels, wearing components
Polyamide offers improved wear protection and better compressive and fatigue strength than other materials for the most diverse of wearing applications.
Wear covers
Wear covers manufactured from PA 6 G SL save on weight and can support heavy loads. They are low- wearing on the mating partner surfaces.
Gear wheels
Gear wheels manufactured from PA 6 G L are significantly quieter and have a longer service life even without additional lubrication.
Nozzles
PA 6 G PLUS can be cast to the specific dimensions required by the customer. This enables a reduction in the production time and costs for applications such as e.g. sealing caps and atomizer nozzles. The new part only weighs a fraction of comparable metallic components, which results in improved, easier handling and lower installation costs.
General description
POM has a combination of higher hardness and dimensional stability while remaining highly impact-resistant. This plastic has a low coefficient of friction, moderate resistance to wear, excellent spring characteristics, high alternating fatigue resistance, good dielectric properties, high dielectric strength, low dielectric loss factor, good chemical resistance – particularly to solvents – and is very resistant to stress cracking.
Characteristics and properties
• High mechanical strength, rigidity, hardness, and toughness
• Very high resilience capacity
• Good creep resistance
• High impact resistance, even at low temperatures
• Very high dimensional stability (low moisture absorption)
• Good sliding properties and wear resistance
• Excellent machinability
• Good electrical insulation properties and favourable dielectric behaviour
• Physiologically safe (suitable for contact with foods)
Bearings and bushings
POM is a good, versatile sliding material which – thanks to its mechanical properties – enables high bearing loads. However, it is not as wear-resistant as e.g. PA or PET-C.
Electrical components
Natural POM-H is used to manufacture complex electrical inspection parts which require dozens of narrowly toleranced longitudinal boreholes. Glass fibre reinforced POM-C is also used for applications which require high rigidity and strength.
Construction parts
POM-C offers exceptional fatigue strength and notched impact resistance properties for construction parts for prosthetic devices which are exposed to sustained loads. Glass fibre reinforced POM-C is used for spring elements, housing parts, snap fits, and levers which require high rigidity and strength.
Gear wheels
Precision parts made from POM remain dimensionally stable regardless of the ambient conditions to which they are exposed.
ATEX
Due to its good electrical conductivity, POM-C EC is a preferred material for this area.
Conformity
POM-H and POM-C are suitable for contact with foodstuffs. POM-C is suitable for contact with water.